Traits Of Fish Research Articles

Effects of light and artificial fish shelter (PVC pipe) on some phenotypic traits of stinging catfish (Heteropneustes fossilisBloch, 1794)

Light and shelter are very important ecological factors that can affect many traits of fish. Therefore, a study was conducted to explore the effect of light and shelter on some phenotypic traits of stinging catfish (Heteropneustes fossilis Bloch, 1794). During experiment, equal-sized juveniles (mean ± SE: 9.04 ± 0.09 cm) were collected and reared in aquariums dividing into four treatment groups, such as T1 (0L:24D without pipe), T2 (0L:24D with pipe), T3 (12L:12D without pipe) and T4 (12L:12D with pipe). Each treatment had 36 fish, which were randomly distributed into three replications. The fish were kept up to 120 days, and then, the growth performance and skin colour were analysed. The results showed that both lighting and shelter conditions as well as their interactions had significant effects on some traits expression. The analyses revealed that lighting condition significantly influenced body area, head width and skin coloration, while shelter condition significantly affected total and standard length, body area, and their interaction showed significant effects on body area, head width and anal fin length. Thus, this study indicates that stinging catfish show better growth performance and colour patterns especially in dark and sheltered conditions which could be recommended for the successive production of this highly priced fish species.

Fish trait preferences: a review of existing knowledge and implications for breeding programmes

AbstractContinued growth of the aquaculture sector will rely on the availability of fish with traits that respond to the needs and preferences of these users along the value chain. Such trait responsiveness requires that fish breeding programmes have reliable knowledge of these users’ trait preferences. The present study found from a non‐systematic literature review, that no fish breeding programme had reported user preference in their product‐profile design. A systematic literature review was then carried out to identify studies which have assessed fish trait preferences of different users, categorized by market segment and gender. This identified relatively few such studies (n = 28 total), highlighting a lack of published information in this area. Some preferences were shared broadly among a range of users (e.g. size measures such as length or weight). A number of traits were of restricted preferences such as survival (important to farmers, hatchery and nursery operators) while appearance or taste dominated in the preferences for traders and consumers. Some of the preferred traits of users are not targets for selection in breeding programmes reported to date (e.g. body texture, nutritional value) The review also makes clear that there can be range of preferences that differ by gender and social or economic status of the user. Greater acceptance of more sustainable aquaculture products will require improved information on user preferences. This will need innovative tools to translate generally expressed preferences into well‐defined traits and to assess their trade‐offs for their incorporation in genetic improvement programmes that will better target benefits to users.

Effects of Copper Oxide Nanoparticles (CuO-NPs) on Parturition Time, Survival Rate and Reproductive Success of Guppy Fish, Poecilia reticulata

The purpose of the present study was to evaluate acute and chronic effects of CuO-NPs on survival rate and reproductive success of mature guppy (Poecilia reticulata) and their larvae. During the acute toxicity test, mature fish and their larvae were exposed to series of different concentrations of (0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 mg L−1) CuO-NPs for 96 h and during the chronic phase we exposed mature individuals to 0, 5, 10 mg L−1 of CuO-NPs for 8 weeks. Results showed a significant correlation between mortality rate and CuO-NPs concentrations. Furthermore, the LC50 96 h of CuO-NP for mature and larvae of P. reticulata were 28.354 and 5.649 mg L−1, respectively. Finally, the fish exposed to series of CuO-NP concentrations exhibited various clinical signs such as darkening of skin, anxiety and death with open mouth. Chronic exposure affected reproductive traits of fish, with greatest effects reported in treatment with 10 mg L−1 of CuO-NPs. Those individuals had lowest reproductive success, prolonged parturition time and highest mortality rate. Results highlight toxic potential of CuO-NPs on mature and larvae fish, both increased mortality rate and lower reproductive success, by increasing parturition time and reducing number of larvae.

Linking fish trait responses to in‐stream habitat in reconstructed valley‐plugged stream reaches of the Coastal Plain, U.S.A.

