Seasonal variations in physico-chemical parameters of Buleji and Paradise Point rocky shores at Karachi coast

Abstract

The aim of the current study was to determine common physico-chemical parameters (salinity, temperature, chlorophyll-a, dissolved oxygen, and pH) of coastal water of two rocky shores from Buleiji and Paradise Point rocky shores at Karachi monthly basis, from November 2007 to April 2009. The range of air and surface water temperature of Buleji varies from 19 ºC to 30 ºC and 21ºC to 29 ºC, respectively. Almost similar air temperature and seawater temperature (19º to 29º C) were recorded at Paradise Point. Salinity ranged from 35 to 39 ‰ at Buleji while it ranged between 35 to 40 ‰ at Paradise Point. The lowest concentrations of dissolved oxygen was recorded in November’07 and November’08 at both sites, at Buleiji which were 1.6 mg/L and 1.7 mg/L while at Paradise Point it was 1.8 mg/L and 1.7 mg/L, respectively. The pH value ranged from 7.0 to 8.3 at Buleji and from 7.5 to 8.4 at Paradise Point. The concentrations of chlorophyll-a were between 1.2 and 3.7 µg cm-2 at Buleji while it ranged from 0.9 to 3.3 µg cm-2 at Paradise Point. Results showed that the obtained values of temperatures, salinity, pH and   chlorophyll-a are favorable for the continued survival of marine biota but the values of dissolved oxygen were found to be below 4 mg/L which are not suitable for various species. Prolonged periods of minimal dissolved oxygen directly upset larval stages of numerous marine organisms. In Karachi coastal areas, seasonal accessibility of surface water is very responsive to the monsoon climate and physiography of coastal belt. These concerns were used to inform the common people and decision-makers about the state of the coastal environments. To protect these dynamic significant habitats, the government organizations and researchers should work with appropriate consideration.