Biogenic Reef 2016

      The Biogenic reef at Cherry Point has been a tremendous ecological success story that we continue to study.  This past year several students have used the reef to study the macroalgal community (seaweed)  as well as the success of the reef from an oyster restoration standpoint.  The macroalgal community on the biogenic reef was far more developed in diversity and abundance than areas we studied in the Rappahannock.  We attribute this to the  supply of zygotes that are entering the mouth of the Piankatank which is more open to the Bay and ultimately the ocean, as well as the fact that turbidity in the lower Piankatank is less than the Rappahannock.  In terms of oyster reef restoration, we found that the biogenic reef was truly that, home to a diverse assemblage of organisms and not solely oysters.  There is a mix of oysters, mussels and barnacles, all important filter feeders, who contribute to improved water quality as they consume phytoplankton and help remove sediments.  We found that Ready Reef pyramids were actually the winners in our oyster reef comparison study as they provided the least competition for space and optimized the growth and success of just the oysters.  Taylor floats proved to be the least effective oyster restoration strategy we examined because the density of the oysters was too high and they offer little in the way of overall sustained habitat value.  The biogenic reef is the hands-down winner for diversity, durability and ecosystem enrichment as you can easily glean from the photos here.
      For 2017 we have an ambitious plan to look at the ecological succession on the reef over time, using the data we have already collected as well as this upcoming summer.  We are going to do some experiments to see how much influence blue crabs have on organizing the life on the reef.  Do they consume mussels more than oysters?  Will mussels outcompete the oysters for space on the reef?  Also, we would like to continue to catalog the organisms and fish we find on and around the reef, which has been a really fun marine biological exercise.  We continue to thank the Cherry Point homeowners for their generosity in allowing us to study their wonderful reef!

Fall Reef Update

After several visits to the reef in October, my summary of the biogenic reef right now is "If you build it, they will come"!  Wow, the amount of life and the diversity on the reef structures is really amazing!  It is truly a "biogenic" reef, not just an oyster reef.  On this past sampling we observed a great diversity of life on the reef which included an extraordinary strike of oyster spat, ribbed mussels, sponges, barnacles, various macroalgae (seaweed), mud and blue crabs, naked gobies, and so on.  The reef structures have become home to the host of species that you would expect to find on a natural reef structure in the Chesapeake Bay- which is the idea!  The interesting thing about the design of the reef and the site at Cherry Point is that the structure lifts the organisms off of the sediment high enough to reduce smothering and the natural sandiness of the substrate eliminates the muddy coating that you can often find in other parts of the rivers.  The result is a very "clean" fouling surface where macroalgae grow really well and the filter feeders have less clogging due to lower turbidity.  Cherry Point is one of those really ideal places for this type of structure to harbor the highest diversity the Bay has to offer.  We have also been measuring the settling of the reef components and they appear to be quite stable and we find that the sand moves around them, but that they are maintaining their profiles nicely.  We are working on our report for the residents of Cherry Point, to pull together our findings, and we hope to continue to monitor and study the reef as it ages through the coming year.  This has been a fantastic learning experience for our students and a lot of fun to watch the reef grow and develop.  Thanks CPPOA!

This is how the reef looked in May 2015

This is the same section in October 2015!

August Sampling

We had another great day out on the reef today.  The students collected water quality data, did some seining, measured the reef structure settlement and we even snorkeled a little!  Unfortunately we had some rather high turbidity today, so the photos are rather poor, but we still saw some great creatures.  My prediction that we would catch a sea horse came true, and in fact two have now been caught, as well as a tiny juvenile spadefish.  We observed a lot of very large blue crabs perched on the biogenic reef and some "doublers", mating crabs, as well.  Interestingly, today we caught more fish off the reef for the first time, due to large accumulations of sea grass and algae around our off-reef area that are offering refuge to many fish including silver perch, northern kingfish, northern pipefish and an abundance of small blue crabs.  I am also wondering if the presence of so many large predatory blue crabs on the reef has motivated the fish to find other refuge.  While snorkeling up close to the reef we could see that oyster spat have settled on the reef surface creating more surface area and adding to the ecosystem services of the reef by filtering the water.  Overall the reef is still carpeted with various algae, and encrusted with barnacles and now oyster spat, while large blue crabs lurk around the legs and underside and fish use the space around the structures for hiding places.  It has become a seasoned fouling surface and we hope to see more species next month!

Observations from the July Sampling

     Today we completed our third observation of the Biogenic reef and we had some really great finds!  The new sections of the reef that have been in the water for just under two months are totally covered with a thick carpet of red algae.  We saw a few crabs hiding in this tiny forest and it looks like they are using the structure!  The older sections of the reef are developing a more mature mixed algal cover with various green and red algae and barnacles mixed in throughout.  Juvenile blue crabs are scurrying around the reef surface and there were abundant silversides in all sections of the reef.  The really cool part was the seine catch- we caught the usual big haul of silversides, but this time we also caught 2 juvenile striped bass, 3 northern kingfish (also called sea mullet or roundheads) and 3 pipefish.  We can see these fish in our underwater photos clearly hanging out under the reef structure and using it for refuge.  In the seine haul away from the reef structure, we caught no fish, which is becoming a trend- we catch fish near the reef and none away from the structure.  We are also observing fairly distinct zones in the reef where there are visible differences in the reef surface in the offshore, middle and nearshore areas, probably related to light availability and water flow.
      Three months into our sampling we have observed the reef go from fairly bare rock surface with little associated life to a living three dimensional, photosynthetic surface with a host of organisms using it for food and refuge.  Today we observed three valuable species on the reef- blue crabs, striped bass and northern kingfish, all prized for food and two important recreational fish species.  As this is called a "biogenic" reef it is living up to its name!