Composition Of Trophic Guilds Research Articles

Composición histórica de los ensamblajes de peces en el sistema lagunar de alvarado, golfo de México

The composition of fish assemblages in the Alvarado Lagoon System was updated with information collected between 1966 and 2008, divided into nine collection periods. A temporal analysis of the variation in species richness, species richness indices, rarity, and composition of ecological and trophic guilds was also carried out. A total of 113 species were recognized, 66 of which were present in most of the collection periods, forming a group with a constant presence in the lagoon system, in which marine and freshwater species predominated. This group showed the highest levels of similarity between collection periods; this was confirmed by the richness and rarity indices. Functionally, the composition of the ecological and trophic guilds did not show significant differences. The composition of the trophic guilds showed a prevalence of invertebrate consumers, macrocrustaceans, and small fish, supporting the fact that migratory marine species were the most numerous, with minor contributions from the other guilds. The contribution of marine or freshwater visitor species was not important in the characteristics of the assemblages. These results suggest that the environmental conditions of the Alvarado Lagoon System have remained without severe changes during the study period, thus allowing both the constancy of the fish community and that of the ecological and trophic guilds.

A quick evaluation of ecological restoration based on arthropod communities and trophic guilds in an urban ecological preserve in Mexico City

BackgroundRestoration practices usually emphasize on the structural part of the biodiversity; also, most studies have focused on plants and very few have been conducted on arthropods and its function after restoration. The Pedregal de San Angel Ecological Reserve (PSAER) is a protected area immersed in Mexico City and it has been drastically affected by different anthropogenic disturbances. The aim of this study was to compare the relative diversity, richness, and abundance of species level identification, but also the composition through an analysis of ordination of taxonomic (species, family, and order level) and functional (trophic guild) traits of arthropods in three sites subjected to ecological restoration within the PSAER. Restored sites were also compared to conserved and disturbed sites, to evaluate whether restoration efforts are effective at the reserve.MethodsArthropods were sampled using pan traps during September 2013 in 11 sites (three restored, four conserved and four disturbed) inside the PSAER. All sampled species were taxonomically identified at species of morphospecies (inside a family) and assigned to a trophic guild. Differences in diversity, richness and abundance were evaluated through effective number of species, comparisons of Chao’s1 estimated richness and a non-parametric Kruskal–Wallis test, respectively. Both taxonomic and trophic guild composition were evaluated using a multivariate analysis and a post hoc test.ResultsWe found some differences in richness, abundance, and diversity between sites, but not a clear pattern of differentiation between restored to disturbed sites. The NMDS showed differences at species and order level, and with trophic guilds, among site types. Families were not useful to differentiate types of sites. Regarding guilds, predators were more abundant in conserved sites, while phytophagous insects were more abundant in disturbed sites.ConclusionsSpecies and order level were useful to identify differences in communities of arthropods in sites with different management. The trophic guild approach provides information about the functional state of the restored sites. Nevertheless, our quick evaluation shows that restoration efforts at PSAER have not been successful in differentiate restored to disturbed sites yet.

Drivers of fish trophic guild composition in lakes of the Upper Paraná River floodplain

Drivers of fish trophic guild composition in lakes of the Upper Paraná River floodplain

Effect of the matrix-edge-forest interior gradient on the phyllostomid bats assemblage in sub-Andean forest fragments

The edge effect is one of the consequences of forest fragmentation and is one of the main drivers of alteration of ecological and ecosystem processes. Trophic guilds and species of bats have shown differential responses to this phenomenon. Our goal was to describe the change in bat species richness, abundance, evenness, and species composition of trophic guilds associated with a matrix edge-forest interior gradient. Therefore, we conducted a bat sampling with 16 mist nets covering such gradient in four sub-andean forest fragments (10-50 ha). In total, we captured 566 individuals of 21 species of phyllostomid bats. Bat species richness and abundance were higher in the matrix and edge and were similar between fragments. Evenness showed the lowest values in the matrix and forest edge and was different between forest patches. Some shrub frugivorous bats were more abundant in the edge, and others were more abundant in two fragments. Species composition of canopy frugivorous bats was similar along the gradient but was significantly different between fragments. In contrast, the species composition of nectarivores was similar throughout the matrix-interior forest gradient and between patches. Our data suggest that bat responses at assemblage-level are affected by the disturbance gradient from the matrix to forest interior, even at short distances form fragment borders, and are dependent on the trophic guild.

