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Lampedusa Island and the location of the study site at Capo Madonna
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In the southern Mediterranean Sea, replicate samples of six common upper-infralittoral algae (Cystoseira
barbatula, Cystoseira
spinosa, Sargassum
vulgare, Halopteris
scoparia, Dictyota
fasciola, and Dictyota
dichotoma) were collected with the major goal of investigating the composition and structure of molluscan assemblages between the algal specie...
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Citations
... The architectural complexity of macroalgae can be evaluate based on algae length, coverage of epibionts (Carvalho et al., 2018), biomass (Duarte et al., 2020;Leite et al., 2021), fractal dimensions (McAbendroth et al., 2005), and interstitial indices (Dibble and Thomaz, 2006;Thomaz and Cunha, 2010), and vary according to the algae taxonomic identity and environmental characteristics such as rainfall, nutrient input, hydrodynamics, photoperiod, and biological interactions (Steneck and Dethier, 1994;Jorge et al., 2012;Sirison and Burnett, 2020). Macroalgae complexity has been shown to be one the best predictors of the diversity and abundance of the phytal epifauna (Chemello and Milazzo, 2002;Carvalho et al., 2018Carvalho et al., , 2022Gan et al., 2019), and generally the communities in more complex macroalgae are richer, and more diverse and abundant than those in less complex algae (Hacker and Steneck, 1990;Duarte et al., 2020;Carvalho et al., 2018;Craveiro and Rosa Filho, 2024). ...
While they are extremely abundant and ecologically important, the epiphytic foraminifera of tropical reefs are still poorly known. The present study describes the foraminiferal assemblages associated with macroalgae on tropical reefs of the Brazilian coast. Samples of four species of macroalgae, two foliose (Padina antillarum and Ulva lactuca) and two corticated (Palisada perforata and Gelidiella acerosa), were collected from intertidal sandstone reefs at Pina, Enseada dos Corais, and Toquinho (Northeastern Brazil). Overall, only 13.3% of the 708,754 foraminifera specimens were alive, belonging to 37 species, with dominance of Rosalina anglica. Most tests were hyaline-perforate and conical in shape, and most species were permanently or temporarily sessile. The majority of living foraminifera were attached to the surface of Palisada and Gelidiella, and no attached specimens were found in either Padina or Ulva. The species richness and abundance of the living foraminifera varied significantly among the macroalgae, occurring the high values in P. perforata. The assemblages varied significantly between the two species of corticated macroalgae, and between the corticated and foliose species, but not between the two foliose algae. Some of the specimens of Glabratella and Rosalina were reproducing, and had juveniles attached to the parental test. This is the first study to focus on the ecological interactions of the epiphytic foraminifera of the tropical southern Atlantic Ocean, and its results indicate that the characteristics of the epiphytic assemblages can be used as a proxy for the understanding of the structure and function of microbenthic communities on tropical reefs.
... This was surprising as the mixed frond habitat units were created to mimic naturally occurring intra-individual variability often displayed by S. vestitum (Stelling-Wood et al., 2020. We hypothesised that higher morphological variability within a habitat unit, representing more complex habitat, would positively correlate with the abundance of associated organisms (Chemello & Milazzo, 2002;Warfe et al., 2008) and would support more size-diverse associated communities. This, however, was not the case in our study with our findings suggesting that increased heterogeneity in a habitat does not necessarily result in higher abundances of associated fauna. ...
