Oyster Reefs
Oysters are often found in groups, called “reefs” or “beds”. These reefs offer refuge for myriad species of fish, crab, and other marine life. Oyster beds have 50 times the surface area of simple ocean floor. These nooks and crannies offer protection and homes to the other species of marine life.
From a clump to a reef
Oyster reefs surfacing at low tide. "Oyster reefs" by USFWS Headquarters is licensed under CC BY 2.0
Oysters create reefs by growing on top of and next to each other. The mass of oysters creates huge calcium carbonate structures cemented together by the oysters of past and present. Oyster shells are made of calcium carbonate. Oysters create their shells by secreting proteins and minerals from their mantle extracellularly. This creates new layers of shell. Oysters don't shed their shell, they enlarge them as they grow.
Oysters in the same vicinity will often reproduce simultaneously. This gives each oyster a better chance for their eggs to fertilize and the larvae to make it to adulthood. The strong forces of the ocean are unforgiving, and most oyster larvae don't survive. This is why oysters have adapted to reproduce in large numbers. Oysters rely on safety in numbers when it comes to survival. Oyster larvae prefer to latch on to other oysters. Over time, small groups of oysters grow to become large reefs. Clumping together makes survival becomes more probable. These reefs have the potential to reach a few meters high. A full sized reef contains thousands, even millions of oysters. Reefs were once so large that ships traveling the North American East Coast had to navigate around them. Today, reefs are rarely found in numbers even close to historic levels.
When reefs grow large enough, they can serve as protective barriers for shorelines. They protect from the powerful waves generated by storms and natural weathering processes. This is how oyster reefs can be important tools to mitigate the increased storm surge caused by climate change. Oysters support the coastal ecosystems they inhabit. Those coastal ecosystems then support many of the ecosystems we know on land. Oysters don't only benefit the shore, but also the communities of people who enjoy and rely on these habitats.
Oyster reefs are home to many types of marine life
Oyster reefs are among one of the best sanctuaries for many species of marine life found along the coast. They offer protection for countless species, including fish, crabs, periwinkles and other bivalves. They are a nursery for commercially important species, such as striped bass, flounder, mackerel, and menhaden. The reef allows young fish refuge from predators and storms. They are a place to safely grow into adulthood. The large concentration of species in the reef also supports larger fish. Larger fish feed on smaller marine life that venture too far from the safety of the reef.
Oyster reefs create habitat for hundreds of marine species. Each level of the marine environment supports the biodiversity of the levels above and below it. The phytoplankton serve as food for oysters and allow them to grow in numbers and form their reefs. The oyster reefs allow smaller marine life to live and reproduce. The smaller marine life serve as food for larger marine life. When an organism dies, its nutrients provide food for lower level organisms. The cycle repeats, creating a healthy ecology. A disruption at any level of this pyramid affects all other levels. This is why oysters are so vital to the biodiversity of the coastal environments.
Living Shorelines and protection from climate change
Across the world, coastal communities are struggling with erosion and the effects of climate change. This includes sea level rise and increased storm surges that can send waves deep into populated areas. As communities look for answers, oysters have a role to play.
“Living shorelines/breakwaters” are important to environment and human sustainability. Living shorelines are coastal environments consisting of natural material, plants, and animals. They act as a barrier between the ocean and inland communities. Many communities rely on sea walls, inorganic, man-made structures that does not contribute to an ecosystem. A living shoreline supports populations of plants and animals of all levels. As we have learned, shorelines are more resilient and adaptable than sea walls. Marshes, mangroves, and oyster reefs are all examples of living shorelines.
There is an important association between seagrass meadows and oyster reefs. It links habitat conservation, sediment stabilization, and wave attenuation. Seagrass meadows are declining on a global scale due to natural environmental stressors. The reintroduction of oyster reefs could aid in restoring seagrass beds in coastal systems. Oyster reefs provide physical protection for enhanced seagrass growth. They also improve water quality through filtration.
In Alabama, a group of marine biologists conducted a research experiment. Over a period of three years they studied the association between oyster reefs and seagrass meadows. They obtained continuous records of the species’ densities, water temperature, salinity, and dissolved oxygen. We do the same thing at each of our upweller locations. The scientists discovered and proved that seagrass density increased following the reef deployment. This proves that, among their other benefits, oyster reefs are also a key factor in restoring seagrass meadow populations. Oyster reefs reduce the forces of wave action and increase water clarity. This has a positive effect on the seagrass beds.
Hope for the future
People have realized the benefits of living shorelines to our ecosystems, communities, and shoreline.
Many living shoreline projects like this one use concrete bases to promote the formation of oyster reefs. In this before & after image, you can see how the concrete promotions reef formation. "Before & After: Oyster reef living shoreline partner project" by U. S. Fish and Wildlife Service - Northeast Region is marked with CC PDM 1.0
New York’s Living Breakwater Project incorporates green infrastructure projects into their shoreline development. New York hopes this will prepare for devastating storms while providing ecological benefits. In 2012, Staten Island saw the devastating effects of hurricane Sandy. Since then, New York has taken action to ensure their communities are better protected in the future. This includes developing oyster reefs along parts of Staten Island.
Countries in the developed world are turning back to natural solutions to storms and erosion. Many developing countries are embracing it as well. Unfortunately, we've replaced much of the world’s natural coastline with man-made infrastructure for short-sighted economic gains. States like New York are showing that living shorelines are not only good for the environment, but also good for our people, communities, and economy.