Date of Award

Spring 3-10-2016

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Biology

Advisor

Rhian G. Waller

Second Committee Member

Kevin Eckelbarger

Third Committee Member

Robert Steneck

Abstract

The purpose of this study was to determine the basic reproductive biology and seasonality of the Patagonian fjord coral Desmophyllum dianthus. Desmophyllum dianthus is a deep-sea solitary scleractinian found throughout the world’s oceans and an important benthic habitat builder. The Chilean Patagonian fjords are the only known location where this species occurs >50 m and thus are the only place to collect samples efficiently, effectively and economically. Corals were collected via SCUBA approximately every three months (when conditions permitted) from August 2012 to September 2013 from three sites within the Northern Patagonian fjords – Lilihuape (n=76) and Punta Huinay (n=59) in the Comau fjord, and Punta Mamurro (n=44) in Reñihue fjord. The objectives of this study were to determine sexuality, reproductive mode, oocyte size, fecundity and seasonality using histological techniques. Environmental data (temperature, salinity and light) was also analyzed to compare to seasonal reproductive trends and bring reproductive data into context. This study determined that

Desmophyllum dianthus is dioecious (gonochoristic), having both male and female individuals. This species is also highly seasonal, spawning in the austral winter (August) and beginning gamete production in early spring. The fjord was coolest and most saline in August 2012, potentially cueing spawning. No planula larvae were found in any of the 8,000 histological sections. Due to the presence of late stage oocytes in August 2012, it is likely D. dianthus’s mode of reproduction is spawning rather than brooding. However this distinction could not be determined in this study. Oogenesis starts in September producing previtellogenic oocytes (size range: 25 – 200 μm) that slowly developed into vitellogenic oocytes by June. Vitellogenic oocytes ranged from 200 – 380 μm. Fecundity is relatively high compared to other deep-sea scleractinians, ranging from 2,448 (± 5.13 SE) to 172,328 (±103.67 SE) average potential oocytes per polyp. This research provides the first insight into Desmophyllum dianthus reproductive biology and yields an important baseline for continuing work on this benthic habitat builder in the Chilean fjords, and in the deep ocean.

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