Impact of environmental change on primary production in model marine coastal ecosystems
Abstract
Coastal ecosystems, including estuaries, provide a range of services to humans,
mediated by the species within these ecosystems. Microphytobenthos (MPB) play a
vital role in many key processes within estuarine ecosystems, and provide a food
source for higher trophic levels. Anthropogenic activity is already causing changes to
ecosystems, through pollution, overexploitation and, more recently, climate change.
Increasing temperature and carbon dioxide levels, and altered biodiversity, are likely
to affect species, and their interactions, within these ecosystems. Much ecological
research has focused on the effects of a single stressor on specific species or
ecosystems, with relatively little work examining the effects of multiple stressors.
The research in this thesis investigates the effects of altered environmental variables
(light, tidal regime, temperature and carbon dioxide) and different macrofaunal
diversity on primary production (MPB biomass) through a series of manipulative lab-based mesocosm experiments. This work also examines the temporal variability of
environmental stressors on species across two trophic levels. Results demonstrate how
multiple environmental stressors interact in a complex and non-additive way to
determine an ecosystem response (MPB biomass, nutrient concentration), and the
effects of altered biodiversity were underpinned by strong species effects. Temporal
variation of stressors had a strong effect on ecosystem response. In marine coastal
ecosystems, environmental changes through ocean acidification will have economic
and social repercussions, directly impacting the human services and livelihoods that
these systems provide. As such, future research should be focused on identifying and
mitigating the inevitable multiple effects that future global change may have on
coastal ecosystems.
Type
Thesis, PhD Doctor of Philosophy
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