Abstract Understanding how functionally similar species segregate resources to minimize competition is vital for predicting evolutionary factors and patterns of coexistence. We conducted a study in Mata de Itamacaoca, in the middle Munim River basin, Maranhão, northeastern Brazil, to characterize the functional morphology and trophic niches of five coexisting Characiform species in this area - including a recently described species, and to investigate whether their functional morphology is a key determinant of their trophic niches. Our analysis of functional morphology and diet, employing linear measurements to predict dietary specializations, showed that these species are predominantly generalist insectivores with a significant morphological overlap. This study underscores the influence of species' natural history on their ecological characteristics, contributing to more effective conservation strategies. coexistence Itamacaoca basin Maranhão Brazil diet specializations overlap characteristics strategies

Resumo Compreender como espécies funcionalmente semelhantes segregam recursos para minimizar a competição é vital para prever fatores evolutivos e padrões de coexistência. Conduzimos um estudo na Mata de Itamacaoca, na bacia do médio rio Munim, Maranhão, nordeste do Brasil, para caracterizar a morfologia funcional e nichos tróficos de cinco espécies de Characiformes coexistentes nesta área - incluindo uma espécie recentemente descrita, e investigar se a morfologia funcional dessas espécies é determinante para seus nichos tróficos. Nossa análise da morfologia funcional e da dieta, empregando medidas lineares para prever especializações alimentares, mostrou que essas espécies são predominantemente insetívoras generalistas com sobreposição morfológica significativa. Este estudo ressalta a influência da história natural das espécies em suas características ecológicas, contribuindo para estratégias de conservação mais eficazes. coexistência Itamacaoca Munim Maranhão Brasil descrita dieta alimentares significativa ecológicas eficazes

Resumo O objetivo deste estudo foi determinar a ecologia trófica de juvenis e adultos de Acestrorhynchus falcirostris durante o período de enchente e cheia em seis lagos de ilha adjacentes ao rio Solimões. Assim, investigamos: i) a posição trófica, através do nicho trófico fracional; ii) a largura de nicho; iii) sobreposição de nicho; iv) a estratégia alimentar. Os espécimes foram coletados durante os anos de 2014 a 2017, utilizando redes de emalhar com malha variando de 30 a 120mm entre nós opostos. Por meio da análise do conteúdo estomacal, observamos a preferência no consumo de itens de origem animal. Os juvenis consumiram insetos em maiores proporções (IAi% = 50%), enquanto os adultos consumiram preferencialmente peixes (IAi% = 99,98%). Apesar da grande oferta de alimentos disponíveis no período da cheia, os juvenis eram os únicos a consumir itens de origem alóctone, como por exemplo, os insetos. Os juvenis apresentaram uma estratégia alimentar e composição alimentar diferente para os adultos. Os juvenis foram considerados onívoros com uma estratégia generalista, enquanto os adultos foram considerados piscívoros com uma estratégia alimentar mais especialista. Assim, a composição alimentar, amplitude do nicho, posição trófica e a estratégia alimentar de Acestrorhynchus falcirostris muda em função do estágio de desenvolvimento.

Abstract The aim objective of this study was to determine the trophic ecology of juvenile and adult Acestrorhynchus falcirostris during the rising and flood (high-water) period in six island lakes adjacent to the Solimões River. As such, we investigated: i) the trophic position, through the fractional trophic niche; ii) the niche breadth; iii) niche overlap and iv) the food strategy of the species. The specimens were collected during the years 2014 to 2017, using gillnets with mesh sizes ranging from 30 to 120mm between opposite knots. Through the analysis of stomach contents, the preference in the consumption of items of animal origin was observed. Juveniles consumed insects in greater proportions (IAi% = 50%), while adults consumed fish (IAi%=99,98%). Despite the large supply of food items available in the high-water period, juveniles were the only ones to consume items of allochthonous origin, such as insects. Juveniles presented a different dietary strategy and dietary composition to adults. Juveniles were omnivores with a generalist strategy, while adults were piscivores with a specialist strategy. Thus, the food composition, niche breadth, trophic position and feeding strategy of Acestrorhynchus falcirostris change due to the stage of development.

