January 2017: Thoughts from the Coastal Scientist

The purpose of TAC Updates and “Thoughts from the Coastal Scientist” is to summarize information (facts and data) from meetings and to articulate other questions, concepts, and connections that the TAC is considering. The information is intended only to help advance TAC discussions and is NOT intended to be used by an individual or group as final or conclusive statements. All information presented through this TAC page during the State of Our Estuaries report development is considered preliminary until it is published by PREP in December 2017.


The Technical Advisory Committee had its third meeting on January 6th, 2017 to solicit input for the development of the 2017 PREP Data Report and 2018 State of Our Estuaries (SOOE) Report. This third meeting was focused on oysters and clams; populations, harvesting, health, restoration (oysters) and included new data since 2011. In addition, there was a presentation on the social indicator project, which has been formally underway since 2015. Project leads are currently refining a list of possible social indicators that PREP will consider for inclusion in the 2018 SOOE Report.

We also talked about the upcoming TAC calendar. Right now, we are anticipating our next TAC meeting in March and then a more comprehensive (perhaps even taking place over multiple days) meeting in mid to late April. That will be the final TAC meeting before our first draft of the 2017 Data Report and the 2018 State of the Estuaries Report. Please stay tuned to this newsletter and the PREP e-mail list for more information on this process.

Below, please find a quick synopsis of our discussions from January 6th regarding clams and oysters…much more detailed notes will be sent out to everyone on the TAC mailing list later this month – if you’re not on that list or aren’t sure if you are please email Kalle.Matso@unh.edu to be included.

How are clams (in Hampton-Seabrook Estuary) and oysters (in the Great Bay Estuary) doing? And what can we do about it?

Clams and oysters are having a real hard time. While eelgrass declines—as of 2015, we’ve lost close to half of the eelgrass we had in 1996, the peak in recent years—are significant, clams and oysters are worse off still, having declined by over 90% since their recent peaks in 1997 and 1993, respectively.

So, what’s going on? For clams in Hampton-Seabrook, the combination of disease and predators (green crabs) seems to be most

significant. Warming water temperatures are related to both of these factors and exacerbates clam problems . Studies from other estuaries have indicated that anthropogenic pollution—both nutrient and toxic—has been associated with clam health impacts, and should be looked at as well.

With oysters, it’s a similar story. Along the entire east coast, diseases are having a huge impact on oysters. In our area, the disease MSX seems to be tapering, but the other disease, known as Dermo—both diseases are caused by protozoan organisms—is increasing significantly with warming water. Whereas oysters in the early 1990s lived over 10 years and grew to over 200mm, oysters today live 3 to 5 years and shell heights top out around 110 mm.

What can we do? Without new information, options are limited, but there are actions to consider. For clams, decreasing green crabs could help. This can happen by opening up new markets for green crabs, selling the crabs for soup base in restaurants or for bait. With new information on how the different stressors interact to impact clams, more management options will arise.

So, let’s talk about oysters now. At the recent TAC meeting (Jan. 6, 2017), we talked about the highest-impact stressors or impediments to rebuilding oyster habitat in the Great Bay Estuary. While disease was the highest impact stressor, the group agreed that it was the least amenable to management action. Another high-impact stressor is sedimentation. However, it’s unclear whether the sediment is simply being resuspended and stirred up from within the estuary, or, in contrast, whether it’s being delivered from the tributaries. Either way, efforts need to focus on stormwater management as well as building back up the amount of structure (e.g., eelgrass and oysters) in the estuary to baffle water velocity.

Another identified stressor was available substrate for oyster spat to settle on. This stressor was seen as both a high impact impediment AND highly amenable to management. There was less agreement on whether human harvesting of oysters was a significant stressor, though all agreed that it is amenable to management through regulation changes. Other potential stressors mentioned included: low number of spawn-producing oysters (i.e., spawning stock biomass) as well as predation (green crabs again). More research is necessary to understand how much of an impact these stressors are having.

As part of the January 6th meeting, Ray Grizzle from UNH reviewed efforts to restore oyster habitat in the Great Bay Estuary, funded in large part by The Nature Conservancy with contributions from PREP. (see Ray and Krystin Ward’’s report HERE). While restoration has had some limited success, more experimentation is required to isolate the best methods to restore habitats, given new findings from Ray and Krystin’s work as well as NH Fish and Game’s Robert Eckert  (See Eckert’s thesis HERE) as well as issues related to sedimentation.

Finally, Ray reported on work done by himself and colleague Krystin Ward to update our understanding of how much oyster habitat actually exists in the Great Bay Estuary. (see report HERE) For example, Ray and Krystin found an additional 10 or so acres near Adam’s Point by looking in places that folks hadn’t looked before. This kind of mapping is critical to do every 5 years or so to better understand the state of this resource.

Additionally, PREP’s Jill Farrell and Plymouth State University’s Dr. Shannon Rogers shared options for new indicators to include that have socio-ecological ties. These included data relating to aquaculture activity in the Little Bay. The 2018 State of Our Estuaries Report will include 4 new social indicators that will begin to explore the social/human indicators of a healthy estuarine system.

PREP is part of the U.S. Environmental Protection Agency’s National Estuary Program, a joint program between local, state and federal agencies established under the Clean Water Act with the goal of protecting and enhancing nationally significant estuarine resources. PREP is supported in part by an EPA matching grant and is housed within the School of Marine Science and Ocean Engineering at the University of New Hampshire.