Article

Abundance of giant sea anemones and patterns of association with anemonefish in the northern Red Sea

October 2005
Journal of the Marine Biological Association of the UK 85(05):1287 - 1292

October 2005
85(05):1287 - 1292

DOI:10.1017/S0025315405012440

Authors:

Nanette Chadwick

Auburn University

Michael Arvedlund

reef consultants

Patterns of distribution and abundance of giant sea anemones and anemonefish were compared among coral reefs along the coastline of Sinai in the northern Red Sea. The sea anemones varied widely in abundance between reef areas containing different habitat types. They were rare on steep reef slopes with abundant coral cover (=low-density anemone sites, 0.09–0.68 anemones per 1000 m2 of reef area), but were common at a site containing patch reefs interspersed with sand (=high-density anemone site, 6.00–8.11 anemones per 1000 m2). Distributions of the endemic two-band anemonefish (Amphiprion bicinctus) varied significantly between the two main host anemone species. At the high-density site, individuals of the sea anemone Heteractis crispa either did not contain anemonefish, or were occupied by single juvenile fish as shown in previous studies. At low-density sites H. crispa usually hosted clusters of juvenile anemonefish. In contrast, individuals of the sea anemone Entacmaea quadricolor hosted either single adult fish (high-density site) or pairs of breeding adults (low-density sites), frequently in addition to some juvenile fish. Mechanisms that prevent anemonefish from reaching adult size and forming breeding pairs in H. crispa may include high fish mortality above a size threshold because this host cannot adequately protect them from predation when they become large, active emigration of fish to E. quadricolor as described in previous reports, and/or environmentally-controlled cessation of fish growth. We conclude that in the northern Red Sea, individuals of H. crispa potentially serve as nurseries for anemonefish.

Population dynamics of corkscrew sea anemones Bartholomea annulata in the Florida Keys

Article

Mar 2017

Corkscrew sea anemones Bartholomea annulata are important ecologically as hubs of a mutualistic network involving cleaner shrimps and client fishes on Caribbean reefs. They also are collected for the ornamental aquarium trade, but little is known about their population dynamics to support conservation management. We quantified variation in population structure among regions of the Florida Keys and levels of human impact within region. The Upper Keys and lowimpact sites supported higher population abundance and proportions of small anemones than the Lower Keys and high-impact sites. At 2 sites where we monitored anemone dynamics every 2 mo for 1 yr, individuals recruited frequently and grew rapidly to maximum body size and then remained static or shrank. Fewer than half the individuals survived all year, indicating rapid population turnover, with mortality occurring mostly among small individuals or large ones that appeared to senesce beforehand. Stasis of large individuals (or lack thereof) exerted the most influence on population size. We conclude that in Florida, corkscrew anemones experience relatively high recruitment and survival at sites with low human impact and in the Upper Keys, where summer water temperatures are cooler than in the Lower Keys. Populations are highly dynamic and appear to rely on frequent recruitment, potentially linked to the presence of resident adults at high enough abundances for fertilization of broadcast propagules. The ephemeral nature of these anemones has important implications for the dynamics of their anemoneshrimp symbionts, for reef fishes that utilize them as parasite cleaning stations, and for the conservation management of their populations.

Anemonefish musical chairs and the plight of the two-band anemonefish, Amphiprion bicinctus

Article

Full-text available

Nov 2016
ENVIRON BIOL FISH

Anemonefishes’ obligatory mutualism with sea anemones dictates their occurrence in marine habitats. We examined whether the spatial distribution, number, and size of the host anemones Heteractis crispa and Entacmaea quadricolor affected the settlement, habitat usage, and survival of the two-band anemonefish, Amphiprion bicinctus. In a 200 × 50 m study site off the coast of Israel in the Gulf of Eilat, we followed the fish and anemone populations initially in 13 censuses from October 1996 to August 1997 and follow-up censuses from 1998 to 2015. Based on size, anemonefish were categorized as adults, juveniles, or settlers. Settlers tended to cluster together but displayed significantly dispersed distributions in relation to adult individual fish and breeding pairs. Adult and juvenile anemonefish associated more with, and exhibited higher survival in, E. quadricolor. Settlers primarily inhabited H. crispa, with similar survival rates in the two anemone species. H. crispa was less occupied compared to E. quadricolor, but 95 % of the 233 anemones hosted fish during at least one census. From 1997 to 2015, anemone and anemonefish numbers plummeted by 86 % and 74 %, respectively. In 2015, all 27 remaining anemones were occupied, with most E. quadricolor inhabited by adults. The anemones left at the study site, on average, hosted more fish per anemone than those in the original population. This saturated habitat could hinder new anemonefish individuals from settling. These results indicate that if the anemone population does not recover, the anemonefish could face local extinction.

Four dense assemblages of the bulb-tentacle sea anemone Entacmaea quadricolor and associated clownfish in Hong Kong

Article

Feb 2014

Clownfish and their associated sea anemones are icons of tropical and subtropical coastal ecosystems, but bleaching and collecting for the aquarium trade has reduced their population densities in several Indo-Pacific locations. We surveyed four Entacmaea quadricolor populations and their associated clownfish Amphiprion clarkii in Hong Kong. These assemblages represented a combination of exposed and sheltered, flat bottomed and sloped conditions. Different from tropical areas, where E. quadricolor is usually found in sheltered shallow waters, the four populations in Hong Kong were distributed in 4–10 m depths, being densest on a 40 × 80 m slope of volcanic rocks (34.2–76.6% substrate cover and 48.7–102.1 ind m−2) at an exposed site. This distribution pattern could be explained by the high turbidities associated with river discharge and sedimentation rates in local waters, which discourage the establishment of E. quadricolor populations in sheltered bays; shallow habitats might not be suitable for E. quadricolor in Hong Kong due to strong wave actions generated by typhoons. Amphiprion clarkii was present at low densities (0.07–0.26 fish m−2) across the sites. Our data provide a baseline for monitoring the changes of these conspicuous members of shallow water communities in Hong Kong.

Microhabitat use and photoacclimation in the clownfish sea anemone Entacmaea quadricolor

Article

Full-text available

May 2013

Many reef-building corals photoacclimate by increasing levels of chlorophyll per microalgal cell with depth, but mechanisms of photoacclimation in coral reef sea anemones remain poorly understood. We determined variation in ambient irradiance and patterns of abundance, microhabitat use, chlorophyll and microalgal cell concentrations in clownfish sea anemones Entacmaea quadricolor from 0 to 43 m depth on a coral reef at Aqaba, Jordan, northern Red Sea. In shallow areas, anemones occupied shaded reef microhabitats exposed to significantly lower irradiance than in the adjacent open water, but on the deep reef slope they occupied unshaded habitats. Anemone abundances were the highest observed thus far in the Red Sea, and peaked at mid depth on the reef slope. Microalgal abundance in anemone tentacles increased four-fold from the shallow to deep reef, while chlorophyll-a concentrations per algal cell did not vary significantly with depth. We conclude that E. quadricolor photoacclimates using two major mechanisms: (1) occurrence in shaded microhabitats when shallow, thus reducing exposure to high irradiance, and (2) increasing microalgal abundance with depth, thereby enhancing photosynthetic efficiency at low irradiance.

Host preference and habitat segregation among Red Sea anemonefish: Effects of sea anemone traits and fish life stages

Article

Full-text available

Sep 2012

Competition drives habitat segregation between adults and juveniles in many types of organisms, but little is known about this process in anemonefish that compete for host sea anemones which differ in habitat quality. We performed field and laboratory experiments to determine causes of habitat segregation in 2-band anemonefish Amphiprion bicinctus on coral reefs in the northern Red Sea, where juvenile fish mainly occupy leathery sea anemones Heteractis crispa, and breeding adults almost exclusively inhabit bulb-tentacle sea anemones Entacmaea quadricolor. E. quadricolor were usually larger than H. crispa, and expanded more in response to fish presence. Adult fish visually concealed a larger proportion of their body surface area among the relatively thick tentacles of E. quadricolor than among the thinner tentacles of H. crispa, while juveniles were concealed equally well in both hosts. During field experiments, vacated E. quadricolor were colonized rapidly by fish, whereas H. crispa were not. In laboratory choice experiments, fish at all post-settlement life stages preferred E. quadricolor, and large individuals monopolized this host and relegated subordinates to H. crispa. We conclude that competitive exclusion drives habitat segregation among life stages of this anemonefish and that host anemone traits underlie this process. The non-preferred host H. crispa may function as a refuge for juvenile fish while they wait for space to become available in the preferred host E. quadricolor, where they are able to attain sexual maturity.

Abundance and diversity of anemonefishes and their host sea anemones at two mesophotic sites on the Great Barrier Reef, Australia

Article

Full-text available

Dec 2012

Anemonefishes and their host sea anemones are iconic inhabitants of coral reef ecosystems. While studies have documented their abundance in shallow-water reef habitats in parts of the Indo-Pacific, none have examined these species on mesophotic reefs. In this study, we used autonomous underwater vehicle imagery to examine the abundance and diversity of anemones and anemonefishes at Viper Reef and Hydrographers Passage in the central Great Barrier Reef at depths between 50 and 65 m. A total of 37 host sea anemones (31 Entacmaea quadricolor and 6 Heteractis crispa) and 24 anemonefishes (23 Amphiprion akindynos and 1 A. perideraion) were observed. Densities were highest at Viper Reef, with 8.48 E. quadricolor and A. akindynos per 100 m2 of reef substratum. These results support the hypothesis that mesophotic reefs have many species common to shallow-water coral reefs and that many taxa may occur at depths greater than currently recognised.

Nutrient transfer in a marine mutualism: Patterns of ammonia excretion by anemonefish and uptake by giant sea anemones

Article

Full-text available

May 2008

Many symbioses involve multiple partners in complex, multi-level associations, yet little is known concerning patterns of nutrient transfer in multi-level marine mutualisms. We used the anemonefish symbiosis as a model system to create a balance sheet for nitrogen production and transfer within a three-way symbiotic system. We quantified diel patterns in excretion of ammonia by anemonefish and subsequent absorption by host sea anemones and zooxanthellae under laboratory conditions. Rates of ammonia excretion by the anemonefish Amphiprion bicinctus varied from a high of 1.84μmole g−1h−1 at 2h after feeding, to a basal rate of 0.50μmoleg−1h−1 at 24–36h since the last meal. Conversely, host sea anemones Entacmaea quadricolor absorbed ammonia at a rate of 0.10μmole g−1h−1 during the daytime in ammonia-enriched seawater, but during the night reduced their absorption rate to near zero, indicating that ammonia uptake was driven by zooxanthella photosynthesis. When incubated together, net ammonia excretion was virturally zero, indicating that host anemones absorbed most of the ammonia produced by resident fish. Adult anemonefish weighed about 11g under laboratory conditions, but on the coral reef may reach up to 64g, resulting in a maximal potential ammonia load of >200μmoleh−1 produced by two adult fish during daylight hours. In contrast, host sea anemones weighed about 47g in the laboratory, but under field conditions, large individuals may reach 680g, so their maximal ammonia clearance rates may reach about 70μmoleh−1 during the daytime. As such, the ammonia load produced by adult anemonefish far exceeds the clearance rate of host anemones and zooxanthellae. Ammonia transfer likely occurs mainly during the daytime, when anemonefish consume zooplankton and excrete rapidly, and in turn the zooxanthellae are photosynthetically active and drive rapid ammonia uptake. We conclude that zooplanktivorous fishes that form mutualisms with coral reef cnidarians may serve as an important link between open water and benthic ecosystems, through the transfer of large quantities of nutrients to zooxanthellate hosts, thus enhancing coral reef productivity.

