Sublittoral Macrobenthic Infaunal Assemblages of Two Nearby Embayments from Central Chile

The benthic assemblages in two Central Chile nearby embayments were studied from quantitative samples collected from 15 sites at depths of 8–65 m. The macrobenthic infauna (<0.5 mm) of both bays was greatly dominated by polychaetes. Some 93 taxa were identified, of which 51 were polychaetes. The average macrofaunal abundance for all stations (15,021 ind. m⁻²) is very close to the values reported for the neighboring areas. Numerical classification and ordination (DCA) of sites resulted in three site-groups mostly reflecting differences in the bottom sediments: the muddy-bottom stations of Concepción Bay and the shelf-associated stations, the sandy-bottom stations of San Vicente Bay and an heavily polluted station at San Vicente port. Classification of species showed that the muddy-bottom stations and the sandy-bottom sites had characteristic species assemblages. The macrofaunal assemblages presented high dominance values, which were due to the high numerical abundances of a few species in the collections.     

Population Dynamics of the Polychaetous Annelids of an Intertidal Habitat in Upper Old Tampa Bay,Florida

Following an extensive red-tide induced mass mortality of the benthic macrofauna of a sandy intertidal habitat, the population dynamics of the polychaete species were studied. Detailed studies of the 12 most abundant species are presented. Data concerning total population levels, reproduction, recruitment, distribution within the intertidal zone, and gut content analyses are integrated in order to explain the observed spatial and temporal patterns of distribution and abundance. Potential competive interactions for food are considered to be the most important factor for explaining the observed ecological patterns. The polychaete species studied are divided into three trophic guilds: an omnivorous guild that feeds predaciously and as non-selective deposit feeders, a surface feeding guild consisting of species usually considered to be selective surface deposit feeders, and a subsurface feeding guild usually considered as non-selective infaunal deposit feeders. Within and between guild interactions are discussed.     

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.     

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.     

Diets and trophic‐guild structure of a diverse fish assemblage in Chesapeake Bay,U.S.A.

Dietary habits and trophic‐guild structure were examined in a fish assemblage (47 species) of the Chesapeake Bay estuary, U.S.A., using 10 years of data from >25 000 fish stomachs. The assemblage was comprised of 10 statistically significant trophic guilds that were principally differentiated by the relative amounts of Mysida, Bivalvia, Polychaeta, Teleostei and other Crustacea in the diets. These guilds were broadly aggregated into five trophic categories: piscivores, zooplanktivores, benthivores, crustacivores and miscellaneous consumers. Food web structure was largely dictated by gradients in habitat (benthic to pelagic) and prey size. Size classes within piscivorous species were more likely to be classified into different guilds, reflecting stronger dietary changes through ontogeny relative to benthivores and other guilds. Relative to predator species and predator size, the month of sampling had negligible effects on dietary differences within the assemblage. A majority of sampled fishes derived most of their nutrition from non‐pelagic prey sources, suggesting a strong coupling of fish production to benthic and demersal food resources. Mysida (predominantly the opossum shrimp Neomysis americana) contributed substantially to the diets of over 25% of the sampled predator groups, indicating that this species is a critical, but underappreciated, node in the Chesapeake Bay food web.     

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.     

Signals from the benthos: Development and evaluation of a benthic index for the nearshore Gulf of Maine

We developed a benthic index for the nearshore Gulf of Maine to provide researchers and environmental managers a way to make spatial and year-to-year comparisons of benthic condition. The data set used included 248 stations sampled for physical, chemical, and biological variables by the National Coastal Assessment in 2000–2003. We used logistic regression with 49 candidate measures of benthic species diversity, pollution sensitivity-tolerance, and community composition to discriminate sites with high and low benthic environmental quality (BEQ). BEQ was based on the concentrations of metal and organic contaminants in the sediments, total organic carbon, sediment toxicity, and dissolved oxygen level of the bottom water. An analysis of similarity test showed that the community composition of low BEQ stations was significantly different (p < 0.001) from high BEQ stations. Ten of the 49 benthic metrics showed a strong ability to discriminate stations. We developed several candidate benthic indices and tested them with independent data from Massachusetts Bay and Casco Bay to help select and validate the best index. A model using the Shannon-Wiener diversity measure, Rosenberg's species pollution tolerance measure, and the percent capitellid polychaetes (or percent Capitella spp.) strongly discriminated stations, with an area under the receiver operating characteristic (ROC) curve of 0.82 and a classification accuracy of 80%. Signal detection theory (ROC curves and positive–negative predictive value curves) was used to evaluate the index and to predict how well an index developed for one geographic area might work in another area with a different prevalence of the degraded condition. We show how these techniques can also guide decisions by environmental managers about choosing thresholds and weighing costs and benefits of particular actions.     