Abstract Aim Studies of natural variations in fish diet allow, in turn, a better understanding of environmental changes along the hydrological cycle that can affect resources and, hence, biodiversity conservation. With this in mind, the present study aimed to understand how spatial and ontogenetic aspects (using Standard Length as proxy) define dietary composition, trophic position and trophic niche breadth for a small characid (Bryconamericus exodon) in streams located in two rivers of the Brazilian Pantanal. We also assessed whether spatial differences influence the structuring of trophic networks. Methods Fish were sampled monthly in the rainy season (October/2017 to March/2018) in four tributaries of the Negro and Apa Rivers, using different sampling methods. In the laboratory, fish were measured and weighed, followed by excision of stomach for posterior analysis. Results We analyzed 211 individuals, 126 from the Apa River (Standard lengthmin= 11.28mm; Standard lengthmax= 43.53mm) and 85 from the Negro River (Standard lengthmin= 13.26mm; Standard lengthmax= 40.05mm), that consumed mainly aquatic insects (Alimentary indexTotal= 87.97%), followed by terrestrial insects (Alimentary indexTotal= 9.02%). Dietary composition was mainly influenced by spatial variation (Pseudo-F1,194=12.21; p<0.001), followed by ontogenetic variation (Pseudo-F1,190=7.23; p<0.001), however, for trophic niche breadth, we did detect a higher importance of spatial variation (t=4.71; p<0.001) and an absence of ontogenetic variation (t=1.24; p=0.213). No spatial variation was detected for complementary specialization (p=0.998); only connectance showed a significant variation (p=0.047) with higher mean values in the Negro River (C= 0.27 ± 0.016) when compared to those of populations in the Apa River (C=0.22 ± 0.019). In addition, trophic position was not influenced by spatial (t= -1.77; p=0.077) or ontogenetic (t=0.69; p=0.494) variations. Conclusions B. exodon is considered an insectivorous species whose dietary composition can be explained more by spatial than ontogenetic variation. allow turn hence conservation mind proxy Bryconamericus Pantanal networks October/2017 October2017 October 2017 (October/201 March/2018 March2018 March 2018 Rivers methods laboratory weighed analysis 21 individuals 12 lengthmin 11.28mm 1128mm mm 11 28mm lengthmax 43.53mm 4353mm 43 53mm 8 13.26mm 1326mm 13 26mm 40.05mm, 4005mm 40.05mm , 40 05mm 40.05mm) Alimentary indexTotal 87.97%, 8797 87.97% 87 97 87.97%) 9.02%. 902 9.02% . 9 02 9.02%) PseudoF1,194=12.21 PseudoF11941221 PseudoF Pseudo F1,194=12.21 F1 194 F (Pseudo-F1,194=12.21 p<0.001, p0001 p p<0.001 0 001 PseudoF1,190=7.23 PseudoF1190723 F1,190=7.23 190 7 23 (Pseudo-F1,190=7.23 however t=4.71 t471 t 4 71 (t=4.71 t=1.24 t124 1 24 (t=1.24 p=0.213. p0213 p=0.213 213 p=0.213) p=0.998 p0998 998 (p=0.998) p=0.047 p0047 047 (p=0.047 C= C (C 027 27 0.2 0.016 0016 016 C=0.22 C022 22 (C=0.2 0.019. 0019 0.019 019 0.019) addition t= (t 1.77 177 77 -1.77 p=0.077 p0077 077 t=0.69 t069 69 (t=0.69 p=0.494 p0494 494 B October/201 October201 201 (October/20 March/201 March201 2 879 87.97 90 9.02 PseudoF1 PseudoF1,194=12.2 PseudoF1194122 F11941221 F1,194=12.2 19 (Pseudo-F1,194=12.2 p000 p<0.00 00 PseudoF1,190=7.2 PseudoF119072 F1190723 F1,190=7.2 (Pseudo-F1,190=7.2 t=4.7 t47 (t=4.7 t=1.2 t12 (t=1.2 p021 p=0.21 p=0.99 p099 99 (p=0.998 p=0.04 p004 04 (p=0.04 0. 0.01 01 C=0.2 C02 (C=0. 1.7 17 -1.7 p=0.07 p007 07 t=0.6 t06 6 (t=0.6 p=0.49 p049 49 October/20 October20 20 (October/2 March/20 March20 87.9 9.0 PseudoF1,194=12. PseudoF119412 F1194122 F1,194=12. (Pseudo-F1,194=12. p00 p<0.0 PseudoF1,190=7. PseudoF11907 F119072 F1,190=7. (Pseudo-F1,190=7. t=4. t4 (t=4. t=1. t1 (t=1. p02 p=0.2 p=0.9 p09 (p=0.99 p=0.0 (p=0.0 0.0 C=0. C0 (C=0 1. -1. t=0. t0 (t=0. p=0.4 p04 October/2 October2 (October/ March/2 March2 87. 9. PseudoF1,194=12 PseudoF11941 F119412 F1,194=12 (Pseudo-F1,194=12 p0 p<0. PseudoF1,190=7 PseudoF1190 F11907 F1,190=7 (Pseudo-F1,190=7 t=4 (t=4 t=1 (t=1 p=0. (p=0.9 (p=0. C=0 -1 t=0 (t=0 October/ (October March/ PseudoF1,194=1 PseudoF1194 F11941 F1,194=1 (Pseudo-F1,194=1 p<0 PseudoF1,190= PseudoF119 F1190 F1,190= (Pseudo-F1,190= p=0 (p=0 - PseudoF1,194= F1194 F1,194= (Pseudo-F1,194= p< PseudoF1,190 PseudoF11 F119 F1,190 (Pseudo-F1,190 p= (p= PseudoF1,194 F1,194 (Pseudo-F1,194 PseudoF1,19 F11 F1,19 (Pseudo-F1,19 (p PseudoF1,1 F1,1 (Pseudo-F1,1 PseudoF1, F1, (Pseudo-F1, (Pseudo-F1 (Pseudo-F