Clownfish hosting anemones (Anthozoa, Actiniaria) of the Red Sea: new associations and distributions, historical misidentifications, and morphological variability

Article

Full-text available

Dec 2021

Background The Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region. We sought to clarify a historical record and recent literature sources that disagree on the diversity of host anemone species in the Red Sea, which contains one endemic anemonefish, Amphiprion bicinctus Rüppell 1830. Results We conducted 73 surveys spanning ~ 1600 km of coastline from the northern Saudi Arabian Red Sea to the Gulf of Aden and encountered seven species of host anemones, six of which hosted A. bicinctus. We revise the list of symbionts for A. bicinctus to include Stichodactyla haddoni (Saville-Kent, 1893) and Stichodactyla mertensii Brandt, 1835 which were both observed in multiple regions. We describe Red Sea phenotypic variability in Heteractis crispa (Hemprich & Ehrenberg in Ehrenberg, 1834) and Heteractis aurora (Quoy & Gaimard, 1833), which may indicate that these species hybridize in this region. We did not encounter Stichodactyla gigantea (Forsskål, 1775), although the Red Sea is the type locality for this species. Further, a thorough review of peer-reviewed literature, occurrence records, and misidentified basis of record reports dating back to the early twentieth century indicate that it is unlikely that S. gigantea occurs in the Red Sea. Conclusions In sum, we present a new guide for the host anemones of the Red Sea, revise the host specificity of A. bicinctus, and question whether S. gigantea occurs in the central and western Indian Ocean.

Sea Anemones and Anemonefish: A Match Made in Heaven

Chapter

Full-text available

Sep 2016

Sea anemones are amongst the most venomous organisms on earth and yet there are species of fish and crustacea that are known to tolerate anemone venoms and live in association with them in a mutually beneficial relationship. One of natures most compelling displays of symbiotic behavior is found in the relationship between anemonefish and their sea anemone host. This relationship was first described more than a century ago and despite it being widely studied since, our understanding of the evolution of the relationship and the mechanisms and behaviors involved remains shrouded in mystery. Anemonefish (Family: Pomacentridae) comprise of a distinct group of 28 species that are able to live within sea anemones. Despite the large diversity of anemones in the tropics, only ten species are suitable as hosts for anemonefish. Within these species, only certain pairs of anemone and anemonefish are compatible and found in the wild together. This relationship is obligatory for the fish and in some cases for the anemone, meaning that the symbionts are entirely or heavily dependent on each other for survival. Symbioses between the two groups provide the following benefits: mutual protection from predators, an exchange of nutrients, improved reproductive and lifetime fitness. While past studies have explored the different patterns of host species that fish use and multiple authors have examined the mechanisms involved in protecting fish from anemone venom, how fish acquire immunity from the anemone’s stinging tentacles and why only certain anemone species are found associated with some anemonefish more often than others still remains uncertain.

Measuring Body Size in Small Marine Fishes: A Comparison of Three Non-intrusive Methods Measuring Body Size in Small Marine Fishes: A Comparison of Three Non-intrusive Methods

Article

Full-text available

May 2013

Studies of non-intrusive techniques are important in fisheries biology, because research methods may inadvertently cause damage to the study organisms. In addition, current effects of human–environment interactions coupled with future trends in global climate change likely will lead to increased monitoring of fish population dynamics. The aim of this study is to analyze the effectiveness of three simple non-intrusive techniques to accurately obtain body length measurements of anemonefish and other small fishes. Frequently used catch and recapture methods are stressful to fishes, and can alter their behaviors upon release, thus negatively impacting field ecological studies. Alternate methods to non-intrusive sizing of reef fishes are needed, and these methods should be compared to determine the most effective and efficient means of collecting the targeted data. Three non-intrusive techniques were employed to obtain accurate fork length (FL) measurements of the two-band anemonefish, Amphiprion bicinctus. Comparison of these methods revealed that fish lengths from visual estimates by self-contained under water breathing apparatus (SCUBA) divers did not differ significantly from those estimated using both video-mirror and Tps-mirror techniques (ANOVA, F(2,60) 5 1.572; p 5 0.22). Under laboratory conditions, fish sizes from manual measurements also did not differ significantly from those obtained using either mirror method (ANOVA, F(2,81) 5 0.489; p 5 0.61), demonstrating that the mirror techniques accurately assess fish size under both laboratory and field conditions. These methods were not effective in identifying or tracking individual fish among years in the field, due to high rates of fish mobility and turnover. However, they were useful in determining short-term anemonefish migration among sea anemone hosts.

Ammonia flux, physiological parameters, and Symbiodinium diversity in the anemonefish symbiosis on Red Sea coral reefs

Article

Full-text available

May 2011
SYMBIOSIS

Despite the ecological importance of anemonefish symbioses, little is known about how nutritional contributions from anemonefish interact with sea anemone physiology and Symbiodinium (endosymbiotic dinoflagellate) genetic identity under field conditions. On Red Sea coral reefs, we measured variation in ammonia concentrations near anemones, excretion rates of anemonefish, physiological parameters of anemones and Symbiodinium, and genetic identity of Symbiodinium within anemones. Ammonia concentrations among anemone tentacles were up to 49% above background levels, and anemonefish excreted ammonia significantly more rapidly after diurnal feeding than they did after nocturnal rest, similar to their excretion patterns under laboratory conditions. Levels of 4 physiological parameters (anemone protein content, and Symbiodinium abundance, chlorophyll a concentration, and division rate) were similar to those known for laboratory-cultured anemones, and in the field did not depend on the number of anemonefish per anemone or depth below sea surface. Symbiodinium abundance varied significantly with irradiance in the shaded reef microhabitats occupied by anemones. Most anemones at all depths harbored a novel Symbiodinium 18S rDNA variant within internal transcribed spacer region 2 (ITS2) type C1, while the rest hosted known ITS2 type C1. Association with Symbiodinium Clade C is consistent with the symbiotic pattern of these anemones on other Indo-Pacific reefs, but the C1 variant of Symbiodinium identified here has not been described previously. We conclude that in the field, anemonefish excrete ammonia at rapid rates that correlate with elevated concentrations among host anemone tentacles. Limited natural variation in anemonefish abundance may contribute to consistently high levels of physiological parameters in both anemones and Symbiodinium, in contrast to laboratory manipulations where removal of fish causes anemones to shrink and Symbiodinium to become less abundant.

Benefits to host sea anemones from ammonia contributions of resident anemonefish

Article

Mar 2009
J EXP MAR BIOL ECOL

Large ectosymbionts (especially fishes and crustaceans) may have major impacts on the physiology of host cnidarians (sea anemones and corals), but these effects have not been well quantified. Here we describe impacts on giant sea anemone hosts (Entacmaea quadricolor) and their endosymbiotic zooxanthellae (Symbiodinium spp.) from the excretion products of anemonefish guests (Amphiprion bicinctus) under laboratory conditions. Starved host anemones were maintained with anemonefish, ammonia supplements (= NH3 gas and NH4+ ion), or neither for 2 mo. In the presence of external ammonia supplements or resident anemonefish, the zooxanthellae within host anemones increased in abundance (173% and 139% respectively), and provided the hosts with energy that minimized host body size loss. In contrast, anemones cultured with neither ammonia nor anemonefish harbored significantly lower abundances of zooxanthellae (84% of initial abundance) and decreased > 60% in body size. Although they maintained higher zooxanthella abundances, anemones cultured with either ammonia supplements or resident anemonefish exhibited significantly lower ammonia uptake rates (0.065 ± 0.005 µmol g- 1 h- 1, and 0.052 ± 0.018 µmol g- 1 h- 1 respectively) than did control anemones (0.119 ± 0.009 µmol g- 1 h- 1), indicating that their zooxanthellae were more nitrogen sufficient. We conclude that, in this multi-level mutualism, ammonia supplements provide essentially the same level of physiological contribution to host anemones and zooxanthellae as do live resident fish. This nutrient supplement reduces the dependence of the zooxanthellae on host feeding, and allows them to provide abundant photosynthetically-produced energy to the host.

Parental and environmental determinants of larval dispersal-associated traits and post-settlement physiology

Thesis

Mar 2021

Daphne Cortese

Environmental changes induced by human activities impact marine and terrestrial ecosystems worldwide. While facing these perturbations, species may respond in a variety of ways, including migration to a more suitable habitat via dispersal, acclimation via phenotypic plasticity or adaptation via genetic changes. The main opportunity for dispersal in sedentary marine organisms such as coral reef fish is the pelagic larval phase, during which larvae journey in open water before settling onto a suitable habitat. Marine larval dispersal depends on physical factors, such as ocean currents, but is also largely determined by biological larval traits, such as physiology, behaviour and morphology. However, in which way offspring traits associated to dispersal are influenced by either their local environment or their parental legacy, remains less well studied. After larval settlement, phenotypes can still be affected by environmental stressors and thus it is vital to also understand their ability to acclimate to environmental stressors induced by human activities. To answer these questions, I used the orange fin anemonefish Amphiprion chrysopterus as a model species and combined in situ and laboratory analyses. First, by using laboratory reared larvae of wild spawned eggs I explored the influence of maternal size on dispersal-associated traits throughout ontogeny (swimming performance and body size) and demonstrated that larger mothers produce larvae that swim faster (Chapter 2). Then, I investigated how anemonefish parental environmental conditions, such as anemone habitat size (proxy of habitat quality and degradation) affect offspring phenotype (i.e. egg size, larval size and larval swimming performance) and found that parents living in larger habitats produce larger eggs (Chapter 3). In addition, I explored the transgenerational and developmental effects of water flow regimes on larval and juvenile morphology, physiology and survival. Results show that early life survival can be affected by the water flow regime that their parents live in, suggesting differential investment (Chapter 4). In the last part of the thesis I focused on the direct effects of chronic exposure to environmental stressors, such as anemone bleaching (Chapter 5) and artificial light at night (ALAN, Chapter 6) on juvenile A. chrysopterus phenotypes and survival in the wild. I demonstrated that anemone bleaching affects the physiology and behaviour of fish and that both bleaching and ALAN reduce fish growth but not survival, suggesting that wild fish may trade-off growth with survival, even though reduced growth at early stages may have life-long fitness effects. The results of this PhD provide a better understanding of the origin of the variability in the factors influencing the dispersal process as well as the post-settlement phenotype in an iconic coral reef fish. This knowledge may help to better predict how fish populations will respond to climate change. Such predictions are key to mitigating the impacts of climate change and improving the conservation strategies, for example by targeting the most important marine areas and fish phenotypes to protect.

