Assessment of three mangrove forest systems for future management through benthic community structure receiving anthropogenic influences

Abstract

The abundance and variation in population and species composition of benthic organisms reflects environmental conditions, which can be used in long term monitoring and management of mangrove forests. This study assessed the three mangrove forest systems Sandspit back waters (SBS), Korangi-Phitti creek (KPM) and Sonmiani Bay (NB) based on the associated benthic community with respect to environmental variations. The samples for macrobenthos and sediment and pore water analyses were collected from 96 cores at three stations in each forest stand. The average values for nutrients in pore water were apparently higher at NB and lower at SBS. A total of 48 macrobenthos species were recorded from the three stands. Species diversity and density was higher at SBS and lower at NB. Crustaceans, polychaetes and molluscs were the most abundant and diverse groups. In this study, the benthic fauna was distinct between the three mangrove systems and the species composition and abundance reflects the responses to variations in environmental parameters. The distribution of polychaete families such as Capitellidae, Spionidae and Cirratullidae reflects that KPM is the most polluted with respect to organic pollution and NB is the least polluted mangrove area. SBS, located near Layari River, appears to be more eutrophic due to higher nutrient loadings. Dry sediments, nutrient loadings, and concentration of Cu and Mn appeared to regulate the forest community structure and negatively correlate with the diversity and density of macrobenthos. The information and suggestions given in this study can be used in the effective management of mangroves forests areas in future.