All ETDs from UAB

Advisory Committee Chair

Charles D Amsler

Advisory Committee Members

Bill J Baker

Juan Lopez-Bautista

Robert U Fischer

James B McClintock

Donald Potts

Document Type

Dissertation

Date of Award

2014

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

The physiology of many species of Antarctic marine algae was evaluated under a variety of biotic and abiotic factors found or predicted for the western Antarctic Peninsula. The potential biological stressors, filamentous algal endophytes, had few effects on their macrophyte host's physiology which may be the cause for their persistence in this marine community. Adversely impacted hosts include Pachymenia sp. and Iridaea cordata. In areas of high endophyte infection Pachymenia sp. was significantly less resistant to forces that could penetrate their thalli. Maximum quantum yield near endophyte infection was significantly lower in I. cordata. Endophyte abundance is significantly lower in female gametophytes with carposporophytes than in unfertilized gametophytes and tetrasporophytes of I. cordata. The effects of potential abiotic stressors, near-future climate change conditions (including oceanic pH 7.8-7.6 and a temperature increase of 2 °C) were evaluated in the canopy-forming brown macroalgae Desmarestia anceps and D. menziesii, and the crustose calcified and fleshy red macroalgae Clathromorphum obtectulum and Hildenbrandia sp. The physiological responses of these macroalgae were measured through growth, photosynthetic parameters, chlorophyll a, calcium carbonate, and phlorotannin content. Species responded uniquely to each factor, notably Hildenbrandia sp. increased growth in high temperature * low pH treatments and D. menziesii increased phlorotannin content in low pH treatments and increased saturating irradiance in high temperature * low pH treatments. The effects of crustose coralline algae on the settlement preferences of invertebrate larvae were examined. An interaction between coralline algae and invertebrate larvae would be particularly important for community dynamics if climate change impacted the physiology or dominance of these Antarctic coralline species, but no significant settling preference was observed for any coralline algal extract. In light of the competitive advantage Hildenbrandia sp. may have in near future crustose algal communities, this may be a positive finding. This dissertation shows that Antarctic algae are for the most part resilient to the biological and abiotic stressors assessed in these studies, and though macroalgae do not impact invertebrate settlement in the benthic environment, I provide a record for settlement patterns in this geographic region.

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