Habitat‐forming organisms provide three‐dimensional structure that supports abundant and diverse communities. Variation in the morphological traits of habitat formers will therefore likely influence how they facilitate associated communities, either via food and habitat provisioning, or by altering predator–prey interactions. These mechanisms, however, are typically studied in isolation, and thus, we know little of how they interact to affect associated communities. In response to this, we used naturally occurring morphological variability in the alga Sargassum vestitum to create habitat units of distinct morphotypes to test whether variation in the morphological traits (frond size and thallus size) of S. vestitum or the interaction between these traits affects their value as habitat for associated communities in the presence and absence of predation. We found morphological traits did not interact, instead having independent effects on epifauna that were negligible in the absence of predation. However, when predators were present, habitat units with large fronds were found to host significantly lower epifaunal abundances than other morphotypes, suggesting that large frond alga provided low‐value refuge from predators. The presence of predators also influenced the size structure of epifaunal communities from habitat units of differing frond size, suggesting that the refuge value of S. vestitum was also related to epifauna body size. This suggests that habitat formers may chiefly structure associated communities by mediating size‐selective predation, and not through habitat provisioning. Furthermore, these results also highlight that habitat traits cannot be considered in isolation, for their interaction with biotic processes can have significant implications for associated communities.
... These short-thali algae, mainly composed of filamentous and articulated calcareous algae, are as influential as the erect macroalgae over associated phytal invertebrate communities (Lalonde and Downing, 1992;Becerra-Muñoz and Schramm, 2006;Berthelsen et al., 2015;Kramer et al., 2012). The significant impact of the algal habitat on the associated invertebrate communities is unsurprising, given the well-established correlation between habitat structure and assemblage characteristics, as previously highlighted in studies (Hacker and Steneck, 1990;Chemello and Milazzo, 2002;Fraser et al., 2020a;Fraser et al., 2020b). Total abundance and cryptofauna composition were influenced by EAM characteristics, but cryptofauna biomass, richness, and diversity were not. ...
... The significance of microhabitat in shaping the structure and composition of associated fauna, as previously noted (Stella et al., 2010;Chemello and Milazzo, 2002), is unsurprising. Microhabitat structure can even outweigh the influence of environmental factors on the composition of cryptofauna across broad-scale latitudinal gradients (Fraser et al., 2020a;Fraser et al., 2020b). ...
... Habitat complexity can determine organism distribution (Figueiredo et al., 2013;Gartner et al., 2013). High complexity habitats present higher food availability due to a larger surface for microalgae colonization and provide greater protection against predators (Chemello and Milazzo, 2002). In an experiment with artificial shelters, Park et al. (2015) observed a higher number of juvenile Pandalopsis japonica Balls, 1914 attached to the brushtype shelter and related this finding to the higher availability of independent spaces in relation to the other shelter types. ...
Neocaridina davidi (Bouvier, 1904) is a shrimp commonly used in aquaculture throughout the world. It is an exotic species in several places. We investigated the preference of N. davidi for four types of shelter (rock, Vesicularia sp., Egeria sp., and wood) and its nictemeral activity variation. Individuals were divided into three experimental groups: males, non-ovigerous females, and ovigerous females. They were placed in tanks with the four shelter types and observed every 3 hours for 72 hours. Neocaridina davidi presented cryptic behavior with 82.1 ± 8.69% of individuals sheltering per observation. Sheltering was higher during the daytime (88.8 ±5.54%) than at nighttime (75.4 ± 5.53%). Vesicularia sp. was the most used shelter followed by wood. The least used shelter type was a rock. Swimming and walking were more frequently observed at nighttime, especially for ovigerous females. We have demonstrated the importance of providing shelter for the maintenance of N. davidi in tanks as well as its higher activity at nighttime.
... These are all micrograzers species that feed upon the organisms in the biofilm established on the macroalgae surface, such as microalgae and diatoms (Chemello & Milazzo, 2002;Ferguson, 2008;Mello and Maestrati, 1986;Montfrans et al., 1982). Hydrodynamics can also directly affect the formation of biofilm, increasing its density and biomass as the energy levels increase (Salta et al., 2013), which could be resulting in increased food availability for micrograzer gastropod TA B L E 5 Linear mixed effects model results for the diversity index values among groups. ...
... This pattern of trophic distribution is similar to other marine vegetated habitats in Brazilian coast and in other localities (Antit et al., 2013;Cavalcante et al., 2019;Longo et al., 2014;Urra et al., 2013). According to Duarte et al. (2020), macroalgal morphology has a great influence on functional diversity of associated molluscan assemblages, especially considering the diversity of feeding strategies, which may explain why many different trophic categories are represented by a high number of species in Sargassum habitats since this brown macroalga is considered to have a highly complex morphology (Chemello & Milazzo, 2002). ...
