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Percentage of Prochilodus costatus individuals initiating spawning migration during each lunar phase over the 3-year study period. Numbers above bars represent the migration initiation rate per day with the increasing water level
Source publication
The arrival of the rains and the hydrological changes they cause are essential in the reproductive cycle of Neotropical migratory fishes, but their association with the onset of migration is still poorly understood. This study aimed to determine the role played by rainfall, hydrological changes, and the lunar cycle as triggers for migration of Proc...
Citations
... It is triggered by seasonal environmental fluctuations initiated with the onset of the rainy season (Barletta et al. 2010;Zaniboni-Filho et al. 2017). Changes in river hydrology, such as flow peaks, along with alterations in water quality parameters such as temperature, conductivity, and transparency, appear to be important cues for individuals to recognize the appropriate time to initiate gonadal preparation, reproductive migration, and spawning (Godinho et al. 2010;Pesoa and Schulz 2010;Perini et al. 2013;Lopes et al. 2018). Studies have also shown that Neotropical migratory species have a high degree of geographic recognition of the area they inhabit and can exhibit reproductive and feeding homing behaviors (Godinho and Kynard 2006;Godinho et al. 2007;Lopes et al. 2019Lopes et al. , 2021. ...
... The alteration in environmental characteristics from downstream to upstream of the dam appears to induce disorientation in translocated individuals. Species of Prochilodus genus depend on the hydrological and geographical characteristics of the environments they inhabit to undertake reproductive migrations to specific points in the river basin within well-defined time windows (Lopes et al. 2018(Lopes et al. , 2019Peressin et al. 2023). The translocation of P. argenteus individuals to the reservoir, which has completely different hydrological and ecological characteristics from the river they inhabit, causes them to lose both their spatial and temporal references for reproductive migration. ...
... The Upper São Francisco River presents an opportunity for investigating the impact of large reservoirs on the migratory behavior of Prochilodus species due to the diverse environmental conditions it encompasses, including free-flowing and dammed stretches. The conducted migratory studies in these varied environments (Godinho and Kynard 2006;Lopes et al. 2018;Peressin et al. 2023; this study), contribute robust evidence to our understanding of how the presence of large reservoirs influences the migratory patterns of these species. Notably, migratory species in Neotropical floodplain rivers, sharing seasonal reproductive strategies akin to those observed in the genus Prochilodus (Winemiller 1989), are confronted with analogous challenges. ...
One of the most conspicuous impacts of dam construction on fish is the blocking of their migratory routes. However, the formation of the reservoir, a lentic environment with distinct hydrological and ecological characteristics, can also constitute an obstacle to migration. This impact, however, is poorly explored in the scientific literature. Therefore, this study aimed to assess the movements of Prochilodus argenteus tagged with radiotelemetry transmitters and manually translocated across the Três Marias Dam in the São Francisco River. The Três Marias reservoir covers an area of 1,090 km2 and ranks among the largest artificial reservoirs in Brazil. Individuals translocated to the Três Marias reservoir showed reduced movement rates and home ranges. They appeared disoriented in the new environment, with many of them settling near fish farms and remaining there throughout the study period. A comparative analysis with existing literature on Neotropical species' reproductive migration through artificial reservoirs revealed a trend: the ability of migratory fish to navigate reservoirs diminishes with their area, especially those exceeding 50 km2 or with a residence time surpassing 30 days. These results indicate that caution is needed when designing fish passage facilities for dams that form larger artificial reservoirs in the Neotropics. Even if these facilities are efficient in attracting and translocating migratory species, behavioral and physiological thresholds may prevent them from reaching suitable areas to complete their reproductive cycle in the new environment formed.
... Further, for Z. flavescens and C. strigosus, which represent the dominant species of recruits detected in these surveys and are also some of the key species targeted in the aquarium industry [8,27,49], investigation into sustainable catch limits will be important to understand, especially during heatwave years. Photoperiod and temperature are the key factors in phasing reproductive seasonality, but other environmental cues include nutritional status [50], lunar cycle [51] and precipitation [52]. Such data, if collected during the time of the surveys, could help provide a more detailed understanding of local conditions driving recruitment and how they interact with temperature. ...
Understanding how temperature affects coral reef fish recruitment success is crucial for assessing impacts of ocean warming on coral reef resilience. We utilized a long-term fish survey dataset along the west coast of Hawaiʻi Island to investigate the role of sea surface temperature (SST) in influencing recruitment timing and density. The dataset consisted of 17 years of surveys, with 25 sites annually surveyed in the months of May, July, September and November. We found that peak recruitment, i.e. the maximum number of recruits recorded across all surveys per year, usually occurred during July surveys. For sites where peak recruitment for that year occurred outside July, there were significantly fewer fish recruits than for sites whose peak recruitment occurred in July. The results show that the timing of peak recruitment is influenced by anomalously warm or cool years prior to spawning. The decrease in recruit density outside these times is likely influenced by recruits being exposed to temperatures warmer and cooler than their optimum. Our results show that climate variability is having an impact on the timing of peak recruitment, creating a mismatch between the thermal optimum of developing recruits and the thermal environment they develop in, negatively affecting recruit density in critical coral reef habitats. Altered and reduced recruitment has the potential to disrupt reef community structure and long-term fisheries sustainability in Hawaiʻi, with important management implications for coral reefs in the future.
