Distribution of polychaete feeding guilds in sedimentary environments of the Campeche Bank, Southern Gulf of Mexico

The aim of this study was to analyze the trophic structure of the polychaete assemblages found in the Campeche Bank, southern Gulf of Mexico and to examine the effect of the sediment composition on the spatial distribution of the feeding guilds. In all, 2,662 organisms belonging to 160 species and 16 feeding guilds were identified. Filter-feeders (Fabricinuda trilobata and Bispira melanostigma) dominated. Five groups of stations were defined based on feeding guilds: one, in the southwest, characterized by motile jawed burrowers (17.14% contribution); the second, from the southeast to the northwest, characterized by seven guilds (45.25%), mainly filter-feeders and surface deposit-feeders; the third, in the southwest, characterized by three guilds (42.13%), mainly discretely motile tentaculate filter-feeders and motile unarmed burrowers; group four, in the east, was characterized by sessile tentaculate filter-feeders (63.68%); and group five, in the center and to the north, was characterized by four guilds (53.69%), mainly discretely motile tentaculate filter-feeders. The variety of feeding guilds was higher in the northwest with seven guilds, and the lowest variety was found in the east and south with only one or two guilds. Contrary to the starting hypothesis, the sediment composition was not the main factor that determined the distribution of the polychaete feeding guilds. Instead, salinity and depth were more important for the spatial arrangement of the trophic groups. The feeding guilds of polychaetes proved to be more sensitive to environmental changes than density or diversity.     

Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp-fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay.     

Seasonal and spatial variations of fish trophic guilds in a shallow,semi-enclosed tropical estuarine bay

A study on seasonal and spatial variations of feeding habits and trophic guilds of dominant fish species in Pattani Bay during March 2003 to February 2004 was aimed at classifying diet composition, identifying dominant food components of each species, categorizing trophic guilds of the community and evaluating effects of habitat characteristics and seasonality on guild organization. Most fishes showed high food intake, fed on a diverse range of food items but relied heavily on calanoid copepods and shrimps. All species, with the exception of Epinephelus coioides, were classified as specialist feeders. Four main dietary guilds were classified. Three of these were classified as the guilds dominated by at least two major food items. Significant variations in trophic guilds of 28 fish species based on habitat types and seasons were also identified. They could be divided into three seasonal groups and three site-groups and a single site. Trophic organization for each season and habitat ranged from two to four groups. This information identifies groups of fishes that seasonally and spatially utilize different food resources within a semi-enclosed estuarine bay ecosystem.     

Trophic relationships of polychaetes associated with different algal growth forms

The trophic relations of the polychaete species associated with four different algal growth forms (filamentous, fan-shaped, bush-like and encrusting) were studied in the North Aegean Sea. Samples for the spatial analysis were collected in summer with a quadrate sampler (400 cm²) at a depth range of 15–40 m. Filamentous and encrusting forms were also seasonally sampled in order to detect the temporal changes. A total of 5,494 individuals belonging to 79 species were classified to 12 feeding guilds, considering the type of food, the feeding apparatus and the motility patterns involved. Carnivores dominated, followed by herbivores and filter-feeders, among all the algal forms studied, excepting the fan-shaped form where filter-feeders prevailed mainly due to a massive recruitment of spirorbids. With respect to the abundance of the various feeding guilds, filamentous and fan-shaped forms discriminated, whereas bush-like and encrusting forms showed high similarity. The occurrence of polychaete feeding guilds among both filamentous and encrusting forms showed seasonal changes, with summer and spring samples, respectively, discriminating. The results of the trophic group analysis conformed to previous information provided by a taxon composition analysis of the dominated by the same algae communities. However, a functional study can give additional information and is thus a useful tool for the study of hard bottom communities.     

