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Abstract
Recent technological developments have increased our ability to collect observations in
marine ecosystems. With these developments comes the potential to more accurately
discern spatial and temporal patterns and ultimately, to better-understand the
effect of compounding anthropogenic stressors. In this thesis, I apply seascapescale
data collection and analytical approaches to untangle relationships between
environmental and human-mediated drivers in a range of marine habitats. I begin
by evaluating a semi-automated survey approach against simulated diver transects,
establishing that up-scaling observations on temperate reefs is likely to give more
reliable estimates than traditional surveys. I demonstrate that fine-scale spatial
modelling of temperate reef algae is easily implemented with relatively small data sets,
and provides insight into relationships acting at both large (kms) and small (10’s of m)
scales. To demonstrate the relevance to coastal management, I explore relationships
between key algal habitats on temperate reefs and human recreational use, using
a multi-species distribution model. Relationships between habitat-forming algae,
and recreation activities (fishing, boat anchoring, visitation) explained ~49% of the
variation explained by the model, and 3 of 5 algal groups (turfs, encrusting, kelp, other
canopy, and understorey) were associated with at least one human activity. Applying
similar techniques, I then investigate the influence of boat moorings on a seagrass
meadow dominated by a threatened, slow-growing species. Secondary effects - shading
and edge-attrition - were cumulative drivers of abundance, though two colonising
seagrasses were less-affected. The seascape approach allowed for the simulation of
management intervention (installing non-contact mooring designs) posited to reduce
disturbance. Finally, by applying seascape techniques to the disturbance caused by
boat moorings in sediment systems, I could identify relationships between bacterial
diversity and physical disturbance (acting at a scale of metres), fine sediments
(influenced by disturbance), and depth. The influence of moorings was cumulative,
with a negative relationship to OTU richness when moorings were densely arranged.
Such fine-scale sampling of microbial communities revealed their potential to respond
dramatically to small changes in environmental conditions. My research demonstrates
the promise of technological and analytical developments, and encourages the uptake
of seascape ecology.