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22 pages, 4536 KiB

Open AccessArticle

Dietary Habits of Hardhead (Ariopsis felis) and Gafftopsail (Bagre marinus) Catfish Revealed through DNA Barcoding of Stomach Contents

by Ana R. Osowski, Matthew B. Jargowsky, Pearce T. Cooper, Sean P. Powers and J. Marcus Drymon

Fishes 2023, 8(11), 539; https://doi.org/10.3390/fishes8110539 - 31 Oct 2023

Cited by 1 | Viewed by 1869

Abstract

A better understanding of trophic interactions between hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus) is crucial for developing multi-species management strategies for the northern Gulf of Mexico (GOM). These two species are often aggregated in food web [...] Read more.

A better understanding of trophic interactions between hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus) is crucial for developing multi-species management strategies for the northern Gulf of Mexico (GOM). These two species are often aggregated in food web models; however, limited data are available to substantiate this approach. Therefore, the present study aimed to describe the dietary habits of hardhead catfish and gafftopsail catfish using analysis of stomach contents aided by DNA barcoding. Hardhead (n = 693) and gafftopsail (n = 655) catfish were sampled in the northern GOM from 2015–2019 using both fisheries-dependent and -independent techniques. The average percent number (%N), average percent mass (%M), prey specific number (%PN), prey specific mass (%PM), and prey-specific index of relative importance (%PSIRI) were computed to quantify prey species. The stomach content analysis identified distinct differences in diet between hardhead and gafftopsail catfish. Crustaceans were the most important prey for hardhead catfish, while gafftopsail catfish showed a significantly broader dietary breadth and were primarily piscivorous. Multivariate analyses indicated that the location of capture explained the greatest amount of diet variability for both species. These findings address fundamental knowledge gaps regarding the dietary habits of hardhead and gafftopsail catfish in northern GOM ecosystems. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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7 pages, 893 KiB

Open AccessCommunication

Regional Variation in the Trophic Ecology of Wahoo (Acanthocybium solandri) in the Western Atlantic Ocean

by Brendan Gough, Alexandra Prouse, Michael A. Dance, R. J. David Wells and Jay R. Rooker

Fishes 2023, 8(10), 519; https://doi.org/10.3390/fishes8100519 - 20 Oct 2023

Viewed by 1433

Abstract

Intrinsic tracers, such as stable isotopes of carbon and nitrogen, are common dietary markers that accumulate in the muscle tissue of consumers and can be used to determine the dietary sources and trophic positions of consumers. The aim of this study was to [...] Read more.

Intrinsic tracers, such as stable isotopes of carbon and nitrogen, are common dietary markers that accumulate in the muscle tissue of consumers and can be used to determine the dietary sources and trophic positions of consumers. The aim of this study was to assess regional variation in the trophic ecology of wahoo (Acanthocybium solandri) using bulk stable isotopes. Muscle biopsies of wahoo were collected from four regions in the western Atlantic Ocean: the eastern Gulf of Mexico, western Gulf of Mexico, Northwest Atlantic Ocean, and Caribbean Sea. Muscle tissue δ¹³C and δ¹⁵N values for wahoo ranged from −15.8‰ to −18.8‰ and from 7.2‰ to 12.8‰, respectively. Wahoo collected in the Caribbean Sea displayed the highest mean δ¹³C value (−16.3‰), and individuals from this region were statistically different from the three other regions sampled. Mean δ¹⁵N values were elevated for wahoo collected in the eastern and western Gulf of Mexico (11.4‰ and 11.1‰, respectively), and the values were over 2‰ higher than samples from the Northwest Atlantic Ocean and Caribbean Sea. Trophic position (TP) was estimated using δ¹⁵N baselines (zooplankton) and δ¹⁵N wahoo values for each region, and mean TP was 0.4 to 0.9 higher in the Caribbean Sea relative to the three other regions, suggesting that wahoo in this region feed on higher-trophic-level prey. The results indicate that δ¹⁵N baselines and the trophic positions of wahoo each vary as a function of their geographic location, which supports the hypothesis that this species feeds opportunistically throughout its range. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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12 pages, 2235 KiB

