Revisiting the Reefs

By Alee Knoell

Oysters, lately they seem to be the belle of the estuary. But hey, it’s a well deserved title- they do quite a lot! And with oyster monitoring back in full swing, they are getting even more attention here at the reserve. With accessibility often requiring battling nor’easter winds and sinking as low as knee-deep in marsh mud, these crusty little shellfish sure keep things spicy.

For you long-time NERRds, long-term oyster monitoring is no new concept. Initiated in 2014, the project was intended to shine a light on the oh-so-miraculous oyster. I could fill this entire page with fun facts and tidbits as to why the oysters deserve the spotlight, but instead I’ll let my colleagues- or past versions of them- fill you in via this well-crafted piece from 2016. My main focus on this particular chunk of cyber-space is to talk about our recent monitoring efforts.

From left to right: Biologist Pamela Marcum and volunteers Walt Newsom, Debbie Dix, and Russ Sumter.

The goals and objectives of oyster monitoring haven’t diverted much off of the initial trajectory. Through this project, we still aim to do the following:

  • evaluate the status of oyster populations in the area,
  • estimate oyster abundance and size, and
  • provide baseline estimates of reef, population, and community structure metrics for future assessments

At the start, the goal was to sample as many reefs as possible during the winter season (December – March), in each region wrapped within our boundaries. With our year hiatus in sampling, we developed a fresh new approach to oyster monitoring. Instead of a mad dash up and down the Intracoastal Waterway each monitoring season, we are implementing a “regional rotation”. The idea is that we will be able to sample more reefs per each region by sticking to one a year (i.e. the Northern region, consisting of the Tolomato and Guana Rivers), and visiting a different region the next.

Oyster monitoring season is a fun time of year, brimming with beautiful days on the water and visits to less frequented corners of the stunning GTM estuary. It isn’t all boat rides and bird-watching, though; oyster monitoring has a lot of (very muddy) moving parts.

Biologist Pamela Marcum collects oysters for lab measurements while biologist Alexandria Knoell estimates percent cover.

Once we reach our destination, measuring tape is laid on the selected reef, along which six points are randomly selected to place a 1m x 1m quadrat (shown above) used to evaluate percent cover. Percent cover is estimated by dropping a pin at each of the 100 intersections of the quadrat grid and recording what the pin lands on, such as a live live oyster, mussel, or mud.

Volunteer Jeff Finnan preparing to lay a quadrat along the transect.

Other metrics obtained in the field include cluster* abundance, the height of the tallest cluster in the quadrat, and measurements of the oyster cluster or shell (if any) at each corner of the quadrat. The latter two of these measurements are newer additions to our protocol. In three of these six randomly selected quadrats , a smaller quadrat is used to collect a small sample from the reef.

*A cluster is a grouping of oysters and oyster shell in which five or more oysters are live.

Monitoring crew braving bad weather to monitor the reefs. From left to right, biologist Pamela Marcum and volunteers Mike Darragh, Steve Brown, and Debbie Dix.

Samples are taken back to the lab where live oysters, mussels, and clams are measured and recorded. The mud crabs, contrary to the past procedure, do not get measured, and thus escape harassment by our curious calipers. Barnacles are also counted and small snails and other anomalies are documented.

All of these measurements and observations allow us to assemble the beautifully diverse puzzle that is our estuary, of which the oysters contribute a large and vital piece.

Volunteers Diane Downing and Remo Mondazzi processing oyster samples with biologist Alexandria Knoell.

If you want to get involved in oyster monitoring with us at the GTM Research Reserve, you can help us out on the reefs or even in the lab collecting data.

Follow along with our monitoring here on the blog and also on Flickr where we post photos taken along the way.

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