Improvements of Population Fitness and Trophic Status of a Benthic Predatory Fish Following a Trawling Ban

Trawl fisheries have been shown to cause overfishing and destruction of benthic habitats in the seabed. To mitigate these impacts, a trawling ban has been enforced in Hong Kong waters since December 31, 2012 to rehabilitate the ecosystem and enhance fisheries resources. Previous studies demonstrated that reduced trawling activities would increase the heterogeneity of benthic habitats, thereby enhancing species richness and abundance of benthic fauna and providing more prey resources for predatory fishes. This study aimed to test a hypothesis that the population and trophic dynamics of the Bartail flathead Platycephalus indicus, a heavily fished benthic predatory fish, at inner and outer Tolo Channel of Hong Kong (i.e., EI and EO) improved with increases in their body size, abundance, biomass, trophic niche, and trophic position after the trawl ban. Samples were collected from trawl surveys before and after the trawl ban to compare the pre-ban and post-ban populations of P. indicus from EI and EO. Body size, abundance, and biomass were assessed in 2004, 2013–2014, and 2015–2016, whereas trophic niche and trophic position were analyzed based on stable isotopes of fish samples collected in dry season of 2012, 2015, and 2018. Following the trawl ban, the abundance and biomass of P. indicus increased in EO, with body size increased in EI. Furthermore, as indicated by the results of stable isotope analysis (SIA) on their tissues and prey items, trophic niche, and trophic position of P. indicus increased in EI and EO, respectively. Our study demonstrated that the trawl ban had promoted the recovery of a predatory fish population through restoring size structure and trophic dynamics.

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Body size is negatively correlated with trophic position among cyprinids

Royal Society Open Science ◽

10.1098/rsos.150652 ◽

2016 ◽

Vol 3 (5) ◽

pp. 150652 ◽

Cited By ~ 8

Author(s):

Edward D. Burress ◽

Jordan M. Holcomb ◽

Karine Orlandi Bonato ◽

Jonathan W. Armbruster

Keyword(s):

Body Size ◽

Trophic Position ◽

Isotope Analysis ◽

Negative Relationship ◽

Species Traits ◽

Food Web Structure ◽

Mechanical Constraints ◽

Web Structure ◽

Significant Negative Relationship ◽

Multiple Levels

Body size has many ecological and evolutionary implications that extend across multiple levels of organization. Body size is often positively correlated with species traits such as metabolism, prey size and trophic position (TP) due to physiological and mechanical constraints. We used stable isotope analysis to quantify TP among minnows across multiple assemblages that differed in their species composition, diversity and food web structure. Body size significantly predicted TP across different lineages and assemblages, and indicated a significant negative relationship. The observed negative relationship between body size and TP is contrary to conventional knowledge, and is likely to have arisen owing to highly clade-specific patterns, such that clades consist of either large benthic species or small pelagic species. Cyprinids probably subvert the physiological and mechanical constraints that generally produce a positive relationship between body size and TP using anatomical modifications and by consuming small-bodied prey, respectively. The need for herbivorous cyprinids to digest cellulose-rich foods probably selected for larger bodies to accommodate longer intestinal tracts and thereby to facilitate digestion of nutrient-poor resources, such as algae. Therefore, body size and TP are likely to have coevolved in cyprinids in association with specialization along the benthic to pelagic resource axis.

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Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal

PLoS ONE ◽

10.1371/journal.pone.0256339 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0256339

Author(s):

Samanta Dodino ◽

Nicolás A. Lois ◽

Luciana Riccialdelli ◽

Michael J. Polito ◽

Klemens Pütz ◽

...

Keyword(s):

Trophic Position ◽

Isotope Analysis ◽

Trophic Niche ◽

Bottom Trawl ◽

Winter Period ◽

Shrimp Fishery ◽

Trawl Fishery ◽

Magellanic Penguins ◽

Winter Foraging ◽

Spatial Use

Magellanic penguins (Spheniscus magellanicus) disperse widely during winter and are a major consumer of marine resources over the Patagonian Shelf. Magellanic penguins were equipped with geolocators at Martillo Island in late February- early March 2017 and recaptured at the beginning of the next breeding season to recover the devices and to collect blood samples for stable carbon (δ13C) and nitrogen (δ15N) isotope analysis. We evaluated their whole winter dispersal and their trophic niche by sex during the last month of the winter dispersal. Also, we evaluated their spatial overlap with bottom trawl and shrimp fisheries using data from satellite fisheries monitoring. Penguins dispersed northwards up to 42°S and showed latitudinal spatial segregation between sexes during May to August (females were located further north than males). In contrast, during the last month of the winter dispersal females were located more southerly and showed lower trophic position than males. Also, females did not dive as deep as males during winter. We found high overlap between both fisheries and penguin’s spatial use in regions with documented interaction. However, no sex-specific statistical differences with fisheries overlap were found. Our results highlight the importance of understanding the spatial domains of each sex and assessment of their potential conflicts with bottom trawl fishery and shrimp fishery during the winter period.