A Mediterranean Fine-sand Polychaete Community and the Effect of the Tube-dwelling Owenia fusiformis DELLE CHIAJE on Community Structure

Samples were taken in fine-sand community of the North Latium coast in February and September for two years. Eigthy-eight species of Polychaetes were identified. The most abundant was Owenia fusiformis which was highly correlated to the clay fraction in the sediments. Species richness and abundance of other polychaete species were related to the abundance of this tubicolous species which provides a spatial refuge from predators and implements sediment stability. There was a persistency in the community structure in spite of seasonal fluctuations in the abundance of dominant species.     

Ant diversity and its relationship with vegetation and soil factors in an alluvial fan of the Tehuacán Valley, Mexico

In this study, we analyze the ant community found along an alluvial fan located in the Tehuacán Valley, central Mexico. Considering that this fan is composed of four terraces with different soils and vegetation structures, our main goal was to determine whether there are significant differences in ant diversity among terraces. To accomplish this goal, we determine species richness and abundance in order to calculate diversity and evenness indices. In addition, we classify species in different feeding guilds to evaluate whether differences among terraces exist. We expected higher ant diversity and variety of food guilds in terraces with sandy soils and complex vegetation structures than in terraces with argillic and calcic horizons. Correlations between several diversity parameters, and soil percent-sand and vegetation structure were also conducted. A total of 26 ant species were recorded along the fan. Species richness was not different among terraces whereas abundance was higher in sandy soils and on terraces with complex vegetation structure. Particularly, the abundance of the harvester ant Pogonomyrmex barbatus was higher in these terraces decreasing total ant diversity and evenness. Species richness within feeding guilds was similar among terraces with the generalized foragers as the most common. Our work suggests that percentage of sand in the soil and complexity of vegetation structure of the alluvial fan studied might be influencing ant distribution and favoring the abundance of numerically dominant species which could be affecting the diversity patterns of the whole community.     

Oceanographic conditions and diversity of sea stars (Echinodermata: Asteroidea) in the Gulf of California, México

Species richness is one of the best indicators of biodiversity. However, there are few investigations on concordance of diversity patterns and environmental settings for marine regions. The objectives of this study were to correlate species richness of shallow water (< 200 m deep) sea stars with key oceanographic factors in the Gulf of California, México, and to predict species richness of Asteroidea using multiple regressions. In these analyses the Gulf was divided into nine sections of one degree in latitude (from 23-31 degrees N), at each section we recorded: continental shelf area (at 100 and 200 m depth), temperature mean and range at three depth levels (0, 60 and 120 m), thermocline depth, surface nutrient concentrations (nitrates, phosphates and silicates), surface photosynthetic pigment concentration, and integrated productivity. Sea star species richness at each latitudinal section was estimated from literature data, new collections and museum records. Species were assigned to one of the following feeding guilds: predators of small mobile invertebrates (I), detritivores (D), predators of colonial organisms (C), generalist carnivores (G), and planktivores (P). There are 47 shallow water asteroid species in the Gulf of California (16 I, 15 D, eight C, six G, one P and one not assigned). Total species richness and guild species richness showed strong latitudinal attenuation patterns and were higher in the southernmost Gulf, an area characterized by a narrow shelf, high temperature, and low nutrient concentrations. Species diversity for each guild was correlated to a set of oceanographic parameters: temperature, nitrate concentration, and integrated productivity were linked to richness in must cases. We detected that nutrients and surface pigments always presented negative relationships with species richness, indicating that productive environments limit asteroid diversity in the study area. Finally, the postulated regression models to estimate species richness from oceanographic data were significant and highly precise. We conclude that species richness of Asteroidea in the Gulf of California is related to oceanographic conditions and can be estimated from regional oceanographic information.     