Patterns of functional diversity of macroinvertebrates across three aquatic ecosystem types, NE Mediterranean

This study is focused on investigating the variation patterns of macroinvertebrate guilds functional structure, in relation to the taxonomic one, across aquatic ecosystem types along the salinity gradient from freshwater to marine and the resulting implications on guild organization and energy flows. Synoptic samplings have been carried out using the leaf-pack technique at 30 sites of the aquatic ecosystems of the Corfu Island (Greece), including freshwater, lagoon, and marine sites. Here, we analyzed the macroinvertebrate guilds of river, lagoon, and marine ecosystems, as: i. taxonomic composition and population abundance ii. trophic guilds composition and relative abundance; and iii. body size spectra and size patterns. The following variation patterns across the three ecosystem types were observed: a. trophic guild composition and body size spectra were more conservative than taxonomic composition within and among ecosystem types, where, trophic guild and size spectra composition were more similar between river and lagoon ecosystem types than with marine ones; b. a dominance on resource exploitation of large species over smaller ones was inferred at all sites; and, c. higher body size-specific density of individuals was consistently observed in lagoon than in freshwater and marine ecosystems. Results extend previous findings suggesting a common hierarchical organization of benthic macroinvertebrate guilds in aquatic ecosystems and showing that lagoon ecosystems have higher energy density transferred to benthic macroinvertebrates than both freshwater and marine ecosystem types.

A standardized assessment of forest mammal communities reveals consistent functional composition and vulnerability across the tropics

The understanding of global diversity patterns has benefitted from a focus on functional traits and how they relate to variation in environmental conditions among assemblages. Distant communities in similar environments often share characteristics, and for tropical forest mammals, this functional trait convergence has been demonstrated at coarse scales (110–200 km resolution), but less is known about how these patterns manifest at fine scales, where local processes (e.g. habitat features and anthropogenic activities) and biotic interactions occur. Here, we used standardized camera trapping data and a novel analytical method that accounts for imperfect detection to assess how the functional composition of terrestrial mammal communities for two traits – trophic guild and body mass – varies across 16 protected areas in tropical forests and three continents, in relation to the extent of protected habitat and anthropogenic pressures. We found that despite their taxonomic differences, communities generally have a consistent trophic guild composition, and respond similarly to these factors. Insectivores were found to be sensitive to the size of protected habitat and surrounding human population density. Body mass distribution varied little among communities both in terms of central tendency and spread, and interestingly, community average body mass declined with proximity to human settlements. Results indicate predicted trait convergence among assemblages at the coarse scale reflects consistent functional composition among communities at the local scale, suggesting that broadly similar habitats and selective pressures shaped communities with similar trophic strategies and responses to drivers of change. These similarities provide a foundation for assessing assemblages under anthropogenic threats and sharing conservation measures.

Understanding Fish Assemblage Structure in Lentic Ecosystems: Relative Effects of Abiotic Factors and Management Legacies

AbstractWe investigated associations of fish assemblages and habitat characteristics (e.g., morphology and water chemistry) from 45 natural lakes and reservoirs in Iowa to determine whether species or trophic guild composition and environmental correlations were concordant between waterbodies of different origins. Overall, fish assemblage composition between natural lakes and reservoirs was consistently dissimilar based on a permutational multivariate ANOVA. Species composition from nonmetric multidimensional scaling ordinations for reservoirs was correlated with a variety of limnological and physical characteristics, whereas species composition and trophic composition of natural lakes were weakly associated with habitat characteristics. Species richness was positively related to waterbody and watershed size for reservoirs but not for natural lakes. Conversely, species richness was negatively correlated with increasing eutrophic conditions in natural lakes but not in reservoirs. Overall, distinct differences in assemblage composition were observed between natural and artificial lentic ecosystems and may have resulted from underlying differences in limnological, physical, and anthropogenic influences between systems. Dissimilar management legacies between waterbody types, such as limited or no stocking of nonrecreationally important species and the use of piscicides, may have additionally had overriding effects on the observed assemblage–environmental relationships. For instance, lower trophic richness and species richness in reservoirs appeared to have resulted from replacement of a diversity of small‐bodied native species by relatively few commonly stocked sport fishes. Our results emphasize the need to consider waterbody origin and the potential influence of historical or current management strategies on fish assemblage characterization and subsequent inferences made from environmental correlations.

