Trophic ecology of bottom fishes assemblage along coastal areas of Thailand

Food preferences, feeding attributes, trophic guilds, and ontogenetic changes in diet compositions of 45 fish species collected along coastal waters in the southern areas of the South China Sea, Thailand were examined. Most species had high food intake and fed on specific ranges of food types. Shrimp was the most important food (31.7%), followed by calanoid copepod (16.8%), fish (12.7%) and gammarid amphipod (8.3%). These fishes can be categorized into six different trophic guilds and further divided into four categories namely; piscivore, zooplanktivore, zoobenthivore and miscellaneous/opportunist. Numbers of feeding guilds at each depth vary between four and five. Four of these are consistently found throughout the year at all zones; shrimp predator, piscivore, calanoid copepod feeder and a combination of polychaete and other food feeders. Ontogenetic studies indicate that fishes are more likely to group according to species rather than size. This scientific information is important when examining the complex association between fishes and identifying groups of species using similar resources.     

不同孔径筛网对底栖多毛类采样效果的研究

本文根据大亚湾50个站底栖生物生态调查资料,对孔径1mm和0.5mm筛网中多毛类的种类数、主要种、平均密度、平均生物量进行比较分析。结果表明,孔径1mm的为14种/站、9种、110个/m~2和8.03g/m~2,而0.5mm为22种/站、12种、216个/m~2和0.71g/m~2;1mm筛网多毛类密度(X)与0.5mm的密度(Y)呈线性正相关关系,其回归方程为:Y=0.93X+113.77;在估算海域生产力中,应当使用0.5mm孔径筛网。     

Succession patterns of polychaetes on algal‐dominated rocky cliffs (Aegean Sea,Eastern Mediterranean)

Ecological succession has been scarcely investigated on sublittoral rocky cliffs. The few relevant studies deal with the structure of the developing community and are limited to higher taxa or sessile forms. The objective of the present study was to examine succession patterns on algal‐dominated rocky cliffs both at the structural (species composition) and functional (feeding guild composition) level, using Polychaeta, a dominant taxon in this marine habitat, as a reference group. Cement panels were seasonally installed on the rocky substratum (25–30 m depth) and sampled every 3 months over a 1‐year period. Twenty‐nine polychaete species were recorded, previously reported from the surrounding benthic community, and classified into eight feeding guilds. Most species were assigned as sessile filter‐feeders; this guild dominated in abundance and biomass. A strong effect of the length of immersion and of the seasonal onset of succession on the developed communities was assessed: species composition analyses suggested convergence into a similar organization as succession proceeds, whereas the impact of starting season on succession was stronger when analysing feeding guilds. In both cases succession was faster on panels installed in winter. The main emerging patterns were in agreement with relevant surveys of the entire benthic fauna, thus supporting the efficacy of polychaetes as a surrogate group for studying ecological succession in the benthic marine environment.     

Polychaete taxocenes variability associated with sediment pollution loading in the peter the great bay (the East Sea/Japan Sea)

Variations in species diversity and abundance of polychaete taxocenes that occurred in 1980–1989 under different contamination levels of bottom sediments were studied in three areas of Peter the Great Bay. The most polluted area was shown to be the Golden Horn Inlet where contaminant contents in the bottom sediments exceed the threshold values of negative biota alterations. Amursky Bay is characterized by a moderate level of contamination, while Ussuriysky Bay has the lowest level of contamination. Pollutant contents vary considerably within the same areas and their separate patches are polluted differently. An integral index characterizing the contamination of bottom sediments is proposed. This index is an average grade of the rank value of contaminant contents in sediments. The index was used to compare the contamination level and data on polychaete species diversity and abundance. The highest species diversity of polychaetes is found in the least affected zones. Monotonous decrease of the species number, as well as decrease in the indices of diversity and evenness, is correlated with pollution level increases. Significant growth of the average polychaete biomass and polychaete density is observed in the case of an increase of contamination from low to moderate levels. Conversely, the biomass and abundance of polychaetes decline following an increase in contamination.     

