Effects of climate change on marine ecosystems and potential management responses
Marine ecosystems are fundamental to supporting life on Earth and underpinning many human economies and societies. However, the goods and services ecosystems produce are increasingly affected by a multitude of human impacts, including climate change and its interactions with other human pressures. T...
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| Format: | Thesis |
| Language: | English |
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The University of Queensland, School of Biological Sciences
2011
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| Online Access: | https://espace.library.uq.edu.au/view/UQ:268772/BrownThesisChpt2_Supplement_Tables.xls https://espace.library.uq.edu.au/view/UQ:268772/S4160274_phd_finalthesis.pdf https://espace.library.uq.edu.au/view/UQ:268772/S4160274_phd_finalthesis_abstract.pdf https://espace.library.uq.edu.au/view/UQ:268772 |
| Summary: | Marine ecosystems are fundamental to supporting life on Earth and underpinning many human economies and societies. However, the goods and services ecosystems produce are increasingly affected by a multitude of human impacts, including climate change and its interactions with other human pressures. To plan future uses of marine ecosystems and achieve conservation goals, we need innovative management approaches that are informed by a solid understanding of the impacts of climate change already apparent, and predictions of how systems could respond in the future. For marine systems there is currently no global synthesis of the observed impacts of global warming and ocean acidification, models for predicting ecosystem change are in their infancy and we have few approaches for adapting management to climate change impacts. To address knowledge gaps, I use a combination of approaches: global meta-analysis of field data to synthesise the contemporary climate change response; a literature review to synthesise methods for understanding biological responses to climate change; an ecosystem model forced by predictions from global climate models to investigate future changes to food webs; a population model to investigate alternative strategies for fisheries management under a changing climate; and a general model to understand management of interactions between regional human impacts and global climate change. I conduct a synthesis using the largest database yet compiled for observations of marine biological responses to climate change. I show wide-spread yet variable contemporary responses of marine systems to climate change. The variability in distribution, phenology, demographic and abundance responses implies reorganisation of marine food webs, so that future food webs may function differently. I review statistical approaches used to relate biological observations and climate variables and demonstrate several common shortcomings, including failure to consider spatial and temporal autocorrelation and multiple drivers of change. Examples from the literature show that considering interactions between multiple drivers improves understanding of variability in biological responses to climate change. I then link climate and ecosystem models to predict how climate-driven primary production change may affect food webs and cause changes in abundances of higher trophic level species. Generally, abundances increase in response to primary production increases, but this response may reverse for particular species through biological interactions such as predation and competition. Consequently, marine ecosystem management requires strategies that are robust to considerable uncertainty regarding trophic interactions. Delays between scientific recommendations to reduce catches when fisheries decline and action in response to recommendations are a common inefficiency in management. I develop a model of a fishery where implementation of catch regulation changes are delayed and population growth varies temporally to simulate the effects of climate change. I show that fisheries impacted by climate-driven changes in primary production are at lower risk of collapse if delays are reduced. Thus, fishery management can respond to climate change impacts by acting rapidly to changes in population size, even if detailed information about climate impacts is unavailable. Management can also ameliorate the negative impacts of climate change on ecosystems by reducing other local stressors such as eutrophication, but interactions between multiple stressors may complicate determination of the management response. I develop a general model for the management of stressors that interact synergistically or antagonistically with climate change. Antagonistic interactions slow ecosystem decline, but may be difficult to manage since it can be unclear whether a local stressor should be increased or decreased to ameliorate climate change impacts. Synergistic interactions cause greater rates of ecosystem decline, but counter-intuitively may be easier to manage because the local stressor should always be reduced. Thus, quantifying interactions is important for prioritising management action on climate change across regions and ecosystems. Climate change ecology has the opportunity to assist sustainable management of marine ecosystems. Understanding variability in the biological responses to climate change requires further analysis of how climate impacts on one trophic level affect other trophic levels, and the interactive effects of local human threats, such as fishing, and global climate change. Development of adaptive management strategies requires incorporating economic and social costs into models of interactions between human stressors. Understanding these impacts will support development of management approaches that are robust to uncertainty and assist in sustainable management of marine ecosystems impacted by climate change. |
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