Distribution and diversity of polychaetes along a bathyal escarpment in the western Mediterranean Sea

Knowledge of the diversity of deep-sea polychaetes in the Mediterranean Sea is still scarce and fragmentary, due to the absence of comprehensive taxonomic revisions of several families, with the majority of recent works relying on higher level taxonomy. In the present work samples were collected with a box-corer along the Sardinian Slope, a bathyal escarpment area located in the western Mediterranean Sea, at seven depth levels separated from each other by a 300 m interval, ranging from 600 to 2400 m. Samples were sifted with a 0.3 mm mesh, and polychaetes were identified at the lowest taxonomic level and characterised from the biogeographic and tropho-functional point of view. Ninety-seven taxa were recorded, 60 of which identified at the species level; eight taxa are likely to be undescribed species, possibly endemic to the Mediterranean Sea, whereas another seven are reported for the first time for the Mediterranean Sea. The majority of taxa shows an Atlantic-Mediterranean or strictly Mediterranean distribution, thus confirming the similarity between Atlantic and Mediterranean deep-sea assemblages, but also the unicity of the latter. Conversely, cosmopolitan taxa, usually considered common in deep-sea assemblages, represented a minor component. The trophic guild composition of the assemblage varied along the slope, with shallower assemblages (600–900 m) including a relatively high percentage of predators and microphagous omnivores, while deeper assemblages (1500–1800 m) showed a > 90% percentage of deposit- and filter-feeders, with the 1200 m assemblage characterised by intermediate features. This outcome suggests that in the presently investigated area, the environmental conditions of shallower samples allow the stable occurrence of at least two trophic levels, whereas deeper assemblages depend mainly on organic matter coming from shallower levels and from the water column. The examined polychaete assemblages are characterised by low density and a complete absence of dominance, with the evenness index J’ ranging from 0.72 to 1; the wide ranges of the H’ index (0.50–2.67) and of Hill's N1 (1.65–14.65) suggest a high variability at low spatial scale. If compared to Atlantic deep-sea polychaete assemblages the assemblage studied shows an almost ten-fold lower organism abundance, but species diversity is only two- to four-fold lower, suggesting that biodiversity in Mediterranean deep-sea environments is possibly underestimated. Diversity of polychaete assemblages in the deep Mediterranean Sea is likely to be underestimated due to their low density, and adequate sampling strategies should be planned to have a better insight into the functioning and diversity of these communities.

Орнитокомплексы равнинных и горных лесов южного Вьетнама: видовой состав и распределение по трофическим гильдиям

Bird communities were studied during field surveys in five protected forested territories in the south of Vietnam: Yok Don National Park, Dong Nai Biosphere Reserve, Bu Gia Map National Park, Bidoup-Nui Ba National Park and Chu Yang Sin National Park. Lowland communities showed higher species diversity than montane ones. The similarity measure of bird species composition was rather high among three lowland forests and between two montane forests, however, few species were common for both lowland and montane communities. The study of the ecological structure of bird communities was based on trophic guilds composition. Six guilds of forest birds were conventionally defined: insectivore, predatory, frugivore, nectarivore, granivore and omnivore. All guilds were presented in all studied bird communities, but their portion varied between lowland and montane forests. The high similarities of guild proportions between all lowland and both montane forests demonstrated, assumingly, that the found ecological structures are stable for each type of community. Although species composition of trophic guilds varied greatly between lowland and montane communities, the similarity measure was greater among predatory birds and less among “plant-eating” birds (frugivore, nectarivore and granivore guilds combined). Apparently, that reflects greater dependence of “plant-eating” birds upon plant species composition in lowland and montane forests. The complex assessment of bird communities based on species composition and ecological structure can be useful for comparative studies of bird distribution in diverse ecosystems and for temporal monitoring of degrading or restored natural habits.

Do environmental variables predict the trophic structure of fish fauna in a subtropical river (Uruguay River Ecoregion)?

