| dc.description.abstract | Changes in the autotrophic pico- (0.2–
2 μm), nano- (2–20 μm), and microplankton
(>20 μm) biomass (chlorophyll a) and primary
production were measured in the estuarine and
coastal waters off Cochin, southwest coast of India
during the onset and establishment of a monsoon.
During this period, the estuary was dominated
by nutrient-rich freshwater, whereas the coastal
waters were characterized with higher salinity values
(>30 psu) and less nutrients. The average
surface chlorophyll a concentrations and primary
production rates were higher in the estuary (average
13.7 mg m−3 and 432 mgC m−3 day−1) as
compared to the coastal waters (5.3 mg m−3 and
224 mgC m−3 day−1). The nanoplankton community
formed the major fraction of chlorophyll
a and primary production, both in the estuary
(average 85 ± SD 8.3% and 81.2 ± SD 3.2%)
and the coastal waters (average 73.2 ± SD 17.2%
and 81.9 ± 15.7%). Nanoplankton had the maximum
photosynthetic efficiency in the coastal waters
(average 4.8 ± SD 3.9 mgC mgChl a m−3
h−1), whereas in the estuary, the microplankton
had higher photosynthetic efficiency (average 7.4 ± 7 mgC mgChl a m−3 h−1). The heavy cloud
cover and increased water column turbidity not
only limit the growth of large-sized phytoplankton
in the Cochin estuary and coastal waters but also
support the proliferation of nanoplankton community
during the monsoon season, even though
large variation in nanoplankton chlorophyll a and
production exists between these two areas. | |
