Seagrass Importance in Food Provisioning Services: Fish Stomach Content as a Link between Seagrass Meadows and Local Fisheries

Abstract

The links between ecosystem processes and functions and ecosystem services (i.e. the human
benefits from those) are elusive. In this paper, the food provisioning service of seagrass meadows is
operationalized through the study of the stomach contents of 13 important commercial fish species in
Chwaka Bay, Zanzibar. Using local fishers’ knowledge on bait, scientific knowledge about the structure
of the meadows (associated flora and fauna), stomach content analysis and multivariate statistics, the food
provisioning service associated with seagrasses and its importance for fish (as important diet component)
and for humans (in small-scale artisanal fisheries) are described. The study presents the food items for 13
commercial fish species identified at the lowest possible taxonomical level and compares with previous
literature findings. In addition, differences in stomach contents of Siganus sutor and Leptoscarus vaigiensis
caught with both drag-nets and dema basket traps are investigated in order to explore bait presence and
indirectly evaluate fishers’ knowledge on bait preference. The results show that most of the items consumed
by commercial fishes are associated with seagrass beds and that there are clear indicators that the bait
traditionally used seems to be effective. The paper elaborates on the consideration of seagrass ecosystems
in a holistic perspective, the difficulties in valuation of ecosystem services and finally the crucial importance
of these aspects for human well-being and sustainability in coastal communities of the Western Indian
Ocean.