Resumo Objetivo O estudo das variações naturais na dieta dos peixes permite, por sua vez, uma melhor compreensão das alterações ambientais ao longo do ciclo hidrológico que podem afetar os recursos e, consequentemente, a conservação da biodiversidade. Com isso em mente, o presente estudo teve como objetivo compreender como os aspectos espaciais e ontogenéticos (usando o Comprimento padrão como proxy) definem a composição da dieta, posição trófica e amplitude de nicho trófico para um pequeno caracídeo (Bryconamericus exodon) em riachos localizados em dois rios do Pantanal brasileiro. Também avaliamos se as diferenças espaciais influenciam na estruturação das redes tróficas. Métodos Os peixes foram amostrados mensalmente na estação chuvosa (Outubro/2017 a Março/2018) em quatro tributários dos rios Negro e Apa, utilizando diferentes métodos de amostragem. Em laboratório, os peixes foram medidos e pesados, seguido de excisão do estômago para posterior análise. Resultados Foram analisados 211 indivíduos, sendo 126 do Apa (Comprimento padrãomin= 11,28mm; Comprimento padrãomax= 43,53mm) e 85 do Negro (Comprimento padrãomin= 13,26mm; Comprimento padrãomax= 40,05mm), que consumiram principalmente insetos aquáticos (Índice alimentarTotal= 87,97%), seguidos de insetos terrestres (Índice alimentarTotal=9,02%). A composição da dieta foi influenciada principalmente pela variação espacial (Pseudo-F1,194=12,21; p<0,001), seguida da variação ontogenética (Pseudo-F1,190=7,23; p<0,001), no entanto, para amplitude de nicho trófico, detectamos uma maior importância da variação espacial (t=4,71; p<0,001) e ausência de variação ontogenética (t=1,24; p=0,213). Não foi detectada variação espacial para especialização complementar (p=0,998); apenas a conectância obteve uma variação significativa (p=0,047), com valores médios maiores no rio Negro (C= 0,27 ± 0,016) quando comparados aos das populações do rio Apa (C=0,22 ± 0,019). Além disso, a posição trófica não foi influenciada por variações espaciais (t=-1,77; p=0,077) ou ontogenéticas (t=0,69; p=0,494). Conclusões B. exodon é considerada uma espécie insetívora, cuja composição da dieta pode ser explicada mais pela variação espacial do que pela variação ontogenética. permite vez consequentemente biodiversidade mente usando proxy Bryconamericus brasileiro tróficas Outubro/2017 Outubro2017 Outubro 2017 (Outubro/201 Março/2018 Março2018 Março 2018 amostragem laboratório pesados análise 21 indivíduos 12 padrãomin 11,28mm 1128mm mm 11 28mm padrãomax 43,53mm 4353mm 43 53mm 8 13,26mm 1326mm 13 26mm 40,05mm, 4005mm 40,05mm , 40 05mm 40,05mm) Índice alimentarTotal 87,97%, 8797 87,97% 87 97 87,97%) alimentarTotal=9,02%. alimentarTotal902 alimentarTotal=9,02% . 9 02 alimentarTotal=9,02%) PseudoF1,194=12,21 PseudoF11941221 PseudoF Pseudo F1,194=12,21 F1 194 F (Pseudo-F1,194=12,21 p<0,001, p0001 p p<0,001 0 001 PseudoF1,190=7,23 PseudoF1190723 F1,190=7,23 190 7 23 (Pseudo-F1,190=7,23 entanto t=4,71 t471 t 4 71 (t=4,71 t=1,24 t124 1 24 (t=1,24 p=0,213. p0213 p=0,213 213 p=0,213) p=0,998 p0998 998 (p=0,998) p=0,047, p0047 p=0,047 047 (p=0,047) C= C (C 027 27 0,2 0,016 0016 016 C=0,22 C022 22 (C=0,2 0,019. 0019 0,019 019 0,019) disso t=1,77 t177 t= 1,77 77 (t=-1,77 p=0,077 p0077 077 t=0,69 t069 69 (t=0,69 p=0,494. p0494 p=0,494 494 p=0,494) B insetívora Outubro/201 Outubro201 201 (Outubro/20 Março/201 Março201 2 879 87,97 alimentarTotal90 alimentarTotal=9,02 PseudoF1 PseudoF1,194=12,2 PseudoF1194122 F11941221 F1,194=12,2 19 (Pseudo-F1,194=12,2 p000 p<0,00 00 PseudoF1,190=7,2 PseudoF119072 F1190723 F1,190=7,2 (Pseudo-F1,190=7,2 t=4,7 t47 (t=4,7 t=1,2 t12 (t=1,2 p021 p=0,21 p=0,99 p099 99 (p=0,998 p004 p=0,04 04 (p=0,047 0, 0,01 01 C=0,2 C02 (C=0, t=1,7 t17 177 1,7 (t=-1,7 p=0,07 p007 07 t=0,6 t06 6 (t=0,6 p049 p=0,49 49 Outubro/20 Outubro20 20 (Outubro/2 Março/20 Março20 87,9 alimentarTotal9 alimentarTotal=9,0 PseudoF1,194=12, PseudoF119412 F1194122 F1,194=12, (Pseudo-F1,194=12, p00 p<0,0 PseudoF1,190=7, PseudoF11907 F119072 F1,190=7, (Pseudo-F1,190=7, t=4, t4 (t=4, t=1, t1 (t=1, p02 p=0,2 p=0,9 p09 (p=0,99 p=0,0 (p=0,04 0,0 C=0, C0 (C=0 17 1, (t=-1, t=0, t0 (t=0, p04 p=0,4 Outubro/2 Outubro2 (Outubro/ Março/2 Março2 87, alimentarTotal=9, PseudoF1,194=12 PseudoF11941 F119412 F1,194=12 (Pseudo-F1,194=12 p0 p<0, PseudoF1,190=7 PseudoF1190 F11907 F1,190=7 (Pseudo-F1,190=7 t=4 (t=4 t=1 (t=1 p=0, (p=0,9 (p=0,0 C=0 (t=-1 t=0 (t=0 Outubro/ (Outubro Março/ alimentarTotal=9 PseudoF1,194=1 PseudoF1194 F11941 F1,194=1 (Pseudo-F1,194=1 p<0 PseudoF1,190= PseudoF119 F1190 F1,190= (Pseudo-F1,190= (t= p=0 (p=0, (t=- PseudoF1,194= F1194 F1,194= (Pseudo-F1,194= p< PseudoF1,190 PseudoF11 F119 F1,190 (Pseudo-F1,190 (t p= (p=0 PseudoF1,194 F1,194 (Pseudo-F1,194 PseudoF1,19 F11 F1,19 (Pseudo-F1,19 (p= PseudoF1,1 F1,1 (Pseudo-F1,1 (p PseudoF1, F1, (Pseudo-F1, (Pseudo-F1 (Pseudo-F

