Phytoplankton dynamic responses to oil spill in Mumbai Harbour

Abstract

The oil spill caused by collision of MSC-Chitra with MV-Khalijia on August 7, 2010 in Mumbai Harbour and surrounding area contaminated the shore and resulted in augmented level of PHc (6692.4-16902.2 mew g/l), though it was seen in low concentration (4.8-6.3 mew g/l) before oil spill (September, 2009). An enhanced concentration of chlorophyll a (2.4-39.2 mg/m sup (3)) during pre-spill decreased significantly (0.8-1.5 mg/m sup (3)) during oil spill. The ratios of chlorophyll a / phaeophytin were always >1 (2.7- 8.0) before oil spill which decreased to <1 (0.8-0.9) during the period of oil spill indicating an unhealthy condition of phytoplankton cells. Thus significantly high oil contamination in the region resulted in degradation of pigments and led markedly poor ratios of chlorophyll a / phaeophytin (<1) within a week of oil spill. The subsequent observations (after 16-31 days) showed an exemplary improvement in chlorophyll a (3.4-43.4 mg/m sup (3)). The phytoplankton population also revealed an impact of oil, with markedly decreased cell counts within a week (107 X 10 sup (3)- 109 X 10 sup (3) /l) at highly affected areas and increased significantly within a fortnight (17036 X 10 sup (3)- 50488 X 10 sup (3) /l). The continuous presence of Skeletonema costatum as a predominant species followed by Navicula, Thalassiosira, Nitzschia, Chaetoceros and Coscinodiscus revealed no significant alteration in community structure except composition of phytoplankton due to oil spill