... In this region, the São Francisco mainstream is a free-flowing river more than 400 km in length. Migratory fish populations are able to complete their life cycle along this area (Lopes et al., 2018(Lopes et al., , 2019, where an important floodplain region is found (Araújo et al., 2020). ...
Aim This study aimed to evaluate whether the upper São Francisco River basin floodplain is still used as a nursery by migratory fish and present the current status of the area’s ichthyofauna after almost 40 years since the only survey was conducted in the region. Methods Sampling occurred in seven perennial lagoons and six temporaries from São Francisco River or its direct tributaries using gillnets and trawls. Temperature, pH, and transparency of each lagoon were measured. The estimated richness was calculated, and the fish assemblage from both perennial and temporary lagoons was compared using NMDS and ANOSIM. Results Forty species were captured, of which four were non-native and three were migratory. Although there was a low abundance of migratory species, most captured individuals were juveniles. Moreover, the perennial lagoons showed higher species richness. Conclusions After almost 40 years, the floodplain lagoons of the upper São Francisco basin remain important for the recruitment of migratory species and harbor an impressive proportion of fish fauna in the upper São Francisco area. However, the reduction of migratory species and the presence of non-natives may be a sign of the degradation of these environments, emphasizing the need for conservation measures in this area.
... In general, mature fish of estuary-associated species move from the estuary to the marine environment for spawning (Pittman and McAlpine 2003). These movements are often predictable, being triggered by seasonal shifts in temperature (Quinn and Adams 1996;Dahl et al. 2004) or weather events such as heavy rainfall leading to significant increases in river inflow (Koster et al. 2017;de Magalhães Lopes et al. 2018;Perez et al. 2019). In addition, rhythmic cycles, such as lunar and diel cycles, also play an important role in the timing of these movements (Pittman and McAlpine 2003;Forsythe et al. 2012;Walsh et al. 2013). ...
... its well-known significance as a feeding area for migratory species (Lopes et al., 2018). ...
... The migratory period, spawning locations, and skipped breeding pattern observed in P. argenteus are similar to those reported by Lopes et al. (2018Lopes et al. ( , 2019 for P. costatus. Other Prochilodus species also migrate upstream to spawning sites and reproduce in the rainy season in various river basins, including Amazon (P. ...
... costatus/P. argenteus) (Godinho & Kynard, 2006;Lopes et al., 2018Lopes et al., , 2019, and Jequitinhonha (P. hartii) (Silva et al., 2021). ...
The migratory behavior and spawning of Curimatá‐pacu ( Prochilodus argenteus ) were assessed in a free‐flowing remnant spanning approximately 450 km. This evaluation was conducted using radio‐tagging and egg sampling, with identification performed through metabarcoding techniques. Among the studied individuals, half migrated 100–365 km upstream, primarily in response to the initial rise in river discharge at the onset of the wet season. Conversely, the remaining fish did not exhibit upstream movement, indicating a partial migratory behavior. The presence of eggs exclusively in the headwaters suggests that breeding occurred solely among fish inhabiting the upstream sites. The observed migratory traits resembled those of other congeneric species.
... The temporal results of the species richness and functional richness also coincided with periods of high and low rainfall, resulting in positive associations. Precipitation is one of the main environmental variables that modulate fish reproduction (Lopes et al., 2018) since it affects a variety of hydrological factors that are directly related to spawning, including flow, transparency, electrical conductivity and fluviometric level (Baumgartner et al., 2008). This corroborates the fact that fish reproduction is highly influenced by the environmental conditions to which they are exposed. ...
