Unraveling the functional diversity of macrobenthic community from Prydz Bay, Indian sector of the Southern Ocean

Abstract

Antarctic marine ecosystems show rich macrobenthic diversity with a high level of endemism and biomass which is under the threat of global climate change. Till date, information regarding the structure of macrobenthic communities from Prydz Bay is extremely meagre. The present study investigates the spatial pattern of macrobenthic communities, and their response to environmental factors from Prydz Bay complemented with trait-based functional diversity patterns. Samples were collected from 8 stations during the 11th Indian scientific expedition to the Southern Ocean. A total of 57 species of macrobenthos belonging to 8 phyla and 33 families were identified. The macrobenthic communities were dominated by families, Lumbrineridae, Glyceridae, Ophiuridae, and Epimeriidae. Macrobenthos abundance in the study area ranged from 0 to 1592 indv.m-2, whereas biomass ranged from 0 to 1210.2 g m-2. CLUSTER analysis divided the entire macrobenthic community into four groups based on 13.5% similarity. SIMPER analysis delineated species Nacella kerguenlensis and Rossella antarctica as the main contributors for establishing similarity in macrobenthic community composition across the groups. Canonical correspondence analysis (CCA) showed environmental variables like clay %, depth, and sediment total organic carbon as the governing factors in structuring the composition of macrobenthic species. Biological trait analysis (BTA) was performed to visualize the functional diversity of the total macrobenthic population based on morphological and ecological characteristics. A total of 23 traits in 6 categories were used to assess the functional diversity of the study area. The most widespread trait categories were epifaunal environmental position, motile locomotion strategy, sexual brooder and spawner, burrowing living habitat, predatory and detritivore feeding strategies. Investigating the functional diversity of macrobenthic assemblages using BTA represents a novel step towards evaluating the ecological status of the benthic realm of Prydz Bay. RLQ approach in combination with fourth-corner analysis was used to evaluate the relationships among biological traits, macrobenthic species and environmental parameters.The RLQ analysis revealed the positive association of tube dwelling and burrowing polychaetes with silty substratum, and the sessile organisms were found to be negatively correlated with the presence of carnivores/predators. The present study gives a comprehensive understanding about the macrobenthic community structure along with biological trait categories from Prydz Bay.