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Coastal habitats have great ecological importance with estuarine environments providing feeding sites for many fish species, especially during juvenile life stages. This study investigates the diet composition and trophic guild organization of the common and abundant ichthyofauna in shallow areas of the Todos os Santos Bay (TSB), Bahia, Brazil, and their relationships with environmental parameters. Six fish sampling campaigns were carried out in the shallow zones (infralittoral) of the Paraguaçu River estuary which encompasses the inner and outer (marine exposure) reaches of the TSB. The stomach contents of 1231 individuals belonging to common and abundant species were examined. A total of 32 food items were identified and fish were into four trophic guilds: detritivores, zoobenthivores I, zoobenthivores II, and zooplanktivores. The relationship between the guilds and environmental parameters showed that zoobenthivores II and zooplanktivores guilds had a positive relationship with salinity and pH, explaining 86% of data variability, though only the salinity variable was significant. This study provides basic information about the diet composition of common and abundant species in the TSB and their organization into trophic guilds. In addition, demonstrates that shallow waters fish across all guilds have broadly similar diets, comprising food items that are usually associated with bottom waters.

The species Hyphessobrycon bifasciatus, also known as the 'lemon tetra', is a small characin fish distributed in coastal rivers from the southern state of Bahia to the state of Rio Grande do Sul, and also in the upper Paraná river basin, found in small rivers and lagoons. Its diet varies between small invertebrates and plant debris. They are oviparous animals that lay their eggs on the bottom or in groups of plants, which hatch approximately two days after fertilization. In light of this, the present study aimed to describe the population structure of H. bifasciatus in terms of feeding and length-weight relationship in a dammed neotropical stream located in the municipality of São Roque, SP, Brazil. Specimens of H. bifasciatus were captured in two collection campaigns (November 2021 and July 2022). The fish were collected using a three-meter-long trawl net, with a 1 cm mesh and a sampling effort of 30 minutes at each point. Subsequently, they were transported to the laboratory, where their length and standard weight were recorded, along with their stomach contents. A total of 101 specimens were analyzed, 41 females and 60 males. The species had an average body length of 2.5 ± 0.46 cm and an average total weight of 0.33 ± 0.19 g for females, and 2.8 ± 0.60 cm and 0.45 ± 0.27 g for males. We obtained a length-weight relationship of y = 0.4317x - 0.7574, R² = 0.9393 for males, and y = 0.3413x - 0.5237, R² = 0.8704 for females. The size range varies from the 1.6-2.0 centimeter class to the 3.6-4.0 centimeter class. The main food items were plant material and filamentous algae, abundant in both sexes. Finally, it is concluded that this species forms large schools near macrophytes, exhibits peaceful behavior, and feeds mainly on plant items.

Many ecosystem functions depend on the structure of food webs, which heavily relies on the body size spectrum of the community. Despite that, little is known on how the size spectrum of soil animals responds to agricultural practices in tropical land‐use systems and how these responses affect ecosystem functioning. We studied land‐use‐induced changes in below‐ground communities in tropical lowland ecosystems in Sumatra (Jambi province, Indonesia), a hot spot of tropical rainforest conversion into rubber and oil palm plantations. The study included ca. 30,000 measured individuals from 33 high‐order taxa of meso‐ and macrofauna spanning eight orders of magnitude in body mass. Using individual body masses, we calculated the metabolism of trophic guilds and used food web models to calculate energy fluxes and infer ecosystem functions, such as decomposition, herbivory, primary and intraguild predation. Land‐use change was associated with reduced abundance and taxonomic diversity of soil invertebrates, but strong increase in total biomass and moderate changes in total energy flux. These changes were due to increased biomass of large‐sized decomposers in soil, in particular earthworms, with their share in community metabolism increasing from 11% in rainforest to 59%–76% in jungle rubber, and rubber and oil palm plantations. Decomposition, that is the energy flux to decomposers, stayed unchanged, but herbivory, primary and intraguild predation decreased by an order of magnitude in plantation systems. Intraguild predation was very important, being responsible for 38% of the energy flux in rainforest according to our model. Conversion of rainforest into monoculture plantations is associated by an uneven loss of size classes and trophic levels of soil invertebrates resulting in sequestration of energy in large‐sized primary consumers and restricted flux of energy to higher trophic levels. Pronounced differences between rainforest and jungle rubber reflect sensitivity of rainforest soil animal communities to moderate land‐use changes. Soil communities in plantation systems sustained high total energy flux despite reduced biodiversity. The high energy flux into large decomposers but low energy fluxes into other trophic guilds suggests that trophic multifunctionality of below‐ground communities is compromised in plantation systems. The study links size spectrum, energy fluxes and diversity of soil invertebrate communities under the massive land‐use change in Indonesia. Energy in soil food webs of plantations is sequestered in large decomposers and does not reach high trophic levels, which may compromise stability and multifunctionality of these systems.