Ecosystem services provided by communities are related to the diversity of functional traits, and biotic functional simplification occurs when this diversity is reduced. Thus, we used the approach of functional indices, applied to the abundance of fish larvae and traits of the spawning stock, to evaluate the spatial and temporal variations in the functional diversity of the fish community of a Neotropical reservoir. The following hypotheses were tested: (i) different environmental conditions between reproductive periods lead to temporal variations in the functional diversity of the community, and (ii) the spatial heterogeneity (longitudinal and lateral) of the environmental conditions formed in the reservoir causes functional biotic simplification to occur from lotic towards lentic areas since the original community was formed by rheophilic species. Larval collections were carried out monthly, at night, between October and March, from 2009 to 2016, with plankton nets equipped with a flowmeter in nine sample areas categorised into three longitudinal zones (fluvial‐FLU, transition‐TRA and lacustrine‐LAC) and three sides (upper‐UPP, middle‐MID and lower‐LOW). Water samples were obtained to measure the temperature and turbidity. Precipitation and reservoir quotas were obtained from official agencies. After the identification of captured larvae, we determined which species were present and used the functional traits of the adults (parental stock), obtained from specialised literature, and functional richness (FRic) and its corresponding standardised effect size (SES.FRic) were computed. The spatiotemporal variations in these indices were evaluated through the two‐way block factorial MANOVA/ANOVA. Their association with environmental variables was inferred through multiple linear regression models. Altogether, 51,995 larvae were captured with the highest abundance in the period V, longitudinally in LAC and TRA and laterally in LOW. Among these, the functional indices were higher in periods IV and V. The highest values of FRic occurred longitudinally in FLU and laterally in LOW. Among the abiotic conditions, rainfall and water temperature were the most influential variables over functional indices and total larvae abundance. The results indicate that fish reproduction is linked to spatiotemporal variations in abiotic conditions confirming our first hypothesis. The second hypothesis was partially supported because functional biotic simplification was observed in the longitudinal gradient, with reductions in FRic in LAC. However, this reduction was not observed in the lateral gradient. We showed that the temporal variability of abiotic conditions is important for the high functional diversity of reservoirs.
... The timing and triggers for the migration of aquatic species, such as diadromous and potamodromous fish, are important ecological information (Loury et al. 2021). Breeding migration is a key life-history event for the migratory species, and its spatiotemporal dynamics are affected by various environmental factors (Baer et al. 2018;Benitez and Ovidio 2018;Lopes et al. 2018;Hewitt et al. 2022;Stott and Miner 2022). Hydrological factors, such as water temperature and discharge, which are susceptible to climate change, strongly influence the motivation for migration (Baer et al. 2018;Lopes et al. 2018;García-Vega et al. 2022;Harada and Nagayama 2022). ...
... Breeding migration is a key life-history event for the migratory species, and its spatiotemporal dynamics are affected by various environmental factors (Baer et al. 2018;Benitez and Ovidio 2018;Lopes et al. 2018;Hewitt et al. 2022;Stott and Miner 2022). Hydrological factors, such as water temperature and discharge, which are susceptible to climate change, strongly influence the motivation for migration (Baer et al. 2018;Lopes et al. 2018;García-Vega et al. 2022;Harada and Nagayama 2022). Identifying and quantifying the role of hydrological factors as migration triggers will also provide a valuable reference for future conservation and fishery management applications. ...
This study examined the combined effects of water temperature and discharge on the downstream spawning migration of ayu Plecoglossus altivelis, with reference to their hierarchical interactions and relative importance in the Nagara River in central Japan. Fish catches from the sebari-ami traditional fishing method, which can catch ayu migrating downstream for spawning, were recorded at seven fishing sites from September to November in 2020 and 2021. Overall, decision trees showed that the daily catch increased when the daily water temperature (the mean of the 24-hour data) fell below approximately 18 °C and when the water discharge increased regardless of intensity, indicating the hierarchical effects of these hydrological factors on the downstream spawning migration of ayu. After mid-October, when the daily water temperature rapidly dropped below approximately 15 °C, daily catches further increased, and large catches occurred on days of increased discharge, indicating active migration occurring below 15 °C. At a spawning site, the proportion of large individuals (> 80 g) was high in the early phase of the spawning seasons. These findings can help accurately predict the timing of ayu spawning migration and support sustainable fishing practices within a context of climate warming.
... Nevertheless, their migration trends are often not well understood, and much of the migration variance is not properly explained by the few environmental variables typically used in models [16]. Different fish species have been found to use different environmental cues to time their reproductive migration, such as photoperiod [17], temperature [18], discharge [19], hour in a day [20], lunar cycle [21], atmospheric pressure [22], or precipitation [23]. In fishes, especially the first two environmental cues are believed to be fundamentally important for gonadal maturation and reproductive migrations [24,25]. ...
... Together with photoperiod, which regulates physiological processes, water temperature appears to be a determining cue that interacts with the photoperiod signal to synchronize the final stages of reproductive development with optimal environmental conditions [26]. In weak seasonal variation in photoperiod and temperature, such as the ones in tropical regions, environmental cues related to current weather conditions and tidal strength may be more relevant for the timing of the onset of migration or reproduction itself [23,27]. In the case of nocturnal migrations aimed at avoiding the risk of predation on migrating adults, low light levels associated with the phase of the moon may also be an important cue for migration [28]. ...
... Timing of reproductive migrations have mostly been studied in terms of environmental cues that trigger migration from feeding to breeding grounds [23]. However, upon arrival near breeding grounds, some species gather at staging grounds days to weeks before the onset of reproduction, waiting for specific environmental cues that determine the final timing for the onset of reproductive effort [29,30]. ...
