Microalgal in waters and sediments of Surabaya mangrove areas

Mangrove areas stored the highest carbon content in the tropics which is three times higher than the average carbon in mainland tropical forest areas. The nutrients surround may support the growth of primary producers such microalgae. The community of microalgae was observed during the high and low tide in wet season (December 2021). Five water samples were collected during high tide, while during low tide three stations was visited to obtain the sediment samples. Supporting parameters include chlorophyll a, nutrient content, ORP, DO, and pH was measured in situ. The results showed that the microalgae communities both in waters and sediments of Surabaya mangrove areas was always consisted of Chaetoceros sp., Pleurosigma sp. and Skeletonema sp. in each sample. The abundance of microalgae in waters and sediments was ranged from 32 - 7,898 and 15,200 - 17,200 cells mL-1, respectively. Based on the Simpson's dominance index (D), waters and sediments samples were resulting a range from 0.15 - 0.19 and 0.17 - 0.23, respectively. Whereas the Shannon's diversity index (H′) ranged from 1.94 - 2.04 for water samples and 1.99 - 2.17 for sediment samples. The equitability index (E) of both waters and sediments was range from 0.13 - 0.63 and 0.42 - 0.86, respectively. These results show that Surabaya mangrove areas is classified as an oligotrophic area.