Abstract Upwellings are important oceanographic processes that induce several changes in marine ecosystems, including in the benthic-pelagic coupling (BPC) that plays a major role in coastal areas. However, there is little available information about the possible effects of coastal upwellings on the trophic role of predators and in the BPC. Thus, here we investigate possible seasonal and ontogenetic changes in the trophic interaction of a demersal predator, the Brazilian flathead Percophis brasiliensis, from an upwelling ecosystem. Sampling was carried out for one year during two coastal upwelling events. Based on stomach content analysis (SCA) were recorded seasonal diet shifts, probably driven by coastal upwellings, leading to an increase in pelagic prey and changing the trophic coupling pathways. Stable isotope analysis revealed that isotopic niche decreased with the body size, as well as the values of the Levins’ index. Also, significant, and positive relationships were observed between δ13C and δ15N versus total length. Our results showed that the demersal predator has a relevant trophic role in the BPC which is probably influenced by coastal upwellings. ecosystems benthicpelagic benthic (BPC areas However Thus brasiliensis ecosystem events SCA (SCA shifts pathways size Levins index Also significant δC δ C δN N length

Resumo Ressurgências são importantes processos oceanográficos que induzem diversas mudanças nos ecossistemas marinhos, inclusive no acoplamento bento-pelágico (ABP) que desempenha um papel importante nas áreas costeiras. No entanto, existem poucas informações sobre os possíveis efeitos das ressurgências costeiras no papel trófico de predadores e no ABP. Em vista disso, aqui investigamos as possíveis mudanças sazonais e ontogenéticas nas interações tróficas de um predador demersal, o tira-vira Percophis brasiliensis, em um ecossistema com ressurgência. A amostragem foi realizada ao longo de um ano durante dois eventos de ressurgências costeiras. Baseado nas análises de conteúdos estomacais (ACE) foram registradas mudanças sazonais na dieta provavelmente impulsionadas pelas ressurgências costeiras, levando a um aumento de presas pelágicas e alterando as vias de acoplamento trófico. As análises de isótopos estáveis revelaram que o nicho isotópico diminuiu com o tamanho do corpo, assim como os valores do índice de Levin. Além disso, relações significativas e positivas foram observadas entre δ13C e δ15N versus comprimento total. Nossos resultados mostraram que o predador demersal tem um papel trófico relevante no ABP que provavelmente é influenciado por ressurgências costeiras. marinhos bentopelágico bento pelágico (ABP entanto disso tiravira tira vira brasiliensis ressurgência ACE (ACE corpo Levin δC δ C δN N total

ABSTRACT The South Pacific hake, Merluccius gayi, is an ecologically and economically important species in Ecuador. However, studies regarding its feeding habits remain scarce. This study aimed to characterize the food and feeding habits of M. gayi in the Ecuadorian Pacific Ocean by sex, sexual maturity stages, size classes, and years. Hakes obtained (n = 2993) from industrial fishing (captured with seine nets) were analyzed from September 2013 to December 2014. Their diet was composed of 27 prey species. The most important prey was the euphausiid Nyctiphanes simplex (52%) and the same hake species (M. gayi; 31%) according to the prey-specific index of relative importance (%PSIRI), making this species a cannibal predator. Results show no significant dietary differences between female and male hakes or immature and mature males, but found differences between immature and mature females and individuals from four size classes and hake between 2013 and 2014. According to Levin’s Index, the species showed a low trophic niche breadth (Bi = 0.03), making it a selective specialist mesopredator with high specialization. The trophic overlap analysis based on Jaccard’s index by sex was low (J = 0.23) for indetermined individuals, moderate (J = 0.59) for males and females, and high (J = 0.78) for immature females and males; moderate values were noted for size classes (J = 0.42-0.63) and low for years (J = 0.31). Based on the Cortés index, the trophic level totaled (TLk = 3.22), indicating that this species is a primary and secondary carnivore mesopredator. This information supports the understanding of the relations between predators and prey and the flow of nutrients and energy in marine ecosystems, which serve as a base for ecosystemic fishing management. Ecuador However scarce M stages n 2993 captured nets 201 2014 2 52% 52 (52% (M 31% 31 preyspecific specific %PSIRI, PSIRI %PSIRI , (%PSIRI) predator Levins Levin s Index Bi 0.03, 003 0.03 0 03 0.03) specialization Jaccards Jaccard J 0.23 023 23 0.59 059 59 0.78 078 78 0.420.63 042063 0.42 0.63 42 63 0.42-0.63 0.31. 031 0.31 . 0.31) TLk 3.22, 322 3.22 3 22 3.22) ecosystems management 299 20 5 (52 (%PSIRI 00 0.0 0.2 02 0.5 05 0.7 07 7 420 0.420.6 04206 042 0.4 063 0.6 4 6 0.42-0.6 0.3 32 3.2 29 (5 0. 0.420. 0420 04 06 0.42-0. 3. ( 0.420 0.42-0 0.42-

