Changes in the soft-bottom macrobenthic diversity and community structure from the ports of Mumbai, India.

Soft-bottom macrobenthic diversity and community structure were assessed at Mumbai and Jawaharlal Nehru ports during three different periods between 2001 and 2002 (November 2001 post-monsoon 1, April/May 2002 pre-monsoon, and October 2002 post-monsoon 2). A total of 43 macrobenthic invertebrate species belonging to five phyla were recorded. Macrofaunal abundance (PM1 186, PreM 106, and PM2 31 ind m(-2)) and species diversity index (PM1 0.87, PreM 0.73, and PM2 0.30) were very low in all the seasons. Polychaetes were the most dominant macrobenthic group (72.09%) followed by decapoda, amphipoda, and bivalves (4.56%). Canonical correspondence analysis showed that sediment texture, temperature, and suspended particulate matter were the most important environmental variables influencing polychaete species composition. Significant seasonal variations were observed, influenced by dissimilar monsoonal patterns. Macrobenthic population density during November 2001 was higher than that of October 2002 post-monsoon season. Pre-monsoon season recorded more carnivorous polychaete species than post-monsoon seasons. The present study showed lower values of polychaete diversity index in all the seasons compared to earlier studies. Out of 31 polychaete species, 19 have been reported for the first time from this area. Polychaete species and Glycera longipinnis, Paraprionospio pinnata, and Cossura coasta recorded from 1985 to 1986 were also observed in the present study. Species like Sigambra constricta, Perinereis cavifrons, Prionospio polybranchiata, and Parheteromastus tenuis were not recorded in the present study, although they were observed during earlier studies in this area.