Determination of functional structure of soft-bottom marine macrobenthic communities of the Samsun Shelf Area using biological traits analysis

Biological Traits Analysis (BTA) was used to investigate the functional structure of marine macrobenthic communities along the Samsun Shelf Area (SSA). Benthic samples were collected seasonally from five different locations and at four different depths using a Van Veen grab sampler. Macrofaunal communities distributed in the SSA were assessed using 10 biological traits to identify characteristic traits for each depth and location. It was found that variability of benthic ecosystem functions in the SSA was driven by biological traits such as maximum size, living habit, sediment position, feeding mode and type of reproductive behavior. Bivalves, polychaetes and crustaceans of small to medium size, biodepositing, burying themselves in the sediment (burrowers) and feeding in suspension were relatively more abundant at depths of 0–60 m. However, the biomass of Amphiura, Abra, Papillicardium and some polychaetes characterized by medium to large sizes, diffusive mixing, free living and feeding on deposit and subsurface deposit showed higher values at depths below 60 m. In general, it is concluded that the functional structure of the benthic infauna in the SSA has adapted to physical disturbance, and communities distributed in this area consist mainly of taxa resistant to mechanical pressure.

Responses of Functional Traits of Macrobenthic Communities to Human Activities in Daya Bay (A Subtropical Semi-Enclosed Bay), China

The biological trait analysis (BTA) is regarded as a promising approach to unravel how ecosystem functions respond to human-induced disturbances. This study considered the four sampling locations associated with different human activities in Daya Bay, that is, the domestic and industrial sewage discharge area (SED), mariculture area (MRC), nuclear power plants thermal discharge area (NTD), and an area with relatively low human disturbance as a reference (REF). Thirty modalities of nine traits were selected in BTA. Our results showed a clear shift in the functional structure of macrobenthic communities between the sampling locations, except for the case between NTD and REF. The trait composition in the communities did not highlight any seasonal patterns. Bioturbation, longevity, tolerance, body size, feeding habit, and environmental position were the key traits to characterize the functional structure of macrobenthic communities and demonstrated predictable responses along the environmental gradients. Water depth, DO, Chl-a, NH4+, and petroleum contaminants in sediments were the main variables influencing the trait composition. In addition, the taxonomic index (H′) and functional diversity index (Rao’s Q) showed clear differences among the sampling locations. Although there were no significant differences between NTD and REF in terms of the trait composition and functional diversity, a potential function loss in NTD still can be detected through the integrated analysis with taxonomic diversity. We suggest that the traits (except for fragility, larval development, and living habits) selected and the diversity indices (H′ and Rao’s Q) could serve as promising indicators of ecological conditions in Daya Bay.

Functional Trait Responses of Macrobenthos to Anthropogenic Pressure in Three Temperate Intertidal Communities

With the increasing impact of human activities on marine ecosystems, there is a growing need to assess how the components of marine ecosystems (e.g., macrobenthos) respond to these anthropogenic pressures. In this work, the trait-based approach was used to assess the effects of anthropogenic pressures represented by the area of land-based aquaculture pond (Pond Area) and heavy metals on the macrobenthic communities in three intertidal zones[Aoshan Bay (AO), Wenquan River and Daren River (RW), and Xiaodao Bay (XD)] of Laoshan Bay, Shandong Peninsula, China. Compared with RW and XD, AO was under more pressure in terms of the average concentrations of heavy metals and total organic carbon (TOC) in sediments and also in the Pond Area. Fuzzy correspondence analysis (FCA) showed that there were significant differences in the composition of functional traits among the three regions (PERMANOVA; p < 0.05). In the highly polluted area, macrobenthic communities exhibited a combination of traits, such as relatively short life span, weak mobility, feeding on deposits, and more tolerant to organic matter, whereas in a less polluted area, they exhibited a combination of traits, such as relatively long life span, relatively high mobility, and more sensitivity to organic matter. The RDA results showed that the distribution of the trait modalities was significantly affected by heavy metals (Hg and Cd), TOC, Pond Area, and sampled location. Variation partitioning analysis (VPA) indicated that the shared influence of sediment-related pollution factors and Pond Area contributed most to the variance of the functional traits, which implied that human activities directly and/or indirectly lead to changes in functional traits of macrobenthic communities in the intertidal zones.

Efficiency of sampling gears (Quadrate and Core) and Taxonomic Resolution on the Soft Bottom Intertidal Macrobenthic community of Port Blair coast

Ecological studies of a region cannot proceed forward without the evaluation of species diversity. With the ever-increasing demand for studies to understand the change in the macrobenthic communities, the focus has primarily been shifted towards faster results to track down the changes from the prior environments. Therefore, studying the complete benthos faunal diversity of an area leads to an unrealistic approach. Thus, researchers tend to depend on various sampling gears, which ease the work capacity. The present study compared two samplings gears (core and quadrate) in two different habitats to understand the diversity of the macrobenthic communities. In terms of abundance, the core gear showed higher significant differences as compared to quadrate. However, the gears did not significantly differ among the diversity indices (Margalef's index and Shannon- Winer index) and the cluster analysis (Bray-Curtis similarity index and nMDS). The present study found that the 'information loss' was minimal with the aggregated data at a higher taxonomic level. Spearman rank correlation coefficient revealed that the information loss was low up to family-level and the correlation coefficient decreases as the taxonomic level increases after family-level. Nonetheless, the choice of sampling gears did not influence the diversity of the soft-bottom intertidal macrobenthic communities.

Comparison of macrobenthic communities between the invasive Spartina alterniflora and native Suaeda glauca habitats in the Yellow River Delta

Salt marsh habitats in estuaries play important roles in species compositions and macrobenthos abundances. Here, the macrobenthic communities and environmental conditions in two habitats, which are dominated by the invasive species Spartina alterniflora (SA) and native species Suaeda glauca (SG), in the Yellow River Delta were studied to assess habitat function. The seasonal data showed that the species diversity and abundance of macrobenthos in the SA habitat were much higher than those in the SG habitat. The functional groups in the former showed significant seasonal changes and shifted from polychaeta (68%) in spring to mollusca (97%) in autumn, but in the latter, it was dominated by crustacea (63-86%), mollusca (1-25%) and polychaeta (9-13%), and only mollusca exhibited obvious seasonal changes. The sediments in the SA habitat contained richer organic matter contents and exhibited higher Chl- a concentrations than those in the SG habitat, although the grain sizes were coarser in the SA habitat. At the seasonal scale, macrobenthos in the SA habitat displayed significant negative correlations with salinity and organic matter. The results indicated that the macrobenthos functional groups in the SA habitat were simpler and more sensitive to environmental changes than those in the SG habitat. The vegetation structures may give rise to the differences in macrobenthos distributions in both habitats, which need to be further observed and explored.