Anthropogenic impacts on coastal habitats can result in alterations of diversity parameters in marine invertebrate assemblages. Macroalgae beds are highly susceptible to human‐induced disturbances, supporting a great diversity of molluscan species and being ecologically important for coastal ecosystems. This study investigates the diversity alterations on Sargassum ‐associated molluscan assemblages from areas with different distances from a main source of pollution within a historically impacted bay in Brazil. In general, sites closer to the pollution source presented lower species diversity, trophic diversity, and taxonomic relatedness among species. Beta diversity among assemblages was highly correlated with environmental differentiations among localities due to heavy metal concentrations in algal tissue. Bittiolum varium was the dominant species and was mainly responsible for differences in community parameters. Several trophic groups were well‐represented in Sargassum ‐associated molluscan fauna, but assemblages were mostly dominated by micrograzers. A seasonal trend was observed in diversity alterations, with lower diversity during warm season at most sites except Santa Rita, possibly because it is the site less affected by human impacts. The importance of other environmental variables, such as hydrodynamism, for molluscan composition is also discussed. Our results highlight the potential of Sargassum ‐associated molluscan assemblages for the study of impacted areas and reinforce the importance of using multiple community metrics to understand the biodiversity patterns of marine invertebrates under anthropogenic impacts.
... The role of seaweed architectural complexity as a predictor of invertebrate communities is unclear as even congeneric algae with similar forms can harbour very different diversity of invertebrate assemblage (Wikström and Kautsky 2004;Bates 2009). Furthermore, the role of algal morphological complexity on invertebrate assemblages can vary across scale, from the branching pattern of individual thalli (Chemello and Milazzo 2002) to the distribution of individuals in space, the heterogeneity of thalli arrangements, and the fragmentation of algal beds (Roberts and Poore 2006). To that effect, while algal canopy increases alpha diversity it can also reduce spatial variation of temperature and desiccation during low tide, leading to a decrease in understory beta diversity of sessile organisms (Scrosati et al. 2021;Catalán et al. 2023). ...
Intertidal seaweed beds form three-dimensional structures providing habitat for a variety of species. As such, ecosystem-based management of seaweed harvesting must take into consideration the impact of the harvest not only on the biomass but also on the morphology of the seaweed. We compare the morphology and vertical distribution of biomass and shoots in Ascophyllum nodosum from three sites with a 20 + year history of commercial harvesting with three corresponding control sites in southern New Brunswick, Canada. We found no significant impact of harvest history on the vertical distribution of shoots or biomass within individual clumps. At two of the three harvested sites, large clumps had a wider circumference than those at the control sites, suggesting that long-term harvesting increases the growth of shoots throughout the clumps; presumably caused by an increase in light penetration through the harvested canopy. We also compare biomass of littorinids, the most abundant invertebrates found in A. nodosum beds at low tide and found no significant difference between control and harvested sites. We conclude that the harvest of A. nodosum according to the current regulations in New Brunswick, does not have long-term impact on the morphology of the algae or on the abundance of its main inhabitant.
... The potential herbivory pressure on recruits of C. compressa of a decapod (Clibanarius erythropus), a gastropod (Cerithium vulgatum), an amphipod (Gammarus sp.), and an isopod (Idotea balthica) was assessed in laboratory. The species and their densities were selected in function of field observations and information reported in the literature for fucoid species (Engkvist et al., 2000;Chemello and Milazzo, 2002;Gozler et al., 2010;Gunnarsson and Berglund, 2012;Suzuki et al., 2020;Hong et al., 2021;Navarro-Barranco et al., 2022). ...