Valley‐plug formation is a challenging consequence of stream channelization especially in physiographic regions with highly erodible soils. Upstream channel degradation and incision results in accelerated sediment delivery processes wherein downstream aggradation decreases stream power and creates sand‐clogged channels. Channel reconstruction is now meeting hydrogeomorphic goals related to valley‐plug remediation, yet there exists a need to understand how this practice also facilitates ecological restoration. We evaluated fish trait response to in‐stream habitat conditions in channelized, recently restored, and “least‐disturbed” reference reaches of Coastal Plain streams in West Tennessee. Restored reaches were ecologically similar to channelized reaches, having higher proportions of nest‐guarding omnivores that were correlated with higher percentages of pool habitats and lower wetted width:depth ratios compared to reference reaches. Reference reaches had higher proportions of fast‐water dwelling and specialized insectivores that were correlated with high abundance of large woody debris, high‐wetted width:depth ratios, and low percentages of pool habitats. We conclude that in‐stream habitats in reconstructed channels have yet to promote reach‐scale ecological restoration relative to fish assemblage organization because trait‐habitat associations were not similar to reference conditions. However, our results lend to the development of ecological restoration targets that can be incorporated in future channel reconstruction projects in valley‐plugged, channelized streams of the Coastal Plain.

Trait‐based ecology of fishes: A quantitative assessment of literature trends and knowledge gaps using topic modelling

AbstractSpecies traits are a new data currency to enhance our understanding of ecological patterns and processes. Trait‐based studies of fishes are numerous in comparison with other animal groups, reflecting the diversity of fish forms and functions they provide to aquatic ecosystems. We conduct a retrospective examination of literature to identify knowledge gaps and provide guidance for future research in trait‐based fish ecology. We apply an automated text mining and topic modelling to track the evolution of research topics within peer‐reviewed articles of functional traits in marine and freshwater fishes published over the past half century, explore the inter‐connections among those topics and identify emerging avenues for investigation. By mapping the topic landscape of the literature, 16 latent topics emerged that vary in their prevalence. Our results show a decline in the frequency of studies using reproductive traits to model and explore the way fish allocate energy for reproduction, and increase in studies reporting functional diversity metrics and utilizing the concept of multivariate functional space. Research focused on contributions of fish traits to ecosystem functioning also has increased in frequency. We revealed large gaps in information between growing and decreasing topics and that these gaps were derived from different types of traits being considered. We suggest that scientists break‐free from the traditions of their research field by targeting investigations that: (a) apply functional diversity metrics to a broader assortment of traits, (b) focus on traits influencing energy allocation to growth/reproduction and (c) integrate trophic‐web and behavioural studies with other topics.

Changing patterns of growth in a changing planet: How a shift in phenology affects critical life‐history traits in annual fishes

Abstract Changes to the timing of key life‐cycle events can alter selection on life‐history traits and have the potential to drive a cascade of effects at the community level. We investigated how the growth rate and sexual maturation of two annual killifish species (Austrolebias bellottii and Austrolebias nigripinnis) were altered by a change in the pattern of precipitation. These are annual species, endemic to ephemeral pools, persist in desiccated sediment as partly developed embryos. We sampled 18 pools supporting populations of both species in a Pampa region adjacent to the Rio Negro in western Uruguay throughout the austral winter of 2015. Fish growth and maturation were monitored from pool inundation to habitat desiccation, along with environmental variables. The region experienced an unprecedented mid‐winter desiccation of pools that usually contain water from autumn to late spring, typically only desiccating in summer. Many desiccated pools were re‐inundated from later rains, generating a second cohort of killifish in some pools (53%) in response to atypical conditions. The second cohort developed more rapidly than the first, with 40% earlier attainment of asymptotic body size. Rapid development of second‐cohort fish was associated with earlier maturation and greater investment in reproductive tissue. The study demonstrated the capacity of annual fish to express developmental plasticity that buffered the negative consequences of an atypical seasonal climatic cycle. The capacity of these annual fishes to cope with alternations to their life cycle will depend on the ability of egg banks in the sediment to tolerate an increased unpredictability of precipitation. Overall, we demonstrate how phenotypic plasticity can mitigate the negative impacts of climate change and associated altered phenology.

