TO WHAT EXTENT DOES SELECTIVE DEFORESTATION ALTER MANGROVE TROPHODYNAMICS? A CASE STUDY FROM GHANA, WEST AFRICA.

Mangrove forests are highly important ecosystems whose functioning is threatened by numerous anthropogenic activities. In many coastal regions, mangrove wood is used as a source of timer and fuel, but the impact of environmental changes linked to this pervasive long-term selective deforestation on ecosystem functioning is poorly understood. Mangroves act as ecosystem engineers, with their complex root systems trapping allochthonous materials and building up carbon-rich sediments, as well as forming a nursery and foraging habitat for many species. Their degradation through selective deforestation could reduce the diversity of basal resources and energy flow pathways within estuarine food webs, thereby decreasing trophic diversity and resilience. To assess the extent to which mangrove degradation affects trophodynamics, we conducted ¹³C, ¹⁵N, and ³⁴S stable isotope analyses on samples from a range of basal food sources and consumers (fish and crustaceans) at estuarine sites along the coast of Ghana. Our results indicate that the selective deforestation of mangroves may degrade trophic ecosystem functioning, as evidenced by a greater prevalence of generalist feeding strategies, a rise in the extent of dietary niche overlap between groups, and lower trophic diversity at sites with increasingly less mangrove cover. We will discuss these results in light of the interactions between trophic structure and ecosystem functioning and stability.

Primary Presenter: Andrew Sweetman, Scottish Association for Marine Science (Andrew.Sweetman@sams.ac.uk)

Authors:

Rachael Hall, Heriot-Watt University  (Rachael.hall@sams.ac.uk)

James Bell, CEFAS  (James.bell@cefas.gov.uk)

Marija Sciberras, Heriot-Watt University  (m.sciberras@hw.ac.uk)

Bernard Assiam, University of Cape Coast  (bernard.assiam@stu.ucc.edu.gh)

Furkan Abubakar, University of Cape Coast  (abubakarfurkan@gmail.com)

Albert Koomson, University of Cape Coast  (albert.koomson@ucc.edu.gh)

Geslaine Gonçalves, Scottish Association for Marine Science  (geslaine.lemosgoncalves@sams.ac.uk)

Bhavani Narayanaswamy, Scottish Association for Marine Science  (Bhavani.Narayanaswamy@sams.ac.uk)

Emmanuel Acheampong, University of Cape Coast  (emmanuel.acheampong@ucc.edu.gh)

Benjamin Nyarko, University of Cape Coast  (bnyarko@ucc.edu.gh)

Joseph Aggrey-Fynn, University of Cape Coast  (jaggrey-fynn@ucc.edu.gh)

Andrew Sweetman, Scottish Association for Marine Science  (Andrew.sweetman@sams.ac.uk)