Antecedent Geologic Controls on the Distribution of Oyster Reefs in Copano Bay, Texas

Copano Bay is a shallow (< 2-3 m), microtidal estuary in south central Texas. In an effort to both determine the distribution as well as investigate the controls on the distribution of oyster reefs, a geophysical survey of Copano Bay was conducted in June and July 2007. Surficial sediment analysis confirms that the recent sedimentation in Copano Bay is comprised of mostly estuarine mud with little sand or shell, large extents of oyster reefs and smaller areas of sand. Seismic stratigraphy analyses verify that the first oyster reefs in Copano Bay formed atop topographic highs in the Pleistocene surface. About 6 ka, sea level rise slowed to near its present rate and sediment supply decreased tremendously to Copano Bay decreasing the amount of suspended sediment. The first oyster reefs began forming around this time using these fluvial terraces as suitable substrate. Once the initial reefs were established, additional reefs began forming atop these initial reefs, or on the eroded shell hash material from the initial reefs. During this time of slow sea level rise and low sediment input to the bay, oyster reefs thrived and reef and shell hash material covered a majority of the bay surface. Once climate change increased sediment input to the bay, the reefs began to decrease in size due to siltation. The reefs have continued to decrease in size causing a 64 percent reduction in oyster reef and shell hash area from approximately 4.8 ka to today.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Oceanography

Grantor

Texas A&M University

Year dc:date.issued

2011

Author dc:creator

• Piper, Erin Alynn

Advisor dc:contributor.advisor

• Dellapenna, Timothy

Committee members dc:contributor.committeemember

• Bryant, William
• Sager, William
• Schulze, Anja

• Oyster Reef
• Estuary
• sedimentation
• geology
• geologic controls
• bottom type

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7930

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2FETD-TAMU-2010-05-7930