Distribution and Diversity of Macrobenthos in Sangu River, Bangladesh

This study was conducted to understand the macrobenthos distribution and abundance in Sangu River to monitor the aquatic pollution level. Both surface and sub-surface water and benthic sediments were collected from three stations of the Sangu River. A few indices viz. Shannon-wiener, Simpson, Margalef’s and Evenness were used to estimate the macrobenthic assemblages. In this study, a total of 11 major taxa comprising total 870 macobenthic species were identified. Shannon-wiener index was maximum (1.58) at lower part (LP) which indicated moderate to heavily pollute aquatic environment of the Sangu River. The average diversity values of Shannon, Evenness, Simpson and Margalef’s indices were 0.97, 0.43, 0.39 and 1.54 respectively. The concentration of dissolved oxygen was the lowest (4.90 mg/L) at LP and the highest (5.08 mg/L) at upper part (UP). This study showed that macrobenthos abundances was influenced by higher temperature, salinity, and pH. The percentage of organic carbon content was maximum (98.18%) at LP where the macrobenthic abundance was 330 individuals/m2, whereas it was minimum (80.77%) at UP where macrobenthic abundance was 248 individuals/m2 that indicated carbon content also influence the assemblages of the macrobenthos in the Sangu River. A clear gradient of physico-chemical and benthic soil parameters fluctuation was also found to be responsible for the variations of macrobenthos assemblage in the Sangu River. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 9(2), 2020, P 27-34

Relationships between characteristics of macrobenthic assemblages and environmental variables in the Heihe River Basin, China

To clarify the characteristics of macrobenthic assemblages and their response to the aquatic environment in the upper and middle reaches of the Heihe River, water quality, sediments and macrobenthos measurements were conducted in the summers of 2018 and 2019. The results showed that 50 species of macrobenthos were identified, belonging to 3 phyla, 7 classes, 15 orders and 32 families, mainly arthropods (37 species) and mollusks (11 species). Argyroneta aquatica, Chlaznius sp., dragonfly nymphs, Palaemon modestus, Radix auricularia, Cyraulus albus and Suecinea sp. were the dominant species in the whole study region; most of these are pollution-tolerant and moderately tolerant species. The macrobenthos density and biomass ranged from 10 to 577 ind./m2 and from 0.0907 to 50.0562 g/m2, respectively, showing high spatial heterogeneity. Predators were the main functional feeding group. One-way analysis of variance clarified that Margalef's index and the Shannon–Wiener index differed significantly among the spatial areas (P < 0.05). Canonical correspondence analysis showed that the spatial heterogeneity of the macrobenthos was affected by the water temperature and the total nitrogen and total phosphorus in sediments (P < 0.05).

Benthic communities in three Mediterranean touristic ports: MAPMED project

Mediterranean ports are sources of significant economic activity and at the same time they act as recipients of considerable anthropogenic disturbance and pollution. Polluted and low-in-oxygen sediments can negatively impact benthic biodiversity and favour recruitment of opportunistic or invasive species. Macrobenthic communities are an important component of the port biota and can be used as environmental quality indicators. However, a baseline database for benthic biodiversity in Mediterranean ports has not yet been widely established. Macrobenthic assemblages were recorded in three Mediterranean touristic ports under the framework of the ENPI CBC MED project MAPMED (MAnagement of Port Areas in the MEDiterranean Sea Basin). Samples were collected from Cagliari (Sardinia, Italy), Heraklion (Crete, Greece) and El Kantaoui (Tunisia) ports during February, May and September 2012. The sampling stations were selected according to the different sectors within each port (i.e. leisure, fishing, passenger/cargo vessels and shipyard). A total of 277 taxa belonging to 12 phyla were found, of which the 96 taxa were present in all three ports. El Kantaoui port hosted the highest number of macrobenthic taxa. Mollusca were the most abundant group (34%) in all ports. The highest percentage of opportunistic taxa per station was found before the touristic period in the shipyard of Heraklion port (89.3%).

Habitat-Diversity Relations between Sessile Macrobenthos and Benthic Copepods in the Rocky Shores of a Marine Protected Area