Adaptive effects of parental and developmental environments on offspring survival, growth and phenotype

Article

Full-text available

Nov 2022
FUNCT ECOL

Phenotypic adjustments to environmental variation are particularly relevant to cope with putative environmental mismatches often imposed by natal dispersal. We used an intergenerational cross‐transplant field‐based experiment to evaluate the morphological and physiological effects of parental and postsettlement water flow environments on the orange‐fin anemonefish Amphiprion chrysopterus through ontogeny (at pre‐ and postsettlement stages). Offspring born from parents under high water flow had an 18% higher caudal fin aspect ratio (a compound measure of shape) at the presettlement stage, 10% slower growth after settlement, and 55% lower survival after settlement compared to offspring from low water flow parents. At the presettlement stage, caudal fin length was determined by parental caudal fin length. At the postsettlement stage, fish survived equally well with similar phenotypes in both high and low developmental flow environments. However, results suggest potential developmental phenotypic plasticity in caudal fin length, which increases more under low water flow during development. After settlement, growth was the only morphological or physiological trait that was associated with parental water flow, which was lower from parents under high flow, as was survival. These results give important insights into the parental contribution, both genetic and nongenetic, in determining early offspring phenotype and subsequent growth and survival. Our results also suggest that offspring may possess flexibility to cope with a wide range of local environments including those different from their parents. Overall, the findings of this study show the fitness consequences of living in different environments and the likely trade‐offs between parental and offspring fitness in a wild population. Read the free Plain Language Summary for this article on the Journal blog.

Anthropopause positively influenced Red Sea Clownfish (Amphiprion bicinctus) populations but not the host Sea Anemone (Actiniaria spp.) in Eilat, Israel

Article

Sep 2022
MAR POLICY

(Download till 8/11/2022 https://authors.elsevier.com/c/1fnAk_,iw2Hjk7) The anthropopause, when humans were restricted to their homes because of the COVID-19 pandemic, allowed wildlife to reoccupy areas that were previously used by humans. The coral reef at Eilat has been deteriorating for the past 50-years, and includes the sea anemones, that have symbiotic associations with clownfish. The lack of appropriate niches in the form of sea anemones has also resulted in a drastic decline in the endemic Red Sea Clownfish (RSCF). We surveyed 7500 m of the reef to quantify the number of sea anemones and RSCF on five tourist frequented beaches. The pre-pandemic survey was conducted in 2019 and the post-pandemic in 2021. Overall, the average number of sea anemone per sample plot was 0.23/100m (range 0-6); and there was no significant difference between the years. However, the mean number of RSCF per 100 m was 0.15 (range 0-6); and there were significant differences between the years with on average double the individuals in 2021. We found a significant positive correlation between the number of anemones and RSCF recorded on transects. In both years, 50 RSCF were in sea anemones; (78%) adults and 11 (22 %) juveniles. All 38 adults and two juveniles populated the bulb/digitiform-tentacle sea anemones Entacmaea quadricolor, while 9 juveniles were in the leathery anemone Heteractis crispa. Our study demonstrates that the COVID-19 closures for the past two years were conducive to the RSCF and resulted in an increase in their numbers.

Bleaching Susceptibility and Resistance of Octocorals and Anemones at the World’s Southern-Most Coral Reef

Article

Full-text available

May 2022

Coral reefs are amongst the most biodiverse ecosystems on earth, and while stony corals create the foundational complexity of these ecosystems, octocorals and anemones contribute significantly to their biodiversity and function. Like stony corals, many octocorals contain Symbiodiniaceae endosymbionts and can bleach when temperatures exceed the species’ upper thermal limit. Here, we report octocoral bleaching susceptibility and resistance within the subtropical Lord Howe Island coral reef ecosystem during and after marine heatwaves in 2019. Octocoral and anemone surveys were conducted at multiple reef locations within the Lord Howe Island lagoon during, immediately after, and 7 months after the heatwaves. One octocoral species, Cladiella sp. 1, experienced bleaching and mortality, with some bleached colonies detaching from the reef structure during the heatwave (presumed dead). Those that remained attached to the benthos survived the event and recovered endosymbionts within 7 months of bleaching. Cladiella sp. 1 Symbiodiniaceae density (in cells per µg protein), chlorophyll a and c 2 per µg protein, and photosynthetic efficiency were significantly lower in bleached colonies compared to unbleached colonies, while chlorophyll a and c 2 per symbiont were higher. Interestingly, no other symbiotic octocoral species of the Lord Howe Island lagoonal reef bleached. Unbleached Xenia cf crassa colonies had higher Symbiodiniaceae and chlorophyll densities during the marine heatwave compared to other monitoring intervals, while Cladiella sp. 2 densities did not change substantially through time. Previous work on octocoral bleaching has focused primarily on gorgonian octocorals, while this study provides insight into bleaching variability in other octocoral groups. The study also provides further evidence that octocorals may be generally more resistant to bleaching than stony corals in many, but not all, reef ecosystems. Responses to marine heating events vary and should be assessed on a species by species basis.

Habitat limits the poleward establishment of anemonefishes in a climate change hotspot

Article

Nov 2021
ESTUAR COAST SHELF S

Climate change is modifying marine species' distribution with consequences for the structure and function of ecosystems. The warming and strengthening East Australian Current (EAC) is driving the tropicalisation of subtropical marine ecosystems through changing overwinter survival of tropical species. However, this can be complex for obligate symbionts, such as anemonefishes. Here, we documented fine-scale temporal changes in the density of anemonefishes and assessed the influence of latitude, temperature, and the availability of host sea anemones. Juvenile, subadult and adult Amphiprion akindynos and A. latezonatus occurred at all study locations: North Solitary Island (equatorward), South Solitary Island, and Fish Rock (poleward). While the sea anemone Heteractis crispa was readily available at Fish Rock, we found that a lack of another sea anemone Entacmaea quadricolor hindered the establishment of adult A. akindynos and A. latezonatus populations. Minimum water temperature was also a bottleneck for the tropical anemonefish A. akindynos, but not for the subtropical A. latezonatus. Our findings suggest anemonefishes are capable of contributing to the tropicalisation of the east coast of Australia. However, poleward establishment is currently limited by the absence of the preferred host sea anemone.

Climate Change Leads to a Reduction in Symbiotic Derived Cnidarian Biodiversity on Coral Reefs

Article

Full-text available

Mar 2021

Symbiotic relationships enable partners to thrive and survive in habitats where they would either not be as successful, or potentially not exist, without the symbiosis. The coral reef ecosystem, and its immense biodiversity, relies on the symbioses between cnidarians (e.g., scleractinian corals, octocorals, sea anemones, jellyfish) and multiple organisms including dinoflagellate algae (family Symbiodiniaceae), bivalves, crabs, shrimps, and fishes. In this review, we discuss the ramifications of whether coral reef cnidarian symbioses are obligatory, whereby at least one of the partners must be in the symbiosis in order to survive or are facultative. Furthermore, we cover the consequences of cnidarian symbioses exhibiting partner flexibility or fidelity. Fidelity, where a symbiotic partner can only engage in symbiosis with a subset of partners, may be absolute or context dependent. Current literature demonstrates that many cnidarian symbioses are highly obligative and appear to exhibit absolute fidelity. Consequently, for many coral reef cnidarian symbioses, surviving changing environmental conditions will depend on the robustness and potential plasticity of the existing host-symbiont(s) combination. If environmental conditions detrimentally affect even one component of this symbiotic consortium, it may lead to a cascade effect and the collapse of the entire symbiosis. Symbiosis is at the heart of the coral reef ecosystem, its existence, and its high biodiversity. Climate change may cause the demise of some of the cnidarian symbioses, leading to subsequent reduction in biodiversity on coral reefs.

Keep your friends close and your anemones closer – ecology of the endemic wideband anemonefish, Amphiprion latezonatus

Article

Full-text available

Dec 2020
ENVIRON BIOL FISH

Endemic marine species often exist as metapopulations distributed across several discrete locations, such that their extinction risk is dependent upon population dynamics and persistence at each location. The anemonefish Amphiprion latezonatus is a habitat specialist, endemic to two oceanic islands (Lord Howe and Norfolk) and the adjacent eastern Australian coast from the Sunshine Coast to Southwest Rocks. To determine how extinction risk varies across the limited number of locations where A. latezonatus occurs, we quantified ecological, biological, and behavioural characteristics at six locations and four reef zones. The abundance of A. latezonatus and its host anemones varied considerably throughout its range, with A. latezonatus abundance being very low at Sunshine Coast and Elizabeth Reef, low at Lord Howe Island and Norfolk Island, and moderate at North Solitary Island. This species was not detected at Middleton Reef, despite local abundance of their host anemones. Abundance of A. latezonatus was generally correlated with depth and host anemone abundance, from which we infer that extirpation risk is directly proportional to their host anemone population’s size. Consistent with this, A. latezonatus social group size was positively correlated with the number of anemones inhabited. A. latezonatus may be impacted by interactions and competition with other anemonefish species in shallow (< 10 m) waters, but competition has little effect in deeper water where population abundances are highest. Significant differences in population characteristics demonstrate a need for location-specific conservation strategies and identify the Sunshine Coast population as most vulnerable.

Patterns of coexistence of six anemonefish species around subtropical Okinawa-jima Island, Japan

Article

Full-text available

Dec 2018
CORAL REEFS

The species diversity of anemonefish in tropical regions has been explained by the niche differentiation hypothesis or cohabitation hypothesis. However, anemonefish community structure has seldom been investigated in high-latitude areas. To understand the mechanism underlying species diversity of anemonefish in the northern limits of their distribution and to compare with previous results from tropical and other areas, we investigated the community structure of anemonefish around the western coast of Okinawa-jima Island, Japan. Seven species of host anemones and six species of anemonefish were distributed across the 12 study sites. The diversity index of anemonefish and the host anemone varied among sites; anemonefish diversity increased with diversity of host anemones, which was associated with the ratio of sandy areas and distance from shore. The density of each species of anemonefish increased with the density of the primary host anemone, which suggests that niche differentiation may be occurring. However, results of two species of host anemone (Stichodactyla mertensii, Heteractis magnifica) associated each with two species of anemonefish did not support the niche differentiation hypothesis. Forty-seven percent of S. mertensii were shared by Amphiprion clarkii and A. sandaracinos simultaneously, supporting the cohabitation hypothesis. Amphiprion ocellaris and A. perideraion used the same host H. magnifica, but never shared a host simultaneously. Moreover, anemone size and water depth did not differ between the two anemonefish species, suggesting the possibility of the lottery model. In subtropical Okinawa, 86.7% of species interactions supported the niche differentiation hypothesis, 6.7% supported the cohabitation hypothesis, and 6.7% supported the lottery hypothesis. The mechanisms of coexistence of anemonefish in subtropical regions include not only niche differentiation and cohabitation but also the lottery hypothesis, which has not been reported in tropical regions.