Trophic interactions represent the routes through which energy flows upwards within ecosystems and the understanding of such structuring under varying environmental conditions is still challenging. Here we test the hypothesis that differences in environmental variables act as environmental filters on the composition and trophic structure of local the fish fauna of a subtropical mountain river. We predict that differences in the trophic structure of the fish fauna occur along the river continuum. Main environmental parameters have been measured and fishes were sampled quarterly between August 2013 and May 2014 at six sampling sites in the main channel of the Pelotas River, Upper Uruguay ecoregion. We collected 3848 individuals belonging to 38 species, 4 orders and 11 families. The most (82.1%) consisted of small- and medium-sized individuals. The species were classified into eight trophic guilds: aquatic insectivorous, carnivorous, detritivorous, detritivorous/aquatic insectivorous, herbivorous, iliophagous, omnivorous and piscivorous. In general, herbivorous and piscivorous guilds were the most representative in both number and biomass. Significant differences detected by Permanova were for richness, numerical abundance and biomass between all the sites sampled. Relationships between the environmental variables and the composition of trophic guilds were observed along the longitudinal gradient by RLQ and fourth-corner analyses. The abundance of guilds omnivorous, aquatic insectivorous and herbivorous increases with higher values of chlorophyll-a and vegetation cover, especially characterizing the upstream sites (S1, S2 and S3). On the other hand, the abundance of the iliophagous, detritivorous/insectivorous and piscivorous guilds increases with greater values of width, temperature, inorganic phosphorus and total solids, a fact observed in downstream sites (S4, S5 and S6). Thus, it was possible to identify a clear variation in the trophic structure of the fish fauna along the Pelotas River (upstream-downstream), in which the local variables were efficient in predicting environmental filters that influence the trophic organization. In this scenario, our study follows the longitudinal model and evidences a greater accumulation of energy in food webs in the upstream-downstream direction, which favors the greatest abundance of piscivorous, detritivorous and iliophagous verified in stretches of greater volume and dimensions of river. These results highlight the importance of the local variables and the interrelationships in the lateral connectivity processes along the river continuum.

Urbanization impacts on the trophic guild composition of bird communities

ABSTRACTUrbanization transforms the landscape and generates loss of pristine habitats. We investigated the urbanization effect on bird communities in a growing South American city (Santa Fe, Argentina) and hypothesized that if habitat structure and human disturbance change along an urban gradient, the richness and abundance of trophic guilds should also vary accordingly. We placed 50 transects 100 m long × 50 m wide in five districts with different levels of urbanization, determined by habitat structure variables. We recorded the number and abundance of species and the amount of pedestrians and vehicles passing through each transect. We recorded 23% of all bird species known for the Santa Fe province and categorized them within 19 trophic guilds. The percentage of area covered by herbaceous vegetation, water bodies and trees and shrubs had a positive relationship with the richness and abundance of most of trophic guilds (hawking aerial, terrestrial, bark and foliage insectivores; terrestrial and generalized granivores; generalized, aquatic diving and foliage omnivores; hawking aerial, aquatic diving and striding carnivores; nectarivores; and aquatic filters). Pavement surface and human disturbance variables had a negative relationship with the richness, and high buildings and pavement surface had a positive relationship with the abundance of terrestrial omnivores and coursing aerial insectivores. Variation partitioning revealed that habitat structure and human disturbance were better predictors of the richness than the abundance of each trophic guild. Results showed that trophic guilds associated to vegetation strata were seen to increase their richness and abundance towards green areas, even if they presented generalist or specialist habits. Urban planners should conserve or manage the surrounded natural spaces when the growth of the city is directed to these areas and increase the availability of environmental features within the urban matrix.

