Chesapeake Bay Oyster Reef Biotope, Phoebus, Virginia, USA

Environment

Environment

Human settlements

Human settlements

Compacted

Surrounding area

The Chesapeake Bay oyster reefs were once very abundant. The oyster reefs were once so vast that they were navigational hazards to the shipping industry. Oysters were so abundant that the Chesapeake Bay was the largest producer in the oyster industry at that time.

However, by 1920, overharvesting reduced the reefs to less than one third of what they once were. For the next several decades, pollution, siltation due to poor farming techniques, and the loss of forested land further reduced the oyster population in the Bay. During the middle of the 20th century, parasites that carried diseases killed off even more oyster reefs. Although restoration efforts today allow the oyster populations to begin to rebound, the Bay’s oyster reefs represent only about one percent of what they once were.

The area that I chose to highlight shows the shallow edges of oyster reefs to become exposed during low tide. I chose this location because it’s easier to film a true oyster reef. Animals that are exposed to air at low tide survive by closing up and sealing in life sustaining moisture. At high tide, oysters and the creatures that grow on their reefs become active and feed again. Oyster reefs can be found as deep as twenty five feet.

Local governments create artificial reefs by placing spoils of old bridges, concrete reef balls, and other hard structure for oysters and other encrusting or fouling creatures to live on. These reefs also attract crustaceans, baitfish, and predatory fish.

Oysters in this area often attach and grow on any hard substance, such as rip rap jetties, pilings, docks or other man made structure. An oyster reef can also form on cultch (historical oyster shells or discarded shells from industry). In many shallow areas at the edge of a larger, deeper reef, you can fund clusters of oysters that create shallow habitat for fish and invertebrates. These clusters of oysters, and the gaps between them, provide many hiding places and hunting areas for small fish and crabs.

Underwater landscape

Typically, oyster reefs are more visible close to shore and exposed during low tide in the lower Chesapeake Bay. Oysters thrive in all tributaries of the Chesapeake as far up as Baltimore when conditions are right. Oyster reefs in the upper bay typically aren’t exposed at low tide and are generally found from three to twenty feet deep. In the Northern areas of the Bay, cold winters often freeze up the Bay’s shallow waters and kill off oysters around the shorelines. The Southern areas of the Bay don’t see temperatures cold enough to ice up those tributaries.

Many urban and suburban areas, combined with rural farming pollution, result in nutrients that cause pollution problems, such as nitrogen and phosphate. Typically, areas with little current and high nutrient concentrations have more macroalgae blooms, like Ulva lactuca and several Gracilaria species. Some macroalgae can be a good thing, as it provides cover and food for fish and crabs. But, die offs can create siltation which also is problematic for larval oysters.

Water clarity can range from gin clear to murky depending on several factors. Heavy rain runoff, onshore heavy winds, or boat wake traffic can cause the water to become murky (as was the time when I was there to film my BIN video). Areas with more current have less macroalgae than shallow bays. Oyster reefs also provide habitat for other encrusting creatures, such as tunicates, mussels, sponges and soft corals.

Fishes:

• Chasmodes bosquianus (Blenniidae)
• Gobiesox strumosus (Gobiesocidae)
• Gobiosoma bosc (Gobiidae)
• Cyprinodon variegatus variegatus (Cyprinodontidae)
• Fundulus heteroclitus (Fundulidae)

Crustacean:

• Balanus improvisus (Balanidae)
• Balanus subalbidus (Balanidae)
• Palaemon pugio (Palaemonidae)
• Eurypanopeus depressus (Panopeidae)
• Rhithropanopeus harrisii (Panopeidae)
• Panopeus herbstii (Panopeidae)

Molluscs:

• Crassostrea virginica (Ostreidae)
• Geukensia demissa (Mytilidae)
• Ischadium recurvum (Mytilidae)
• Clibanarius vittatus (Diogenidae)

Aufwuch:

• Ulva lactuca (Ulvaceae)
• Gracilaria tikvahiae (Gracilariaceae)

Threats to ecology

Oyster reefs provide habitat for many creatures that form a food web that benefits the health of the entire Chesapeake Bay. Oysters filter clean the water by filtering as much as fifty gallons of water per day. Oysters form reefs, as larval oysters, or spat, land on a hard object, and other oysters land and grow on them, forming vast underwater reef ecosystems, providing hiding places and structure for all kinds of fish and invertebrates.

Not only does the restoration of oyster reefs increase the water quality and life in the bay, there are economic benefits as well. Regulated harvesting of oysters, combined with conservation efforts of the businesses that benefit from that economy, recycle shucked (used) oyster shells back to the reefs and other areas to create hard bottoms for oyster spat to land, grow, and flourish. Oyster reefs are also important to other watermen, like the crabbing and fishing industry.

My fascination with this biotope began with my love for blennies. There are two blennies that frequent the Bay, the striped blenny (Chasmodes bosquianus) and the feather blenny (Hypsoblennius hentz).

I caught my first Bay blenny when I was in college many years ago, and kept her in my saltwater tank for several years. She was my favorite fish among many expensive exotic marine fish that I bought in local fish stores. At that time, I was a Zoology major, and a friend was studying striped blennies, and his specimens fascinated me.

Striped blennies are very intelligent benthic fish with fascinating and often humorous behaviors. My dream was to have an aquarium of them, and what better way to have them than to try and mimic their natural habitat as much as possible. Because of blennies, I’ve developed the same passion for oyster reefs and the many creatures that can be found there.

Riparian zone

Trees near the aquatic habitat

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Bibliography

• → A Comprehensive List of Chesapeake Bay Basin Species 2007 - A Comprehensive List of Chesapeake Bay Basin Species 2007 by Interstate Commission on the Potomac River Basin for the Chesapeake Bay Program and US EPA
  ISBN EPA 803-R-07-004
  
• → Special Scientific Report No. 65 of the Virginia Institute of Marine Science - A Check List of the Biota of Lower Chesapeake Bay by Marvin L. Wass et al
  
• → Life in the Chesapeake Bay by Alice Jane Lippson, Robert L. Lippson
  ISBN 9780801883385, 0801883385
  

Sitography

Comment by the expert