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Zooplankton predators and prey: body size and stable isotope to investigate the pelagic food web in a deep lake (Lake Iseo, Northern Italy)

Journal of Limnology ◽

10.4081/jlimnol.2016.1490 ◽

2016 ◽

Cited By ~ 6

Author(s):

Barbara Leoni

Keyword(s):

Body Size ◽

Stable Isotope ◽

Body Length ◽

Trophic Position ◽

Isotope Analysis ◽

Large Body ◽

Zooplankton Community ◽

Open Water ◽

Northern Italy ◽

Food Sources

Seasonal changes in trophic position and food sources of deep subalpine lake (Lake Iseo, Northern Italy) zooplankton taxa were investigated during the year 2011. Furthermore, it's combined carbon and nitrogen Stable Isotope Analysis (SIA) with size-specific analyses of both, the major predatory cladoceran (Leptodora kindtii, Focke) and two potential preys (Daphnia longispina complex and Eubosmina longicornis). SIA studies have been extremely useful to track the energy flow through complex trophic network, however, if it is applied to analyze relation between two/few species may lead to misleading interpretations. In fact, integrating size-specificity allowed for understanding why L. kindtii nitrogen isotopic fingerprint fully overlapped with Daphnia, in spring. By investigating changes in L. kindtii's feeding basket, we found that in spring, L. kindtii mainly relied upon E. longicornis as prey, Daphnia being of too large body size for being captured by L. kindtii. Among preys encountered directly in front by a free-swimming Leptodora, only those able to fit into basket opening can be captured. As basket diameter increases with animal body length, size selection of prey depends on L. kindtii body length. As in other deep, subalpine lakes, E. longicornis was less 15N-enriched than Daphnia, most likely because of exploiting nitrogen fixing, cyanobacteria colonies, commonly detected in Lake Iseo with the onset of thermal stratification. Cyclopoid adults were at the top of zooplankton food chain and they could potentially be feeding on Daphnia. They, however, likely fed in a different habitat (>20 m deep water), as suggested by a rather than negligible carbon fractionation. The results overall suggest that size-specificity is crucial for addressing space and time changes in trophic links between organisms composing the two hierarchical levels within open water zooplankton community.

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Body size–trophic position relationships among fishes of the lower Mekong basin

Royal Society Open Science ◽

10.1098/rsos.160645 ◽

2017 ◽

Vol 4 (1) ◽

pp. 160645 ◽

Cited By ~ 20

Author(s):

Chouly Ou ◽

Carmen G. Montaña ◽

Kirk O. Winemiller

Keyword(s):

Body Size ◽

Trophic Interactions ◽

Fish Assemblages ◽

Trophic Position ◽

Isotope Analysis ◽

The Body ◽

Tropical Fish ◽

Feeding Guilds ◽

Mekong Basin ◽

Lower Mekong Basin

Body size is frequently claimed to be a major determinant of animal trophic interactions, yet few studies have explored relationships between body size and trophic interactions in rivers, especially within the tropics. We examined relationships between body size and trophic position (TP) within fish assemblages in four lowland rivers of the Lower Mekong Basin in Cambodia. Stable isotope analysis (based on δ 15 N) was used to estimate TP of common fish species in each river, and species were classified according to occupation of benthic versus pelagic habitats and major feeding guilds. Regression analysis yielded strong correlations between body size and TP among fishes from the Sesan and Sreprok rivers, but not those from the Mekong and Sekong rivers. The Mekong fish assemblage had higher average TP compared with those of other rivers. The relationship between body size and TP was positive and significantly correlated for piscivores and omnivores, but not for detritivores and insectivores. The body size–TP relationship did not differ between pelagic and benthic fishes. Body size significantly predicted TP within the orders Siluriformes and Perciformes, but not for Cypriniformes, the most species-rich and ecologically diverse order in the Lower Mekong River. We conclude that for species-rich, tropical fish assemblages with many detritivores and invertivores, body size would not be an appropriate surrogate for TP in food web models and other ecological applications.