Abstract This study aimed to analyze the diet and trophic niche breadth of an insectivorous bat very common in an urban environment in southern Brazil. To analyze the feeding habit of Molossus rufus, it was necessary to collect fecal samples in urban colonies in the city of Maringá, State of Paraná. Samplings occurred from November 2018 to September 2019, including rainy and dry seasons. The fragments found in the samples were identified up to the level of order or family whenever possible. Percentage of volume and frequency of occurrence, Feeding Index (IAi%), PERMANOVA, and trophic niche breadth were used. Thus, a total of 140 samples were obtained, 92 for the rainy season and 48 for the dry season. In terms of percentage of volume, the diet consisted mainly of Hymenoptera (46.9%) in the rainy season and Coleoptera (39.2%) in the dry season. The results for standardized trophic niche breadth were Ba = 0.36 for the rainy season and Ba = 0.37 in the dry season, indicating a low food diversity. In conclusion, there was a food preference on the part of M. rufus according to the season evaluated, with Hymenoptera and Coleoptera being the most relevant dietary items. Brazil Maringá Paraná 201 2019 seasons possible occurrence IAi%, IAi IAi% , (IAi%) PERMANOVA used Thus 14 obtained 9 4 46.9% 469 46 (46.9% 39.2% 392 39 2 (39.2% 036 0 36 0.3 037 37 diversity conclusion M evaluated items 20 (IAi% 1 46.9 (46.9 39.2 3 (39.2 03 0. (IAi 46. (46. 39. (39. (46 (39 (4 (3 (

Abstract The hydrological regime leads to fluctuations in the availability of food resources for fish, which may reflect in their diet variation. Our main goal was to analyze the relationship between water-level fluctuations and the diet and the body condition of Trachelyopterus galeatus in the Upper Paraná River floodplain. The fish used in the study were sampled quarterly along nine years, at nine sampling stations. Our results showed that diet of T. galeatus varied in response to oscillations in the hydrometric level, with the consumption of terrestrial invertebrates being positively related to hydrometric level, while the consumption of aquatic invertebrates was negatively related. The trophic niche breadth and feeding activity were not affected by hydrometric level, but the fish body condition was positively affected. The high food plasticity allows T. galeatus to consume the most available resources (e.g., terrestrial invertebrates in high water levels), which probably contributed to the increase in its body condition in higher hydrometric levels. In summary, the hydrological dynamic is fundamental for the diet variation of omnivorous fish, which can take advantage of the resource availability according to the hydrometric level, increasing its body condition when allochthonous resources as terrestrial invertebrates are supposed to be more available. waterlevel level floodplain years stations T e.g., eg e g (e.g. levels, levels , levels) summary e.g. (e.g e.g

Resumo O regime hidrológico leva a flutuações na disponibilidade de recursos alimentares para os peixes, o que pode refletir na variação de sua dieta. O principal objetivo foi analisar a relação entre as oscilações do nível hidrométrico e a dieta e condição corporal de Trachelyopterus galeatus na planície de inundação do alto rio Paraná. Os peixes foram amostrados trimestralmente durante nove anos, em nove locais. Nossos resultados mostraram que a dieta de T. galeatus variou em resposta às oscilações do nível hidrométrico, com o consumo de invertebrados terrestres sendo positivamente relacionado com o nível hidrométrico, enquanto o consumo de invertebrados aquáticos foi negativamente relacionado. O nicho trófico e a atividade alimentar não foram afetados pelo nível hidrométrico, mas a condição corporal dos peixes foi positivamente afetada. A alta plasticidade alimentar permite que T. galeatus aproveite recursos mais disponíveis (por exemplo, invertebrados terrestres em níveis elevados), o que provavelmente contribui para o aumento da condição corporal em níveis hidrométricos elevados. Em resumo, a dinâmica hidrológica é fundamental para a variação da dieta de peixes onívoros, que podem aproveitar a disponibilidade de recursos de acordo com o nível hidrométrico, aumentando sua condição corporal quando recursos alóctones, como invertebrados terrestres, são supostamente mais disponíveis. Paraná anos locais T afetada por exemplo elevados, elevados , elevados) resumo onívoros alóctones

Abstract The spatial gradients created after the installation of large reservoirs produce a great diversity of biotopes, which affects the distribution and structuring of aquatic communities, mainly fish. Thus, we hypothesized that the fishes living in the lotic stretch (river zone, closest to the natural environment) of the reservoir would have lower overlap and higher niche breadth than fishes living in the lentic stretch. Samples were collected in six sections (lentic and lotic) of the Chavantes Reservoir, middle Paranapanema River. A total of 1478 individuals distributed in 13 species were sampled in both stretches. Many resources were acquired by species, and we observed that nine species present significant differences when comparing the two stretches. Furthermore, only \emph{Schizodon nasutus biotopes communities fish Thus river zone environment Reservoir River 147 1 stretches Furthermore \emphSchizodon emphSchizodon \emph Schizodon emph 14

Abstract We assessed the effect of a flood pulse on the diet composition, trophic niche breadth, and feeding intensity of the mandi catfish Pimelodus blochii (Pimelodidae) in the middle Xingu River region, throughout different hydrological periods. Specimens were collected monthly between December 2020 and November 2021, using gillnets. Specimens were measured for standard length (cm) and body weight (g) and then eviscerated to remove the stomach, which was weighed and stored for content identification. In total, we analyzed 93 stomachs of P. blochii, with the species’ diet predominantly composed of fish (86.5%) and terrestrial plants (6.9%). However, this dietary composition varied seasonally, particularly during the flood period when the species exhibited an omnivorous/carnivorous diet, as opposed to other periods when it had a carnivorous/piscivorous diet. Trophic niche breadth also varied, with the species showing a more specialist diet during the filling period. Finally, there was no difference in the amount of food (g) ingested during the hydrological periods. These results highlight the influence of the flood pulse on the feeding ecology of P. blochii, particularly regarding the diet composition. Our findings contribute to advancing the understanding of the relationship between abiotic dynamics and the life history of Amazonian fish species. Pimelodidae (Pimelodidae region 202 2021 gillnets cm (cm g (g stomach identification total 9 P 86.5% 865 86 5 (86.5% 6.9%. 69 6.9% . 6 (6.9%) However seasonally omnivorouscarnivorous omnivorous carnivorous carnivorouspiscivorous piscivorous Finally 20 86.5 8 (86.5 6.9 (6.9% 2 86. (86. 6. (6.9 (86 (6. (8 (6 (