Diet selectivity of juvenile blue crabs (Callinectes sapidus) in Chesapeake Bay

Shallow coves in Chesapeake Bay have abundant food and serve as nursery grounds for juvenile blue crabs. In this study, we examined the relationships between the diet of very small (4-40?mm CW) juvenile blue crabs and the benthic infauna in shallow, unvegetated nursery coves. We compared infauna in benthic samples with gut contents of juvenile blue crabs from six shallow coves in each of two sub-estuaries (Rappahannock and York Rivers) in Chesapeake Bay, Virginia, USA. Benthic communities differed depending on river and location, with abundant clams in upriver regions and abundant polychaetes in downriver regions. Juvenile crabs, like adults, appeared to be opportunistic feeders, with gut contents including clams, amphipods, polychaetes, small crustaceans, plant matter, and detritus. There was a positive relationship between polychaetes in the benthic samples and in crab guts, suggesting that juvenile crabs are opportunistic feeders on polychaetes in the benthos. Moreover, Ivlev's electivity index and foraging ratio showed that clams and polychaetes were selectively eaten at all locations. Alternatively, crabs selectively rejected amphipods. Crab densities corresponded positively with polychaete densities, which suggests that there may be bottom-up control of crab distributions and that food resources are important in nursery habitats.     

Trophic structure of macrobenthos in the Tagus estuary and adjacent coastal shelf

The trophic structure of benthic communities in the Tagus estuary and adjacent coastal shelf was characterized according to a functional guild approach, based on sampling surveys conducted between 1987 and 2000. Macrobenthic organisms were assigned to seven distinct trophic groups (herbivorous, filter feeders, surface deposit feeders, subsurface deposit feeders, carnivores, filter feeders/detritivores, carnivores/detritivores) and the dominance of these groups was related to environmental variables using multivariate ordination techniques. Surface-deposit feeders were numerically dominant in the Tagus estuary, making up 52% of the benthic communities, while in the adjacent coastal shelf the assemblage was dominated by both surface-deposit feeders and filter feeders (37% and 33%, respectively). When biomass was considered, filter feeders and filter feeders/detritivores were the dominant groups in the estuary, while for the adjacent coastal shelf filter feeders represented 83% of the total biomass. Salinity, depth and sediment composition were the main factors structuring spatial distribution. Surface-deposit feeders were the most abundant macrobenthos of the upper estuary. Surface deposit feeders also dominated the middle and the lower estuary but the proportion of filter feeders as well as other trophic groups increased with salinity. Generally, a more even distribution of trophic structure was found at stations with high salinity. In the adjacent coastal shelf, the trophic diversity decreased with depth. The trophic structure revealed that filter feeders dominated in abundance and biomass in shallow sandy sediments (<25 m), while in deeper sandy mud and muddy habitats (>50 m to 260 m), deposit feeders and carnivores were the most important groups in abundance and biomass, respectively.     

Diets and trophic guilds of small fishes from coastal marine habitats in western Taiwan

The diets and trophic guilds of small fishes were examined along marine sandy beaches and in estuaries at depths <1·5 m in western Taiwan, Republic of China. Copepods were the most frequently identified item in fish guts, indicating they are key prey for the fish assemblages studied. Piscivore, crustacivore, detritivore, omnivore, zooplanktivore and terrestrial invertivore trophic guilds were identified. The zooplanktivore guild contained the most fish species. Maximum prey size consumption was positively correlated with standard length (L_S) in seven species and at the assemblage level and negatively correlated with L_S in a single detritivorous species. The diet data and trophic guild scheme produced by this study contribute to an understanding of coastal marine food webs and can inform ecosystem‐based fisheries management.     

莱州湾多毛类底栖动物生态特征及其对环境变化的响应

研究了2010年莱州湾15个站位的多毛类底栖动物群落生态特征及其对主要海水化学、沉积物环境变化的响应,并与1998年的相关研究进行了对比,以期对莱州湾生态质量现状进行健康评价。结果表明:与1998年相比,2010年底栖动物种类组成和生物多样性发生了较大的变化,底栖动物中绝对优势种为小头虫(Capitellacapitata)。夏季,H’与硝酸盐、石油类、重金属铅、铜、锌、铬呈负相关,说明多毛类动物多样性随着富营养化程度的提高而相应降低,营养物质氮的大量输入,重金属的污染,对莱州湾多毛类动物群落产生了一定负面影响。ABC曲线和BOPA指数结果显示,底栖动物的丰度优势度曲线高于生物量曲线,表明莱州湾底栖动物群落处于重度扰动状态,并且以小头虫为主的多毛类动物显著增加预示了莱州湾已经受到了一定程度的污染。加强海水养殖管理,合理利用海洋生物资源,对底栖动物群落的稳定性和环境的可持续利用具有重要意义。     