Open AccessArticle

Is a Fishing Moratorium Needed in Lake Honghu, Southern China? A Stomach Content Analysis of the Anchovy (Coilia brachygnathus)

by Abelneh Yimer Melaku, Liang Cao, Jiang-Zhong Shen and E Zhang

Fishes 2023, 8(10), 501; https://doi.org/10.3390/fishes8100501 - 8 Oct 2023

Cited by 2 | Viewed by 1375

Abstract

Since 2017, a fishing moratorium has been enforced in Lake Honghu as part of Chang–Jiang’s biodiversity conservation strategy. However, given that the lake is a semi-closed aquatic ecosystem and no longer serves as a habitat for certain fishes of the mid–lower Chang–Jiang basin, [...] Read more.

Since 2017, a fishing moratorium has been enforced in Lake Honghu as part of Chang–Jiang’s biodiversity conservation strategy. However, given that the lake is a semi-closed aquatic ecosystem and no longer serves as a habitat for certain fishes of the mid–lower Chang–Jiang basin, the efficacy of this moratorium remains uncertain. To address the question from a trophic ecology perspective, a stomach content analysis was performed on captured anchovies of C. brachygnathus, a current predominant species in Lake Honghu, from November 2020 to October 2021. The results showed that copepods, shrimps, and macrophytes were the main components of this anchovy’s diet, and there were size-related shifts in diets. The dominance of C. brachygnathus, a pelagic–littoral omnivore in this lake, implies a lacustrine environment shift triggered by continued human disturbances. The utilization of macrophytes as the main food items by large-sized anchovies of Lake Honghu has partially contributed to the rapid degradation of submerged vegetation. This highlights the need to remove large-sized individuals of C. brachygnathus and Carassius auratus, another benthic-omnivorous dominant fish, in order to effectively restore the aquatic vegetation and ecosystem of Lake Honghu. The current implementation of fishing moratoriums in subtropical shallow floodplain lakes such as Lake Honghu should be reviewed critically. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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17 pages, 1947 KiB

Open AccessArticle

Isotopic Turnover and Fractionation of δ¹⁵N and δ¹³C in Captive Pseudopleuronectes americanus (Walbaum)

by Addie L. Binstock, Audrey S. Fox and John A. Mohan

Fishes 2023, 8(9), 469; https://doi.org/10.3390/fishes8090469 - 21 Sep 2023

Viewed by 1356

Abstract

Stable isotope ratios of nitrogen (δ¹⁵N) and carbon (δ¹³C) are ubiquitous ecological tracers used to elucidate an organism’s diet and habitat. However, the application of stable isotope ratios to reconstruct a consumer’s ecology relies upon accurate rates for isotopic [...] Read more.

Stable isotope ratios of nitrogen (δ¹⁵N) and carbon (δ¹³C) are ubiquitous ecological tracers used to elucidate an organism’s diet and habitat. However, the application of stable isotope ratios to reconstruct a consumer’s ecology relies upon accurate rates for isotopic turnover at both a tissue and species-specific level. This study estimated isotope turnover rates and trophic discrimination factors in four different tissues (liver, digestive tissue, muscle, and skin) with variable metabolic activity in winter flounder Pseudopleuronectes americanus using a controlled diet-switch experiment. Differences in half-lives were noted among the tissues and between the experimental diets for both δ¹⁵N and δ¹³C. The experimental diets of krill and mysis had variability in nutritional composition, resulting in similar turnovers in δ¹⁵N but slower turnovers in δ¹³C for fish fed krill. Turnovers in both δ¹⁵N and δ¹³C were strongly influenced by metabolism, with the contribution reaching up to 98%, as fish exhibited minimal overall growth. The results of this study demonstrate the importance of considering differences in the catabolic activity of tissue maintenance for fish exhibiting minimal growth, as well as differences in metabolic assimilation of dietary sources that vary in their protein and lipid contents. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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7 pages, 559 KiB

Open AccessCommunication

Lipid Correction for Carbon Stable Isotope Analysis of Yellowfin Tuna

by Michael A. Dance and Mitchell S. Lovell

Fishes 2023, 8(9), 446; https://doi.org/10.3390/fishes8090446 - 1 Sep 2023

Cited by 3 | Viewed by 1435

Abstract

Carbon stable isotopes (δ¹³C) are widely used in ecological studies to understand diet, food web dynamics, and movements of marine fishes. Still, δ¹³C is influenced by lipid content and often requires chemical extraction or mathematical correction. Here, we developed [...] Read more.