Resumo Avaliamos o efeito do pulso de inundação na composição da dieta, amplitude de nicho trófico e intensidade alimentar do bagre mandi Pimelodus blochii (Pimelodidae) na região do médio rio Xingu, ao longo de diferentes períodos hidrológicos. A coleta dos espécimes ocorreu mensalmente entre dezembro de 2020 e novembro de 2021, utilizando redes de espera. Os espécimes coletados foram mensurados quanto ao comprimento padrão (cm) e peso total (g) e, em seguida, eviscerados para remoção do estômago, que foi pesado e armazenado para identificação do conteúdo. No total, foram analisados 93 estômagos de P. blochii, sendo a dieta da espécie composta predominantemente por peixes (86,5%) e plantas terrestres (6,9%). No entanto, essa composição da dieta variou sazonalmente, especialmente durante a cheia, quando a espécie apresentou uma dieta onívora/carnívora, em contraste com outros períodos em que teve uma dieta carnívora/piscívora. A amplitude do nicho trófico também variou, e a espécie apresentou uma dieta mais especialista durante a enchente. Por fim, não houve diferença na quantidade de alimento ingerido (g) entre os períodos hidrológicos. Esses resultados evidenciam que o pulso de inundação exerce influência na ecologia alimentar de P. blochii, principalmente em relação à composição da dieta. Nossos achados contribuem para o avanço do conhecimento sobre a relação entre dinâmicas abióticas e a história de vida de espécies de peixes amazônicas. Pimelodidae (Pimelodidae Xingu hidrológicos 202 2021 espera cm (cm g (g seguida estômago conteúdo 9 P 86,5% 865 86 5 (86,5% 6,9%. 69 6,9% . 6 (6,9%) entanto sazonalmente cheia onívoracarnívora onívora carnívora onívora/carnívora carnívorapiscívora piscívora carnívora/piscívora enchente fim amazônicas 20 86,5 8 (86,5 6,9 (6,9% 2 86, (86, 6, (6,9 (86 (6, (8 (6 (

Abstract The role of fishes in trophic dynamics in the aquatic ecosystems has been studied by analyzing fish diet and trophic position in ecosystems using diverse methods (e.g., visual inspection of stomach contents and feces, stable isotopes, DNA sequencing). Thanks to the advances in high-throughput DNA sequencing technology, the use of the metabarcoding method has increased in recent years, proving to have greater precision and taxonomic scope than other methods, and allowing the analysis of a larger number of samples simultaneously in less time. This review describes the metabarcoding method, discusses its advantages and limitations, and presents experimental and analytical alternatives to address such limitations. Additionally, we provide a synthesis of the current state of knowledge of the metabarcoding method applied to the analysis of the trophic fish ecology to understand the scope and limitations of using this method in Mexico.

Resumen El papel de los peces en la dinámica trófica de los ecosistemas acuáticos se ha estudiado usando diferentes métodos que permiten determinar su dieta y posición trófica (inspección visual del contenido estomacal y heces, isótopos estables, secuenciación de ADN). Con los avances tecnológicos en la secuenciación de alto rendimiento del ADN, el uso del método de metabarcoding se ha incrementado en los últimos años, demostrando tener mayor precisión y alcance taxonómico que otros métodos, además de que permite el análisis simultáneo de un mayor número de muestras en un menor tiempo. En esta revisión, se describen los pasos del método de metabarcoding, discutiendo sus ventajas y limitaciones, así como las alternativas experimentales y analíticas propuestas para atender dichas limitaciones. Además, se presenta una síntesis del estado del conocimiento del método de metabarcoding aplicado al análisis de la ecología trófica de peces para entender los alcances y las limitaciones de este método en México.

Resumen. El tiburón sedoso Carcharhinus falciformis es una de las especies de tiburón más importantes en las capturas de la pesquería de pequeña escala de la costa mexicana del Pacífico. En el presente trabajo reportamos los principales componentes alimentarios de C. falciformis capturados por la flota pesquera de pequeña escala en Acapulco, Guerrero, México, de acuerdo con la talla (neonatos y juveniles) y el sexo (machos y hembras), así como la amplitud de su nicho y nivel trófico. Se recolectaron en total 165 estómagos de C. falciformis, de los cuales 57 presentaron contenido estomacal y 108 se encontraron vacíos. Se identificaron en total 11 componentes alimentarios: 4 crustáceos, 3 peces, 2 cefalópodos, 1 tortuga marina y 1 ave. De acuerdo con el índice de importancia relativa especifica de la presa (%IIREP), el grupo de los crustáceos representó el 77.17% de la dieta. El cangrejo Portunus xantusii fue el componente más importante de la dieta de neonatos, juveniles, machos y hembras. Las dietas entre neonatos y juveniles y entre machos y hembras no presentaron grandes diferencias (índice de Morisita-Horn: 0.86 y 0.80, respectivamente). El tiburón sedoso presentó una amplitud de nicho estrecha en todas las categorías, lo que indicó una estrategia de alimentación de tipo especialista (índice de Levin <0.60). De acuerdo con el modelo de Amundsen, C. falciformis mostró una preferencia por P. xantusii. El nivel trófico determinado para C. falciformis indicó que es un depredador secundario.

