Kelimpahan, Komposisi Ukuran dan Pola Pertumbuhan Kepiting Bakau (Scylla serrata) di Estuari Karang Gading Kabupaten Deli Serdang Sumatera Utara

Abstract

Mangrove crabs play a role in increasing oxygen distribution in estuarine areas. The Karang Gading estuary area is located in the Karang Gading mangrove ecosystem. Several parts of the area in the Karang Gading mangrove ecosystem have experienced land conversion into other uses such as settlements, plantations and aquaculture, causing a decrease in habitat quality for mangrove crab resources. The study aims to analyze the abundance, composition, size and growth pattern of mangrove crabs and analyze the relationship between aquatic physico-chemical factors and the abundance of mangrove crabs in the waters of the Karang Gading Estuary, North Sumatra. The research method used is purposive sampling. Measurement of physico-chemical factors of the water includes temperature, pH, water salinity, light penetration, dissolved oxygen, biochemical oxygen demand and C-organic content of substrates. An analysis was carried out on the abundance, composition, size, growth pattern and correlation of mangrove crab abundance with aquatic physico-chemical factors. The results of the study found that the abundance of mangrove crabs ranged from 42.65 ind/m²-56.87 ind/m² with 7 size classes. The largest number of individuals was found in sizes 71–82 mm as many as 18 individuals, and the smallest in sizes 47–58 as many as 5 individuals. The growth pattern at each station is negative allometric which illustrates that the increase in carapace width is more dominant than the increase in body weight. The results of the correlation analysis found that pH, salinity, C-organic content, DO and BOD5 had a strong and positive influence on the abundance of mangrove crabs, while temperature had a negative effect.