Carbon stable isotopes (δ¹³C) are widely used in ecological studies to understand diet, food web dynamics, and movements of marine fishes. Still, δ¹³C is influenced by lipid content and often requires chemical extraction or mathematical correction. Here, we developed a species-specific mathematical lipid correction for white muscle tissue of yellowfin tuna (Thunnus albacares), a highly migratory finfish of considerable economic and ecological value. Lipid extraction was conducted on yellowfin tuna white muscle tissue (C:N range: 2.96–6.49), and both linear and non-linear lipid correction models for δ¹³C were fitted and assessed. Lipid extraction increased δ¹³C, and to a lesser extent, δ¹⁵N values in yellowfin tuna white muscle tissue, but had no effect on δ³⁴S. Both non-linear models provided better fits to the data than the linear model, suggesting an asymptotic relationship between C:N and ∆δ¹³C. Results support the growing body of evidence that C:N ratios can be used to predict lipid corrected δ¹³C and highlight the value of mathematical correction approaches. We provide species-specific parameter estimates that can be used for lipid correction of white muscle tissue for δ¹³C analysis in yellowfin tuna and similar species for which species-specific models have yet to be developed. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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18 pages, 2218 KiB

Open AccessFeature PaperArticle

Parasitic Copepods as Biochemical Tracers of Foraging Patterns and Dietary Shifts in Whale Sharks (Rhincodon typus Smith, 1828)

by Brendon James Osorio, Grzegorz Skrzypek and Mark Meekan

Fishes 2023, 8(5), 261; https://doi.org/10.3390/fishes8050261 - 14 May 2023

Cited by 3 | Viewed by 4761 | Correction

Abstract

Understanding the diet of whale sharks (Rhincodon typus) is essential for the development of appropriate conservation strategies for the species. This study evaluated the use of the parasitic copepod (Pandarus rhincodonicus) as a proxy to infer short-term foraging habitats [...] Read more.

Understanding the diet of whale sharks (Rhincodon typus) is essential for the development of appropriate conservation strategies for the species. This study evaluated the use of the parasitic copepod (Pandarus rhincodonicus) as a proxy to infer short-term foraging habitats and trophic positions of whale shark hosts. To accomplish this, bulk stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope compositions were analysed from 72 paired samples of whale shark skin (dermal) tissues and copepods collected across six years at the Ningaloo Reef aggregation site, Western Australia. This study found that δ¹⁵N from parasites and whale shark hosts were strongly correlated. As turn-over times of the parasite and whale shark differ (months vs. years, respectively), the ability of copepods to predict δ¹⁵N values indicates that the trophic positions of whale sharks remain consistent across these timeframes. Contrastingly, δ¹³C in the parasite and host were weakly correlated, likely reflecting differences in the physiology and lifecycle of the copepod parasite compared to the host. Our results suggest δ¹⁵N from parasitic copepods provides a reliable proxy of the trophic position of their whale shark hosts, but interpretation of δ¹³C values as a proxy for the host will require future studies on the lifecycle of P. rhincodonicus. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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20 pages, 5790 KiB

Open AccessArticle

Integrative Analysis to Manage Aquatic Resources Based on Fish Feeding Patterns in Neotropical Rivers

by Estevan Luiz da Silveira, Nabil Semmar, Eduardo Luis Cupertino Ballester and André Martins Vaz-dos-Santos

Fishes 2023, 8(3), 157; https://doi.org/10.3390/fishes8030157 - 6 Mar 2023

Cited by 3 | Viewed by 2288

Abstract

Feeding ecology is an integrative procedure to highlight different diets, associating feeding trends with governing and regulation factors characterizing foraging species and their environments, respectively. The diet variability of seven fish species forming a community in a Neotropical riverine system was analyzed to [...] Read more.