Richness and trophic guilds of carnivorous mammals in ejido Nuevo Becal, Calakmul, Campeche, Mexico

The prevalent and increasing situations such as the expansion of areas for agricultural use, livestock raising and hunting represent the most complex issues for the conservation of wild species. Mammals of the Order Carnivora are key species in ecosystems because they respond differently to changes in habitat. This study explored the species richness and composition of trophic guilds of the assemblage of the Order Carnivora in an area adjacent to Calakmul Biosphere Reserve, Mexico. From February 2014 to February 2015, 10 stations with camera traps were set within the sub-evergreen tropical forest near water bodies, roads and trails. The structure of the carnivorous assemblage was evaluated through the species richness and trophic guild of species. The recording efficiency of traps was evaluated through the latency to first detection (LTD). A total of 76 photographic records were obtained for eight species of the Order Carnivora, as well as direct observations of three additional species, so the assemblage recorded was composed of 11 species. Four trophic guilds were identified: carnivores (5 species), omnivores (4), insectivores (1), and frugivores (1). The Order consists of two species of large predators (Panthera onca and Puma concolor) and three generalist species (Urocyon cinereoargenteus, Puma yagouaroundi, and Procyon lotor). P. concolor and Leopardus wiedii displayed a low LTD (<140 days-trap). The eleven species recorded represent 26 % of the species of this Order countrywise, and 64 % for the state of Campeche. According to Mexican laws, 55 % of Carnivore species are in a threatened category. The diversity of guilds was similar to other assemblages, particularly for the carnivorous and omnivorous guilds. The diversity observed in the Nuevo Becal region confirms its importance for the conservation of the Order Carnivora, and the relevance of the evaluation of wild population in areas adjacent to large reserves such as Calakmul.

Trophic guilds of EPT (Ephemeroptera, Plecoptera, and Trichoptera) in three basins of the Brazilian Savanna

• We determined EPT trophic guilds based on gut content analysis of specimens from three Brazilian Savannah basins. • Trophic guild composition did not reflect the taxonomic distance among taxa and did not vary among basins. • Local conditions influenced EPT diet and, therefore, trophic guild composition. Insects of the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT) are prominent among stream biota and are associated with many ecological processes in these environments, meaning that a proper definition of their habits is essential. We studied EPT from three watersheds in Brazil (Paraguai, Paraná, and São Francisco) in order to (i) determine the trophic guilds of EPT genera sampled; (ii) determine whether trophic guilds reflect EPT phylogenetic component (taxonomic distance); (iii) compare trophic guild composition among watersheds; and (iv) verify the effect of environmental components in trophic guild composition. Eight trophic guilds were determined based on gut content analysis: detritivores, fine-detritivores, fine-detritivores/algivores, coarse-detritivores, coarse-detritivore/algivores, periphytivores, carnivores, and omnivores. Caddisflies presented the most variable diet and many genera belonged to different trophic guilds in different basins. Overall trophic guild composition did not reflect the taxonomic distance among taxa and it did not differ among the three basins. Instead, EPT guilds were related to local environmental variables, evidencing that their diet probably varies according to local resource availability, highlighting the importance of empirical assessments of diet for ecological studies.

Subtidal benthic megafauna in a productive and highly urbanised semi-enclosed bay (Ría de Vigo, NW Iberian Peninsula)

The Ría de Vigo is a semi-enclosed bay with high primary productivity due to the influence of coastal upwelling-downwelling dynamics. The area is heavily populated and affected by numerous human activities, which lead to sediment modification. Epibenthic megafauna from the non-estuarine zones of this bay has been studied in order to describe its spatial distribution, testing possible differences between inner and outer areas. With that purpose, 75 sites have been sampled by means of a towing dredge. Megafauna was identified to the lowest taxonomic level possible, and each taxon counted and weighted. 113 different taxa were identified and a high spatial heterogeneity was observed in terms of abundance, biomass, taxa richness, diversity and evenness. Suspension-feeding molluscs dominated the innermost part of the studied area, and were substituted by echinoderms towards the external zones; this spatial pattern was also reflected in the results of multivariate analyses. These shifts in taxonomic and trophic guild composition of the assemblages have been tentatively related to differences in pollution levels and primary productivity along the main axis of the bay.