ContextHabitat loss is widely recognized as the main driver of biodiversity loss around the globe, yet the effects of habitat fragmentation on biodiversity have been extensively debated in recent years.ObjectivesWe used a robust dataset of medium and large-sized mammals to test (a) the Habitat Amount Hypothesis, which postulates that species richness can be mainly predicted by the total amount of habitat surrounding the sampling site, and (b) the effects of habitat fragmentation per se, which may be expected to be weak or mainly positive on species richness.MethodsWe compiled information on the occurrence of mammal species in 166 forest fragments across the Atlantic Forest. For each forest fragment, we extracted information on patch size, percentage of forest cover (a proxy for habitat amount), and edge density and number of fragments (fragmentation metrics). We related these metrics to mammalian richness considering separately for all species, forest-dependent species, disturbance-tolerant species, and different trophic guilds.ResultsAll richness measures strongly declined with decreasing forest cover, yet were unaffected by patch size, number of patches and edge density. The only exception occurred with herbivore richness, which was affected by number of patches. However, we found fragmentation per se effects only for herbivore richness.ConclusionsOur results show that mammal richness increased with habitat amount at the landscape, whereas habitat fragmentation per se had significant negative impacts on herbivores only. We therefore recommend maintaining highly forested landscapes and restoring severely deforested areas, being essential for ensuring high richness of mammals.

Context Organic farming is increasingly used worldwide in recent decades, but the role of this farming system in shaping the trophic structure of arthropod communities remains poorly understood, especially at different spatial scales. Therefore, the contribution of landscape heterogeneity in shaping arthropod’s trophic guilds remain understudied. Objectives In this study, we assessed how the evenness, the abundance and the taxonomic richness of arthropod trophic groups were shaped by the local farming system, landscape heterogeneity (including the percentage of semi-natural habitats and organic fields), and their interaction. Methods Arthropod’s trophic guilds (ground and vegetation-dwelling) were sampled in 20 spatial independent pairs of conventional (CF) and organic (OF) fields located in Brittany (Western France) by using pitfall traps and sweep nets replicated in time and space. Results A total of 95,822 arthropods belonging to 197 taxonomic groups were sampled. Farming system has a strong overall positive effect on the community structure of both ground- and vegetation-dwelling arthropods. Landscape heterogeneity, alone and in interaction with farming systems, affected positively the diversity and abundance of most trophic groups for both ground- and vegetation-dwelling arthropods. Organic farming therefore affected the trophic composition of arthropod communities not only locally, but also at the landscape scale. Conclusions Our study highlights the strong positive effect of farming system and the landscape heterogeneity on arthropod communities and more importantly the interconnection between different spatial scales in this process. Taking these aspects into account is therefore crucial in understanding arthropod community dynamics in agroecosystems.

Stable isotope ratios (typically of carbon and nitrogen) provide one representation of an organism's trophic niche and are widely used to examine aspects of food web structure. Yet stable isotopes have not been applied to quantitatively characterize community‐wide aspects of trophic structure (i.e., at the level of an entire food web). We propose quantitative metrics that can be used to this end, drawing on similar approaches from ecomorphology research. For example, the convex hull area occupied by species in δ13C–δ15N niche space is a representation of the total extent of trophic diversity within a food web, whereas mean nearest neighbor distance among all species pairs is a measure of species packing within trophic niche space. To facilitate discussion of opportunities and limitations of the metrics, we provide empirical and conceptual examples drawn from Bahamian tidal creek food webs. These examples illustrate how this methodology can be used to quantify trophic diversity and trophic redundancy in food webs, as well as to link individual species to characteristics of the food web in which they are embedded. Building from extensive applications of stable isotope ratios by ecologists, the community‐wide metrics may provide a new perspective on food web structure, function, and dynamics.

The objective of the investigation was to explore the abundance, composition, and diversity patterns of the fish fauna along the temporal and spatial scale and study the influence of environmental parameters on the fish assemblage in the Rihand reservoir, a large sub-tropical Indian reservoir in India. On the temporal scale, the highest abundance was recorded in the summer season and the lowest in the monsoon season, while on the spatial scale, the highest abundance was recorded from the riverine and the minimum from the lacustrine zone. The highest species richness and diversity were recorded from the riverine zone followed by the transitional and lacustrine zones, respectively. The analysis of the variance of fish abundance revealed insignificant differences between the riverine and the transitional zones. The trophic guild analysis indicated the dominance of carnivores. The output of canonical correspondence analysis depicted the significant influence of the physico-chemical traits on the abundance of fish species. The transparency and specific conductivity were found to be the most critical factors affecting fish assemblages in the Rihand reservoir. This study generated important baseline ecological information that would be useful for the monitoring, conservation, and management of the reservoir ecosystem.