Nearshore environmental conditions influence larval growth and shape changes for a temperate rocky reef fish

Coastal upwelling and other oceanographic processes, exert influences on phenotypic traits of early life stages of marine fishes. However, it remains to elucidate the environmental effects on the morphology of fish larvae. Using geometric morphometrics and otolith microstructure of a temperate rocky reef fish, the labrisomid blenny Auchenionchus crinitus (Labrisomidae), we studied the larval growth, mortality and morphospace of four consecutive cohorts, hatched between austral winter and summer off central Chile. We hypothesize that coastal environmental conditions will influence early life traits of this cryptobenthic fish. The winter cohort, which inhabited colder and well-mixed nearshore waters, grew more slowly and had a more hydrodynamic head shape, while the summer cohort, which lived in warmer and stratified waters, grew faster, but had a more robust shape. Cohorts expressed less ontogenetic allometry as seasons progressed, suggesting that the seasonal increment in water temperature reduces the shape changes with size during larval development. Also, slower- and faster-growing larvae showed large variation from the consensus shape, e.g. had the largest shape disparity. Nonetheless, all cohorts showed similar mortality rates during the first month of life. Finally, increases in zonal wind stress (i.e. sea breeze) and decreases in the sea temperatures (i.e. upwelling events) increased the growth rates of older (> 15 days old) larvae. Therefore, for this cryptobenthic species, differences in growth rate and body shape are related to the seasonal increase in water temperature, and local-scale meteorological conditions.

Numerical study of an Undulatory Airfoil with different leading edge shape in power-extraction regime and propulsive regime

Except for providing propulsion motion, the undulating fins can also be used as one type of flow-driven energy harvester, like a wind turbine. In this paper, the baseline NACA0012 airfoil was used to obtain a series of airfoils with different leading-edge radiuses which were then used as two-dimensional simplified models of a fish body undertaking undulating motion. With the aid of CFD software, the effects of leading-edge shape and Reynolds number on the hydrodynamic characteristics of an undulatory airfoil in its energy-extraction regime and propulsion regime were studied and compared. The results indicated that the energy extraction efficiency of the undulatory airfoil with a thicker leading-edge becomes correspondingly higher at moderate to high Reynolds numbers. However, the energy extraction efficiency is hardly affected by the geometric shape changes of the undulatory airfoil leading edge at low Reynolds numbers. On the other hand, when the undulatory airfoil is in the propulsive regime, it seems that the airfoil with smaller leading-edge radius can achieve a higher propulsive efficiency which coincides with appearance traits in fish observed in nature. In addition, the propulsive performance of the undulatory airfoil can be considerably affected by its leading-edge radius at only low and moderate Reynolds numbers.

Construction of a high-density genetic linkage map and QTL mapping for growth traits in Pseudobagrus ussuriensis

Growth traits of fish are controlled by multiple gene loci called quantitative trait loci (QTLs). For identification of these QTLs, a high-density genetic linkage map is necessary. In the present study, a high-resolution genetic linkage map was constructed for the Ussuri catfish Pseudobagrus ussuriensis using SNPs generated using 2b-RAD technology in an F1 family. The consensus map of P. ussuriensis contained 7435 SNPs that were distributed among 26 linkage groups (LGs) and spanned 2656.718 cM with a resolution of 0.357 cM and a genome coverage rate of 98.926%. Both of the sex-specific maps had 26 LGs: 3914 SNPs were located in the female map with a map length of 2566.285 cM, an average interval resolution of 0.656 cM and a genome coverage rate of 98.913%, and the male map comprised 4411 SNPs spanning 2084.518 cM with a resolution of 0.473 cM and a genome coverage of 98.914%. The average recombination rate ratio of female to male was 1.293:1. Comparative genome mapping revealed 21 1:1 and five 1:2 syntenic relationships between P. ussuriensis LGs and channel catfish chromosomes. Based on the consensus map, 28 growth-trait-related QTLs (one genome-wide and 27 chromosome-wide) were identified in five LGs (LG1, LG4, LG5, LG16 and LG19) with a phenotypic variance explained (PVE) value range of 11.9–20.5%. The high-density genetic linkage map obtained in this study will provide important information for future genetic, genomic and evolutionary studies of P. ussuriensis, and the QTLs will be useful tools for growth mechanism analysis and marker assisted selection (MAS) breeding in this fish.

