Abundance and diversity of macro-invertebrates in the selected mangrove species along the coast of Mbegani in Bagamoyo District, Tanzania

Abstract

Abstract Background Mangrove forests are highly productive ecosystems that serve as biodiversity points, containing many organisations, contributing to carbon storage, improving water quality and providing ecosystem goods and services to improve local means of subsistence. These resilient ecosystems are characterised by their morphological modification and their particular respiratory structures (pneumatophores), which allow them to proliferate in salt-rich environments. Mangroves play a crucial role in maintaining invertebrate and fishery resources, providing shelter and nutrients to a diverse range of species. However, mangrove ecosystems are threatened by anthropogenic activities such as the extraction of building materials, firewood, crushing plants and salt manufacturing, resulting in the disintegration of ecosystems and the loss of inhabitants. This study aimed to determine the abundance and diversity of macro-benthic invertebrates on the different parts (roots, stems and leaves) of common mangrove species of the Mbegani coast, along the Indian Ocean using a completely randomised design. Results The sampling was done using a 1 m2 quadrat focussed on the three mangrove parts, viz. roots, stems and leaves. The results showed that the highest percentage of macro-invertebrates were recorded on Bruguera gymnorhiza (66.8%), followed by Avicennia marina (20.8%) and the least were Ceriops tagal (12.4%), such variation differed significantly between the three mangrove species across the selected plots (F(2,524) = 5.71, p = 0.035). The stems (54.4%) inhabited a large number of macro-invertebrates, followed by roots (32.8%) and the least were leaves (12.8%), which varied significantly between the three mangrove parts sampled across the selected mangrove species (F(2,524) = 7.25; p = 0.008). The majority of macro-invertebrates were planktonic feeders stuck on stems or herbivores shuttling between the roots and leaves of the plants. Macro-invertebrates recorded on Bruguiera gymnorhiza were more diverse than those found in C. tagal. The findings emphasise the importance of macro-invertebrates in the ecological balance of mangrove ecosystems. Conclusion The study concludes that mangroves in the Mbegani ecosystem have a high potential for biodiversity and are important for the coastal community and the ecosystem of the Bagamoyo District. The results contribute to coastal resources management programmes and future surveillance activities.