Taxonomic sufficiency and the influence of rare species on variation partitioning analysis of a polychaete community

Variation partitioning is an important tool to investigate the importance of spatial structure to species distribution in communities, but its use is lacking in marine ecosystems. The influence of rare species and the level of taxonomic resolution are important features to be considered when planning sampling designs and efforts for community studies. We tested the significance of spatial and environmental components to species distribution of a polychaete community, considering how the results varied among models with increasingly rare species (and contrasting metrics), and among models with distinct taxonomic levels. For all models evaluated, both spatial and environmental components significantly explained the structure of species distribution. However, spatial processes explained a higher percentage of variance than environmental ones in almost all models. The inclusion of rare species did not influence the outcome in most models, with the exception of a Chi‐square distance model with all species included. Family taxonomic level was sufficient to detect the relative contribution of both components, but the number of environmental variables included in the model was higher for the genus level. The influence of rare species was related to the metric applied to the analysis. If weight to rare species is not desirable, the use of a few dominant species coupled with the Hellinger function can provide a good surrogate to the whole sampled community in variation partition analysis. The genus level is suggested as an appropriate taxonomic level with which to evaluate the relevance of spatial and environmental components in polychaete community studies.     

Spatial patterns of biodiversity in the Black Sea: An assessment using benthic polychaetes

The current study broadens the biodiversity information available for the Black Sea and neighbouring regions and improves our knowledge about the polychaete biogeographic patterns to be discerned in them. There appears to be a well-defined zoogeocline from the Marmara Sea and Bosphorus Strait to the inner parts of the region (Azov Sea), depicted both as a multivariate pattern and in terms of species (or taxa) numbers. The emergent multivariate pattern complies, to a certain extent, with Jakubova’s (1935) views: three main sectors can be defined in the basin: (a) Prebosphoric, (b) the Black Sea and, (c) the Azov Sea, whereas the Bosphorus Strait and Marmara Sea show less faunal affinities with the afore-mentioned sectors. Patterns derived both from the cosmopolitan and Atlanto-Mediterranean species closely follow the one coming from the polychaete species and genera inventories. As a general trend, species numbers decrease along with the decrease in salinity towards the inner parts of the region. The trend is homologous to that seen in the benthic invertebrate inventories of all the major European semi-enclosed regional seas. Salinity and food availability appear to be the dominant abiotic factors correlated, though weakly, with the various patterns deriving from the taxonomic/zoogeographic categories. With the exception of the Anatolia, polychaete inventories from all sectors appear to be random samples of the total inventory of the region, in terms of taxonomic distinctness values. Therefore, these sectoral inventories can be used for future biodiversity/environmental impact assessment studies. A massive invasion of Mediterranean species after the opening of the Black Sea, in the lower Quaternary period, appears to be the likely biogeographic mechanism through which the old Sarmatic fauna was almost completely replaced by species of marine origin.     

Preliminary data on the composition and distribution of polychaetes in the deep-water areas of the north-western part of the Sea of Japan

During the SoJaBio expedition, the deep sea fauna of the north-western Sea of Japan was sampled in August–September 2010. From this study, 11 epibenthic sledge stations are analyzed, with a focus on species composition, diversity and distribution patterns of polychaetes. A total of 92 polychaete taxa belonging to 70 genera and 28 families and 3 indeterminate species were found. Twelve species and eight genera have not been reported from the Sea of Japan before, but were registered from other deep-sea basins. Calculation of diversity (Shannon–Wiener Index, Pielou's Evenness) showed that the upper bathyal of the Sea of Japan is an area of higher polychaete diversity than the abyssal plain. The increased richness and diversity here could possibly be explained by a zoogeographic overlapping with the shallower species' assemblages of the shelf. At a higher taxonomic level the polychaete fauna of the deep Sea of Japan does not seem to differ from that of other deep-sea regions world-wide. In depths below 2000 m about 30% polychaete species have wide distributional ranges.     