Correlation analysis of mandarin fish (Siniperca chuatsi) growth hormone gene polymorphisms and growth traits

Screening of trait-associated molecular markers can be used to enhance the efficiency of selective breeding. Previously, we produced the first high-density genetic linkage map for the mandarin fish (Siniperca chuatsi) and identified 11 quantitative-trait loci significantly associated with growth, of which one is located within the growth hormone (GH) gene. To investigate the GH gene polymorphisms and their correlation with growth, the complete sequence was cloned and 32 single-nucleotide polymorphisms (SNPs) and one simple-sequence repeat (SSR) were identified. Of which, eight SNPs (G1-G8) and the SSR (GH-AG)were selected for genotyping and correlation analysis with growth traits in a random population. The results showed that the four novel polymorphicloci (G1, G2, G3 and GH-AG) were significantly correlated with growth traits of mandarin fish (P < 0.05). Of these, G1, G3 and GH-AG showed highly significant correlations with multiple growth traits (P < 0.01) and the combined SNP analysis showed that G1-G3 formed four effective diplotypes (D1-D4), among which D1 was highly significantly greater than D4 (P < 0.01) for some important growth traits. In conclusion, our results show that the four polymorphic loci G1-G3 and GH-AG within the mandarin fish GH gene are significantly correlated with growth traits and could be used as candidate molecular markers for selective breedingof superior varieties of mandarin fish.

The relationship between geographic range extent, sea surface temperature and adult traits in coastal temperate fishes

AbstractAimWe use publicly available data to assess the influence of ocean basin, various biological traits and sea surface temperature on biogeographic range extent for temperate, continental shelf fish species spanning 141 families.LocationCoastal waters of the temperate Northern Hemisphere.TaxonTeleost Fishes (Infraclass Teleostei).MethodsWe assess the relationship between species range extent and depth range, maximum body length, schooling behaviour and use of multiple habitats for 1,251 species of northern, temperate, continental shelf fishes in different basins (Atlantic vs. Pacific) and margins (east vs. west) using linear mixed‐effect models with family and genus as nested random effects. We further assess the relationship between species range endpoint distribution and latitudinal temperature gradient using generalized linear models.ResultsWe found strong positive relationships between the number of species northern range endpoints and the steepness of the latitudinal sea surface temperature gradient on the western margins of the Atlantic and Pacific Oceans, but no relationship on the eastern margins of these ocean basins. The strongest predictors of range extent in our global model are ocean basin/margin and depth range. Maximum body length, schooling behaviour and use of multiple habitats are also significant predictors of range extent in the global model. The factors influencing range extent differ by basin and margin.Main conclusionsThere are broad differences in patterns of species range extent and distribution of species ranges among basins/margins. These differences appear to be driven in part by variation in latitudinal water temperature gradient between basin margins. Our data suggest that sharp latitudinal temperature gradients may pose a barrier to dispersal and range expansion along the western margins of the Atlantic and Pacific Oceans, but not necessarily on the eastern margins. Our work also suggests that several post‐settlement traits may be associated with range extent either globally or in some temperate basins.

Trade-offs between life-history traits in a coldwater fish in the Mediterranean Sea: the case of blue whiting Micromesistius poutassou.

A combination of traditional and emerging methodologies was used to assess the trade-offs between several life-history traits (linked to reproduction and condition) and parasitism in a commercially-exploited cold-water species, blue whiting Micromesistius poutassou, in the Mediterranean Sea. The use of histological and gravimetric methods revealed conflicting evidence as to the fecundity type (indeterminate or determinate) of this species. Moreover, there seem to be condition-mediated compensations between egg quality and egg quantity. The effects of parasitism on reproduction and condition are species-specific and occur mainly at high intensities of infection; they include a lower batch fecundity (affecting reproductive potential), a higher hepatosomatic index and a higher spleen-somatic index. Considering the fact that larger fish spawn more eggs and that the minimum landing size is lower than the size at maturity, these results may have implications for the future management of M. poutassou stocks in the Mediterranean Sea. Local environmental conditions may account for geographical differences regarding infection in M. poutassou. Altogether, the results support the idea that the complex trade-offs between parasitism, reproduction and condition need to be considered in order to understand the status of cold-water species such as M. poutassou.

How deforestation drives stream habitat changes and the functional structure of fish assemblages in different tropical regions

Abstract Deforestation can modify stream habitat and the functional structure of fish assemblages. The aims of this study were (a) to identify whether deforestation has a similar effect on local habitats from two biogeographically distinct river basins in a tropical region; (b) to identify how fish trait–habitat relationships were influenced by deforestation; and (c) to compare functional redundancy patterns in these basins. Environmental and biological variables were obtained for 160 stream reaches, 85 located in the Alto Paraná River basin and 75 in the Machado River basin. Traits were associated with body size, habitat preference, food items and foraging period. Linear models were constructed to verify the environmental convergence of habitats across streams from the Alto Paraná and the Machado basins. An RLQ and a fourth‐corner analysis were conducted to investigate how deforestation affected habitat variables and trait–habitat relationships. The nearest relative index (NRI) was used as a functional redundancy measure. Deforestation led to a similar habitat gradient from streams with a higher proportion of coarse roots in more forested catchments to streams with streamside grasses, bare soil and unconsolidated substrate in more deforested catchments; however, a general pattern of fish trait–habitat relationships was not identified across basins. Functional redundancy was associated with a long history of habitat loss in the Alto Paraná streams, whereas functional complementarity was related to more recent and less intense habitat loss in Machado streams. We believe that differences in regional species pools and historical processes between the basins influenced the fish functional responses to deforestation. Nevertheless, the results highlighted the importance of stream habitat heterogeneity and the presence of preserved forest fragments in a region to prevent the loss of unique traits. Decision‐makers should therefore maintain large forest fragments and restore riparian forests to preserve stream habitat and the functional structure of fish assemblages.

Enhanced ambient UVB radiation affects post-mating, but not pre-mating sexual traits in a fish.

Organisms inhabiting shallow aquatic habitats currently experience increasing levels of solar ultraviolet B radiation (UVB). UVB causes damage on cellular and molecular levels and can affect associated life-history traits either through direct exposure or indirectly through oxidative stress generation. We examined UVB effects on pre- and post-mating sexual traits in three-spined stickleback fish (Gasterosteus aculeatus). Adult, reproductively non-active males were assigned to two exposure treatments under semi-natural conditions in an outdoor experiment; one group received natural radiation (UVBnormal) whilst the other group received additional UVB (UVBenhanced). After two months, colour metrics were used to quantify male breeding colouration as pre-mating trait. At the post-mating stage, sperm morphology, number and movement as well as testes mass were determined. Males did not significantly differ in sexual ornamentation between treatments, but UVBenhanced fish had smaller testes as well as fewer and shorter sperm than UVBnormal fish. Sperm movement was not significantly different between treatments. However, in UVBenhanced males, linear and progressive movement of sperm was positively correlated with sperm morphology (head-to-tail length ratio), whereas in UVBnormal males this relationship was negative (but not significant). Additionally, there was a significant treatment by body condition interaction concerning head-to-tail length ratio, i.e. head-to-tail length ratio increased with condition in UVBnormal males whereas there was no relationship in UVBenhanced fish. Our findings reveal that increased UVB levels influence post-mating fitness-relevant traits in males whilst having no significant impact on pre-mating sexual traits, suggesting selectiveUVB-effects at the gamete level with consequences for reproductive performance.

Subtle temperature increase can interact with individual size and social context in shaping phenotypic traits of a coldwater fish.

Temperature and individual egg size have been long studied in the development of fishes because of their direct effects on individual fitness. Here we studied the combined effects of three important factors for fish development, i.e. egg size, social environment and water temperature. Arctic charr (Salvelinus alpinus), a coldwater fish known to be phenotypically plastic, was used to investigate how these factors may affect growth and foraging behaviour of juvenile fish in a benign environment. We accounted for the social environment during early development by comparing fish raised in groups and in isolation. We examined the effect of egg size and a 2 °C difference on foraging behaviour, activity and growth a few weeks after first feeding. Growth trajectories of fish originating from large and small eggs were similar within each temperature: larger fish coming large eggs were at all time larger than smaller fish. There was no indication that small fish raised at a higher temperature grew faster than larger fish raised at a lower temperature. A 2 °C difference in temperature affected the behaviour of fish differently according to body size and/or social context. The foraging probability difference between fish raised in groups and fish briefly isolated was higher at 4.5 °C than at 6.5 °C for both size fish. Finally, there was no repeatability in foraging behaviour and mobility for isolated individuals. These results highlight the importance of small changes in temperature when evaluating growth and behaviour of fishes, and reveal the importance of considering the interaction of temperature with other factors, e.g. individual size and social environment, especially at early stages of development in fishes. We discuss these findings in the context of rapid changes in temperature and how temperature and its interaction with other factors may affect the phenotypes, ecology and evolution of coldwater fishes.