Abstract. The silky shark, Carcharhinus falciformis, is one of the most important shark species in the small-scale fishery landings on the Pacific coast of Mexico. In the present work, we report the main food components of C. falciformis caught by small-scale fisheries in Acapulco, Guerrero, Mexico, according to size (neonates and juveniles) and sex (males and females), as well as reporting the niche breadth and trophic level. A total of 165 stomachs of C. falciformis were collected, of which 57 contained food and 108 were empty. A total of 11 prey groups were identified: 4 crustaceans, 3 fish, 2 cephalopods, 1 sea turtle, and 1 bird. According to the prey-specific index of relative importance (%PSIRI), crustaceans accounted for 77.17% of the diet. The crab Portunus xantusii was the most important component of the diet of neonates, juveniles, males, and females. The diets did not show great differences between neonates and juveniles and between males and females (Morisita-Horn index: 0.86 and 0.80, respectively). The silky shark presented a narrow niche breadth in all categories, indicating a specialist-type feeding strategy (Levin’s index <0.60). According to Amundsen’s model, C. falciformis showed preference for P. xantusii. The trophic level determined for C. falciformis indicated that it is a secondary predator.

ABSTRACT Lionfish was studied in the mesophotic environment. 237 specimens were observed, most in the upper mesophotic zone. Males were larger than females and differences between sexes in growth models were found. Sixteen prey items were identified, the most important being the teleost families Acanthuridae and Monacanthidae, and the crustacean Penaeidae. The mean of δ13C was -17.08 ± 0.36 ‰ and δ15N was 8.68 ± 0.46 ‰, with no differences between sexes. Lionfish occupies a less extensive isotopic niche in mesophotic environment than in shallow sectors; there is an isotopic niche overlap between sexes. Likewise, lionfish has specialized trophic habits. All specimens were mature and in females regression phase predominated. In females, condition factor (CF), gonadosomatic index (GSI) and hepatosomatic index (HSI) increased with gonadal development, reaching peak in the active spawning phase, and decreasing in regression. Males had a condition factor similar to spawning females, but IGS and IHS were lower.

RESUMEN En el ambiente mesofótico se observaron 237 especímenes de Pterois, mayoritariamente en la zona mesofótica superior. Los machos fueron más grandes que las hembras con modelos de crecimiento diferenciados. Se identificaron 16 ítems de presas, siendo los peces Acanthuridae y Monacanthidae y los camarones Penaeidae las más importantes. La media de δ13C fue -17,08 ± 0,36 ‰ y la de δ15N fue 8,68 ± 0,46 ‰, no detectándose diferencias entre sexos. La especie ocupa un nicho isotópico menos extenso que en sectores someros, tiene traslapo entre sexos y hábitos tróficos especialistas (Levin = 0,22). En hembras el factor de condición (FC), el índice gonadosomático (IGS) y el índice hepatosomático (IHS) aumentaron con el desarrollo gonadal alcanzando pico en fase de desove activo, y disminuyendo en regresión. Los machos tuvieron un FC similar al de hembras en desove, pero el IGS y el IHS fueron menores.

RESUMEN La dieta de las tortugas de agua dulce Acanthochelys spixii y Hydromedusa tectifera es poco conocida en el extremo sur del Brasil. En este contexto se examinó el tracto digestivo de 21 individuos de A. spixii y 20 de H. tectifera provenientes de cuatro municipios del estado de Rio Grande do Sul, Brasil. Los ítems consumidos fueron identificados al nivel taxonómico más bajo posible, cuantificados y conservados en etanol de 70 °GL. Se obtuvieron las variables frecuencia de ocurrencia (F %) y el volumen porcentual (V %) de cada categoría de presa y se calculó el índice de importancia alimentaria (IAi %). Se analizó la amplitud del nicho trófico y la estrategia de alimentación de ambas especies. Las dietas se compararon usando la prueba de Mann-Whitney (P < 0,05). Ambas especies presentaron una estrategia de alimentación generalista, consumiendo principalmente insectos Hemiptera, Odonata, Coleoptera y Diptera. No hubo diferencias significativas en el volumen de ítems consumidos por ambas especies (Mann-Whitney, z = -0,387, P = 0,69). En relación con la amplitud de nicho trófico observamos valores bajos para ambas especies, 0,41 en A. spixii y 0,39 en H. tectifera, lo que sugiere una dieta más restringida con uniformidad en el consumo de alimentos, sin embargo, resaltamos que una dieta más restringida no sugiere una especialización trófica, ya que la disponibilidad de los elementos alimenticios tiene variación en el tiempo y el espacio. El estudio aportó información sobre la dieta de las especies de la región, generando datos que pueden utilizarse en programas de conservación de las especies y sus hábitats.

