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Sea urchin-kelp forest communities in marine reserves and areas of exploitation : community interactions, populations, and metapopulation analysesMoctezuma, Gabriela Monta��o 20 December 2001 (has links)
Marine ecosystems can be exposed to natural and anthropogenic disturbances
that can lead to ecological failures. Marine reserves have been lately suggested to
protect marine populations and communities that have been affected by habitat
destruction and harvest. This research evaluates the potential role of two marine
reserves established in Oregon in 1967 (Whale Cove) and 1993 (Gregory Point). The
red sea urchin (Strongylocentrotus franciscanus) was selected as indicator of
population recovery since it is the only species that is commercially harvested.
Changes in density, biomass, average size, size structure, growth and mortality rates
were evaluated through time to assess population recovery. These parameters were
also compared between reserves and adjacent exploited areas to evaluate the effect of
exploitation. Results from Whale Cove (old reserve) indicate that the population in
this area is fully recovered. On the contrary, the population in Gregory Point (new
reserve) showed signs of recovery after six years of being protected. The importance
of red urchins as source populations to provide larvae to adjacent areas was explored
by the analysis of drifter's trajectories. Both reserves might be connected in a network
where larvae produced in Whale Cove will provide recruits to Gregory Point and
adjacent exploited areas, as well as populations in northern California. Gregory Point
releases larvae that become recruits for Whale Cove only when spawning takes place
in winter, otherwise larvae travel to central California. No clear trends were found in
growth and mortality rates between reserves and non-reserves; differences were more
related with food availability, competitors, and age specific mortality.
We applied qualitative simulations to characterize and differentiate the
community network inside reserves and exploited areas. Results suggest that
communities from a particular site can be represented by a set of alternative models
with consistent species interactions. Differences in predator-prey interactions as well
as non-predatory relationships (interference competition, mutualism, amensalism)
were found among sites. Each set of models represents a hypothesis of community
organization that agreed with natural history information. Alternative models suggest
that kelp forest communities are dynamic and can shift from one network
configuration to another providing a buffer against a variable environment. / Graduation date: 2002
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A community-based approach for evaluating tradeoffs across marine ecosystem services in OregonFreeman, Peter M. 28 September 2012 (has links)
As competing uses of our coastlines increase, natural resource agencies are employing marine spatial planning (MSP) to designate areas for different uses or activities in order to reduce conflicts while achieving ecological, economic and social objectives. A central challenge of implementing MSP is development of a rigorous approach for analyzing tradeoffs across the provision of ecosystem services (i.e., the benefits humans receive from nature). This study develops an operational approach to this problem that is founded on community-based methods, ecological production theory, and multi-criteria decision analysis (MCDA). The approach merges ecological models with surveys to identify marine ecosystem services for use in tradeoff analysis. The approach allows for a single set of marine ecosystem services to at once be valued by local stakeholders and measured by biologists, thus connecting social and biological monitoring efforts.
To develop the approach in a real-world context, I examined ecosystem services associated with nearshore marine ecosystems in Oregon, where marine reserves are being introduced for biodiversity conservation. I worked with stakeholder focus groups in three Oregon communities to identify 24 marine ecosystem services. I then linked the ecosystem services with ecological indicators, which I then consolidated to derive 11 items for use in a survey-based tradeoff analysis exercise. I administered the survey to a nonrandom sample of stakeholders in Oregon (n=31), from which their relative preferences and preference weights for ecosystem services were derived. The weights and preference measures may then be used in MSP decision-making.
Furthermore, I grouped the stakeholder survey data in three ways: by location of residence (coastal vs. non-coastal), by eight categories of affiliation (e.g., business owners, conservationists, commercial and recreational fishers, etc.), and by resource use patterns. I then analyzed the various groupings of stakeholders for within- and between-group homogeneity of preferences. Results of the analyses showed that there are statistically significant variations in preferences within and between most groupings. Capturing the variations in stakeholder preferences is important when developing policies that affect different stakeholder groups. Thus, when implementing the survey instrument, I suggest random sampling of stakeholders stratified by location, affiliation, and resource use.
This study provides one of the first examples of a systems-based approach to ecosystem service valuation operationalized to inform MSP, and novel features of the approach have a number of implications for advancing marine research and management. First, by using stakeholders to identify ecosystem services, the approach allows for a tailored implementation of ecosystem-based management at the community level. Second, by integrating ecological and economic information on the provision and value of ecosystem services, the approach provides relevant data for MSP decision-making during the siting, evaluation, and monitoring stages. And third, by applying both stated-preference and MCDA methods, the approach may capture the array of values represented by diverse stakeholder groups. / Graduation date: 2013
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