Annual pattern of zooplankton communities and their environmental response in a subtropical maritime channel system in the northern Bay of Bengal, Bangladesh

Zooplankton plays an important role in aquatic food webs by fluxing of energy from primary producer to subsequent trophic levels in the food chain. The annual pattern of zooplankton communities and potential environmental drivers were studied in the Kohelia channel, Bangladesh from summer 2014 to spring 2015. Samples were collected using net at a depth of 1 m. A total of 32 species belonged to 18 orders, 27 families and 15 taxonomic groups were identified. Of these species, 22 distributed in all four seasons of which 8 were dominant and highly contributing to the total communities. Species number peaked in summer next to winter and fall in spring while maximum abundance was in summer and minimum in spring. Multivariate analyses showed that there was a clear annual pattern in the zooplankton communities. Species diversity and evenness peaked in spring but fall in autumn while the high value of species richness was found in winter. Biological-environmental best matching (BIO-ENV) analyses conformed that community pattern of zooplankton was mainly driven by transparency salinity, and temperature individually or combined with water nutrients. These results demonstrate that annual pattern of the zooplankton community shaped by channel environmental factors in subtropical channel ecosystems, thus might be used for community-based subtropical coastal water bioassessment.     

The impact of Melinna palmata grube, a tube-building polychaete, on meiofaunal community structure in a soft-bottom subtidal habitat

Field investigations were performed in a low-energy subtidal muddy sediment in Loch Creran, a sea-loch on the west coast of Scotland where the impact of Melinna palmata, a tube-building polychaete, on the meiofaunal community structure was assessed. This polychaete was found in high densities and forms prominent faecal casts on the sediment surface. Samples were retrieved from the casts, the feeding area of the polychaete and from an unaffected control area. The number of nematodes, the dominant taxon, did not vary significantly between areas. Of the five most abundant nematode species one was significantly more abundant in the cast area. Diversity and trophic structure of the nematode component of the meiofauna was very similar in all three areas. Copepods were more than twice as abundant in background sediments as in faecal mounds and feeding areas; however, Longipedia spp. were more abundant in the cast areas. For the copepods these findings support models which state that natural disturbances create a mosaic of patches that have different species compositions depending on their states of recovery.     

不同孔径底层筛对胶州湾大型底栖动物取样结果的影响

利用2003年11月在胶州湾所设的20个站,每站成功取4个定量采泥样品,每两个样品分别用底层筛孔径0．5mm和1．0mm的套筛冲洗所得的大型底栖动物样品,进行大型底栖动物栖息密度、生物量及种数比较分析。结果显示,0．5mm孔径底层筛样品的总平均栖息密度、总平均生物量、总种数分别是1．0mm底层筛的样品的1．36,1．19,1．15倍;两种筛所获的样品对大型底栖动物的栖息密度影响最明显,对生物量、种数影响较小;环节动物多毛类、甲壳动物类群中的钩虾类个体较细小,是受底层筛孔径影响最明显的类群;0．5mm孔径底层筛的取样质量明显好于1．0mm孔径底层筛。     

Bacterial polysaccharide as a vehicle for entry of Cr(iii) to a food chain

The feeding of bacterial polysaccharide with bound Cr to two common marine organisms, a polychaete species and the mudsnail Amphibola crenata resulted in an increase in their Cr concentration. For the polychaete, 61% of the total Cr was shown to be from ingested Cr, and autoradiographic evidence following the use of ¹⁴C labelled polysaccharide showed that the polvchaete ingested polysaccharide. It appears that Cr can enter a food chain bound to polysaccharide when polysaccharide is ingested.     

