Posted: Monday 14th July 2014 by Joan
Lizard © Paul Naylor
A guest blog by Peter Jones, Senior Lecturer, Department of Geography, University College London.
It is increasingly recognised that marine ecosystems that have a higher diversity of species are more resilient to impacts from non-native species, climate change, etc. But why is there a link between high diversity and resilience and how can marine protected areas (MPAs) be made more effective in building resilience?
The higher the diversity of species and the population sizes, the more resilient the ecosystem is
Species provide a variety of functional roles in ecosystems, such as nutrient recycling, population control, etc. The higher the diversity of functional groups and the higher the diversity of species and the population sizes within each functional group, the more resilient the ecosystem is, in that it can remain stable in the face of factors that could otherwise perturb it. This is because one species can replace the role of another in the same functional group if that species is depleted by disease, over-harvesting, etc. Also, if environmental conditions change, a species that previously appeared to be redundant, in that it has no apparent functional role, can be better adapted to the new conditions and thereby is able to adopt a functional role, replacing the role of a species which is less well adapted to the new conditions. In these ways the ecosystem is able to remain in a relatively stable state, including the capacity to adapt to changing conditions. This capacity for resilience is increasingly recognised as being important, as the pressures related to human activities which can perturb marine ecosystems, e.g. greenhouse gas emissions and species introductions, increase, potentially shifting ecosystems to alternative states that provide fewer ecosystem services, e.g. food production, greenhouse gas sinks, genetic resources and tourism value.
MPAs can promote the resilience of marine ecosystems by providing for the recovery of species diversity
There are a growing number of studies which demonstrate that effective MPAs can promote the resilience of marine ecosystems by providing for the recovery of species diversity, where this was previously depleted by the impacts of local activities such as fishing, tourism development, pollution, etc. A recent study explores the links between different approaches to conserving MPAs and their effectiveness in promoting resilience by providing for the recovery of species diversity. Drawing on 20 case studies from around the world, including three in the UK, this study considered MPA conservation approaches in terms of ‘governance incentives’, ranging from legal (laws, regulations, etc.), to economic (funding, property rights, etc.), participative (involving local people, etc.), knowledge (shared learning, etc.) and interpretative (awareness raising, educational programmes, etc.). The findings indicate that MPAs are more effective where a higher diversity of incentives is applied, these incentives interacting with each other in a manner which is analogous to the way that different species interact in ecosystems, making the governance system more resilient to local threats from overfishing, pollution, etc. This effectiveness, in turn provides for the recovery of species diversity, making the ecosystem more resilient to wider-scale impacts, such as climate change and introduced species.
The rationale behind this study is to move on from debates about which governance approach is ‘best’ or right’, in focusing on how different governance approaches can be combined. The findings of this study were recently published in the book Governing Marine Protected Areas: resilience through diversity (£40 with discount code DC361), and it is hoped this way of studying how MPAs can be more effectively conserved will provide for ‘good practice’ combinations of governance incentives to be transferred between MPAs. This innovative way of thinking about how we can make MPAs more effective is particularly relevant to the UK, as more MPAs are designated and the focus shifts to how they can be effectively conserved. This recognises that the key to social-ecological resilience is diversity, both of incentives in governance systems and species in ecosystems.
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