Plant Dispersal in a Temperate Stream by Fish Species With Contrasting Feeding Habits: The Role of Plant Traits, Fish Diet, Season, and Propagule Availability

Whether fish mediate plant dispersal in temperate freshwaters is largely unknown. A prerequisite for successful dispersal is ingestion and surviving the journey in the intestinal tract. This study asks whether plant propagules are being ingested under field conditions and what factors shape dispersal potential, focusing on differences across plant species and propagule form (seed or fragment), seasonal differences and plant and fish traits that facilitate dispersal. We focused on three common fish species reported to differ in foraging strategy. Fish were caught monthly over a one-year period in a Dutch lowland stream. Before they were returned to the stream, fish were kept in water for 26 h and their faeces were collected, resulting in 150 faecal samples. Excreted animal remains and plant propagules were identified and enumerated. Plant propagules were tested for viability. In total, 88,579 vegetative fragments of vascular plants, 316 of mosses and 14 of charophytes were identified. Viability was low (<<1%) except for mosses (53.5%). Roach (Rutilis rutilis) and Rudd (Scardinius erythrophthalmus) displayed a preference for filamentous algae and certain plant species (i.e. Elodea nuttallii and Lemna sp.), likely because they were more palatable. Of the 1787 generative propagules of vascular plants that were identified, 120 germinated (6.7%), representing 15 species. Betula pendula, Juncus effusus and Poa trivialis were most abundant. Tench (Tinca tinca) egested most seeds, despite being the least herbivorous species. Particularly, germination was high for seeds that were light (<1.07 mg) and that floated for a long time. Our results show that fish do ingest plant propagules under field conditions and that fish can contribute to vegetative dispersal of vascular plants and several aquatic and riparian moss species. Ingestion of propagules is affected by water temperature and season, their availability in the propagule bank, and their palatability. Both seed traits (related to buoyancy, size and hardness) and fish traits (related to size and identity) were important. Despite substantial dietary overlap, the three fish species displayed subtle differences in their diet, and together can act as vectors for the dispersal of a range of plant and moss species of freshwater systems.

QTL Mapping for Red Blotches in Malaysia Red Tilapia (Oreochromis spp.).

Body color is an interesting economic trait in fish. Red tilapia with red blotches may decrease its commercial values. Conventional selection of pure red color lines is a time-consuming and labor-intensive process. To accelerate selection of pure lines through marker-assisted selection, in this study, double-digest restriction site-associated DNA sequencing (ddRAD-seq) technology was applied to genotype a full-sib mapping family of Malaysia red tilapia (Oreochromis spp.) (N = 192). Genome-wide significant quantitative trait locus (QTL)-controlling red blotches were mapped onto two chromosomes (chrLG5 and chrLG15) explaining 9.7% and 8.2% of phenotypic variances by a genome-wide association study (GWAS) and linkage-based QTL mapping. Six SNPs from the chromosome chrLG5 (four), chrLG15 (one), and unplaced supercontig GL831288-1 (one) were significantly associated to the red blotch trait in GWAS analysis. We developed nine microsatellite markers and validated significant correlations between genotypes and blotch data (p < 0.05). Our study laid a foundation for exploring a genetic mechanism of body colors and carrying out genetic improvement for color quality in tilapia.