Grazing is one of the most important biological factors controlling the abundance of early-life stages of fucoids and one of the major issues when restoring marine forests. Benthic macroinvertebrates (e.g., sea urchins) and fish shape and regulate benthic macroalgal communities from polar to tropical regions and can be responsible for regime shifts leading to the predominance of turfs and/or barren grounds. However, other herbivores (i.e., mesograzers) could also significantly participate in the grazing, especially on early-life stages, hampering the persistence and capacity of Cystoseira sensu lato populations to recover after major disturbances and being a cause of failure of restoration actions. We performed experiments in the field and in mesocosm in order to investigate the herbivory pressure and the effects of different grazers on recruits of Cystoseira compressa. The results highlight that non-strict herbivorous invertebrates, such as Clibanarius erythropus, Cerithium vulgatum, and Idotea balthica, graze on recruits of Cystoseira s.l. spp., with I. balthica showing the highest consumption rate. We concluded that biotic factors such as herbivory, which affect key life stages, can be crucial for the conservation of Cystoseira s.l. forests and need to be better understood and considered on a case-by-case basis when planning restoration actions.
... The underlying substrate, where a quantity of sediment is usually retained, appears to be a more stable microhabitat since it does not usually present large seasonal or annual changes (Urra et al., 2013) algal fronds could vary depending on the structural differences between algae, mainly morphology (Chemello and Milazzo, 2002;Urra et al., 2013), but also composition (e.g., calcium carbonate in coralline algae) or metabolites (e.g., caulerpine in algae of the genus Caulerpa) (Waters et al., 1996;Catra et al., 2019). In the mesolittoral, exposed at low tide, the refuge from desiccation constituted by algae becomes even more important than in the infralittoral (Brown and Taylor, 1999). ...
The molluscan fauna inhabiting the algal turfs of mesolittoral rocky outcrops, dominated by the coralline alga Ellisolandia elongata, has been quantitatively analysed in a Marine Protected Area of Málaga, southern Spain (W Mediterranean). A total of 2520 mollusc specimens belonging to 46 species were identified. This taxocenosis was compared to that previously studied from the infralittoral level, where the alga Halopteris scoparia was prevailing and 4084 specimens belonging to 66 species of Mollusca were found. The species Pisinna glabrata, Skeneopsis planorbis, Nodulus spiralis and Tricolia miniata dominated the mesolittoral stage. The occurrence of congeneric species pairs (Tricolia miniata/Tricolia pullus, Nodulus spiralis/Nodulus contortus) which achieve high abundance in one of the levels and are scarce or absent in the other was striking. Therefore, the coralline algal turf in the lower part of the intertidal zone is not just an extension of the “Photophilous Algae” community but a benthic community its own.
... In the marine environment, seaweeds are key primary producers and habitat formers, providing space, shelter, and food for a variety of associated epifaunal organisms [1] and substrate for numerous small-sized algal epiphytes [2]. The Mediterranean Sea is a global hotspot of marine biodiversity and its macroalgal flora consists of approximately 1200 species [3]. ...
Highly diverse microphyto and meiobenthic communities are associated with large-sized marine macroalgae. Both morphological traits and allelochemical responses of macroalgae affect the composition of these communities, but the relative importance of these factors remains incompletely understood. In this study we investigated the microphytobenthic and meiobenthic communities associated with some native macroalgae and a non-indigenous species (Sargassum muticum) of the north-western Adriatic Sea. These seaweeds were sampled in two coastal sites subjected to different impacts. The possible effects of the structural complexity of the macroalgae and the potential role of allelochemicals (specifically polyunsaturated aldehydes, PUAs) on the associated communities were examined using univariate and multivariate analyses. The results indicate that distinct assemblages were associated with the macroalgae collected at the two different sites. Differences in microphytobenthic communities could be ascribed to differences in the macroalgal morphological traits and in their PUAs production. Conversely, variation of the meiobenthic community seemed to be related mainly to differences in the macroalgal communities at the two sites. This apparent inconsistency between the two analyzed communities suggests that microphytobenthos and meiofauna were differently shaped by the environmental habitat provided by macroalgae in the two sites, that are subjected to different environmental conditions and human activities. Overall, these results indicate that interactions between organisms belonging to different trophic groups (e.g., microphytobenthos and meiofauna) should be investigated in detail to better understand the global role of macroalgae as habitat formers on coastal ecosystems, especially in the case of large-sized introduced species.