Giant ephemeral anemones? Rapid growth and high mortality of corkscrew sea anemones Bartholomea annulata (Le Sueur, 1817) under variable conditions

Article

Full-text available

Oct 2018
J EXP MAR BIOL ECOL

In shelter symbioses, the recruitment, growth, and lifespan of host organisms influence the life history characteristics of symbiotic guests. Corkscrew sea anemones Bartholomea annulata (Le Sueur, 1817) host diverse crustacean ectosymbionts in the Tropical Western Atlantic, some of which are cleaner shrimps that attract and clean Caribbean reef fishes. These sea anemones potentially function as short-lived cleaning stations due to their high mortality and short lifespans relative to that of many reef fishes. A combination of methods (field monitoring , population modeling, manipulative field experiments) was applied to quantify variation in rates of recruitment , growth, shrinkage, and mortality of this anemone. Population projections at reef sites on St. Thomas, U. S. Virgin Islands, indicated that the most important contributors to population growth were the recruitment and fate of the smallest individuals. Field experiments revealed that recruitment and growth varied significantly with reef site, but that lifespan did not. Population modeling demonstrated effects of body size and habitat on life history traits, with smaller anemones growing faster than large ones, and both very large and small individuals dying more frequently than medium-sized ones. The combined data reveal that B. annulata is among the shortest-lived sea anemones, with most individuals surviving < 12 months, and maximum lifespan of only ~1.5-2 years at all examined sites. Together, these patterns suggest that this anemone exhibits characteristics of a weedy species; individuals grow and reach adult body size rapidly and populations have rapid turnover. Life history and recruitment data for crustacean symbionts of B. annulata indicate that this host may be long-lived enough to mediate multiple generations of crustacean associates, fulfilling the expectations of an evolutionarily stable host. The short lifespan of these anemones relative to those of many reef fishes may cause fishes to search frequently for new cleaning stations on Caribbean coral reefs.

The survival and growth rate of three species of sea Anemones from Asexsual reproduction in Pulau Kerumputan and Pulau Karayaan, Indonesia

Article

Full-text available

Jan 2016

A sea anemone is one kind of marine biota whose habitat is found in the coral reef area. Sea anemones have quite high ecological and economical value. Currently, the population keeps on being degraded due to the high intensity of fish catching to meet the demand from domestic market and exports. Therefore, it is necessary of undertake restocking efforts and environment-friendly aquaculture using the seeds of asexual reproduction results in the hatchery. The purpose of this study is to find out the survival and growth rate of three species of sea anemones, namely Stichodactyla gigantea, Entacmaea quadricolor, and Macrodactyla doreensis are cultured in the water of the islands of Kerumputan and Kerayaan, Indonesia, for 4 months, from June - September 2015. The seeds used are from the result of asexual reproduction of a sea anemone with longitudinal body cleavage techniques, from all three parents. The results showed that asexual technology of seeds reproduction are able to produce the survival and growth rate quite well when they are cultivated in natural water. The three species of anemones had different survival and growth rate. The anemones, S. gigantea and E. quadricolor, had the highest survival and growth rate, whereas anemone of M. doreensis had the lowest survival and growth rate. The survival and growth rate of anemones among cultivation sites had no difference at all species of anemones.

Corals

Chapter

Full-text available

Feb 2017

Coral reef degradation worldwide and the concomitant increasing demand for corals to supply the marine ornamental trade have been driving the growing interest for coral aquaculture. Captive breeding and propagation of corals among aquarium hobbyists and public aquariums is a well-known and established activity. In contrast, the scientific community has poorly explored coral production methods. Nevertheless, research on coral biology has dramatically increased in the past decades and resulted in numerous scientific studies that are highly relevant to further advance coral aquaculture. Here we provide an overview of coral aquaculture with particular emphasis on ex situ production methods. A comprehensive review of current asexual and sexual propagation techniques is provided, together with qualitative aspects of corals, such as coral shape and coloration, and quantitative production parameters, such as growth and volumetric productivity. Finally, we thoroughly discuss how the manipulation of abiotic and biotic conditions can maximize coral quality and volumetric productivity.

Anemonefish personalities influence the strength of mutualistic interactions with host sea anemones

Article

Full-text available

Dec 2016
MAR BIOL

The anemone–anemonefish mutualism is one of the most iconic marine mutualisms. For decades, anemonefishes have been known to protect anemones from predators, while anemones provide safe havens for anemonefishes. More recently, it has been suggested that the number of anemonefish influences the survival, growth, and asexual reproduction of anemones. Here, we build on those findings, investigating the effect of four variables (fish number, fish biomass, fish shyness, and anemone colony area), on anemone growth and asexual reproduction. The interaction between Amphiprion percula and Entacmaea quadricolor was used as a tractable system in a controlled aquarium setting. Fish and anemones were monitored in 60 tanks for 18 months, and we recorded all variables at 6-month intervals. We performed single-measure analyses and found that fish shyness, defined as the time spent in the vicinity of the anemone, significantly predicts anemone growth over the entire experiment. Further, we performed repeated-measure analyses and found that both fish shyness and initial anemone colony area significantly predict anemone growth per time period. These data suggest that behavioral variation among individual fish may be an important driver of anemone growth. More generally, this study highlights the importance of behavioral traits in mediating the strength of interspecific interactions such as mutualisms and suggests that such effects should be accounted for when investigating the dynamics of interacting populations.

The abundance and size of giant sea anemones at different depths in the waters of Teluk Tamiang village, south Kalimantan, Indonesia

Article

Full-text available

Jun 2016

Muhammad Ahsin Rifa'i

The depth of waters has a close correlation with intensity of sunlight and waters’ temperature. The deeper the waters from the surface, the less light intensity be received. As a result, temperature also decreases at the deeper layer. This certainly gives effect on the abundance and the body size of giant sea anemones. The purpose of this study is to find out the relationship of the depth of waters to the distribution of abundance and body size of the giant sea anemones in the waters of Teluk Tamiang village, south Kalimantan, Indonesia. Study sites were divided into five stations: three stations in the western part of the waters and two stations in the eastern part of the waters of Teluk Tamiang. Each station was subdivided into three depths: 0-2 m, > 2-4 m, and > 4-6 m. Data of relative abundance and body size of giant sea anemones at different depths were analyzed using Kruskal Wallis test. Distribution of abundance and body size of giant sea anemones based on depths was analyzed using Correspondence Analysis. The results showed that there were three species of giant sea anemones found, namely Stichodactyla gigantea, Entacmaea quadricolor and Heteractis crispa. The abundance and body size of S. gigantea were higher than those of E. quadricolor and H. crispa. However, the distribution of abundance and body size anemones had no significant difference among the depths of waters.

Reef fishes can recognize bleached habitat during settlement: Sea anemone bleaching alters anemonefish host selection

Article

Full-text available

May 2016
Proc Biol Sci

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in pairedchoice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. © 2016 The Author(s) Published by the Royal Society. All rights reserved.

Anemonefish oxygenate their anemone hosts at night (vol 216, pg 970, 2013)

Article

Full-text available

Apr 2013

Seasonal gametogenesis of host sea anemone (Entacmaea quadricolor) inhabiting Hong Kong waters

Article

Full-text available

Feb 2015

Studying gonadal development of annual cycle can reveal the process of gametogenesis and reproductive period, and evaluate fertility and source utilization of a species. Host sea anemones are conspicuous members of tropical and subtropical reef ecosystems, but little is known about its biology including reproductive seasonality. Here we reported a one-year study on the gametogenesis and reproduction of host sea anemone (Entacmaea quadricolor) inhabiting Hong Kong waters. E. quadricolor tissues were sampled in 12 occasions from 5 m and 15 m depths of water, respectively. Histological sectioning of the tissues showed that E. quadricolor was dioecious, and populational ratio of female to male was 1:1.6. The gonadal development was asynchronous within an annual cycle, which included proliferating, growing, maturing, spawning, and resting stages. The spawning occurred between August and October when surface seawater temperature reached the annual maximum (28°C), suggesting that temperature is an important factor modulating the gonadal development and mature of E. quadricolor.

Searching for a Toxic Key to Unlock the Mystery of Anemonefish and Anemone Symbiosis

Article

Full-text available

May 2014
PLOS ONE

Twenty-six species of anemonefish of the genera Amphiprion and monospecific Premnas, use only 10 species of anemones as hosts in the wild (Families: Actiniidae, Stichodactylidae and Thalassianthidae). Of these 10 anemone species some are used by multiple species of anemonefish while others have only a single anemonefish symbiont. Past studies have explored the different patterns of usage between anemonefish species and anemone species; however the evolution of this relationship remains unknown and has been little studied over the past decade. Here we reopen the case, comparing the toxicity of crude venoms obtained from anemones that host anemonefish as a way to investigate why some anemone species are used as a host more than others. Specifically, for each anemone species we investigated acute toxicity using Artemia francisca (LC50), haemolytic toxicity using ovine erythrocytes (EC50) and neurotoxicity using shore crabs (Ozius truncatus). We found that haemolytic and neurotoxic activity varied among host anemone species. Generally anemone species that displayed greater haemolytic activity also displayed high neurotoxic activity and tend to be more toxic on average as indicated by acute lethality analysis. An overall venom toxicity ranking for each anemone species was compared with the number of anemonefish species that are known to associate with each anemone species in the wild. Interestingly, anemones with intermediate toxicity had the highest number of anemonefish associates, whereas anemones with either very low or very high toxicity had the fewest anemonefish associates. These data demonstrate that variation in toxicity among host anemone species may be important in the establishment and maintenance of anemonefish anemone symbiosis.

