Spatio-temporal variations in seaweed diversity and abundance of selected coastal areas in Ghana

Abstract

The coast of Ghana is considered the most seaweed-endowed region in West Africa, although information on the local spatial and temporal distributions and abundance of seaweed species is limited. In this study, seaweed species were sampled monthly from five coastal sites in the Central (Elmina, Komenda, Mumford) and Western (Shama and Takoradi Fisheries) Regions of Ghana during low tides from 2017 to 2019 to determine their diversity and abundance (biomass). Sampling was conducted using two (2) transect lines and quadrats (each of dimension 0.25 m2) at each site. Thirtyfive (35) taxa were identified at the five sites: 15 belonging to Rhodophyta, 11 to Chlorophyta and 9 to Phaeophyta. The Komenda site recorded the highest species diversity index of 2.06 whereas the Takoradi Fisheries had the lowest value of 0.68. Ulva fasciata, Padina durvillaei, Sargassum vulgare, Hydropuntia dentata and Hypnea musciformis were the most dominant species at the sites. A mean monthly biomass of 2.19 g dry wt m−2 was recorded for all five sites during the study period, with the greatest recorded at Takoradi Fisheries (3.53 dry wt m−2) and the least at Komenda (1.10 g dry wt m−2). The greatest biomass of the highly economic important species, H. musciformis, was recorded at Shama. The highest mean monthly biomass was recorded between August and October while the least was observed from December to February. Results from this study indicate considerable spatial and temporal variability in the diversity and abundance of seaweeds across the studied sites. These findings provide important baseline information for conservation and utilization of seaweeds, particularly their cultivation along the Ghanaian coastal waters as an alternate source of livelihood for the local communities.