Background
Animal migrations are periodic and relatively predictable events, and their precise timing is essential to the reproductive success. Despite large scientific effort in monitoring animal reproductive phenology, identification of complex environmental cues that determine the timing of reproductive migrations and temporal changes in the size of reproductive aggregations in relation to environmental variables is relatively rare in the current scientific literature.
Methods
We tagged and tracked 1702 individuals of asp (Leuciscus aspius), a large minnow species, and monitored with a resolution of one hour the size of their reproductive aggregations (counts of sexes present at the breeding grounds standardized by the sum of individuals in the season) over seven breeding seasons using passive integrated transponder tag systems. We examined the size of reproductive aggregations in relation to environmental cues of day number within a reproductive season (intra-year seasonality), water temperature, discharge, hour in a day (intra-day pattern), temperature difference between water and air, precipitation, atmospheric pressure, wind speed and lunar phase. A generalized additive model integrating evidence from seven breeding seasons and providing typical dynamics of reproductive aggregations was constructed.
Results
We demonstrated that all environmental cues considered contributed to the changes in the size of reproductive aggregations during breeding season, and that some effects varied during breeding season. Our model explained approximately 50% of the variability in the data and the effects were sex-dependent (models of the same structure were fitted to each sex separately, so that we effectively stratified on sex). The size of reproductive aggregations increased unimodally in response to day in season, correlated positively with water temperature and wind speed, was highest before and after the full moon, and highest at night (interacting with day in a season). Males responded negatively and females positively to increase in atmospheric pressure.
Conclusion
The data demonstrate complex utilization of available environmental cues to time reproductive aggregations in freshwater fish and their interactions during the reproductive season. The study highlights the need to acquire diverse data sets consisting of many environmental cues to achieve high accuracy of interpretation of reproductive timing.
Graphical abstract
... The secretion of the steroid hormone melatonin from the pituitary gland, which is induced by dark nights, has a large in uence on lunar-related spawning. Several investigations have found that Prochilodontidae sh spawning migration and gonad development take place during the new moon phase [22]. ...
Responses to lunar cycles vary amongst taxonomically distinct marine creatures. We calculated larval fish diversity and density over four successive lunar phases: new, first quarter, third quarter, and full. A bongo net with a mesh size of 300µm mesh size from a tropical nearshore water of the Straits of Malacca, Malaysia. We collected 5,305 fish larvae from 27 different families. Diversity indices for richness (Shannon-Wiener, H), dominance (Simpson, D) and evenness (Pielou, E) decreased from the full lunar phase onwards. Larval density, on the other hand, was much higher during the new lunar phase. We also determined that the larval fish family was either selectively present during each lunar phase or had a peak density during full and new moons. The larval fish assemblages revealed a preference for spawning events during the lunar phases. Human activities in the vicinity area are advised to be minimised during this period to mitigate harmful influence on larval fish recruitment in the nearshore area.
... For an already built fishway, minimum flow releases are often combined with weirs and pools as a means of wetting the channel at low discharge (Fjellheim and Raddum 1996;Rørslett and Johansen 1996), preventing migrating fish from being stranded and dried up due to a lack of connectivity within the fishway. In some cases, it may be best to prevent entry into the fishway during low flow, or to provide high flow provisions to the fishway over short periods to trigger migration in a large proportion of fish aggregated below the fishway (Lopes et al. 2018). ...
Human-induced climate change is already apparent through warming temperatures, altered precipitation, and greater prevalence of extreme weather events (e.g., droughts and floods) all of which are anticipated to be exacerbated in the foreseeable future. Meanwhile, demand for hydropower generation is expected to increase and future hydropower developments will be important for mitigating climate change. Yet, climate change will affect the natural flow regimes, which will undoubtedly impact hydropower operations (e.g., storages and releases), and in turn the impact of altered hydropower operations on the discharge and consequence to fish that live in these regulated systems. Here, we synthesize the current knowledge of climate-induced alterations to hydropower operations and the expected impacts of altered hydropower operations on riverine fishes. We also consider what is needed to adapt to the way environmental threats will change over the typical 50–100 year lifespan of such facilities. Based on our synthesis, we anticipate the impact on native riverine fishes will increase in severity moving forward. Fortunately, we can take proactive measures to mitigate the adverse, yet synergistic, impacts of hydropower and climate change on aquatic ecosystems. Doing so will require extensive foresight, planning, and incorporating novel mitigation strategies into hydropower development. We also call for greater involvement of fisheries professionals in such processes to ensure that fish are not an afterthought. Failure to better consider how to future-proof hydropower in the context of climate change threatens not only fish populations but also the humans that depend on them for livelihoods, nutrition, and socio-cultural benefits.
Graphical abstract