Spatial distribution of fifty ornamental fish species on coral reefs in the Red Sea and Gulf of Aden

Article

Full-text available

Jan 2014

The spatial distribution of 50 ornamental fish species from shallow water habitats on coral reefs were investigated using visual census techniques, between latitudes 11-29°N in the Red Sea, in Jordan, Egypt, Saudi Arabia, and Yemen, and in the adjacent Gulf of Aden in Djibouti. One hundred eighteen transects (each 100×5 m) were examined in 29 sites (3-8 sites per country). A total of 522,523 fish individuals were counted during this survey, with mean abundance of 4428.2 ± 87.26 individual per 500 m² transect. In terms of relative abundance (RA), the most abundant species were Blue green damselfish, Chromis viridis (RA=54.4%),followed bySea goldie, Pseudanthias squamipinnis (RA= 34.7), Whitetail dascyllus, Dascyllus aruanus (RA= 2.6%), Marginate dascyllus, Dascyllus marginatus (RA= 2.0),Red Sea eightline flasher Paracheilinus octotaenia (RA=1.0),andKlunzinger's wrasse, Thalassoma rueppellii (0.7%). The highest number of species (S) per 500 m² transect was found on reefs at the latitude 20° in Saudi Arabia (S=21.8), and the lowest number of species was found at the latitude 15° in Djibouti (S=11.11). The highest mean abundance (8565.8) was found on reefs at latitude 20° in Saudi Arabia and the lowest mean abundance (230) was found on reefs at latitude 22°, also in Saudi Arabia. Whereas, the highest Shannon-Wiener Diversity Index was found in reefs at the latitude 22° (H`=2.4) and the lowest was found in reefs at the latitude 20° (H`=0.6). This study revealed marked differences in the structure of ornamental fish assemblages with latitudinal distribution. The data support the presence of two major biogeographic groups of fishes in the Red Sea and Gulf of Aden: the southern Red Sea and Gulf of Aden group and the group in the northern and central Red Sea. Strong correlations were found between live coral cover and the number of fish species, abundance and Shannon-Wiener Diversity indices, and the strength of these correlations varied among the reefs. A conclusion was done that environmental differences among the reefs and the habitats investigated were important components of abundance variations and species diversity of ornamental fish along latitudinal gradients in the Red Sea and the Gulf of Aden.

Ecological Studies on Two Amphiprion Species in Maldivian Coral Reefs

Article

Full-text available

Jun 2008
Open Fish Sci J

Robert A. Patzner

Amphiprion clarkii and A. nigripes were found in coral reefs of three different atolls in the Maldives. A. clarkii was associated with five species of host anemones, but A. nigripes was only found in Heteractis magnifica. In few cases, both anemonefishes have utilized the same individual of H. magnifica. There was no significant correlation between the size of the anemones and the number of the inside living Amphiprion.

Anemonefish oxygenate their anemone hosts at night

Article

Full-text available

Mar 2013
J EXP BIOL

Many stony coral-dwelling fishes exhibit adaptations to deal with hypoxia among the branches of their hosts; however, no information exists on the respiratory ecophysiology of obligate fish associates of non-coral organisms such as sea anemones and sponges. This study investigated metabolic and behavioral interactions between two-band anemonefish (Amphiprion bicinctus) and bulb-tentacle sea anemones (Entacmaea quadricolor) at night. We measured the net dark oxygen uptake ( , μmol O h) of fish-anemone pairs when partners were separate from each other, together as a unit, and together as a unit but separated by a mesh screen that prevented physical contact. We also measured the effects of water current on sea anemone and quantified the nocturnal behaviors of fish in the absence and presence of host anemones in order to discern the impacts of anemone presence on fish behavior. Net of united pairs was significantly higher than that of both separated pairs and united pairs that were separated by a mesh screen. Anemone increased with flow rate from 0.5 to 2.0 cm s, after which remained constant up to a water flow rate of 8.0 cm s. Furthermore, the percentage time and bout frequency of flow-modulating behaviors by fish increased significantly when anemones were present. We conclude that physical contact between anemonefish and sea anemones elevates the of at least one of the partners at night, and anemonefish behavior at night appears to oxygenate sea anemone hosts and to augment the metabolism of both partners.

Embryology and early ontogeny of an anemonefish Amphiprion ocellaris

Article

Aug 2007
J MAR BIOL ASSOC UK

The present study describes the embryonic development and early ontogeny of Amphiprion ocellaris from fertilization to post hatching. Anemonefish spontaneously spawned at 27–28°C. The newly laid eggs were orange in colour and elliptical in shape (1.8×0.8 mm). Melanin appeared as a black mass situated at the vegetal pole in mature eggs. This is rarely seen in eggs of other fish species. We documented developmental times at 27–28°C to egg activation (0.5 h), cleavage (4 h), blastula (11.5 h), gastrula (20 h), neurula (24.5 h), somite (28.5 h), turnover (72 h), blood formation (113 h) and internal ear and jaw formation (144 h). Hatching occurred 152 h after fertilization. On day 4, the eye buds were pigmented and melanophores formed on the ventral surface of the embryo. Internal ear and gill formation were completed on day 5 and coincided with movement of the opercula and pectoral fins. The mouth formed on day 6 and the digestive tract appeared on day 7. By day 10, the yolk was fully absorbed and a substantial amount of food was observed in the gut. Dark and orange pigments were dispersed and aggregated through muscle contractions by day 14, but red pigments did not appear until the fish were three months old. This study contributes to a further understanding of the embryology and the early ontogeny of damselfish and may help improve the culture of coral reef fish.

Finding NEMO – Nestedness Engendered by Mutualistic Organisation in anemonefish and their hosts

Article

Full-text available

Nov 2006
Proc Biol Sci

The interaction structure of mutualistic relationships, in terms of relative specialization of the partners, is important to understanding their ecology and evolution. Analyses of the mutualistic interaction between anemonefish and their host sea anemones show that the relationship is highly nested in structure, generalist species interacting with one another and specialist species interacting mainly with generalists. This supports the hypothesis that the configuration of mutualistic interactions will tend towards nestedness. In this case, the structure of the interaction is at a much larger scale than previously hypothesized, across more than 180 degrees of longitude and some 60 degrees of latitude, probably owing to the pelagic dispersal capabilities of these species in a marine environment. Additionally, we found weak support for the hypothesis that geographically widespread species should be more generalized in their interactions than species with small ranges. This study extends understanding of the structure of mutualistic relationships into previously unexplored taxonomic and physical realms, and suggests how nestedness analysis can be applied to the conservation of obligate species interactions.

Cohabitation and Competition in Anemonefishes

Chapter

Full-text available

Sep 2022

Assessment of benthic and coral community structure in an inshore reef in Balok, Pahang, Malaysia

Article

Full-text available

Mar 2019

Inshore water reef closer to human activities are often neglected since they are not protected by marine park management. Little is known on how this reef responses to challenging environment in terms of abundance, diversity and benthic community composition. This study provides a quantitative assessment on the benthic community composition at 5 reef sites in Balok, Pahang, Malaysia and observed the ecological adaptation in the reef community towards turbid water environment. Balok reef has 39% overall coral cover with very low macroalgae abundance (4%). A total of 28 coral genera from 12 families have been recorded with Porites the most dominant genus in the coral assemblages. Most reef sites in Balok are categorized under conservation class 1 (CC1), which indicated that resilient and survival of the reef rely on stress-tolerators taxa. The data presented here showed that Balok reef is highly resilient towards constant exposure to high sedimentation and wave action.

Demographic modelling of giant sea anemones: Population stability and effects of mutualistic anemonefish in the Jordanian Red Sea

Article

Jan 2017

Giant sea anemones serve as important hosts for mutualistic anemonefish on Indo-Pacific coral reefs, but their population dynamics and turnover rates remain largely unknown. We used size-based demographic models to determine recruitment, changes in body size and mortality of bulb-tentacle anemones Entacmaea quadricolor and leathery anemones Heteractis crispa over 2years on coral reefs in the northern Red Sea, Jordan. Individuals recruited at consistent rates and grew rapidly until they reached ∼300-cm2 tentacle crown surface area, then mostly remained static or shrank. Mortality rate decreased with body size, and the retention of large individuals strongly influenced population size. Individuals of H. crispa were more dynamic than those of E. quadricolor, possibly due to their hosting significantly smaller anemonefish. Both populations were abundant and stable but dynamic in terms of individuals, with estimated turnover times of only ∼5 and 3years for E. quadricolor and H. crispa respectively. We conclude that some giant anemones may be short lived relative to their fish symbionts, and that stasis rates of large individuals disproportionately affect their populations. These results have implications for conservation management strategies of these major cnidarians on coral reefs, and indicate wide variation between species in the population-level effects of mutualistic interactions.

Sea Anemones

Chapter

Feb 2017

Anna Scott

Sea Anemones that form an iconic association with anemonefishes are highly sought after by marine aquarists. Currently, no commercial culturing protocols have been established for these host anemones, and individuals are sourced from the wild, causing localized depletions in some areas of the Indo-Pacific. This chapter details the reproductive biology of sea anemones, and then outlines potential approaches to culturing host anemones, and future research and industry development needs. Characteristics that appear favorable for captive breeding through sexual reproduction include having predictable annual spawning seasons, releasing large numbers of broadcast spawned gametes that readily fertilize, and larvae with a relatively short planktonic period that settle onto a variety of substrata and require little feeding to optimize growth. Alternatively, propagation using fission, by natural or artificial means, could produce individuals throughout the year. Although, much work remains to be done, aquaculture is a possible solution for addressing concerns about overexploitation, and individuals could be used to supply the trade or restock depleted reefs.

Range extensions in anemonefishes and host sea anemones in eastern Australia: Potential constraints to tropicalisation

Article

Jan 2016

Species distributions at range edges show complex shifts with climate change. The present study examined anemonefish and host sea anemone abundance at their southern distribution limits on the eastern coast of Australia, to identify factors influencing the geographic responses of the symbiosis. Roaming surveys (30min) were conducted at 21 sites (∼30.01-30.95°S) on rocky reefs in a tropical-temperate transition zone. Two species of host anemones (Entacmaea quadricolor and Heteractis crispa) and anemonefishes (Amphiprion akindynos and A. latezonatus) were found, along with Dascyllus trimaculatus. Nearly all anemones and anemonefishes (>99.5%) were associated with vegetated islands and rocky islets, and abundance was influenced by seawater temperature. Greater numbers of H. crispa and A. akindynos than E. quadricolor and A. latezonatus were found; however, most A. akindynos were juveniles. H. crispa provided nursery habitat for both fishes, whereas adult fishes utilised only E. quadricolor. A southern range extension was found for E. quadricolor, and overwintering of A. latezonatus had extended poleward since the mid-1990s. The paucity of islands and rocky islets south of our surveys, and host-usage patterns, could constrain future range extensions. These findings showed climate-driven latitudinal shifts are complex and are likely to be variably constrained for different species.

