Title: Chlorophyll-a dynamics in relation to environmental parameters in a tropical lagoon
Abstract: The chlorophyll-a dynamics and environmental factors of the Ologe lagoon, Lagos were investigated for 2 years (Feb., 2002 – Jan., 2004). The environmental indices reflected seasonal changes related to rainfall distributive pattern and tidal seawater incursion. Air temperature (27-34 C), surface water temperature (25-32C), transparency (24-76cm), total dissolved solids (48-294mg/l), salinity (0-0.5‰), conductivity (83-631μS/cm), pH (5.8-8.1), total alkalinity (42-162mg/l), biochemical oxygen demand (0-28mg/l), chemical oxygen demand (639mg/l), total hardness (62-342mg/l), cations, and heavy metals recorded increasing values in the dry season than the wet months, while dissolved oxygen (7-12.7mg/l), total suspended solids (7-378mg/l), nitrate-nitrogen (0.021.02mg/l), phosphate-phosphorus (0.03-1.79mg/l) and silicate (2.05-9.54mg/l) had higher values in the wet season than the dry season. Estimation of phytoplankton biomass by chlorophyll-a concentration ranged from 0.1 to 64.5ug/l with mean value of 16.99ug/l. Values for chlorophyll-a were higher in the dry than wet season for the lagoon. Analysis, using Pearson correlation co-efficient recorded positive relationship between chlorophyll-a values and air temperature, surface water temperature, salinity, conductivity, total dissolved solids, pH, transparency, biochemical oxygen demand, chemical oxygen demand, alkalinity, total hardness and cations. Analysis using ANOVA showed significant differences in the sample means of physico-chemical parameters of effluent discharge station (OL4) and the other stations within the lagoon at 5% level of probability. Recorded chlorophyll-a values placed the Ologe lagoon between the mesotrophic and eutrophic status. It is suggested that increasing tidal influence associated with reduction in rain events may have encouraged elevated salinities and created conditions for the development of more algal cells, hence higher chlorophyll a records. [Journal of American Science 2010;6(12):327337]. (ISSN: 1545-1003).
Publication Year: 2010
Publication Date: 2010-01-01
Language: en
Type: article
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Cited By Count: 6
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