A bit of belated news report from our Oysters Rock program
(a paraphrasing of a draft report issued by Mr. Chris Judy, MD DNR)
Mr. Chris Judy from MD DNR visited Ft Carroll last November to sample the oyster reef that is located between the fort and Key Bridge in an effort to assess the health of this population of oysters (we are on the northern edge of oyster habitat on the bay due to low salinity) and effectiveness of our restoration effort. This site is one of many that DNR is monitoring as we all work to reestablish a thriving oyster population in the Bay. It is exciting to think how a thriving oyster population might help us restore our waterways to health. DNR’s goal is to assess the oyster population at Ft Carroll paying close attention to those grown there in the most recent summers (2012 and 2013).
Mr. Judy not only found oysters we planted in the last two summers, he also found oysters from other plantings prior to 2013 that were noticeably larger and older (from prior plantings by various groups that are using Fort Carroll). Perhaps the most encouraging finding was there are naturally occurring oysters on this reef (see the picture to the immediate left). These individuals are approximately 4” long and prove natural reproduction (spat set) occurs in the river. Low salinity in the area inhibits spat set, which leads to sparse populations. This is why it is good to continue seeding young oysters to boost the population on the reef. The good news is that oysters can grow here naturally.
Restore Rock Creek’s Oysters Rock program has been growing oysters for a few years now. Last June, we planted over 25 or so bushels of live, healthy young oysters on the reef (see a picture of them all posing with Chris Wallis, the Oysters Rock Project Coordinator to the immediate right). There are more than 70 families who actively participate in this program on Rock Creek.
Salinity in Rock Creek and Fort Carroll is enough to support a healthy barnacle population on the creek, but salinity is close to the limits for healthy oysters. So, our populations can be stressed, especially when it rains a lot and when we have mahogany tides. Last summer was a very good year for our young oysters.
Once these young oysters are planted, they must contend with conditions in the Patapsco and with predators. So, it is not surprising that mortality ranges up to 64%. This number includes mortality while in cages on Rock Creek and while in the river.
Mr. Judy found evidence of numerous other organisms growing on, and with, the oysters. This is an indicator of a healthy river bottom. Specifically, he identified barnacles, mussels (both the dark false and the recurved — to the left), mud worms, tube worms, and bryozoans (soft and encrusting — to the right).
There were a few species missing that are typically expected like naked gobys and small mud crabs. It was not possible to determine why these typical oyster bar residents were not present but Mr. Judy speculates the water might simply be too cold or the river bottom suffers from low oxygen levels