December 2016 TAC Update


October 28th TAC Meeting at NHDES Offices

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.

As part of PREP’s ongoing commitment to transparency, trust building and strong science we will be posting periodic blogs to update you on our Technical Advisory Committee process. If you’d like to be on the mailing list for the TAC to be notified of meetings, etc. please email

– The October 28th TAC Meeting notes (focusing on eelgrass and macroalgae) are now available – click here.
– September’s meeting notes are also online – click here.

Here’s the critical issue involving eelgrass and macroalgae: As noted in the paper referred to below, “seaweeds have increasingly been implicated in the destruction of seagrass beds, particularly where nutrient pollution is high, where fishing has reduced top-down control of seaweeds, or where invasive seaweeds have been introduced.” Bloom-forming seaweeds thrive in these conditions and accelerate the degradation of seagrass habitats, either through shading the eelgrass or by changing the sediment characteristics such that eelgrass can’t thrive.

Well…is that what’s happening in the Great Bay Estuary? As is often the case, experts disagree. As PREP’s Coastal Scientist, my current take can be synopsized by the following bullets:

  • There’s enough data to suggest that both invasive and non-invasive seaweeds have gotten much more abundant since the 1970s. These data are compelling enough that we would be remiss if we did not invest more resources to understand whether and to what extent seaweeds may be causing problems for eelgrass, shellfish and benthic communities.
  • There is not enough data to conclude that seaweeds are, in fact, causing problems for eelgrass, shellfish and benthic communities.
  • Our current macroalgae monitoring/research approach needs to be significantly augmented so that we can answer the following questions:
    • Is the current abundance of macroalgae enough to shade the eelgrass?
    • Is the current abundance of macroalgae enough to change the sediment characteristics enough to detrimentally impact eelgrass?
    • Is the current abundance of macroalgae enough to have a detrimental impact on shellfish and/or benthic communities?
  • When these questions are answered, depending on the answers, other questions may follow. For example, if the answer to either of the questions above is “yes,” then we’ll need to better understand the different types of macroalgae involved and the specific conditions that are allowing the seaweeds to thrive. That way, we can determine appropriate management interventions.

• If you are curious about macroalgae and seagrass relationships, you can read a good synthesis paper on the subject here:

PREP anticipates that the next TAC meeting will take place in early January. Stay tuned!

To explore more about the TAC process and to review materials, agendas, meeting summaries and more CLICK HERE

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.