Vertical stratification of feeding guilds and body size in beetle assemblages from an Australian tropical rainforest

Abstract The vertical stratification of insect species assemblages inhabiting tropical rainforests is well established but few have examined whether these patterns are reflected in vertical stratification of body size or feeding guilds. We used Malaise and Flight Interception Traps to sample beetle assemblages from five locations, at both canopy and ground zones of a tropical lowland rainforest site near Cape Tribulation, Australia. Beetles from 4 years of sampling were sorted to Family and morphospecies, and allocated to one of five feeding guilds. Within feeding guilds the number of species and individuals, from canopy‐ and ground‐caught traps were compared. The body lengths of species were measure and compared within feeding guilds and families. Herbivores was the dominant guild but was not the majority of all species or individuals. Most beetle species (69%) were less than 5 mm in length and the mean size of canopy‐caught species was greater than that for ground‐caught species. This was probably due to slightly more species of plant feeders (herbivores and xylophages) present in the canopy, which were significantly larger than saprophages, fungivores and predators. Among feeding guilds, there were few overall canopy–ground differences. These results contrast with species composition results presented elsewhere where strong differences between the canopy and the ground were evident. We suggest that our guild groupings may have been too coarse to detect fine‐scale differences and that resource partitioning may have also masked faunal stratification. We propose that fine‐scale differences in resources between the canopy and the ground, together with strong microclimate gradients, are likely to be important in structuring the vertical stratification of insect assemblages at the level of species, but not with respect to functional groups.     

胶州湾多毛类环节动物优势种的生态特点

根据1998-2004年春、夏、秋、冬四季对胶州湾进行大面站综合调查监测的底栖生物多毛类资料,分析了多毛类优势种的季节变化和年际变化。结果表明:不同季节多毛类优势种组成和优势地位出现一定的变化,但不倒翁虫(Sternaspisscutata)、寡鳃齿吻沙蚕(Nephtysoligobranchia)和中蚓虫(Mediomastuscaliforniensis)在各季度月优势地位相对稳定;考察1998-2004年不同年份的多毛类优势种,发现不倒翁虫、寡鳃齿吻沙蚕在各个年份均居优势地位,变化较小,而其它的种类在不同的年份出现一定的变化,2003年和2004年索沙蚕(Lumbrinerislatreilli)优势度居首位,而在其它年度则没有成为优势种,这可能反映了近年来胶州湾生态环境出现了一定变化;通过考察主要优势种的分布和密度变化,可以发现这几个主要种都是广分布的小型种,在底质颗粒较细,有机质含量丰富的海域,不倒翁虫、中蚓虫、寡鳃齿吻沙蚕等数量较大;而在水流湍急、底质为砾石的7号和9号站,则很少分布,这也反映了底质对多毛类的分布有决定性影响     

The Distribution of Polychaete Feeding Guilds in Organic Enriched Sediments of San Vicente Bay,Central Chile

The benthic macroinfauna (>500 μm) of San Vicente Bay, Central Chile (36°44′S; 73°09′W) was studied at 8 sublittoral stations along a 6.5 km length transect from the San Vicente fishery harbor out to the open sea, during October 1991, January 1992 and October 1992. Structural changes of the benthic macroinfauna were evaluated a) functionally in terms of polychaete trophic guilds, and b) numerical classification and ecological ordination. Multivariate analysis was used to explore polychaete fedding guild responses to environmental variables. The principal objective of the study was to test whether changes in functional groups (within and between stations) are related to perturbation induced by anthropogenic organic enrichment, or are a consequence of natural environmental fluctuations. Trophic guilds of polychaetes associated with the sandy environment of the bay, showed a clear seasonal dominance of carnivores during the spring 1991–1992 and of surface suspension - deposit feeders, sessiles or discretely motile and tentacled polychaetes (F-SD-SDT, see Annex) in summer 1992. This guild distribution could be due to the sediment stability and a greater niche diversification in the more sandy stations. However, there were only a few significant relationships between trophic guilds and total organic matter and silt-clay fraction. This limits the utility of the guilds as indicators of perturbations induced by organic enrichment. Over 95% of the variation in the guild data was explained by environmental factors such as water depth, station distance from the harbor, silt-clay, sand, grain size and organic matter content. The comparison between reported faunistic and sedimentary data and the data obtained in this study, suggests that there is an increase of the organic enrichment of the sediments in the most inner area of this embayment. However, there is no evidence of this being directly responsible for the polychaete feeding guild distribution of San Vicente Bay.     