Composition, structural characteristics and temporal patterns of fish assemblages in non-tidal Mediterranean lagoons: A case study

The importance of transitional water ecosystems as nursery habitats and feeding grounds for fish species is well-known. Detailed studies of colonization patterns of fish guilds in response to biotic and abiotic drivers are however unevenly distributed among ecosystem types. We address here the temporal variability of fish assemblages in small non-tidal lagoons in the Mediterranean basin. The study was carried out at the Acquatina lagoon (Lecce, Italy) where four stations, situated in two habitat types along a confinement gradient, were sampled twice per month for one year with fyke nets. Forty-five taxa ranging across 20 families were collected, with the most abundant species, Atherina boyeri, accounting for more than 95% of total abundance. Pooling all species together (excluding sand smelt), the structural features of the assemblage, relative abundance of families, and abundance of individual species all showed significant temporal patterns. Mean abundance peaked in Summer and Autumn and fell in Winter, whereas taxonomic richness and diversity were highest in Summer and lowest in Spring. Within the fish assemblage, multivariate ordination showed temporal segregation of species belonging to the same family or genus and expected to be functionally similar, suggesting that they avoid competition for space and resources by timing inward migration and peak occurrence differently. Of the environmental driving forces, which also showed temporal patterns of variation, salinity was the main factor affecting the distribution of individuals and species. The catch of young individuals of several marine species confirmed the role of this small lagoon as a nursery and feeding area, and emphasized the need for further studies.     

钦州湾桐花树群落沉积物及植物体中重金属元素累积与分异研究

Mangrove wetlands can reduce heavy metal pollution by trapping heavy metals. In this study, the concentration,transport and bioaccumulation of Cr, Cd, Cu, Zn and Pb in the sediments and different parts of Aegiceras corniculatum at four different sites in the Qinzhou Bay in southwestern China were investigated. The results showed that although the potential ecological risk of all five heavy metals was slight, the concentration of Cr was at a moderate pollution level due to the emissions of industries and aquaculture waste water. Core sediment records indicated that the concentrations of heavy metals at the depth of 0–20 cm were relatively high, showing an increasing trend of heavy metals over the past 20–30 years. Cr, Cu, Pb and Cd accumulated mainly in the roots of A. corniculatum, while Zn accumulated mainly in the stems. Aegiceras corniculatum showed the strongest transport capacity for Zn and Cu and the strongest bioaccumulation ability for Cd. Compared with other mangrove communities, A. corniculatum can be chosen as a restoration species in tropical and subtropical coastal zones polluted by Zn, Cu and Cd.     

Bioaccumulation of PCB congeners in marine benthic infauna

Field concentrations of polychlorinated biphenyls (PCBs) were measured in sediment and nine marine soft bottom invertebrate species. Lipid- and organic carbon normalised biota-sediment accumulation factors (BSAFs) were determined for 29 nonplanar and 11 coplanar congeners. To investigate whether the bioaccumulation was in thermodynamic equilibrium with the sediment, the determined BSAFs were compared to theoretically calculated ones to obtain a BSAFdet./BSAFtheor-ratio. Large interspecific variations were found: one suspension feeding and one deposit feeding species of brittle stars (Amphiura filiformis and A. chiajei), and one predatory polychaete (Glycera rouxii) had ratios>1 for congeners with logKow>6.5. In these species there was also a linear relationship between logKow and BSAF, both for coplanar and for planar congeners but with lower values for coplanar ones. For other species the pattern was more scattered. Only the deposit feeding polychaete Melinna cristata had BSAFdet./BSAFtheor-ratios<1 for all congeners. Thus, the interspecific variations in bioaccumulation did not correlate with differences in feeding strategies, but may be caused by differences in biotransformation, and in age and size of the analysed specimens.     

Fish assemblages of small estuaries of the Portuguese coast: A functional approach

The importance of estuaries for coastal environments is widely acknowledged but their role, structure and ecological status have been the focus of recent scientific efforts mainly concerning large estuarine areas. In this work we used fish assemblages to establish, for the first time, the functional and ecological role of five small estuarine systems along the Portuguese south and southwest coasts. Our results showed that, at a functional approach, fish communities did not differ between estuaries, and that all systems presented a seasonal pattern in diversity values, ecological and feeding guilds. These small estuaries contribute to the support of coastal fish populations by providing temporary habitats to the critical life stages of marine species, shelter and feeding grounds, and should be considered in an ecological and conservation perspective.     

