NISCAIR Online Periodicals Repository Collection: IJMS Vol.38(2) [June 2009]

Potential microbial diversity in mangrove ecosystems:A review

Title: Potential microbial diversity in mangrove ecosystems:A review

Authors: Sahoo, K.; Dhal, N.K.

Abstract: Mangroves provide a unique ecological niche to different microbes which play various roles in nutrient recycling as well as various environmental activities. Mangrove forests are large ecosystems distributed in 112 countries and territories comprising a total area of about 181,000 km² is over a quarter of the total coastline of the world. The highly productive and diverse microbial community living in mangrove ecosystems continuously transforms nutrients from dead mangrove vegetation into sources of nitrogen, phosphorous and other nutrients that can be used by the plants and in turn the plant-root exudates serve as a food source for the microbes. Analysis of microbial biodiversity from these ecosystems will help in isolating and identifying new and potential microorganisms having high specificity for various applications. The present study consists literature on diversity of predominant microbes such as bacteria, fungi and actinomycetes from mangrove ecosystems.

Page(s): 249-256

Assessment of metal concentration in the sediment cores of Manakudy estuary, south west coast of India

Title: Assessment of metal concentration in the sediment cores of Manakudy estuary, south west coast of India

Authors: Kumar, Sugirtha P; Edward, J K Patterson

Abstract: Base line data on the metal concentration was obtained from three core sediments (S1, S2 and S3) of Manakudy estuary on the south west coast of India. The acid leachable trace metals (Cr, Cu, Ni, Co, Pb, Zn and Cd) showed peak values at sulphidic phase . There is moderate level of pollution related to anthropogenic activities. The trace metals were associated with Fe and Mn indicating their adsorption onto Fe-Mn oxyhydroxides. The correlation of trace metals with sulphur indicates that they were precipitated as metal sulphides. Correlation matrix showed elegant association between trace metals and Fe, Mn, S and mud. The Igeo values revealed that all the core samples fell within uncontaminated to moderately contaminated category. The concentration factor was low (C_fⁱ <1) indicating low contamination in the core samples. The anthropogenic factor (AF) values indicate moderate anthropogenic inputs.

Page(s): 235-248

Phytoplankton species assemblages and their relationship to hydrographic factors—a study at the old port in Mangalore, coastal Arabian Sea.

Title: Phytoplankton species assemblages and their relationship to hydrographic factors—a study at the old port in Mangalore, coastal Arabian Sea.

Authors: Harnstrom, Karolina; Karunasagar, Indrani; Godhe, Anna

Abstract: Several environmental variables were monitored and water samples were examined from over a period of 17 days in December 2005 and January 2006 to understand the taxonomic structure of coastal phytoplankton communities at a coastal site near Mangalore. The phytoplankton community was characterized by identifying and quantifying microalgal taxa; in conjunction, also determined Chl a, inorganic nutrients, oxygen, salinity, temperature, total bacteria, and tidal range. Canonical correspondence analysis (CCA) was used to trace temporal phytoplankton community changes, and to examine the relationships between species composition and environmental factors. These variables were subjected to analysis, pair-wise, to identify correlations. The species diversity of the phytoplankton community changed rapidly, and high species diversity coincided with significantly higher relative diatom abundance, and lower species diversity coincided with significantly higher proportions of phytoplankton taxa other than diatoms and dinoflagellates. In addition, the Chl a concentration was positively correlated to the relative proportion of dinoflagellates. The relative abundance of some species was dependent on specific environmental variables, such as Chaetoceros tenuissimus that was found inversely correlated to salinity. We also found that the stage of the tides may have implication on the sampling, because it has an influence on species diversity and the proportion of specific microalgal groups. At declined water level, the relative proportion of diatoms and dinoflagellates was low, and generally the Chl a concentrations were also lower during low tide.

Page(s): 224-234

Estuarine characteristics of lower Krishna river

Title: Estuarine characteristics of lower Krishna river

Authors: Kumari, V Rajani; Rao, I Mrutyunjaya

Abstract: Present study consist the spatial and temporal variations of depth, temperature and salinity, currents, flushing times and classification of the Krishna estuary. Temperature exhibited a distinct seasonal variation with higher values in premonsoon (30.0±0.09°C) and monsoon (29.2±0.08°C) seasons compared to that of winter (26.6±0.06°C). Salinity and current pattrns shows distinct seasonal and spatial variations noticed. Changes in hydrodynamic conditions infers that the river mouth as a positive type of estuary. Flushing times varied with seasons and locations due to changes in river discharges and circulation pattern. Considering the two dimensional Hansen and Rattray's stratification and circulation diagram, the estuary has been classified as partially mixed with no stratification type during postmonsoon and stratified during monsoon and premonsoon seasons.

Page(s): 215-223