Analysis of trophic structure of two carnivore assemblages by means of guild identification

We evaluated the existence of trophic guild structure, considering seasonal and annual variation, in two terrestrial carnivore assemblages: one from Santa Cruz province (Argentinean Patagonia, composed by six carnivore species), and the other from Doñana National Park (SW Spain, composed by five carnivore species). To identify trophic guilds, we first studied seasonal and annual diets of predators, calculated trophic overlap among species pairs, and then constructed overlap matrices (similarity matrices). We determined guild membership objectively by entering the similarity matrices into the clustering technique unweighted pair-group method with arithmetic averaging. Carnivores from both assemblages were grouped, respectively, into four feeding guilds. Lagomorphs and rodents promoted the formation of two feeding guilds in both study sites, although the taxonomic composition of predator species that composed them was different. The ungulates-edentates feeding guild was only present at Santa Cruz, whereas the birds and reptiles feeding guild was only present at Doñana. Invertebrates and fruits were the base for the formation of a guild composed by species of the same taxonomic origin both in Santa Cruz and Doñana. Guild structure of Santa Cruz and Doñana assemblages did not exhibit seasonal or annual variation, although the specific guild composition changed over the two studied periods for both assemblages. This structure probably responded to discontinuities in resource spectra in Santa Cruz and fluctuations in rabbit abundance in Doñana. Our results support the hypothesis that establishes that guilds are originated by opportunistic convergence of species on abundant and energetically rewarding resources.     

Seasonal fluctuations of resource abundance and avian feeding guilds across forest–farmland boundaries in tropical Africa

Seasonal fluctuations in climatic factors are expected to increase in future decades. However, little is known about the response of tropical species communities to seasonal fluctuations in climate and resource availability, particularly across different habitat types. We examined the relationship between spatio‐temporal fluctuations in the abundance of fruits and invertebrates and two avian feeding guilds, i.e. frugivores and insectivores, in forest and farmland habitats in western Kenya. Fruits and invertebrates fluctuated substantially throughout the year, but seasonal fluctuations were asynchronous between the two habitat types. Species richness and total abundance of frugivores and insectivores also fluctuated strongly and were closely related to the abundance of their respective resources. Frugivore species richness fluctuated anti‐cyclical in forest and farmland habitats, suggesting that several frugivorous species tracked fruit resources across habitat boundaries. In contrast, insectivorous bird richness fluctuated synchronously in the two habitat types, suggesting a lack of local‐scale movements across habitat boundaries. We conclude that bird communities strongly respond to seasonal fluctuations in resource availability, but responses differ between feeding guilds. While frugivores seem to respond flexibly to seasonal fluctuations, for instance by tracking fruit resources across habitat boundaries, insectivorous birds appear to be more susceptible to the expected increase in seasonal fluctuations in resource availability.     

A partial food web involving predatory gastropods on a Pacific fringing reef

An analysis of the feeding habits of a diverse assemblage of predatory gastropods on a Guam fringing reef, shows that seven major prey categories are eaten, namely polychaetes, sipunculans, gastropods, bivalves, crustaceans, ophiuroids, and fish. The three largest feeding groups are the polychaete feeding guild which mainly consists of species of Conus, the gastropod guild dominated by species of the Muricidae and the sipunculan guild consisting mainly of the Mitridae. There is considerable dietary overlap between members of feeding guilds, but interaction between guilds is low and accounted for by the relatively few generalist species in the community.     

