Author: Benjamin Michael Fitzpatrick

Publisher:

Published: 2012

Total Pages: 171

ISBN-13:

[Truncated abstract] The goal of this work was to investigate the finescale habitat associations and determine the effect of human impacts on coral reef fish assemblages. Initially I investigate how finescale spatial habitat variation influences the distribution and abundance of coral reef fishes. Significant variation in the reef fish assemblage was driven by variation in habitat. Consequently finescale habitat variation needs be accounted for in spatial or temporal surveys of coral fish assemblages. My second question investigated how protection from fishing influences the overall variation in coral reef fish assemblages, while my third question investigated how consistent the differences in protected fish assemblages are through time. Protection from fishing accounted for significantly more variation in fish assemblages than that explained by finescale habitat alone. This was driven by an average abundance and length of target species being higher inside sanctuaries and a response in non-target species indicating that there are some trophic interactions occurring between fishes. I found that both target and non-target species can be more abundant at protected reefscapes through time, consistent with the theory that protected areas can achieve recovery and lasting maintenance of fish assemblage structure relative to adjacent fished locations. I also investigated how fish assemblages within shallow coral reef habitats differ to those of adjacent continental shelf habitats to a depth of 100m. Cross-shelf sampling produced significant new knowledge on the depth and habitat specificity of many species previously only known from shallow coral reef environments. Many target species protected by shallow water protected areas are found as adults in unpotected shelf waters suggesting shallow water protected areas alone may not be effective for all species equally. Expanded depth distributions for many species revealed some refuge at depth from shallow water climate related impacts, though it is uncertain how this might contribute to persistence in populations at a local or regional scale. Many species are confined to one or a few shallow water habitats for their entire post recruitment lifehistory as opposed to others that can range across many. Fish assemblages associated with deeper water habitats are composed of higher order predators and high numbers of unique species, suggesting they will respond very differently to shallow waters when impacted by fisheries. Diversity and unique species associated with deep water habitats approached those found at shallow coral reef habitats. Habitat specialization changes dramatically from species to species and was not easily predicted. This research holds a number of key implications. Firstly the design of coral reef marine protected areas and associated monitoring programs should account for variation in benthic habitat. Fishing and other human impacts affect significantly different elements of coral reef fish assemblages depending upon the biological and physical parameters of the benthic habitat found. Marine protected areas should incorporate this habitat variability wherever practical, as discrete elements of trophic structure were significantly associated with different habitats...