Feeding ecology is an integrative procedure to highlight different diets, associating feeding trends with governing and regulation factors characterizing foraging species and their environments, respectively. The diet variability of seven fish species forming a community in a Neotropical riverine system was analyzed to characterize the resource and consumer linkages, providing a detailed assessment of adaptive feeding behaviors of fishes living in different ecological states transiting from natural/resilient spaces to anthropic pressions-linked disturbed ones. Fishes were sampled along four sites during a year, and their stomach contents were analyzed. Feeding data were analyzed by applying quali- and quantitative methods with multi-levels and multifactor aspects to determine target food categories (percentage of occurrence) and identify feeding patterns (correspondence and cluster analyses, CA-HCA). Factors and scales governing target food categories were also tested. A total of 483 stomachs were dissected, and 30 food categories were identified. CA-HCA highlighted 10 feeding trends (FTs) combining several foods co-occurring at distinct levels. These FTs indicated characteristic diets and high diversity of feeding behaviors concerning multiple and narrow diets, different alimentary needs related to ecomorphological features, different plasticity ranges (adaptability, tolerance) and a spatial governing effect (headwater to river mouth environmental quality loss). These multiple factors provided essential information on overcoming ways of environmental constraints and optimization ways of food balances helping to better manage the richness and working of neotropical river systems. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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18 pages, 2753 KiB

Open AccessArticle

Food Web Connectivity in a Mangrove–Seagrass–Patch Reef (MSP) Seascape: Lessons from a Tropical Back-Reef in Puerto Rico

by Antonietta Quigg, R. J. David Wells, Jay R. Rooker, Ronald L. Hill, Larissa L. Kitchens, Michael A. Dance, David L. Moulton, Phillip J. Sanchez and Beatrice Padovani Ferreira

Fishes 2023, 8(1), 44; https://doi.org/10.3390/fishes8010044 - 8 Jan 2023

Cited by 1 | Viewed by 3713

Abstract

Alterations to the functions and connectivity of mangrove–seagrass–patch reef (MSP) seascapes have the potential to impact the survival, foraging activities, and movement of reef-dependent invertebrates (e.g., crabs and shrimp) and fishes. In the current study, we examined carbon flow in the Guánica Biosphere [...] Read more.

Alterations to the functions and connectivity of mangrove–seagrass–patch reef (MSP) seascapes have the potential to impact the survival, foraging activities, and movement of reef-dependent invertebrates (e.g., crabs and shrimp) and fishes. In the current study, we examined carbon flow in the Guánica Biosphere Reserve in southwestern Puerto Rico using pigment analysis of particulate organic matter and stable isotope analysis of carbon (δ¹³C) and nitrogen (δ¹⁵N) in flora and fauna. Several lines of evidence pointed to N₂ fixers (cyanobacteria) being important for fueling primary productivity in this oligotrophic ecosystem including low (<0.7 µg L⁻¹) chlorophyll, prevalence of cyanobacteria based on pigment signatures, and the isotope signatures of seagrass and red mangrove leaf tissue (enriched δ¹⁵N values) and consumers (depleted δ¹⁵N values). Food web mixing models based on stable isotopes (δ¹³C and δ¹⁵N) revealed that multiple producers (phytoplankton, benthic microalgae, seagrasses, etc.) contributed organic matter to the consumers (zooplankton, invertebrates, and fishes) in the MSP seascape at the center of the reserve. Contribution estimates for common benthic invertebrates (crabs and shrimp) were taxon-specific, and the highest input was generally linked to particulate organic matter (POM) and benthic microalgae (BMA)/seagrass producer categories, although meaningful mangrove contribution was observed for some taxa. Similarly, contribution estimates for fishes were highest for POM and BMA/seagrass, with the latter producer category being more important for species known to migrate from mangroves or patch reefs to seagrass beds at night (bluestriped grunt, French grunt, and white grunt). Although all fish investigated were observed in mangrove prop-root habitats, input of organic matter from mangroves to these consumers was typically limited for most of the species examined. Understanding these complex seascapes contributes to our understanding of the ecology of these vital ecosystems. Full article

(This article belongs to the Special Issue Trophic Ecology of Fishes)

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