Day and night trophic variations of dominant fish species in a lagoon influenced by freshwater seeps

The aim of this study was to determine the trophic structure and nycthemeral variations in the diet of dominant fish species (Ariopsis felis, Bairdiella chrysoura, Micropogonias undulatus, Eucinostomus gula, Eucinostomus argenteus, Lagodon rhomboides and Sphoeroides testudineus) in Celestun Lagoon, a biosphere reserve located in the southern Gulf of Mexico, and influenced by freshwater seeps. A total of 1473 stomachs were analysed and nine trophic groups were recorded. Bray–Curtis analyses with analyses of similarity (ANOSIM) statistical tests were used to determine two groups of feeding guilds: zoobenthivores and omnivores, with significant differences between time and habitat. The relationships between fish feeding habits, size class and environmental variables were investigated using canonical correspondence analysis (CCA). Most of the species showed a low niche breadth with high specialization towards amphipod consumption, with the exception of L. rhomboides (0·60), which indicated generalist feeding. This study in a protected area is an important source of information for drawing up conservation policies in relation to the management of aquatic resources, and will aid in the establishment of priority areas for conservation.     

Variations in bird abundance in tropical arid and semi-arid habitats

Temporal variation in bird abundance was studied during a complete annual cycle in a thorn scrub, a thorn woodland and a deciduous forest in northeastern Venezuela. Abundance of site-attached and transient birds from different feeding guilds was determined by mist-netting at 2-week intervals. Diets were investigated by regurgitated samples. The overall avifauna was characterized by a low number of species but they were present all year despite showing strong seasonal fluctuations in abundance. The number of bird species and individuals peaked before and after the reproductive period. These high values probably were associated with movement of species feeding on plant food during the late dry season and the post-breeding dispersion of juveniles. Bird richness and abundance were lowest during the breeding season and in the early dry season when food abundance was low. Birds from different feeding guilds showed distinct patterns of seasonal abundance which tended to be similar at all three sites. Transient birds represented a large portion of the avifauna, particularly in nectarivores, frugivores and granivores during the dry season. We used a canonical correspondence analysis to demonstrate that bird abundance was correlated with breeding activity, rainfall seasonality and food abundance, with the influence of each parameter varying according to feeding guilds, spatial behaviour of individuals and habitats. Despite a great turnover in the occurrence of the diverse food types available, species composition remained strikingly constant during the year, with birds responding to seasonal changes primarily through a generalist feeding habit and a highly variable rate of transience.     

Food habits of fishes in azostera marina bed at aburatsubo, central japan

To clarify the feeding habits of seagrass fishes, the gut contents of 31 fish species collected in aZostera marina bed at Aburatsubo central Japan, were examined. Ontogenetic changes in food preference were recognized in 12 species. In general, juveniles of the latter preyed mainly on small crustaceans (e.g., gammaridean amphipods) or planktonic animals (e.g., calanoid and cyclopoid copepods), subsequently changing to other prey items (e.g., hard-shelled animals) with growth. Cluster analysis based on dietary overlaps showed that the seagrass fish assemblage comprised seven feeding guilds (small-crustacean, planktonic-animal, large-crustacean, polychaete, fish, hard-shelled mollusc and detritus feeders). Of these, small-crustacean feeders and planktonic-animal feeders were the most abundantly represented, including juveniles of several species, which, when adult, transferred to other feeding guilds. On the other hand detritivores were represented by a single species.     

Polychaete community structure of the northwestern coast of Mexico: patterns of abundance and distribution

In August 1998, 72 benthic stations were sampled off the northwestern coast of Mexico. A baseline survey of the polychaete macrofauna was carried out for the southernmost portion of the Southern California Bight (SCB) region. Spatial patterns of polychaete assemblages were characterized to determine evidence of environmental impact from point sources of wastewater discharge near the study area, and to define a standard against which to detect future change. A total of 4231 polychaetous annelids representing 38 families and 210 species were identified, which constituted 53% of the total macrofauna. Families with highest species richness were Spionidae (18 spp.), Onuphidae (15 spp.), and Terebellidae (14 spp.). Species with greatest abundances were Spiophanes duplex (490 ind.), Spiophanes fimbriata (330 ind.), Lanassa sp. D (209 ind.), Pectinaria californiensis (138 ind.), and Euclymeninae sp. A (124 ind.). Based on polychaete assemblages, communities for the southernmost SCB were found to be composed primarily of non-opportunistic species, and no numerically dominant species were found. High values of polychaete diversity (H) indicated the majority of the area of study could be considered an undisturbed environment. Principal Components Analysis (PCA) applied to environmental and faunistic parameters indicated depth, organic carbon, and sediment grain size as the main influences determining the polychaete faunal communities.     