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Trophic roles determine coral reef fish community size structure

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2015-0178 ◽

2016 ◽

Vol 73 (4) ◽

pp. 496-505 ◽

Cited By ~ 12

Author(s):

James P.W. Robinson ◽

Julia K. Baum

Keyword(s):

Body Size ◽

Coral Reef ◽

Food Webs ◽

Reef Fish ◽

Coral Reef Fish ◽

Census Data ◽

Size Structure ◽

Trophic Position ◽

Great Promise ◽

Metabolic Scaling

Relationships between abundance – body size and trophic position – body size can reveal size structuring in food webs and test ecological theory. Although there is considerable evidence of size structuring in temperate aquatic food webs, little is known about the structure of tropical coral reef food webs. Here, we use underwater visual-census data and nitrogen stable isotope analysis to test if coral reef fish communities (i) are size structured and (ii) follow metabolic scaling rules. After examining individuals from over 160 species spanning four orders of magnitude in body size, we show that abundance scaled negatively with body size and, as predicted, individuals sharing energy through predation (carnivorous fishes) scaled more steeply than those individuals sharing a common energy source (herbivorous fishes). Estimated size spectra were, however, shallower than predicted by metabolic theory. Trophic position scaled positively with body size across species and across individuals, providing novel evidence of size structuring in a diverse tropical food web. Size-based approaches hold great promise for integrating the complexities of food webs into simple quantitative measures, thus providing new insights into the structure and function of aquatic ecosystems.

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Is the Relationship between Body Size and Trophic Niche Position Time-Invariant in a Predatory Fish? First Stable Isotope Evidence

PLoS ONE ◽

10.1371/journal.pone.0009120 ◽

2010 ◽

Vol 5 (2) ◽

pp. e9120 ◽

Cited By ~ 33

Author(s):

Takefumi Nakazawa ◽

Yoichiro Sakai ◽

Chih-hao Hsieh ◽

Tadatoshi Koitabashi ◽

Ichiro Tayasu ◽

...

Keyword(s):

Body Size ◽

Stable Isotope ◽

Trophic Niche ◽

Predatory Fish ◽

Isotope Evidence ◽

Time Invariant ◽

The Relationship

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Sympatry with the devil? Niche-based approach explains the mechanisms allowing coexistence of native and non-native salmonids

10.1101/068171 ◽

2016 ◽

Cited By ~ 1

Author(s):

Camille Musseau ◽

Simone Vincenzi ◽

Dušan Jesenšek ◽

Stéphanie Boulêtreau ◽

Frédéric Santoul ◽

...

Keyword(s):

Rainbow Trout ◽

Native Species ◽

Niche Breadth ◽

Trophic Position ◽

Isotope Analysis ◽

Growth Period ◽

Niche Overlap ◽

Trophic Niche ◽

Niche Shift ◽

Marble Trout

AbstractNiche-based hypotheses have been proposed to explain processes and mechanisms of success in the establishment of non-native species into native communities. Competition due to niche overlap may lead to native species niche shift and to native species replacement. To understand the ecological consequences of trophic interactions between non-native rainbow trout and native and endangered marble trout, we used as model system the Idrijca river (Western Slovenia) in which marble trout occurs either in allopatry (MTa) or in sympatry (MTs) with rainbow trout (RTs). We focused on different metrics of niche change such as centroid shift, niche overlap and trophic niche breadth using stable isotope analysis (δ15N and δ13C). Our results showed plasticity in niche overlap between MTs and RTs and niche shift of marble trout when occurring in sympatry with RTs, but not due to a niche replacement of MTs by RTs. Niche breadth of marble trout increases in sympatry and the trophic position during the growth period was higher for MTs than MTa.

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Trophic plasticity of the highly invasive topmouth gudgeon (Pseudorasbora parva) inferred from stable isotope analysis

10.1101/617688 ◽

2019 ◽

Cited By ~ 2

Author(s):

