Study on primary production with emphasis on phytoplankton biovolume and chlorophyll-a in the southern Caspian Sea-Goharbaran region

Document Type : Research Paper

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Abstract

Phytoplankton biovolume and concentration of chlorophyll a are of major concerns in estimating the primary production in aquatic ecosystems. The objective of the present study was to estimate the concentration of chlorophyll a and its relation to variations of some phytoplankton community structure parameters and abiotic factors (environment and nutrients) in the coastal ecosystem of the Caspian Sea in Goharbaran region. Samples were collected monthly from various layers of water (surface, 5 and 10 m) in three depths (5, 10 and 15 m) during 2013-2014. Based on the results the minimum and maximum mean values (±SE) of biomass were obtained in summer (94± 16) and winter (1209± 106) mg/m3, respectively. The minimum and maximum mean values (±SE) of chlorophyll a were recorded in spring (0.39±0.05 µg/L) and autumn (4.56± 0.23 µg/L), respectively. Seasonal changes in the pattern of dominant taxonomic groups of phytoplankton showed important role in relationship between chlorophyll content of the cells and abiotic factors. Temperature (in summer and autumn), phosphorous (in spring), nitrogen (in summer) and silicon (in spring and winter) showed significant effects on incompatibility between phytoplankton biovolume and the concentration of chlorophyll. As conclusion, difference between the patterns of change in chlorophyll and phytoplankton biovolume indicated the importance of choosing appropriate parameters in order to estimate the primary production and to predict the algal bloom, especially in the cage and pen culture sites. Since the rapid changes in the chlorophyll-biovolume relationship could lead to significant errors in the explanation of results and unexpected field observations.

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Iranian Scientific Fisheries Journal
Volume 26, Issue 2
July and August 2017
Pages 121-130

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