Establishment of Three-Dimensional Oyster Reefs in the St. Mary's River
St. Mary's River Watershed Association
January 25, 2011
Background
The American oyster (Crassotrea virginica) is an exceedingly important component of the Chesapeake Bay ecosystem, and this resource has been exploited with few limits for two millennia. Their critical role in estuaries is biological filtration because they remove phytoplankton and particulate matter from the water, and as a consequence they strongly influence nutrient concentrations. It has been estimated that at pre-1870 levels, oysters could filter the entire Chesapeake Bay's water volume in leass than three days.
Oyster reef structure, long since eradicated on the east coast, was a huge pile of connected shell extending from deep water to the surface, and these reefs were often exposed at low tide. Known as "rocks" because of their exposure, they were so extensive that they were hazards to navigation. Like early Native American (10,000 years ago) agriculture and fishing pressure, colonial harvesting of oyster reefs had a relatively minor impact because of low human population density. But all this changed with the influx of Europeans. The tremendous Chesapeake Bay oyster harvests began during the Civil War and peaked in the 1880's when 20 million bushels were taken in Maryland alone. Most scientists agree that the declines in oyster harvests between 1880 and 1905 were due to over-fishing and the destruction of the reefs themselves. Oyster harvests in the Chesapeake have dwindled to less than 100,000 bushels in recent years. The ancient oyster reefs were not only dredged for the food, but for their shells as well. Even roads were paved with crushed oyster shells, and shell from reefs was burned, ground, and added to agricultural fields. Most of the reefs in the Chesapeake were destroyed, and those that remained were flattened by persistent dredging. These human assaults were followed by the introduction of disease against which the oysters had no defense, and the result is that current oyster harvests are less than 1% of historic levels.
Oystermen contend that oyster beds need to be continuously "scraped" with dredges to remain free of sediment that suffocates and kills oysters, but many scientists disagree. Therefore, this has never been substantiated. The susceptibility of flatten reefs to sedimentation may be a consequence, in part, to the loss of three-dimensional structure. It is likely that mounds of dead shell underlying a veneer of living shell promotes water circulation and improves the ecological filtering capacity of oysters. Projects to test these ideas will be forthcoming, but the science and art of restoring reefs is still in its infancy and there is much to learn.
Project Objectives
We propose a pilot project for 2013-2014 to be followed by a more elaborate effort on oyster reef restoration in southern Maryland's St. Mary's River. Aquatic biologists Robert W. Paul, Phd, and Christopher E. Tanner, PhD have designed the project after an extensive research campaign (including seven students, talking to those currently doing oyster restoration projects, and gathering baseline water quality data. Permits have been secured and we will establish six different type of small three-dimensional reefs - all in the upper portion of the St. Mary's River, which has been designated by the State of Maryland as an oyster sanctuary. We will also establish a community outreach program that will: 1) utilize expertise and interest in the local community, 2) engage community members in planning and participating in the project, and 3) provide an outlet for information dissemination. A formal partnership has been created with the St. Mary's River Watershed Association, St. Mary's College, and the Leonardtown Rotary club. Rotarians, St. Mary's College of Maryland (SMCM) students, watershed association members, and citizens will have the opportunity to be involved from the beginning of the project.
Benefits
The primary benefit of this project will be ecological-the expansion of oyster habitat and the improvement of water quality in the St. Mary's River by establishing reefs where oysters will filter and remove sediments and nutrients (nitrogen and phosphorus, in particular) from the water. These are removed directly or indirectly by oysters filtering phytoplankton (floating algae). This filtration also clarifies the water and allows more sunlight to pass through shallow water to the bottom. Here, very beneficial submerged aquatic vegetation (SAV) are rooted and can thrive under improved light conditions. SAV restoration has long been a goal of EPA's Chesapeake Bay Program, but success stories are few and far between in part because of poor light penetration to the bottom. Because SAV provide refuge for juvenile fish, crabs and other animals, ecosystem restoration will be possible if water clarity improves. Our pilot project will not be large enough to document changes in ecosystem health, and the reef(s) will probably not be sufficiently large to demonstrate changes in nutrient/sediment concentrations, but the pilot project will reveal and document the potential for further oyster restoration.
Three additional benefits apart from extensive ecological gains would be: 1) educational and scientific research opportunities, 2) a model for other Chesapeake Bay oyster restoration projects, and 3) the promotion of local environmental stewardship. Rotary International's participation will give visibility to the project, allow for the education and participation of local Rotarians and others at many levels. We will offer educational opportunities for students (at all grade levels and higher ed), community members, and watershed association members as well. Indeed, SMCM students, many SMRWA members, and St. Mary's River residents are already gaining expertise because they are engaged in current St. Mary's River oyster restoration projects. Therefore, a nucleus of concerned, knowledgeable, and engaged people already exists, and their efforts are coordinated through the SMRWA.
Timeline
- Presentation to Rotary 3 PM June 23
- Design/Implementation Plan June 15 - finalized in July
- Ground-breaking ceremony tentative for October 13 in the morning
- Implementation of pilot project - October 2012 through April 2013
- Implementation of all reefs - July 2013 through June 2016
Budget
This project is expected to cost between $200,000 and $300,000
Funders
- St. Mary' sRiver Watershed Association
- Rotary clubs, District 7620, Rotary International
- Boeing Global Corporate Citizenship
- Constellation EcoStar Grant program
- Old Line Bank
- Tidewater Dental
- Reef Ball Foundation
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