Seasonal patterns of tidepool macroalgal assemblages in the North of Portugal. Consistence between species and functional group approaches

Macroalgae are useful organisms to monitor the environmental quality and to detect impacts due to anthropogenic activities. However, it is very important to identify the scales of variation in natural assemblages, particularly for the detection of environmental impacts. Otherwise, changes due to anthropogenic impacts may be confused with differences due to natural temporal variability. Another important task is to determine the appropriate level of taxonomical effort needed to detect changes in the assemblage structure. Many taxonomical surrogates, at higher taxonomic levels than that of species, have been proposed but, the consistence in space and time of the results produced by surrogates with those obtained at specific level should be tested. The objectives of this study are to identify the seasonal patterns of tidepool macroalgal communities using objective procedures and to test the consistence between the patterns obtained considering data at the species level and functional groups. Results showed that the seasonal pattern obtained using functional groups and species was consistent. Tidepool macroalgal assemblages showed a seasonal pattern with significant differences between spring–summer and autumn–winter. This pattern can be explained by changes in environmental variables and the seasonal development of the dominating species. Ulva spp. and the non-indigenous species Grateloupia turuturu were the species responsible for this pattern due to their high seasonality in terms of biomass. Finally, the abundance and species diversity within the corticated functional group was proposed as indicator of environmental impacts due to its relatively constant abundance and its sensitivity to environmental impacts.     

Trophic relationships in tidepool fish assemblages of the tropical Southwestern Atlantic

Trophic studies are fundamental to understanding the dynamics of assemblages and functional roles of species within ecosystems, contributing to the identification of factors responsible for the organization and structure of communities. This study aimed to analyse the trophic organization of tidepool fish assemblages in the tropical Southwestern Atlantic, based on the underlying idea that food resources are not limiting and that trophic guild formation is not driven by food competition. Diets were based on feeding index values of food categories for 12 representative species collected in six tidepools (20º49′ S, 40º36′ W) at quarterly intervals (2005 to 2007). The main food categories were small crustaceans, polychaetes and macroalgae. Multivariate techniques evidenced two multispecific trophic guilds: small‐prey carnivores, including Bathygobius soporator, Bathygobius geminatus, Malacoctenus delalandii and Halichoeres poeyi, and herbivores, including Sparisoma axillare and Acanthurus bahianus. Other species presented significantly different diets and were classified into the following guilds: omnivores feeding on filamentous algae and copepods (Abudefduf saxatilis); large‐prey carnivores (Labrisomus nuchipinnis); omnivores feeding on polychaetes and filamentous algae (Stegastes fuscus); and polychaete feeders (Ahlia egmontis). Gymnothorax funebris and Gymnothorax moringa were classified as carcinophagores and piscivores, respectively. Trophic organization appears related to species convergence toward the use of abundant food resources, driven by a combination of factors allowing some resource partitioning through inter‐specific differences in consumer size, microhabitat, behavior, and trophic specialization.     

Biomarker responses to pollution in two invertebrate species: Scrobicularia plana and Nereis diversicolor from the Cádiz bay (SW Spain)

The clam Scrobicularia plana and the polychaete worm Nereis diversicolor were collected in several sites from a littoral enclosure in SW Spain. The aim of our study was to relate various biomarker responses in these species to a pollution gradient caused by untreated domestic discharges and to verify the adequacy of the selected species as sentinels in this habitat. The biomarkers selected were the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPX) and DT-diaphorase (DT-D). In addition, the activities of cytochrome P450-dependent ethoxyresorufin O-deethylase (EROD) activity, the phase II detoxifying enzyme glutathione S-transferase (GST) and the neurotoxicity marker acetylcholinesterase (AChE) were measured. Metallothionein levels were selected as biomarkers of heavy metals exposure in both species. The results suggest a different response in the water filtering organism (clam) and the sediment eater (polychaete), probably as a consequent of different pollution exposure and that samples from the “Caño Sancti-Petri” were exposed to biologically active compounds that altered some of their biochemical responses. AChE was the most sensitive biomarker in both species and N. diversicolor proved to be a more robust sentinel in this ecosystem.