Mangroves in Ghana – why we need to protect them
This blog post unpacks the findings from two latest reports on the impacts of mangrove deforestation in Ghana. Mangroves are a kind of marine vegetation that exists in coastal areas. These incredible plants are well adapted to the ocean environment and provide many different functions such as acting as nursery habitats for young (juvenile) fish species that, when they are older, swim out into the open ocean and form part of larger fisheries that fishers rely on for their livelihoods. Mangroves also trap sediment which in turn traps carbon (carbon sequestration) as well as reduce coastal erosion and protect coastal communities from violent storms.
There are many human (anthropogenic) threats to mangroves however. In Ghana the main threats are coastal development and logging or deforestation of mangroves for agricultural, development or livelihood purposes. Coastal communities in Ghana have sustainability managed their mangroves for many generations but with population growth, rapid coastal development and the increased use of timber for fuel, this harvesting is reaching unsustainable levels, leading to degraded mangrove forests. The ‘red mangrove,’ is particularly popular in Ghana and other parts of West Africa, as it is high in tannins and gives off a particular flavour when used to smoke fish.
Key findings
Key findings from two reports (“One Ocean Hub – Ghana Impact of mangrove selective deforestation on estuarine benthic biodiversity and ecosystem functioning in Ghana” and “Impact of mangrove selective logging upon estuarine trophodynamics in Ghana”) from PhD researcher Rachael Hall and researchers Emmanuel Acheampong, Joseph Aggrey-Fynn, and Kofi Nyarko from Ghana have shown that the selective deforestation of mangroves:
- degrade the way in which these habitats function
- reduces the efficiency with which energy is passed up the food web and;
- reduces energy being made available to larger predators, which tend to be the species of interest to fishing communities.
They also found the food web within healthier mangroves to be more complex, with a more diverse number of ways in which energy could be passed from plants up to larger predators. The lower diversity of energy pathways within the food web in the selectively deforested mangroves would make it less resilient to change, so the loss of certain species could have a big impact on the food sources available to the fish which local communities rely on for their livelihoods.
In fact, the degradation caused by selective deforestation appears to be enough to alter the way in which fish and crustaceans feed, with fewer species with specialised diets at the selectively deforested site. Instead, most of the organisms there appeared to have a more generalist diet, eating whatever was available, making them more likely to be in competition with one and other, and consequently have less stable populations.
These findings matter because if we want to improve fisheries in Ghana we need to do this in a holistic way, including promoting the health of these mangrove ecosystems. Unsustainable selective deforestation appears to be having a negative impact on the ability of mangroves to support fish populations, potentially meaning that there will be fewer fish available to fisheries, upon which local communities rely.
Methods
The findings of these reports are a result of interdisciplinary and transdisciplinary research between researchers in Ghana and the UK as well as local coastal community members in Ghana. Local communities shared their knowledge about how they harvest the wood and Rachael argues that it is important to improve our understanding of their practices so “we support these communities to harvest in a sustainable way so they can still have the resources they need to give them their livelihoods”. On sharing and learning from each other, she argues, “This is how we tackle these global challenges, through understanding the complexity from all these different angles”.
Fair research partnerships
Talking to the subject of fair Global North-South research partnerships Rachael notes that historically decisions and knowledge were made and generated by the Global North and now the decisions need to be made by the Global South for the Global South, with a fair exchange of knowledge and opportunities by both parties. This needs to include local people and their knowledge. “All the work I have done was not possible without the help of the people in Ghana- particularly the research assistants and lab technicians – it’s a collaborative effort”.
Related SDGs:
