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.