Assessment of coastal and marine ecosystems in West Africa: The case of Ghana.

Coastal and marine ecosystems, as integral component of social, ecological, and economic systems, are critical in providing essential ecosystem services that underpin human activities, including fishing and mining. Effective management of these ecosystems is paramount to safeguarding their vital contributions. This study adopts a socio-ecological framework, "Drivers (D) of human activities (A), associated Pressures (P), State change in coastal and marine environments, Impact (I) on human welfare (W) and Response (R) as measures (M) of management, (DAPSI(W)R(M))," to analyse the complexities of coastal and marine ecosystems in the Ghanaian context. The study identifies various drivers of anthropogenic activities, such as fishing, oil and gas production, and waste disposal. These anthropogenic activities create significant pressures, including selective extraction of living and non-living resources, as well as habitat degradation through substratum loss and pollution. Consequently, these pressures have led to changes in fish biomass and habitat quality, among other ecological shifts.

Adaptive management of environmental challenges in West African coastal lagoons.

Human activities in coastal lagoons over several decades have had a significant impact on their ecology and the valuable ecosystem services they provide. Although there are several management approaches to mitigate the problem, they are unable to link human needs and activities with changes in the state of the environment. This research provides this link via assessment of eleven lagoons in Ghana with a socio-ecological framework (Drivers (D), Activities (A), Pressure (P), State (S), Impact (I) on welfare (W), and Response (R) as a Measure (M); DAPSI(W)R(M)). Data were systematically obtained from relevant publications, previously conducted research, and national reports on the subject and were analyzed using this socio-ecological framework. Results show that basic biological and physiological needs such as food and shelter, social status and dominance, financial self-reliance, and self-actualization are the drivers of fishing, farming, settlements, salt mining, mangrove harvesting, industries, among others. These activities have contributed to pressures of selective extraction of fish and mangroves species, the introduction of heavy metals, organic materials, and smothering of substrates, consequently altering the environment by decreasing the oxygen rate and increasing the biochemical oxygen demand, organic matter, nutrients and pathogens, and reduction in lagoon areas and biodiversity. Thus, ultimately impacting human welfare, such as loss of revenue, employment, and seafood provision. Management options, including addressing the building and fuelwood material sources, afforestation and community ownership of lagoons, the prohibition of construction activities, and research-led management that can support decision-makers to improve the sustainability of these ecosystems, are highlighted. The findings have global implications for guiding local planners and state regulators in the applications of such integrated environmental management.

Age and growth of grey triggerfish Balistes capriscus from trans-Atlantic populations.

Anthropogenic factors that negatively impact reef fishes can include changes in life-history patterns of fisheries-targeted species. Understanding these impacts on growth and population age structure is essential in the management of exploited populations of fishes. This is the first study to directly compare age and growth for a major fisheries species between east and west populations of a transatlantic reef fish. The main goal of this study was to document age and growth in grey triggerfish Balistes capriscus from coastal waters of Ghana in the Gulf of Guinea (GOG) and compare those with the previous growth studies from that region and with the western Atlantic population. A secondary objective of this study was to evaluate the use of otoliths to age triggerfish and to provide a preliminary comparison with spine-derived age estimates. The results obtained from this study provided an updated understanding of the growth and age structure of the eastern B. capriscus population in GOG. The authors documented that shifts in population attributes occurred for B. capriscus after its major decline in abundance. The differences in physical and biotic characteristics of the East and West Atlantic regions and the differences in collection methods of samples make direct comparisons of growth parameters difficult. Nonetheless, overall differences in maximum sizes and ages were apparent; the western Atlantic population had a larger maximum size and older maximum age. The authors also documented that sagittal otoliths can be used to provide age estimates for triggerfish species, and otoliths as an ageing structure had better between-reader precision compared to dorsal spines.