Symbiosis in Fishes: The Biology of Interspecific Partnerships

Article

Apr 2014

Ilan Karplus

Symbiosis in Fishes provides comprehensive coverage of the biology of partnerships between fishes and invertebrates, ascending the phylogenetic scale, from luminescent bacteria, sponges and coelenterates to molluscs, crustaceans and echinoderms. Both facultative and obligatory partnerships are reviewed with emphasis on the behavioral, ecological and evolutionary aspects of fish symbiosis. Each of the eight chapters of this book focuses on a different group of partners. The structure, physiology and anti-predatory strategies of each group are described to provide the necessary background for the understanding of their partnerships with fishes. The formation of the associations, the degree of partner specificity and its regulation, as well as the benefits and costs for the fishes and their associates, communication between partners and their possible co-evolution are discussed in each chapter. This is the first attempt to critically review in a single volume all associations of fishes with invertebrates based on the latest studies in these areas, together with studies published many years ago and little cited since then. Symbiosis in Fishes provides a huge wealth of information that will be of great use and interest to many life scientists including fish biologists, ecologists, ethologists, aquatic scientists, physiologists and evolutionary biologists. It is hoped that the contents of the book will stimulate many to further research, to fill in the gaps in our knowledge in this fascinating and important subject. Libraries in all universities and research establishments where biological sciences are studied and taught should have copies of this exciting book.

Diversity of symbiotic relationship between host sea anemone and anemonefish: an ecological review of their distributions and combinations

Article

Dec 2011

Akihisa Hattori

Trying to find Nemo: quantifying sea anemone and anemonefish abundances on central and southern mid-shelf reefs on the Great Barrier Reef, Australia

Article

Jun 2014

Information on the abundance of species targeted for the marine aquarium trade is needed to help elucidate what levels of exploitation may be sustainable. Accordingly, this study documents the abundance and diversity of anemonefishes and their host sea anemones, which are highly sought after in the trade, using timed swims at seven mid-shelf reefs on the Great Barrier Reef, Australia. Three species of anemone (Entacmaea quadricolor n = 49, Heteractis magnifica n = 7, Stichodactyla mertensii n = 3), and five species of anemonefishes were found (Amphiprion akindynos n = 12, A. perideraion n = 29, A. melanopus n = 11, Premnas biaculeatus n = 2). Many of the surveys sites (58%) did not have anemones or anemonefishes, and at sites where they were present, numbers were generally low. Given these findings, it is essential that collection is carefully regulated to prevent localised extinctions and ensure that reproductive success is not adversely impacted.

Long-term increases in abundance of anemonefish and their host sea anemones in an Australian marine protected area

Article

Mar 2011

Understanding the population dynamics of host sea anemones and their symbiotic anemonefish is important given that pressures such as aquarium collecting and bleaching events are adversely impacting their abundance in some Indo–Pacific locations. We examined long-term trends in anemone and anemonefish abundance at four sites within a ‘no-take’ zone at North Solitary Island, Australia, by comparing data from 2008 to surveys done in 1994 and 1995. Species richness was stable, comprising two anemones,Entacmaea quadricolor and Heteractis crispa, and three anemonefishes, Amphiprion akindynos, A. latezonatus, and A. melanopus. In 2008, densities of the most abundant species, E. quadricolor and A. akindynos, were substantially higher than previously recorded, with increases of up to 532% and 133%, respectively. There was a strong relationship between A. akindynos densities and anemone cover, whereasA. latezonatus had higher densities in deeper waters. Densities of this species remained similar over time, although there was a decline at one site. Heteractis crispa and A. melanopus were found in comparatively low numbers. Potential reasons for the overall increase in abundance include: protection from severe swell events, the lack of major bleaching events, the ability of E. quadricolor to reproduce rapidly by asexual reproduction, and the increasing duration of marine park protection.

Correlates of Environmental Variables with Patterns in the Distribution and Abundance of Two Anemonefishes (Pomacentridae: Amphiprion) on an Eastern Australian Sub-tropical Reef System

Article

Full-text available

Jul 1999

Darren L Richardson

The relationship between characteristics of the reef environment and variations in the distribution and abundance of the anemonefishes Amphiprion akindynos and A. latezonatus was investigated at North Solitary Island, a sub-tropical rocky reef system on the east coast of Australia. During the summers of 1994 and 1995, fish densities and host sea-anemone cover were assessed on replicate 25 m transects at sites where host sea-anemones form semi-contiguous mats throughout the 6–21 m depth range. Multiple regression analyses indicated that environmental variables accounted for 65–71% and 61–80% of the variations in the number of A. akindynos and A. latezonatus among-sites, respectively. Among-habitat comparisons indicated that A. latezonatus densities were positively correlated with depth (r=0.45–0.90), whereas A. akindynos showed no consistent depth-related abundance patterns. Poor correlations (p>0.05) between the densities of each species on transect lines suggested that present-day competition was unlikely to determine the preference of A. latezonatus for deeper depths. Correlations between host sea-anemone cover and fish densities at the within-habitat (depth) scale were comparatively stronger than correlations at among-habitats in both species. These results suggest that among-habitat comparisons can confound finer scale fish-habitat associations within habitat (depth) zones. Evidence suggests that while sea-anemone cover does, to an extent, regulate the local ecology of anemonefishes, other factors are also likely to interact to limit their densities.

Effects of anemonefish on giant sea anemones: Ammonium uptake, zooxanthella content and tissue regeneration

Article

Full-text available

Mar 2005
Mar Behav Physiol

Zooxanthellae symbiotic with stony corals utilise ammonium excreted by resident fish populations. However, the contribution of ammonium produced by anemonefishes to host sea anemones has not been examined. In split-pair laboratory experiments with the giant sea anemone Entacmaea quadricolor, one half of each sea anemone was maintained with two individuals of the endemic anemonefish Amphiprion bicinctus, and the other half was maintained without anemonefish. Sea anemone fragments maintained with anemonefish regenerated significantly faster than those without anemonefish. After 8 weeks of regeneration, there were more endosymbiotic algae (zooxanthellae) in the tentacles of sea anemones with anemonefish than in those lacking fish. Adult anemonefish (8 cm total length) each excreted ammonium at a rate of about 0.97 µM h. Sea anemones that had been maintained without anemonefish for 4 weeks took up ammonia from enriched water at a faster rate than those that had been maintained with anemonefish, which absorbed very little ammonium. We conclude that anemonefishes provide ammonia for their host anemones and zooxanthellae, enhancing rates of tissue growth and regeneration.

Distribution and abundance of giant sea anemones (Actiniaria) in subtropical eastern Australian waters

Article

Full-text available

Jan 1997

Five of the 10 known Indo-Pacific giant anemone species were recorded on subtidal reefs within the eastern Australian subtropics (26°37′S to 30°56′S) during surveys between 1993 and 1995. Giant anemones had a patchy distribution among the 30 localities sampled, and species richness did not display any latitudinal trends within this province. Spatial distribution patterns and abundance of anemones were assessed from total counts and from line-intercept and belt transects. Anemone abundance was significantly higher on reefs to the leeward of the prevailing swell than on more exposed sites, at Julian Rocks and North Solitary Island, northern NSW. Significant reductions in anemone cover were detected among years within shallow reefal sites at North Solitary Island, coinciding with two major storm events. The abundance of the widespread Entacmaea quadricolor at North Solitary Island was the highest reported worldwide. Significant differences were detected between two morphological types of E. quadricolor in terms of microhabitat type, oral disk size and spatial distribution patterns. Important factors influencing the distribution, abundance and spatial patterns of giant anemones over both large and localized spatial scales appear to be water temperature, wave disturbance and water depth.

Social Hierarchies: Size and Growth Modification in Clownfish

Article

Full-text available

Jul 2003
NATURE

Peter M Buston

Conflicts of interest are part and parcel of living in a social group, although these can reduce the fitness of individual members. Here I show that clownfish (Amphiprion percula) adjust their size and growth rate according to their position in the group hierarchy, maintaining a well-defined size difference with respect to individuals above them in social rank. This strategy to prevent conflict is a surprising departure from the more usual ploy used by many animals of modifying their behaviour within the group.

How important are mangroves and seagrass beds for coral-reef fish? The nursery hypothesis tested on an island scale

Article

Full-text available

Nov 2002

There has been much controversy over the degree to which mangroves and seagrass beds function as nursery habitats for the juveniles of fish species that live on coral reefs as adults. In previous studies we have shown that the juveniles of at least 17 Caribbean reef-fish species are highly associated with bays containing mangroves and seagrass beds as nurseries, and that juveniles of these species are absent in bays lacking such habitats. In this study we therefore hypothesised that on islands lacking these bay nursery habitats, adults of these fish species will be absent or show low densities on the coral reef. Densities of the 17 species were compared between the reefs of Caribbean islands with and without mangroves and seagrass beds. On reefs of islands lacking these habitats, complete absence or low densities were observed for 11 of the 17 species, several of which are of commercial importance to fisheries. This finding suggests a Very important nursery function of such habitats and implies that the densities of several fish species on coral reefs are a function of the presence of nearby bays containing mangroves and seagrass beds as nurseries. The results indicate that degradation or loss of these habitats could have significant impacts on reef-fish stocks in the Caribbean.

Do juvenile Amphiprion ocellaris (Pisces: Pomacentridae) recognize conspecifics by chemical or visual cues?

Article

Full-text available

Oct 2003
J MAR BIOL ASSOC UK

Juvenile anemonefish Amphiprion ocellaris were tested in two behavioural laboratory set-ups for their ability to visually or chemically recognize conspecifics. Individuals of two other species of anemonefish, A. clarkii and Dascyllus aruanus, were also used as test specimens for recognition. The results indicate that juvenile A. ocellaris recognize conspecifics visually rather than by olfaction. This is contrary to their finding mechanism of their host anemone. However, the results also indicate that the juvenile A. ocellaris are neither attracted nor deterred by the presence of conspecifics. This is contrary to the settling mechanisms of the damselfish D. aruanus and D. reticulatus, and of the temperate herring Clupea harengus. Hence the results emphasize the variation of sensory abilities and behaviours in fish larvae and juveniles. It is not an area prone for generalizations.

An assemblage of the host anemone Heteractis magnifica in the northern Red Sea, and distribution of the resident anemonefish

Article

Full-text available

Jun 2004
J MAR BIOL ASSOC UK

The Heteractis magnifica assemblage at the tip of the Sinai Peninsula was examined. The actinian size, location, and number of resident anemonefishes were recorded. The anemones were found at depths down to approximately 40 m and the sizes of clustering H. magnifica and clusters were positively correlated with depth. The shallow waters of the anemone assemblage contained few mainly small, solitary actinians. There seemed to be a tendency for solitary actinians to cluster once they reached a certain size-range. The resident anemonefishes Amphiprion bicinctus and Dascyllus trimaculatus were present in very large numbers (approximately 250 and 1800 respectively) and the A. bicinctus home range size was positively correlated with depth.