... Among macrophytes, seaweeds act as biological "formers" of habitat structure, contributing to increase the habitat complexity of rocky shores. Many studies have shown that seaweeds shape their associated communities differently depending on algal architecture, life cycle, chemical defences or physical factors (Chemello and Milazzo, 2002;Jormalainen and Honkanen, 2008;Vázquez-Luis et al., 2008;Pitacco et al., 2014;Veiga et al., 2014;Chiarore et al., 2019;Mancuso et al., 2021aMancuso et al., , 2021bMancuso et al., , 2022. Seaweeds with high structural complexity, A c c e p t e d M a n u s c r i p t expressed as a variety of substrate attributes (such as fractal dimension, degree of branching, thallus width and height, and wet weight), can support well-structured molluscs communities (Hacker and Steneck, 1990;Gee and Warwick, 1994;Chemello and Milazzo, 2002;Bitlis, 2019;Mancuso et al., 2021a). ...
... Many studies have shown that seaweeds shape their associated communities differently depending on algal architecture, life cycle, chemical defences or physical factors (Chemello and Milazzo, 2002;Jormalainen and Honkanen, 2008;Vázquez-Luis et al., 2008;Pitacco et al., 2014;Veiga et al., 2014;Chiarore et al., 2019;Mancuso et al., 2021aMancuso et al., , 2021bMancuso et al., , 2022. Seaweeds with high structural complexity, A c c e p t e d M a n u s c r i p t expressed as a variety of substrate attributes (such as fractal dimension, degree of branching, thallus width and height, and wet weight), can support well-structured molluscs communities (Hacker and Steneck, 1990;Gee and Warwick, 1994;Chemello and Milazzo, 2002;Bitlis, 2019;Mancuso et al., 2021a). ...
... Many studies highlighted the role of the seaweed structural complexity in shaping their epifaunal assemblage, with complex algae supporting higher abundance and greater number of epifaunal species compared to less complex macroalgae (Gee and Warwick, 1994;Chemello and Milazzo, 2002;Bedini et al., 2014;Pitacco et al., 2014;Veiga et al., 2014;Lolas et al., 2018;Veiga et al., 2018;Bitlis, 2019;Chiarore et al., 2019;Poursanidis et al., 2019;Mancuso et al., 2021bMancuso et al., , 2021aMancuso et al., , 2022. For example, foundation seaweeds of the genera Cystoseira, Ericaria, Gongolaria (in the past all ascribed to the genus Cystoseira), seem to have more structured epifaunal assemblage compared to other less structurally complex macroalgae (Chemello and Milazzo, 2002;Mancuso et al., 2021aMancuso et al., , 2022. ...
Brown foundation seaweeds are key elements increasing substrate heterogeneity and shaping the biodiversity in rocky coastal ecosystems. They are, however, vulnerable species that are declining due to multiple anthropogenic and climate change stressors, leading to a shift to less structural complex habitats. We investigate the role of structural attributes of two intertidal macroalgae, Ericaria amentacea and Laurencia obtusa, in shaping the abundance and diversity of their associated epifaunal assemblages. For this aim, we measured seaweeds’ biomass, thallus volume and length (used here as proxy of substrate complexity), and explored which seaweeds’ substrate attribute explained better variation of epifaunal assemblages. Results showed that E. amentacea was more complex than L. obtusa and hosted a higher number of epifaunal individuals. However, unlike that expected, the epifaunal assemblage of L. obtusa was more structured with higher Shannon–Wiener diversity and Pielous’ evenness. Our findings indicate that, besides seaweed’s substrate attributes, other mechanisms such as wave action and chemical defense might play a role in structuring epifaunal assemblages. We suggest that a shift from E. amentacea to L. obtusa population could have effect on structure and abundance of associated epifaunal assemblages. Certainly, further investigations are needed to clear up the consequences of these changes.