Recuperation of theTerra FirmeForest Understory Bird Fauna Eight Years after a Wildfire in Eastern Acre, Brazil

The present study evaluated the characteristics of the understory bird fauna of four fragments ofterra firmeforest in eastern Acre, Brazil, that were impacted by wildfires in 2005. The study investigated the species richness and the composition of trophic guilds using mist-netting on eight transects (four in burned plots and four in control plots in the same forest fragments). Eight plots (0.12 ha) were also established parallel to each transect to record the number of live trees (DBH ≥ 10 cm), palms, and dead trees. Bamboo stems were quantified in 0.024 ha subplots. No significant difference was found between burned and control plots in the species richness or abundance of birds, nor was any significant pattern found in the NMDS ordination of the composition of the communities or guilds. The Principal Components Analysis (PCA) found that the burned plots were physiognomically distinct, due principally to the number of bamboo stems and dead trees. Multiple regressions based on the PCA scores and bird species richness and abundance found no significant trends. The findings of the present study indicate that the understory bird assemblage of the areas affected by a single wildfire in 2005 had almost totally recuperated eight years after this event.

Identifying functional homogeneity in a dynamic environment: Application to soft-substrate fish assemblages off the Portuguese coast

In fish community assessment, measures of functional integrity have shown to be the most suited to detect anthropogenic impacts in a background of natural variation. However, minimising background noise involves the establishment of homogeneous areas, which is still mostly done based on taxonomic approaches or by relying on abiotic factors. The present study proposes a framework to identify functional homogeneity in demersal soft-substrate fish assemblages along the Portuguese coast, by relying on functional metrics such as trophic guild composition. Using metric pairwise constrained k-means (MPCK-means), sampling stations were clustered based on individual categories of functional metrics, while taking into account the minimum achievable homogeneity contained in 5years of bottom trawl surveys. All individual clustering solutions resulting from different functional categories were ultimately combined into a final set of seven assemblage types using an ensemble clustering algorithm. Clustering patterns found were linked to depth, substrate type and latitudinal variation. Biomass-based metrics performed better in comparison to abundance-based metrics, but the combination of both achieved the best results in the definition of a final set of seven assemblage types along the coast.

Riqueza de especies y gremios tróficos de mamíferos carnívoros en una selva alta del sureste de México

The region of Los Chimalapas, in the southeastern Mexico has a high biodiversity, but it faces problems of habitat loss, primarily by livestock and agricultural activities. A group that can provide data on these changes is that of the mammals of the order Carnivora, because its members have a variety of size classes, trophic guild or ecological function and respond differently to changes in habitat. This study characterizes the species richness and composition of trophic guilds of the assemblage of the order Carnivora, 29 trapping stations with phototraps were established within the rainforest , f rom March 2011 to June 2013. There was a collection effort of 8,529 days-trap and it were obtained 543 photographic records of 10 species of the order Carnivora, as well as two additional species recorded by direct observation, so the assemblage was composed of 12 species. Trophic guilds were five: carnivore (5 species), omnivore (4), insectivore (1), frugivorous (1), and the consumer aquatic species (1). The assemblage consist of two species of large size predators, three mesopredators, one species that is considered indicative of good water quality ( Lontra longicaudis) , and three generalist species ( Urocyon cinereoargenteus, Puma yagouaroundi , and Procyon lotor ), that prefer open areas and that are adapted to zones with disturbance, but with low abundance in the area. Also, 66% of species are in any risk category according to Mexican laws, confirming the importance of the Los Chimalapas for the conservation of Carnivora. Keywords: Camera-trap, Chimalapas, conservation, Oaxaca.

Nematode assemblages from submarine caves in Hong Kong

Nematode assemblages from sediments of two submarine caves in subtropical Hong Kong waters were investigated, and compared with those from other local sublittoral sediments. A total of 48 putative nematode species from 44 genera and 18 families were identified from the caves. Species richness of the cave nematode assemblages lay between those of adjacent sandy control sites and muddy control sites. Species diversity of the cave assemblages was much lower than those of the sandy control sites but was comparable with those of local muddy sediment. Nematodes at Conic Island Cave were dominated by non‐selective deposit feeders, while at Steep Island Cave most nematodes were omnivores/predators. This is in contrast with the more even composition of trophic guilds at the nearby non‐cave sites. Multivariate analyses revealed no clear demarcation of community structure among the cave, non‐cave and wreck nematode assemblages, indicating no nematode species association endemic to the cave sediment. Sediment characteristics and water depth are suggested as fundamental in determining nematode community structure and trophic composition in the area investigated. Submarine cave sediment provided a sheltered habitat with limited food resources favourable for non‐selective deposit feeders and omnivores/predators.