Polychaete fauna associated with holdfasts of the large brown alga Himantothallus grandifolius in Admiralty Bay, King George Island, Antarctic

The polychaete community associated with holdfasts of the brown alga Himantothallus grandifolius in Admiralty Bay has been studied. It is the first study of its kind in this area and only the second in the Antarctic. Samples were collected in the summer season of 1979/1980 from a depth range of 10–75 m. Seventy-eight species were found on 19 holdfasts. The community was dominated by Brania rhopalophora and Neanthes kerguelensis. Analysis of similarity showed that polychaete fauna associated with this habitat did not show any partitioning related to depth. Regression analysis showed that densities of both species and individuals decreased with increased holdfast volume. A positive correlation was found between the number of individuals and holdfast volume. Polychaetes from 10 feeding guilds were found with dominance of macrophagous motile herbivores and sessile filter feeders. The complex habitat provided by holdfasts is a shelter for a rich polychaete fauna and may function as important protection from disturbance in the shallow areas of Admiralty Bay.     

福建沿岸红树林湿地多毛类生态分布

根据2009年至2012年在福建沿岸5块典型红树林湿地所作的调查资料,分析了福建沿岸红树林湿地多毛类的物种多样性、生态分布特点以及与环境因子的关系。研究区域春、秋两季共记录多毛类动物45种,其中沙蚕科、海稚虫科和小头虫科3个科种类最为丰富,种类属性为低盐或广盐性种类。多毛类平均密度和生物量分别为190个/m2和2.17 g/m2,样地×季节双因素方差分析表明,密度在不同样地间差异显著,密度和生物量的季节变化均为春季显著高于秋季。此外,林外光滩的多毛类数量要高于林内,不同样地的摄食群组成各异。红树林断面的平均种类数和多样性指数H'与沉积物粘土含量呈显著负相关,与多毛类类群的大尺度空间分布特征关联最为紧密的因子为地理纬度。     

Differences in functional trait responses to elevation among feeding guilds of Aculeata community

The response of communities to environmental change is expected to vary among feeding guilds. To evaluate the response of guilds to environmental factors without considering the taxonomic specificities, it is useful to examine Aculeata bees and wasps, which consist of closely related taxa including different guilds, pollinators, predators, and parasitoids. In this study, we evaluated changes in species diversity (SD) and functional traits of each feeding guild along an elevational gradient in a boreal forest in northern Japan. We used yellow pan traps to collect Aculeata bees and wasps at 200–1600 m above sea level. We investigated six functional traits (trophic level, seasonal duration, body size, elevational range, nesting position, and soil dependency) and the horizontal distribution of the species. The SD of all Aculeata, predators, and parasitoids decreased with an increase in elevation; however, the SD of pollinators did not show any specific trend. Although the functional trait composition of all Aculeata species did not show any trend, that of each feeding guild responded to elevation in different ways. Pollinators increased in body size and showed a decrease in seasonal duration with increasing elevation, suggesting that tolerance and seasonal escape from physical stress at high elevations are important for shaping pollinator communities. Predators increased their elevational range and the proportion of above‐ground nesting species increased with increasing elevation, suggesting that the ability to live in a wider range of environments and avoid unsuitable soil environments at high elevations might be important. Parasitoids changed their hosts and displayed variable traits with increasing elevation, suggesting that brood parasitoids have difficulty in surviving at high elevation. The traits for each guild responded in different ways, even if they were dominated by the same environmental factors. Our findings imply that differences in the responses of functional traits would produce different community assembly patterns in different guilds during further climate change.