Why do anemonefishes inhabit only some host actinians? Env

Article

Full-text available

Mar 1986

Daphne Fautin

The 25 species ofAmphiprion and one ofPremnas (family Pomacentridae) are obligate symbionts of 10 species of facultatively symbiotic sea anemones. Throughout the tropical Indo-West Pacific range of the relationship, a fish species inhabits only certain of the hosts potentially available to it. This specificity is due to the fishes. Five fishes occupy six sea anemone species at Lizard Island, Great Barrier Reef, Australia.Entacmaea quadricolor harborsP. biaculeatus, A. melanopus andA. akindynos. Adults ofPremnas occur deeper than about 3 m in large, primarily solitary actinians; juveniles may occupy peripheral members ofEntacmaea clones in shallow water. Specimens ofA. melanopus live exclusively in clonal anemones, which are found no deeper than 3 m. Most individuals ofA. akindynos inEntacmaea are juveniles, occurring shallow and deep, in solitary anemones or at the margins of clones. Interspecific as well as intraspecific social control of growth may be responsible for keeping fish small at clone fringes. Conspicuous specimens ofE. quadricolor depend upon their anemonefish to survive. Actinians cleared of symbionts disappeared within 24 h, probably having been eaten by reef fishes.Entacmaea, the most abundant and widespread host actinian at Lizard Island and throughout the range of the association, is also arguably the most attractive to anemonefishes. I believe its vulnerability to predation was a factor in its evolving whatever makes it desirable to fishes. Experimental transfers pitted fish of one species against those of another, controlling for ecophenotype of host, and sex, size and number of fish. Competitive superiority was in the same order as abundance and over-all host specificity:P. biaculeatus, A. melanopus, A. akindynos. At least three factors are necessary to explain patterns of species specificity - innate or learned host preference, competition, and stochastic processes.

Socially controlled growth and size-dependent sex change in the Anemonefish Amphiprion frenatus in Okinawa, Japan

Article

Full-text available

Jun 1991

Akihisa Hattori

Social structure, growth and reproductive experience of a protandrous anemonefish,Amphiprion frenatus, were investigated on a coral reef in Okinawa, Japan. In a 67 m × 334 m study area, 24 breeding groups, 10 nonbreeding groups and 2 groups of unknown breeding experience were found around isolated sea anemones. One group usually consisted of 2 or 3 fish. The female in a breeding group was larger than not only her mate but also all males in other breeding groups. The body size and gonadal state of the largest individual in a nonbreeding group were intermediate between the female and male in a breeding group. In both breeding and nonbreeding groups, the largest fish retarded growth of the second largest. After the disappearance or removal of females, their mates took more than 1.5 years to attain the minimum functional female size (about 75 mm in standard length). This delayed sex change can be attributed to strong growth suppression by the female.

Effects of anemonefish on giant sea anemones: expansion behavior, growth, and survival

Article

Full-text available

Nov 2004

The symbiosis between giant sea anemones and anemonefish on coral reefs is well known, but little information exists on impacts of this interaction on the sea anemone host. On a coral reef at Eilat, northern Red Sea, individuals of the sea anemone Entacmaea quadricolor that possessed endemic anemonefish Amphiprion bicinctus expanded their tentacles significantly more frequently than did those lacking anemonefish. When anemonefish were experimentally removed, sea anemone hosts contracted partially. Within 1–4 h in most cases, individuals of the butterflyfish Chaetodon fasciatus arrived and attacked the sea anemones, causing them to contract completely into reef holes. Upon the experimental return of anemonefish, the anemone hosts re-expanded. The long-term growth rate and survival of the sea anemones depended on the size and number of their anemonefish. Over several years, sea anemones possessing small or no fish exhibited negative growth (shrinkage) and eventually disappeared, while those with at least one large fish survived and grew. We conclude that host sea anemones sense the presence of symbiotic anemonefish via chemical and/or mechanical cues, and react by altering their expansion behavior. Host sea anemones that lack anemonefish large enough to defend them against predation may remain contracted in reef holes, unable to feed or expose their tentacles for photosynthesis, resulting in their shrinkage and eventual death.

Anthozoan dominated benthic environments

Article

Full-text available

Jan 1989

Daphne Fautin

The coral reef ecosystem exists and persists only in virtually fully saline water of a particular temperature range, at shallow depths, where the substratum is firm. This is a consequence of the rather narrow physico-chemical tolerances of hermatypic scleractinian corals, the animals that are the main builders of reef framework. Commonly, they are also major occupiers of space in such habitats. However, in other shallow, tropical marine environments, or in the same habitats under different conditions, non-scleractinian anthozoans -- typically zoanthids and octocorals -- occupy comparable expanses of substratum. Likewise, some temperate and deep-water marine communities are dominated by anthozoans, generally actinians. Although these animals do not structure their communities physically, they are, in many respects, functionally comparable to reef-building corals. Thus, such anthozoans appear to comprise a group of ecologically equivalent (which is not to say interchangeable) benthic dominants, the distribution of which is determined mainly by physico-chemical factors, mediated and modulated -- especially on a local scale -- by biotic ones.

Clonality as a taxonomic character of Actinian species

Article

Full-text available

Asterisks (*...*) surround words or phrases that are to be italicized. Sea anemones of some species have been considered to exist both clonally and as solitary individuals. In two temperate taxa, these alternative forms have been demonstrated through molecular techniques actually to belong to separate species. We have sequenced a variable portion of the cytochrome oxidase I mitochondrial gene from both solitary and clonal individuals of two nominal species of actinians that host anemonefish and that are abundant in Indo-Pacific reefs -- *Entacmaea quadricolor* and *Heteractis magnifica*. Our molecular data support the conclusion based on morphology that *H. magnifica* constitutes a single species from the Red Sea to French Polynesia, and encompasses both solitary and clonal morphs. The sequences from *E. quadricolor* differ from those of *H. magnifica*, but are too preliminary for assessment of whether more than a single species is represented.

A field and laboratory study of the symbiotic behavior of fishes and sea anemones from the tropical Indo-Pacific

Article

R.N. Mariscal

Habitat, distribution and abundance of coral reef sea-anemones (Actiniidae and Stichodactylidae) in Sesoko Island, Okinawa, with notes of expansion and contraction behavior

Article

Jan 1985

Y. Hirose

Structure, ecology and zonation of Red Sea reefs (in comparison with South Indian and Jamaican reefs)

Article

Jan 1971

H. Mergner

Protandrous hermaphroditism in six species of the Anemonefish genus Amphiprion in Japan

Article

Jan 1978

Field Guide to Anemonefishes and Their Host Sea Anemones

Article

Aug 1993
COPEIA

Juvenile production of Amphiprion bicinctus (Pomacentridae, Teleostei) and rehabilitation of impoverished habitats

Article

May 1997

This study on the Red Sea fish Amphiprion bicinctus was aimed at developing a method of producing large numbers of juveniles for reintroduction into their symbiotic sea anemones in natural habitats. By establishing reproductive pairs in captivity and providing them with a diet of rotifers and various stages of nauplius and adult Artemia salina, reproduction was achieved at frequencies of 2 to 3 times per month per pair, resulting in large numbers of larvae. Juveniles attaining 16 to 28 mm TL were introduced into sea anenomes on the coral reefs at Eilat, Israel, at depths of 10 to 25 m. Despite heavy losses, numerous juveniles successfully acclimated and survived in their new habitat, many in anenomes previously occupied by adult fish. Three years of follow-up revealed that 8 pairs of such reintroduced fish had grown into maturity and become reproductive. It would appear that this method of production in captivity followed by resettlement in impoverished natural habitats may be effective for community rehabilitation.

Use of back-reef and lagoon habitats by coral reef fishes

Article

Jan 2002

We visually censused fishes along transects on the back-reef and adjacent lagoons of bank-barrier reefs at 6 sites on St. Croix, US Virgin Islands, to determine the extent to which coral reef fishes use lagoon habitats as nurseries. Fishes were recorded by size class (small, 5 cm) on the back-reef, and on 5 lagoon habitat types: patch-reef, rubble, seagrass, algal plain, and sand. We examined densities of 4 focal 'species' (Acanthurus spp. (A. bahi- anus and A. chirurgus), Haemulon spp. (all species of the Haemulon genus), Sparisoma aurofrena- tum, and Scarus iserti), and densities of all species combined to determine spatial and temporal pat- terns of habitat use. Although there was a general tendency for coral reef fishes to use lagoon habitats as nurseries, we discerned 2 patterns of habitat use: 1 group, exemplified by Acanthurus spp. and Haemulon spp., use lagoon patch-reef and rubble as nurseries in preference to back-reef and other lagoon habitats; in contrast, Sparisoma aurofrenatum and Scarus iserti preferentially use back-reef and, to a lesser extent patch-reef, as nursery, juvenile, and adult habitat. Temporal variation was greatest in the small size class and least in the large size class. Most settlement occurred during summer, which is when settlement in lagoon habitats was greatest, with a little settlement in winter in the back-reef habitat. For species that use lagoons as nurseries, lagoon habitats must provide advantages that offset the additional energy expense and predation experienced by both incoming larvae, as they cross over the reef and search for patch-reef and rubble, and juveniles, as they return to the reef during the juvenile-to-adult transition. Given the use of lagoon habitats as nurseries, there is a need for inclusion of lagoons in coral reef reserves.

Morphology and cytology of the olfactory organs in small juvenile Dascyllus aruanus and Amphiprion ocellaris (Pisces: Pomacentridae)

Article

Dec 2003
J MAR BIOL ASSOC UK

The olfactory organs in juvenile Dascyllus aruanus and Amphiprion ocellaris, studied by scanning and transmission electron microscopy (SEM and TEM), consisted of two bilaterally radial rosettes per specimen, fan-shaped, located medio-ventrally, one in each of two olfactory chambers. In D. aruanus the rosette comprises six lamellae, three on each side of a midline raphe; in A. ocellaris 12 lamellae, six on each side. In both species, the sensory regions in the lamellae are continuous, except for the margin of the lamellae, and richly covered with stereocilia. Areas with juvenile bipolar receptor cells were observed in both species. Two dissimilar types of olfactory receptor cells in the sensory epithelium: ciliated and microvillous were observed.

Littoral fauna of the Red Sea: the population of non-scleractinian anthozoans of shallow waters of the Red Sea (Eilat)

Article

Jun 1970

Lev Fishelson

Approximately 22 species of sea anemones and 20 species of alcyonarians were found on the reef fringing the shallow water at Eilat (Gulf of Aqaba) and other localities along the Red Sea coast of the Sinai Peninsula. Investigations showed that these 2 groups of non-scleractinian coelenterates from (on different substrates) well identified colonies, part of them inhabiting sandy bottoms, other groups growing on the reef surface. Observations lead to the conclusion that several of the sea anemones and alcyonarians can act, under certain conditions, as factors limiting the development of hermatypic corals. In some areas, several species of the 2 groups of animals are found together with their symbiotic partners, such as fishes and crustaceans.

