PhD Dissertation Defense: Avery Paxton

The PhD Defense of Avery Paxton will be presented by UNC-CH’s Biology Department and UNC’s Institute of Marine Sciences (IMS). The main location of this event will be in room 222 at IMS in Morehead City, NC. The defense will also be streamed live to conference room 3204 on the 3rd floor of Murray Hall on UNC-CH campus in Chapel Hill, NC. This event will be held on Thursday, February 8th at 9:00 AM.

Title:  Species-Habitat Relationships and Community Structure of Reef Fishes Associated with Temperate Hardbottom Reefs of North Carolina, USA

Abstract: Growing numbers of human-made, artificial structures are installed in coastal oceans for purposes ranging from harnessing energy resources to creating and restoring habitats. Because introduction of these artificial structures in coastal waters can drive ecological changes, it is important to understand how species use artificial structures. I investigated five research questions to discern how fish use artificial structures (e.g., shipwrecks and artificial reefs), as well as natural reefs, of North Carolina, USA. First, I tested how artificial structures and natural reefs that vary in topographic complexity function to support reef fishes and discovered that flat reefs, which are often difficult to detect, provide similar support for reef fishes as more easily detectable complex, high-relief reefs. Second, I examined how reefs support fishes with different thermal affinities and determined that because tropical and subtropical fishes occurred in higher abundances on artificial structures than rocky reefs that deploying additional human-made reefs may help warm-water fishes move poleward from the tropics. Third, I examined spatial relationships between planktivorous fishes, zooplankton (prey), and piscivorous fishes (predators) around artificial structures. I found that aggregations of planktivorous fishes around artificial structures related to spatial patterns across adjacent trophic levels, suggesting that effects of artificial structures propagate across multiple trophic levels. Fourth, I documented how reef fishes reacted to underwater noises typically emitted when searching for oil and gas beneath the seafloor, finding that fish abundance decreased 78% during evening hours when exposed to these loud noises, raising conservation concerns. Fifth, I assessed how quickly newly established artificial reefs create fish habitat and discovered that newly deployed human-made reefs can provide fish habitat comparable to 20-year old artificial reefs within five months. These results demonstrate that artificial structures clearly serve as fish habitat, and as artificial structures continued to be deployed, conservation and management efforts must recognize that species-habitat relationships differ between artificial structures and natural reefs and that installing artificial structures can have both ecological benefits and impacts.

Photo: J. McCord / UNC-CSI