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- de la Torre-Castro, Maricela, 1965-
(författare)
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Humans and Seagrasses in East Africa : A social-ecological systems approach
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present study is one of the first attempts to analyze the societal importance of seagrasses (marine flowering plants) from a Natural Resource Management perspective, using a social-ecological systems (SES) approach. The interdisciplinary study takes place in East Africa (Western Indian Ocean, WIO) and includes in-depth studies in Chwaka Bay, Zanzibar, Tanzania. Natural and social sciences methods were used. The results are presented in six articles, showing that seagrass ecosystems are rich in seagrass species (13) and form an important part of the SES within the tropical seascape of the WIO. Seagrasses provide livelihoods opportunities and basic animal protein, in from of seagrass associated fish e.g. Siganidae and Scaridae. Research, management and education initiatives are, however, nearly non-existent. In Chwaka Bay, the goods and ecosystem services associated with the meadows and also appreciated by locals were fishing and collection grounds as well as substrate for seaweed cultivation. Seagrasses are used as medicines and fertilizers and associated with different beliefs and values. Dema (basket trap) fishery showed clear links to seagrass beds and provided the highest gross income per capita of all economic activities. All showing that the meadows provide social-ecological resilience. Drag-net fishery seems to damage the meadows. Two ecological studies show that artisanal seaweed farming of red algae, mainly done by women and pictured as sustainable in the WIO, has a thinning effect on seagrass beds, reduces associated macrofauna, affects sediments, changes fish catch composition and reduces diversity. Furthermore, it has a negative effect on i.a. women’s health. The two last papers are institutional analyses of the human-seagrass relationship. A broad approach was used to analyze regulative, normative and cultural-cognitive institutions. Cooperation and conflict take place between different institutions, interacting with their slow or fast moving characteristics, and are thus fundamental in directing the system into sustainable/unsustainable paths. Ecological knowledge was heterogeneous and situated. Due to the abundance of resources and high internal control, the SES seems to be entangled in a rigidity trap with the risk of falling into a poverty trap. Regulations were found insufficient to understand SES dynamics. “Well” designed organizational structures for management were found insufficient for “good” institutional performance. The dynamics between individuals embedded in different social and cultural structures showed to be crucial. Bwana Dikos, monitoring officials, placed in villages or landing sites in Zanzibar experienced four dilemmas – kinship, loyalty, poverty and control – which decrease efficiency and affect resilience. Mismatches between institutions themselves, and between institutions and cognitive capacities were identified. Some important practical implications are the need to include seagrass meadows in management and educational plans, addressing a seascape perspective, livelihood diversification, subsistence value, impacts, social-ecological resilience, and a broad institutional approach.
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| 2. |
- Thyresson, Matilda, 1981-
(författare)
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Fish for Food and Ecosystem Function : Fisheries, Trade and Key Ecosystem Processes in Coral Reefs
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fish is a key source of food and income to millions of people living along tropical coastlines. They also play essential roles underpinning key ecosystem processes in coral reefs. For example, herbivorous fish keep algae in check that otherwise may outcompete corals, reducing the reef’s social-ecological values. New fishing methods and globalization have turned fish into global commodities, threatening the ecological resilience of many reefs. This thesis addresses the delicate balance between social and ecological aspects associated with fisheries and trade with reef fish in Zanzibar, Tanzania. Paper I examines how parrotfish contribute to keeping reefs free from algae and shows a non-linear relationship between fish body size and function, hence illustrating that maintaining large fish individuals on coral reefs is particularly important. Gear-based management (GBM) has been suggested as an alternative to no-take marine protected areas (MPAs) to sustain ecosystem processes without threatening fishers’ livelihood. Paper II investigates fishers’ use of different gears and how these gears select different functional groups of fish. Results indicate that gear restrictions could be used to reduce fishing pressure on particularly important groups of fish, but also that such an approach is far from simple. MPAs and GBM are both restrictions targeting fishers, but with increasing global demand for reef fish, it is neither realistic nor fair to place the sole burden of sustainable fisheries on them. Papers III & IV analyze the value chain of fish, from fishers to traders and consumers. Results show that the Zanzibar fishery targets a wide range of fish species and sizes, intended for different markets. The thesis concludes that a sound understanding of the functional properties of fish and more nuanced approaches to regulate fishing may contribute to the management of reef fisheries, but that sustainable solutions will require that measures are taken far beyond the oceans.
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