Acclimating across healthy and degraded reefs

As a result of human activities, many environments are becoming fragmented into areas with different community compositions and selective regimes. The coral reefs of Fiji for example, are divided into ‘fished areas’ (fragments subjected to fishing and trampling) and ‘protected areas’ (fragments with little human pressure) that occur in close proximity and now have differing community compositions and selective regimes. Theory predicts that the species able to survive in such conditions should have highly plastic genotypes allowing them to acclimatise to diverse habitats without the time lag required for local adaptation. Here we use two species -Epinephelus merra (a small grouper) and Sargassum polycystum C. Agardh (a brown macroalga)- which are found in both fished and protected reefs, to investigate this plastic response and understand how these species cope in healthy versus degraded environments. We found that the fish E. merra exhibits plasticity in diet and feeds lower in the food chain in fished reefs than similarly sized conspecifics in protected reefs. The seaweed S. polycystum exhibits plasticity in defensive traits and is able to induce increased defenses in response to being partially consumed. In addition, we found that dense stands of S. polycystum increased the survival and growth of both recruit-sized and mature-sized S. polycystum ramets, suggesting that Sargassum beds protect conspecifics from grazing by herbivorous fishes and construct conditions that facilitate their growth. Implications for management are discussed.

Level thesis:degree_level

Doctoral

Department dc:contributor.department

Biology

Grantor dc:publisher

Georgia Institute of Technology

Year dc:date.issued

2016

Author dc:creator

• Dell, Claire Louise Alice

Advisor dc:contributor.advisor

• Hay, Mark E.

Committee members dc:contributor.committeemember

• Streelman, Todd
• Jiang, Lin
• Stewart, Frank
• Burkepile, Deron

• Coral reef
• Marine protected area
• Phenotypic plasticity

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/1853/58580

OAI identifier oai:identifier

oai:repository.gatech.edu:1853/58580