Species‐area relationships (SARs) are one of the most well‐established conservation biogeography patterns, and in rivers, habitat area is mediated by discharge. Species richness and river discharge have a well‐established positive relationship, but how discharge affects trophic diversity is less clear. Free‐flowing tropical river ecosystems are hotspots of global biodiversity, but they are under increasing threat from water resource developments which alter river discharge regimes. Here we investigate relationships between river discharge metrics and the species richness of freshwater fish trophic guilds in tropical rivers of northern Australia, using data collated from 40 catchments. We analyzed relationships between the species richness of freshwater fish trophic guilds and discharge metrics including mean annual discharge (Q), mean daily dry and wet season discharge, and the coefficient of variation (CVQ) of Q. Invertivores and omnivores were the most species‐rich trophic guilds. Our results show that the species richness of trophic guilds in north Australian freshwater fishes was correlated with multiple components of wet‐dry tropical river discharge regimes. The species richness of predators, invertivores, and herbivore‐detritivores increased with Q and wet season discharge, whereas omnivore and invertivore richness increased with dry season discharge. Increasing variability in discharge had a negative effect on the species richness of invertivores and omnivores, suggesting adverse effects of low discharge periods. We found no statistical support for the hypothesis that the slope of SARs increases with trophic level, as suggested by previous research. These findings suggest that decreases in wet and dry season discharge, or increases in flow variability due to water resource development or climate change, may result in the loss of trophic diversity from tropical rivers. Our results suggest that the conservation of both wet and dry season natural flow regimes in tropical rivers will be needed to protect freshwater fish trophic diversity. Contrary to the trophic theory of island biogeography the slope of predators does not increase with discharge when used to replace area. However, dry season discharge and variability in annual discharge are more strongly correlated with omnivore and invertivore guilds of freshwater fish than other discharge metrics. The credit is Fish images courtesy of the NESP Resilient Landscapes Hub, nesplandscapes.edu.au.

Coastal ecosystems can vary considerably in their habitat characteristics and environmental conditions, resulting in divergent fish community structures. However, comparisons among coastal systems, such as oceanic beaches, bays and coastal lagoons, have not been thoroughly evaluated. We test the hypothesis that coastal systems that differ in wave exposure, habitat structure, salinity gradients and productivity show different assemblages and feeding guilds. The fish assemblages were significantly different among the systems. The bays had the largest number of species, whereas the lagoons had the highest numerical abundance and biomass. The planktivorous guild dominated in numerical abundance in all systems, whereas the opportunists dominated in biomass. The benthivores contributed greatly in abundance to the bays, the opportunists to the coastal lagoons, and the hyperbenthivores to the oceanic beaches. Water transparency and temperature explained a small portion of the variation in the community structure. This study highlighted the complex role that local factors have on the distribution of fishes at the species and trophic levels. These approaches were efficient to describe the structure and functioning of the assemblages in these different coastal systems. This should be viewed as essential for any comparisons of coastal systems, and in particular for conservation planning.

Several authors suggest that greater vegetation complexity provides more shelters, supporting higher parasitoid diversity. Additionally, it serves as visual cue in host searching. This study evaluates how visual stimuli and herbivore-induced vegetation changes affect parasitoid strategies and guilds in low deciduous forest [Yabucu], and Medium Semi-Evergreen forest [Noh-Bec]. We calculated the relative abundance of idiobiont and koinobiont life strategies for each vegetation type and constructed the range-abundance curves of these communities. Also, the relationship of guilds with the different types of damage from herbivory and leaf characteristics were described. The koinobiont:idiobiont (K:I) ratio was 6:1 (86.65% koinobionts and 13.35% idiobionts) in Yabucú and 1:2 (32.78% koinobionts and 67.22% idiobionts) in Noh-Bec. Some guilds were associated with vegetation: a negative correlation between fluctuating asymmetry seedlings (FAS) and parasitoids attacking larvae into the fruiting bodies of fungi was founded; the FAS is an indirect indicator of herbivory, nonetheless, the parasitoids found do not target phytophagous hosts, which makes an inverse relationship plausible and could potentially reduce intra-guild competition. Hyperparasitoids were positively associated with holes in adult plants (HA); with an association with herbivore parasitoids, which could be contributing to the recorded evidence of holes.