In rocky shore systems, sessile macrobenthic assemblages may act as “ecosystem engineers” for many smaller benthic organisms. Thus, the influence of macrobenthic coverage on the diversity and assemblage structure of the harpacticoid copepod fauna was investigated in the rocky shores of a Marine Protect Area (MPA) in the Ligurian Sea (NW, Mediterranean Sea). Two sampling sites were investigated in two seasons at three different depths on both sub-vertical and inclined reefs. A total of 61 species of copepods mainly represented by Miraciidae, Laophontidae, Longipediidae and Thalestridae were found. The complex micro-topography of these substrata provided a wide variety of niches for many species with different lifestyles that suggests the important role of rocky shores to ensure the functioning of coastal ecosystems. The harpacticoid assemblage structure seemed mainly influenced by season and depth. The temporal spread observed is likely one of the underlying mechanisms of niche segregation that allows many species to co-occur in this specific environment along with a subordinate spatial segregation corresponding to the depth gradient. The results seem to support the hypothesis that the different species composition of the “ecosystem engineer” (and consequently its structure changes) are relevant in structuring the copepod assemblages. The comparison with previous data on general meiofauna underlines that higher surrogacy of the taxonomic identification could be used to study rocky shore communities, but the rich diversity that these systems host can only be understood at the lower taxonomic levels. The same holds for future evaluations of impact of environmental changes (including MPA regulations) on meiofaunal assemblages.

Composition, uniqueness and connectivity across tropical coastal lagoon habitats in the Red Sea

Background Tropical habitats and their associated environmental characteristics play a critical role in shaping macroinvertebrate communities. Assessing patterns of diversity over space and time and investigating the factors that control and generate those patterns is critical for conservation efforts. However, these factors are still poorly understood in sub-tropical and tropical regions. The present study applied a combination of uni- and multivariate techniques to test whether patterns of biodiversity, composition, and structure of macrobenthic assemblages change across different lagoon habitats (two mangrove sites; two seagrass meadows with varying levels of vegetation cover; and an unvegetated subtidal area) and between seasons and years. Results In total, 4771 invertebrates were identified belonging to 272 operational taxonomic units (OTUs). We observed that macrobenthic lagoon assemblages are diverse, heterogeneous and that the most evident biological pattern was spatial rather than temporal. To investigate whether macrofaunal patterns within the lagoon habitats (mangrove, seagrass, unvegetated area) changed through the time, we analysed each habitat separately. The results showed high seasonal and inter-annual variability in the macrofaunal patterns. However, the seagrass beds that are characterized by variable vegetation cover, through time, showed comparatively higher stability (with the lowest values of inter-annual variability and a high number of resident taxa). These results support the theory that seagrass habitat complexity promotes diversity and density of macrobenthic assemblages. Despite the structural and functional importance of seagrass beds documented in this study, the results also highlighted the small-scale heterogeneity of tropical habitats that may serve as biodiversity repositories. Conclusions Comprehensive approaches at the “seascape” level are required for improved ecosystem management and to maintain connectivity patterns amongst habitats. This is particularly true along the Saudi Arabian coast of the Red Sea, which is currently experiencing rapid coastal development. Also, considering the high temporal variability (seasonal and inter-annual) of tropical shallow-water habitats, monitoring and management plans must include temporal scales.

Biomonitoring of the Application of Monoculture and Integrated Multi-Trophic Aquaculture (IMTA) Using Macrobenthic Structures at Tembelas Island, Kepulauan Riau Province, Indonesia

Sustainable aquaculture needs to be considered when it comes to the utilization of water resources. The aim of this study was to apply biomonitoring using macrobenthic structures on both spatial and temporal applications of monoculture and integrated multi-trophic aquaculture (IMTA) at Tembelas Island, Kepulauan Riau Province, Indonesia. Samples of sediment were taken from three fish farm locations, namely from an IMTA site, a monoculture site, and a reference site. Macrobenthic organisms obtained through rinsing, sieving, and sorting were then identified under a stereo-microscope. Diversity of the macrobenthic assemblages was analyzed with a Shannon-Wiener index (H’). Equitability was expressed through Pielou’s evenness index. Finally, Bray-Curtis’ non-metric multi-dimensional scaling (NMDS) was used for similarities derived from log (X+1) transformed macrobenthic abundance to provide a visual representation of differences in their structure between sites over time. Results showed polychaetes exhibited differences in both variation and abundance of genera between the farm and reference site. The assemblage of macrobenthos at the IMTA site consisted of 9 genera of gastropods, 3 genera of bivalves, 5 genera of polychaetes, and 2 genera of crustaceans. At the monoculture site, 12 genera of gastropods, 4 genera of bivalves, 8 genera of polychaetes, 1 genera of crustaceans, and 1 genera of ophiuroid were observed. A relatively high abundance was observed at the reference site, with 27 genera of gastropods, 11 genera of bivalves, 3 genera of polychaetes, and 1 genera of crustacean. The favorable water conditions and possible absence of waste input from aquaculture resulting in a more suitable habitat for macrobenthic life may explain this relative abundance. Some of them were recognised as opportunistic taxa, i.e., Capitella sp., Heteromastus sp., and Lumbrinereis sp. Based on the diversity and evenness indices and the MNDS ordination, it can be concluded that the application of IMTA systems results in a suppressed or reduced potential impact on environmental disturbance due to aquacultural activities.