Polychaetes of the mangrove-fouling community at the Colombian Archipelago of San Andres and Old Providence,Western Caribbean

This study records the polychaetes found on the submerged roots of Rhizophora mangl on San Andres and Providence Islands, ColombianCaribbean. Sampling was done in 1998 during the rainy (July) and dry(November) seasons; each season, 17 roots were collected in threedifferent stations with different kinds of human impact, two in San Andresand one in Providence. At the same time temperature, salinity anddissolved oxygen were measured in situ. Aromatic hydrocarbons weremeasured in the laboratory. The polychaetes were removed from the rootsand identified. The available root area for the organisms was alsomeasured.Five genera and 11 species were newly recorded for the ColombianCaribbean. The most abundant families were Terebellidae in Old ProvidenceMc Bean Lagoon, Syllidae in Honda Bay and Nereididae in Hooker Bayon the San Andres Island. Thelepus `setosus' (Terebellidae) and Amblyosyllis sp. (Syllidae) were highly abundant in less polluted samplingstations such as Old Providence Mc Bean Lagoon and Honda Bay. On theother hand, Neanthes `succinea' (Nereididae) were abundant inHooker Bay which was the most polluted station. Salinity seemed to be the mostimportant parameter for the polychaete populations. The populations ofpolychaetes, as a total group, seemed to be related to the root areaavailable on both islands, independent of the season. However, during therainy season, the populations were independent of root area availability,while during the dry season, the populations were dependent on it.     

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

Synopsis As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.     

Trophic structure of the macrobenthic community of Hornsund,Spitsbergen, based on the determination of stable carbon and nitrogen isotopic signatures

Hornsund is a cold-water fjord in southwestern Spitsbergen, Svalbard Archipelago, with a resident biota that exhibit typical low-temperature Arctic features. Carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic signatures of macrobenthic fauna and its potential food sources were measured in summer 2008 to delineate the trophic structure of the bottom community and to identify its principal carbon sources. The soft-bottom fauna at a water depth of 100 m was found to rely primarily on detritus, which is supplied by sedimentation of suspended organic matter from the water column and horizontal transport of refractory macroalgae from euphotic coastal habitats. Through resuspension by bottom currents, deposited particles also contributed to the diet of benthic filter-feeders. Since benthic organisms were significantly enriched in ¹³C compared to epibenthic zooplankton (mainly amphipods and decapods), the stable carbon signature provides a tool to differentiate benthic and pelagic feeding habits. The benthic food web was characterized by a conventional trophic structure with decreasing species numbers in increasing trophic levels. Primary consumers feeding on a mixture of plant matter, fecal pellets, decaying animal tissue, bacteria, and protists accounted for the greatest biomass share (62 % of the total macrobenthic biomass), followed by secondary consumers (38 %). Based on δ¹⁵N signatures, three trophic levels were detected, corresponding to the following feeding guilds: filter-feeders and feeding generalists (mainly bivalves, crustaceans, polychaetes, and some fish), mixed detritivore–carnivores (polychaetes, priapulids, crustaceans, and ophiuroids) and obligate carnivores (ascidians). The average food chain length (4.5 trophic levels) suggests that high-quality food is readily available in this Arctic fjord ecosystem.     

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.     

Recruitment patterns in Antarctic Peninsula shelf sediments: evidence of decoupling from seasonal phytodetritus pulses

Summer phytoplankton blooms on the West Antarctic Peninsula (WAP) shelf result in episodic deposition of labile food material for benthic detritivores. This summer deposition is thought to enhance benthic recruitment of macro- and megafauna. To explore seasonality in benthic recruitment, juvenile invertebrates (>100 μm) were collected in a seasonal time series at three stations on the WAP continental shelf. 4,098 juveniles were collected (average densities 2,000–7,000 m⁻²), with polychaetes dominant (2,581 individuals). The majority of polychaetes showed evidence of enhanced recruitment prior to the summer bloom, although patterns varied across stations. Additional taxa showed recruitment peaks in summer, but again, patterns varied among stations. Based on observed patterns, polychaete taxa are classified as “seasonal”, “marginally seasonal”, and “non-seasonal” recruiters, with the latter two patterns predominating. The year-round presence of small juveniles in most taxa suggests that recruitment occurs continuously, with periodic enhancement. Year-round recruitment is consistent with the presence of a persistent “food bank” of labile organic material in WAP shelf sediments, allowing recruitment to be largely decoupled from seasonal bloom dynamics.     