ABSTRACT Data about the diet of the freshwater turtles Acanthochelys spixii and Hydromedusa tectifera from southern Brazil populations remain little known. In this context, the digestive tract of 21 A. spixii and 20 of H. tectifera individuals from four municipalities in the state of Rio Grande do Sul, Brazil, were examined. The food items were identified at the lowest possible taxonomic level, quantified, and conserved in ethanol 70°GL. The frequency of occurrence (F %) and volume percentage (V %) were estimated, as well as the food importance index (IAi %). The range of the trophic niche and the feeding strategy of both species were analyzed. The diet of A. spixii and H. tectifera was compared through the Mann-Whitney test (P < 0.05). Both species presented a generalist food strategy, consuming mainly insects, represented by Hemiptera, Odonata, Coleoptera, and Diptera. There was no significant difference in the volume of items consumed by both species (Mann-Whitney test, z =-0.387, P = 0.69). Concerning the trophic niche range, we observed low values for both species, it was of 0.41 for A. spixii and 0.39 for H. tectifera suggesting a more restricted diet with uniformity in food consumption, however, we highlight that a more restricted diet does not suggest a trophic specialization, because the availability of food items have variation in time and space. The study contributed information on the diet of species in the region, generating data that can be used in programs for the conservation of species and their habitats.

ABSTRACT There are few studies describing the eating habits of non-human primates (NHPs) that provide information related to the use of food resources of the ecosystem in the Amazon Forest. The objectives of the study were (1) to determine the composition of the diet of six species of NHPs and (2) to evaluate the amplitude and diversity of their diets from the evaluation of the gastric contents of animals hunted for subsistence purposes by inhabitants of three areas of the northern Peruvian Amazon between 2012-2015. Samples of 82 primates of the species Lagothrix poeppigii (n = 30), Sapajus macrocephalus (n = 23), Pithecia monachus (n = 11), Cacajao calvus (n = 8), Cebus albifrons (n = 6) and Alouatta seniculus (n = 4). The NHPs diet consisted of a high variety of fruits, including 133 types of seeds and 39 types of arthropods. The amplitude of the niche according to the Levin Index and the Simpson Diversity Index indicate that L. poeppigii is the most generalist species in terms of fruits and arthropods, followed by C. calvus with arthropods and by S. macrocephalus in the use of fruits. On the contrary, Cebus albifrons is the most specialized species when it comes to fruits and P. monachus when it comes to arthropods.

RESUMEN Se dispone de escasos estudios que describan los hábitos alimenticios de los primates no humanos (PNH) que permiten conocer el uso de los recursos alimenticios del ecosistema en el bosque amazónico. El estudio tuvo como objetivos (1) determinar la composición de la dieta de seis especies de PNH y (2) evaluar la amplitud y diversidad de sus dietas a partir de la evaluación de los contenidos gástricos de animales cazados con fines de subsistencia por pobladores de tres áreas del norte de la Amazonía peruana entre 2012-2015. Se trabajó con muestras de 82 primates de las especies Lagothrix poeppigii (n=30), Sapajus macrocephalus (n=23), Pithecia monachus (n=11), Cacajao calvus (n=8), Cebus albifrons (n=6) y Alouatta seniculus (n=4). La dieta de los PNH estuvo constitui- da por una alta variedad de frutos, entre ellos por 133 tipos de semillas y 39 tipos de artrópodos. La amplitud del nicho según el Índice de Levin y el Índice de Diversidad de Simpson indican que L. poeppigii es la especie más generalista en lo referente a frutos y artrópodos. Por el contrario, Cebus albifrons es la especie más especialista en lo que se refiere a frutos y P. monachus cuando se trata de artrópodos.

Resumo Objetivo O estudo buscou investigar se as mudanças na composição da dieta e na amplitude de nicho trófico de Eigenmannia desantanai podem ser explicadas pelos períodos hidrológicos, rios e/ou ontogenia dos peixes. Métodos As coletas foram realizadas mensalmente nos rios Paraguai e Amonguijá, entre Fevereiro de 2009 a Janeiro de 2011. Resultados Foram coletados 338 exemplares de E. desantanai, sendo 224 do Rio Amonguijá e 114 do Rio Paraguai. Ao todo, foram identificados 21 itens alimentares. Restos de animais digeridos (RAD), Chironomidae, Cladocera e Ostracoda apresentaram maior importância na dieta de E. desantanai. A composição da dieta foi influenciada pelos períodos hidrológicos, seguida pelas diferenças dos rios amostrados e da ontogenia. Em contrapartida, apenas os períodos hidrológicos explicaram a variação na amplitude do nicho trófico de E. desantanai. Conclusões A dieta de E. desantanai é composta principalmente por Chironomidae, Cladocera e Ostracoda, no entanto, os indivíduos consumiram outros alimentos devido às mudanças dos períodos hidrológicos, seguida das características dos rios Amonguijá e Paraguai e da variação ontogenética. Neste contexto, os resultados deste estudo são pertinentes à ecologia alimentar de E. desantanai, fornecendo diretrizes para o manejo e conservação da espécie.

Abstract Aim This study investigated changes in the dietary composition and trophic niche breadth of Eigenmannia desantanai in the context of hydrological periods, rivers, and ontogeny. Methods Collections were performed monthly on the Paraguay and Amonguijá Rivers between February 2009 and January 2011. Results A total of 338 specimens of E. desantanai were collected, 224 of which came from the Amonguijá River and 114 from the Paraguay River. In all, 21 food items were identified. Fully remains of digested animals (RDA), Chironomidae, Cladocera, and Ostracoda showed greater importance in the diet of E. desantanai. Dietary composition was influenced by hydrological periods, followed by differences between sampled rivers, and ontogeny. In contrast, only hydrological periods explained variation in the E. desantanai trophic niche breadth. Conclusions The diet of E. desantanai is mainly composed of Chironomidae, Cladocera, and Ostracoda; however, individuals consumed other food items owing to changes in hydrological periods, followed by characteristics of the Amonguijá and Paraguay Rivers and ontogenetic variation. In this respect, the results of this study are germane to the food ecology of E. desantanai, providing guidelines for the management and conservation of the species.