A negative correlation between behavioural and physiological performance under ocean acidification and warming

Many studies have examined the average effects of ocean acidification and warming on phenotypic traits of reef fishes, finding variable, but often negative effects on behavioural and physiological performance. Yet the presence and nature of a relationship between these traits is unknown. A negative relationship between phenotypic traits could limit individual performance and even the capacity of populations to adapt to climate change. Here, we examined the relationship between behavioural and physiological performance of a juvenile reef fish under elevated CO2 and temperature in a full factorial design. Behaviourally, the response to an alarm odour was negatively affected by elevated CO2, but not elevated temperature. Physiologically, aerobic scope was significantly diminished under elevated temperature, but not under elevated CO2. At the individual level, there was no relationship between behavioural and physiological traits in the control and single-stressor treatments. However, a statistically significant negative relationship was detected between the traits in the combined elevated CO2 and temperature treatment. Our results demonstrate that trade-offs in performance between behavioural and physiological traits may only be evident when multiple climate change stressors are considered, and suggest that this negative relationship could limit adaptive potential to climate change.

Trait–environment relationships in Amazon stream fish assemblages

AbstractStudies of trait–environment relationships provide important tools for the prediction of the response of biological communities to environmental alterations. The Amazon basin presents enormous potential for the development of research on this type of relationship, given the diversity of both its fish fauna and the aquatic ecosystems this fauna inhabits. The present study investigated the association between local environmental variables and the functional traits of fish in 54 streams of six major Amazonian basins. We identified the relationship between the characteristics of the streams (channel morphology, channel habitat units, riparian vegetation cover, large woody fragments and instream cover for aquatic organisms) and fish traits related to locomotion, habitat use and feeding behaviour. The fish fauna of the broader, deeper and more slowly flowing streams was dominated by nektobenthic species that exploit autochthonous resources such as fish and invertebrates. In narrow, fast‐flowing streams, by contrast, there was a predominance of benthic fishes with varying feeding habits, including periphytivorous and invertivorous species. Narrow, shady streams were inhabited by nektonic species adapted for the exploitation of resources from the marginal vegetation. The results of this study contribute to the understanding of the association between the functional structure of fish assemblages and local environmental variables in Amazonian streams. We hope that these findings will stimulate further research into the natural variation in stream fish assemblages that will ensure the development of more effective management strategies that better protect these important aquatic ecosystems.

Spatio-temporal variation in marine fish traits reveals community-wide responses to environmental change

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 610:205-222 (2019) - DOI: https://doi.org/10.3354/meps12826 Spatio-temporal variation in marine fish traits reveals community-wide responses to environmental change Esther Beukhof*, Tim S. Dencker, Laurene Pecuchet, Martin Lindegren Centre for Ocean Life, National Institute of Aquatic Resources (DTU Aqua), 2800 Kongens Lyngby, Denmark *Corresponding author: estb@aqua.dtu.dk ABSTRACT: Marine ecosystems are exposed to a range of environmental and anthropogenic stressors, including climate change and overexploitation. A promising way towards understanding the impacts of such stressors on community composition is by considering species traits rather than species identity. Here, we describe the spatio-temporal dynamics in fish community traits using >30 yr of species abundance data from the North Sea combined with trait information on body size, life history, growth rate, reproduction and trophic level for demersal fish species in the area. We assessed whether the derived patterns and trends in community-weighted mean traits could be explained by a range of environmental stressors and fishing. Our results revealed strong spatial structuring and long-term changes in the trait composition of North Sea fish, with temporal changes not being uniformly distributed in space. Among the environmental drivers investigated, depth was one of the best predictors, primarily explaining the spatial variation in lifespan, growth rate, trophic level and fecundity. This can be explained by variables that co-vary with depth, e.g. temperature, seasonality, salinity and productivity. Finally, we found only weak relationships between fishing and the spatial variation of traits, suggesting that the spatial trait composition of the community is mostly determined by the environment. Yet, long-term changes in trait composition, primarily in body size, have previously been shown to be affected by size-selective fishing. Our study exemplifies how traits can be used to summarize complex community dynamics and responses to environmental and anthropogenic stressors as well as their usefulness for ecosystem-based management. KEY WORDS: Marine fish · Traits · Spatio-temporal · Community weighted mean · North Sea · Community composition · Climate change · Fishing Full text in pdf format Supplementary material PreviousCite this article as: Beukhof E, Dencker TS, Pecuchet L, Lindegren M (2019) Spatio-temporal variation in marine fish traits reveals community-wide responses to environmental change. Mar Ecol Prog Ser 610:205-222. https://doi.org/10.3354/meps12826 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 610. Online publication date: February 01, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.