Effect of the Environmental Factors on the Caloric Content of Benthic and Phytophilous Invertebrates in Neotropical Reservoirs in the Paraná State,Brazil

The complexity of the relations between the organisms and the environment are reflected through the energy content. So we tested the hypothesis on body energy content variation in invertebrates and its relation with some environmental factors (season, habitat type, trophic status and trophic guild). We expected higher energy values for phytophilous fauna, rainy season, in reservoirs with higher trophic levels and for herbivorous invertebrates. The results showed the influence of seasonality and trophic status of the reservoir on the energy content of invertebrates, which was higher in the rainy season and in the mesotrophic reservoirs, due to the input of allochthonous material during this season, confirming our initial prediction. A higher caloric content was recorded for carnivorous and detritivorous invertebrates. The differences between the trophic guilds were primarily related to the opportunistic feeding behavior, which may be considered as one of the main factors controlling the energy flow of benthic and phytophilous invertebrates. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polychaete distribution on the southwestern Atlantic continental shelf

Diversity and distribution of polychaetes on the southeastern Brazilian Shelf (SBS) adjacent to the city of Santos were studied. The study area is situated in the vicinity of Santos Bay with its estuarine complex and other small rivers along the coast. A total of 16,274 specimens belonging to 214 polychaete species were found at 21 sampling stations during two different periods. Two communities occur along the shelf and were related firstly to sediment characteristics. Prionospio dayi (Spionidae) was dominant in the inner shelf community that was characterized by well-sorted, very fine sand. The outer shelf community was found in muddy sediments with high organic matter content and was dominated by subsurface deposit feeders, like Petersenaspis capillata (Sternaspidae) and Leitoscoloplos kerguelensis (Orbiniidae), and by large carnivores such as Aglaophamus sp. (Nephtyidae) and Sigambra sp. (Pilargidae). A transition zone of mixed sediments presenting high diversity and richness was found between these communities. The characteristics of bottom water and food quality in the sediment were important to divide the inner shelf into two sub-areas. Nearshore sampling stations (A group) were more influenced by freshwater input, mainly during summer. This influence is not conspicuous at stations close to 30?m depth (B group). However the effect of South Atlantic Central Water mass (SACW) intrusion on the benthic system was observed on the inner shelf – B group during the summer. The summer intrusion of SACW onto the inner shelf may explain the higher quality of organic matter that resulted in an increase in polychaete abundance and richness.     

Feeding guilds and food resource partitioning in a lake fish assemblage: an ontogenetic approach

Ontogenetic diet patterns and trophic guild structure of a 15 species temperate lake fish assemblage were analysed over wide size intervals (up to seven orders of magnitude in body mass), representing practically the whole life span in most species. A two-step objective clustering technique supplemented with other multivariate statistical tools proved that size-related diet changes clearly played an important role in structuring trophic organization of fishes inhabiting Lake Balaton. As many as 13 out of the 15 fish species showed marked size-related dietary changes with two to four ontogenetic feeding stages. At the assemblage level, 11 trophic guilds were separated. Guild membership was size-dependent in 11 fish species that participated in two to four trophic guilds during their life span. The most complex trophic ontogeny was observed in roach Rutilus rutilus and asp Aspius aspius with four guild memberships. This study showed that trophic status of fishes may be very size-sensitive and thus a universal classification of fish species to general trophic guilds, such as 'planktivore', 'benthivore', 'piscivore' or 'herbivore', should be applied very carefully even in environmental monitoring and fisheries management applications, unless it is supported by relevant results of life span diet analyses.     

Effects of a freshwater canal discharge on polychaete assemblages inhabiting an exposed sandy beach in Uruguay

This paper analyzes the spatial and temporal effects of a freshwater discharge (Andreoni Canal) on polychaete assemblages and the corresponding habitat in a sandy beach of Uruguay. Bimonthly, we examined 17 environmental variables plus polychaete abundance, richness, and diversity of three sites: ‘Andreoni’ (highly disturbed) at the canal mouth, ‘Coronilla’ (moderately disturbed), 1 km far away, and ‘Barra del Chuy’ (less disturbed), 13 km north from Andreoni Canal. The highly disturbed site showed significantly lower values of salinity, beach width, swash width, slope, chlorophyll a, and significantly higher values of sediment organic matter. Polychaete abundance and diversity significantly decreased towards the canal and were positively correlated with spatial variations in salinity, which was the most important factor structuring polychaete assemblages. The results highlighted the negative effects of this artificial freshwater discharge on the sandy beach environment and stress the usefulness of polychaetes as effective and reliable ecological indicators for these ecosystems.