Alternative Ways to Become a Juvenile or a Definitive Phenotype (and on Some Persisting Linguistic Offenses)

Article

Sep 1999

Eugene K. Balon

Lack of knowledge of early and juvenile development often makes it difficult to decide when a fish becomes a juvenile or, for that matter, a definitive phenotype. According to the established life-history model, a fish develops naturally in a saltatory manner, its entire life consisting of a sequence of stabilized self-organizing steps, separated by distinct less stabilized thresholds. Changes are usually introduced during thresholds. In principle, there are two ways to reach the juvenile period: by indirect or by direct development. Indirectly developing fishes have a distinct larva period that ends in a cataclysmic or mild remodeling process, called metamorphosis, from which the fishes emerge as juveniles. During metamorphosis, most temporary organs and structures of the embryos and larvae are replaced by definitive organs and structures that are also possessed by the adults. In contrast, directly developing fishes have no larvae. Their embryos develop directly into juveniles and do not need major remodeling. Consequently, the beginning of their juvenile period is morphologically and functionally less distinct than in indirect development. The life-history model helps to find criteria that identify the natural boundaries between the different periods in the life of a fish, among them, the beginning of the juvenile period. Looking at it from a different angle, when ontogeny progresses from small eggs with little yolk, larvae are required as the necessary providers of additional nutrients (feeding entities similar to amphibian tadpoles or butterfly caterpillars) in order to accumulate materials for the metamorphosis into the definitive phenotypes. Directly developing fishes start with large demersal eggs provided with an adequate volume of high density yolk and so require no or little external nutrients to develop into the definitive phenotype. These large eggs are released and develop in concentrated clutches. It therefore becomes possible and highly effective to guard them in nests or bear them in external pouches, gill chambers or the buccal cavity. Viviparity is the next natural step. Now the maternal investment into large yolks can be supplemented or replaced by direct food supply to the developing embryos like, for example, the secretion of uterine histotrophe or nutrient transfer via placental analogues. When the young of guarders and bearers start exogenous feeding, they are much larger or better developed than larvae of nonguarders and the larva period in the former is reduced to a vestige or eliminated entirely. In the latter case, the juvenile period begins with the first exogenous feeding. Such precocial fishes are more specialized and able to survive better in competitive environments. In contrast, altricial forms retain or revert to a life-history style with indirect development and high fecundity when dispersal is advantageous or essential. Fishes become juveniles when the definitive phenotype is formed in most structures, either indirectly from a larva via metamorphosis or directly from the embryo.

Coexistence of nine anemonefish species: Differential host and habitat utilization, size and recruitment

Article

Jan 2001

The region of Madang, Papua New Guinea, has the highest reported species diversity of both anemonefishes (nine species) and their host anemones (ten species). To determine which factors may allow so many anemonefish species to coexist at this location, we studied their patterns of distribution, abundance, and recruitment. Population surveys at three replicate reef sites within four zones situated at varying distances from the mainland (nearshore, mid-lagoon, outer barrier, and offshore) indicated that each species of host anemone and anemonefish lived within a particular range of zones. Each species of anemonefish lived primarily with one species of host. Anemonefish species that lived with the same host species usually had different distribution patterns among zones (e.g., Amphiprion percula occupied Heteractis magnifica in nearshore zones, while A. perideraion occupied H. magnifica in offshore zones). Monitoring of natural populations showed that there were few changes (losses or recruitment) in the number or species of fishes associated with each individual anemone over periods ranging from 3 to 9 months. Recruitment was monitored on anemones with and without residents (resident fishes were removed) within each of three zones (nearshore, mid-lagoon, outer barrier). Significantly more anemonefishes recruited to anemones without resident fishes than to anemones with resident fishes. Each anemonefish species recruited to particular host species and zones. The distribution and abundance of the recruits of each fish species among zones were positively correlated with the distribution and abundance of resident fishes in the benthic habitat. This suggests that the spatial patterns of recruitment among zones strongly determined the distribution and abundance patterns of the benthic populations, and they were not the result of post-recruitment mortality or movement. Coexistence of the nine anemonefish species on the limited anemone resource was considered possible because of niche differentiation (i.e., differences in host and habitat utilization among zones), and the ability of two small species (i.e., Amphiprion sandaracinos and A. leucokranos) to cohabit individual anemones with other anemonefish species.

Growth of the anemonefish Amphiprion clarkii in temperate waters, with special reference to the influence of settling time on the growth of 0-year olds

Article

Aug 1986

Haruki Ochi

The temperate population of the tropical anemonefish Amphiprion clarkii has a seasonality of reproduction, larval settlement and growth. There was a considerable difference in size (15–47 mm) among 0-year olds in December, after the season of larval settlement and growth. This difference could be attributed mainly to a difference in the duration of the first growing season spent after settlement and a social inhibition of growth of the subordinate late settlers by frequent attacks by the dominant early settlers. The growth equation which was used to describe the growth of tagged individuals estimated that an anemonefish would get an opportunity to spawn within four of five years after settlement. Breeding adult pairs occupied almost all sea anemones essential to breeding within a 5050 m study area, and all 17 new adults that matured from non-breeding juveniles to breeding adults between June 1983 and August 1985 were found in the territories from which either or both of the mated adults had disappeared. The new adults were large juveniles who had resided near those vacant territories before. These results suggest that the onset of breeding by an individual is not only determined by his age, but also by his ranking in the dominance hierarchy. Therefore, the difference in size among 0-year olds in December might give rise to the difference in age of the earliest breeding and might be a factor in making a female apply more reproductive effort at the beginning of the season.

Host selection, location, and association behaviors of anemonefishes in field settlement experiments

Article

May 1995

Nine anemonefish species were reared in the laboratory, and individuals were released in the field (Lizard Island, Australia and Madang, Papua New Guinea) at different distances and orientations away from natural (anemone species the fishes are found with in nature) and unnatural species of host anemones. Experiments were conducted to examine factors that could affect the settlement behaviors of the fishes: current velocity, distance and orientation of the fishes to the anemones, chemical vs visual cues, and presence of conspecific or heterospecific fishes. The fishes were usually attracted toward natural host species of anemones but not towards unnatural host anemone species nor to pieces of dead coral. Host selection during settlement provided the best explanation for the host specificity patterns displayed by anemonefishes in nature. The fishes used chemical cues released from the anemones to identify and locate the appropriate host species and could effectively locate the anemones from a maximum distance of 8 m downstream. Fishes released upstream or to the side of anemones (where anemone chemicals were assumed to be reduced or absent) were much less successful in locating anemones. The ability of the fishes to locate natural host anemones was strongly reduced when there was no water current. The presence of resident anemonefishes on host species of anemones did not influence the attraction behavior of anemonefishes released downstream from the anemones. Once the released fishes got close to or entered the anemones, the resident fishes would generally bite and chase them until the recruits left the anemones. Most fishes were not stung upon initial contact with the anemones.

Growth, reproduction and survival of a tropical sea anemone (Actiniaria): Benefits of hosting anemonefish

Article

Mar 2005

The ecological performance of the sea anemone Heteractis magnifica was examined during a 36-month experiment with respect to season and the presence and numbers of a mutualist (orange-fin anemonefish Amphiprion chrysopterus). Anemones primarily grew during the autumn, with most asexual reproduction occurring in winter; mortality was not strongly seasonal. Individual growth rates did not differ between anemones harboring one or two anemonefish, but these rates were three times faster than for anemones lacking Amphiprion. Anemones with two anemonefish had the highest fission rate, whereas those without anemonefish had the lowest. By contrast, anemones that were not defended by anemonefish suffered higher-than-expected mortality. As a consequence, anemones with two Amphiprion had the greatest net increase in surface area, and those lacking anemonefish had a negligible gain that was statistically indistinguishable from zero after threeyears. Anemonefish not only enhanced anemone survivorship as previously believed, they also fostered faster growth and more frequent asexual reproduction.

Colony architecture of Millepora dichotoma Forskal

Article

Jun 1998
J EXP MAR BIOL ECOL

In the Gulf of Elat, the hydrozoan coral, Millepora dichotoma Forskal exhibits four main morphotypes: encrusting, delicate lace-like, leaf-like bladed and robust “box-work”. The distribution of these morphotypes was found to vary with depth and between locations. The encrusting form was found in all sites and appeared to be the initial growth form adopted by M. dichotoma. The distribution of the other three growth forms suggested that further development from the encrusting form depends upon environmental conditions. The encrusting form was found at all sites but was dominant in highly energetic environments. The lace-like form develops from the encrusting form in low energy environments. In somewhat higher energy environments, repeated damage to the lace-like form moves development towards the bladed growth form and the box-work growth form. A model of this development is presented in which critical factors controlling the development of the different growth forms are sediment levels and damage to colonies. Both of these factors are linked with levels of turbulence in particular environments.

Mutualism can mediate competition and promote coexistence

Article

Oct 2003

Mutualistic interactions are not believed to promote coexistence of competitors because mutualisms produce positive feedbacks on abundances whereas coexistence requires negative feedbacks. Here we show that a mutualism between an anemonefish (Amphiprion) and its sea anemone host mediates the effect of asymmetrical competition for space between the anemonefish and another damselfish (Dascyllus) in a manner that fosters their coexistence. Amphiprion stimulates increases in host area, the shared resource, but social interactions cap the number of anemonefish to two adults per host. Space generated by the mutualism becomes differentially available to Dascyllus because the effectiveness of an anemonefish in excluding its competitor declines with increases in the area it defends. This alters Amphiprion's ratio of per capita intra- to interspecific effects and thus facilitates coexistence of the fishes. This mechanism may be prevalent in nature, adding another major pathway by which mutualism can enhance diversity.

[Eco-ethology of the monogamous anemone fish Amphiprion bicinctus (Field studies in the Red Sea)]

Article

Feb 1974
Z Tierpsychol

H W Fricke

Land of a thousand atolls

Jan 1965

I Eibl-Eibsfeldt

Eibl-Eibsfeldt, I., 1965. Land of a thousand atolls. London: MacGibbon & Kee.

A redescription of Amphiprion nigripes Regan, a valid species of anemone¢sh (family Pomacentridae) from the Indian Ocean

Jan 1971

G R Allen
R N Mariscal

Allen, G.R. & Mariscal, R.N., 1971. A redescription of Amphiprion nigripes Regan, a valid species of anemone¢sh (family Pomacentridae) from the Indian Ocean. Fieldiana, Zoology, 58, 91^101.

The anemone¢shes, their classi¢cation and biology

Jan 1972

G R Allen

Allen, G.R., 1972. The anemone¢shes, their classi¢cation and biology, 1st edn. Neptune City: TFH Publications.

The clown¢sh sea anemones

Jan 1981
71-73

D F Dunn

Dunn, D.F., 1981. The clown¢sh sea anemones. Transactions of the American Philosophical Society, 71, 2^115.

Abundance of giant sea anemones and patterns of association with anemonefish in the northern Red Sea

Abstract

No full-text available

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