Matteo Rolla ◽

Sofia Consuegra ◽

Carlos Garcia de Leaniz

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Condition Factor ◽

Trophic Position ◽

Isotope Analysis ◽

Trophic Niche ◽

Pseudorasbora Parva ◽

Trophic Plasticity ◽

Topmouth Gudgeon ◽

South Wales

AbstractA wide trophic niche and high trophic plasticity are often invoked to explain the successful establishment of many aquatic invaders, but there is little information regarding the diet of most invasive fish in European waters. We combined stomach content and stable isotope analysis (SIA) of13C and15N to examine the trophic niche of the highly invasive topmouth gudgeon (Pseudorasbora parva) in four contrasting ponds and reservoirs in South Wales. Marked differences in diet and trophic position were found among neighbouring systems only a few kilometres apart. The most diverse diet was found in ponds with the fewest number of inter-specific competitors, and resulted in topmouth gudgeon having the highest condition factor, the widest variation in δ13C and δ15N values, and the highest carbon content, typical of generalist feeders. In contrast, topmouth gudgeon that coexisted with other cyprinids, were much more likely to have empty stomachs and relied almost exclusively on plant seeds, resulting in fish having a poor condition factor and low trophic position. Comparisons with other trophic studies indicate that variation in isotope values among neighbouring sites can exceed variation across continents, making it difficult to predict the diet or trophic impacts of the invasive topmouth gudgeon. Given the importance of obtaining reliable data on trophic position for risk assessment, our study shows that the use of SIA could be used to prioritize control and eradication measures that take into account trophic plasticity.

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ISÓTOPOS ESTÁVEIS E OUTRAS FERRAMENTAS EM ESTUDOS TRÓFICOS DE PEIXES EM RIACHOS TROPICAIS

Oecologia Australis ◽

10.4257/oeco.2021.2502.05 ◽

2021 ◽

Vol 25 (02) ◽

pp. 283-300

Author(s):

Míriam Pilz Albrecht ◽

◽

Andressa da Silva Reis ◽

Vinicius Neres-Lima ◽

Eugenia Zandonà ◽

...

Keyword(s):

Stable Isotopes ◽

Environmental Changes ◽

Trophic Position ◽

Isotope Analysis ◽

Aquatic Organisms ◽

Niche Overlap ◽

Trophic Niche ◽

Tropical Streams ◽

Stream Fish ◽

The Impact

Stable isotope analysis (SIA) has become an essential tool in Ecology, being increasingly used in studies of fish in tropical streams. The SIA allows to reconstruct the animals' diet and its intraspecific variation, to trace the contributions of the main basal resources throughout the food web, to calculate trophic position and trophic niche, including niche overlap and its alterations, and to build food webs. The SIA is also used to understand the impact of environmental changes on fish communities and other aquatic organisms. The number of such studies is increasing in Brazil, but there are still several gaps. In this study, we present the basic concepts on stable isotopes analysis in trophic studies of stream fish - especially those of carbon, nitrogen and hydrogen - their premises, uses and limitations, presenting examples from tropical streams. We also explore new conceptual tools in this area, still not used for stream fish in Brazil, such as fatty acids, stable isotopes in specific compounds, nutritional geometry and ecological stoichiometry concepts such as the Threshold Elemental Ratio.

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Trophic position and diet shift based on the body size of Coreoperca kawamebari (Temminck & Schlegel, 1843)

Journal of Ecology and Environment ◽

10.1186/s41610-019-0145-0 ◽

2020 ◽

Vol 44 (1) ◽

Author(s):

Jong-Yun Choi ◽

Seong-Ki Kim ◽

Jeong-Cheol Kim ◽

Jung-Do Yoon

Keyword(s):

Body Size ◽

Trophic Interactions ◽

Littoral Zone ◽

Trophic Position ◽

Juvenile Fish ◽

Isotope Analysis ◽

Central Zone ◽

The Body ◽

Diet Shift ◽

The Relationship

Abstract Background Fish body size is a major determinant of freshwater trophic interactions, yet only a few studies have explored the relationship between the fish body size and trophic interactions in river upstream. In this study, we investigated the relationship between the body size and trophic position (TP) of Coreoperca kawamebari (Temminck & Schlegel, 1843) in an upstream of the Geum River. Results A stable isotope analysis (based on δ15N) was used to determine the TP based on the body size of C. kawamebari. The regression analysis (n = 33, f = 63.840, r2 = 0.68) clearly showed the relationship between the body length and TP of C. kawamebari. The TP of C. kawamebari was clearly divided by body size into the following classes: individuals of size < 10 cm that feed on insects and individuals of size > 10 cm feed on juvenile fish. This selective feeding is an evolutionarily selective tendency to maximize energy intake per unit time. Furthermore, the diet shift of C. kawamebari was led by different spatial distributions. The littoral zone was occupied by individuals of size < 10 cm, and those of size > 10 cm were mainly in the central zone. The littoral zone can be assumed to be enriched with food items such as ephemeropterans and dipterans. Conclusion The TP of C. kawamebari, as a carnivorous predator, will have a strong influence on biotic interactions in the upstream area of the Geum River, which can lead to food web implication.

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