Catching up with Dr. Anna Mikulis, Margaret A. Davidson Fellow 2020-2022
Six years ago, Dr. Anna Mikulis, then a masters student at UNH, started as the 2020-2022 Margaret. A. Davidson Fellow at the Great Bay National Estuarine Research Reserve (NERR). Her aim was to explore the loss of eelgrass in the Bay in the context of biogeochemical stressors, namely nitrogen and phosphorus levels. In February 2026, the work she completed at Great Bay NERR was published in the Journal of Geophysical Research: Biogeosciences. In that time, Mikulis completed her masters degree, earned her doctorate in the Department of Natural Resources at the University of New Hampshire, led a 3-year NERRs Science Collaborative Grant, and moved to Virginia to start her new position as the Manager of Regulatory Affairs at the US Tire Manufacturers Association.
We recently caught up to discuss the findings of her publication, her experience as a Margaret A. Davidson Fellow, and the biogeochemical health of Great Bay.
Mikulis’s science career has been greatly intertwined with the National Estuarine Research Reserve system (NERRs): during her undergraduate studies at the University of Maryland, she spent a summer at the Kachemak Bay NERR as a Hollings Scholar, a NOAA-funded internship opportunity that places students with NOAA facilities for hand-on experience with research, education, policy, and more. After a positive experience in Alaska, Mikulis knew she wanted to work with the NERRS again and sought the graduate-level Margaret A. Davidson (MAD) fellowship with Great Bay NERR.
Every Reserve in the system identifies management and research needs each year, which applicants to the MAD fellowship must incorporate into their 2-year research project. Mikulis was drawn to the GBNERR’s need to better understand how landscape changes and stressors impact the physical and chemical conditions of local ecosystems, and began to investigate how nitrogen inputs from freshwater systems affect the seagrass community in Great Bay. This project worked jointly with the Piscataqua Region Estuary Partnership (PREP) and included clear stakeholder involvement, which Mikulis cited as an important aspect of her research: “I believe the way we solve environmental problems is through collaborative science that addresses the needs of the community.”
Mikulis showed that 65% of the eelgrass in Great Bay had been lost, from about 1,000 hectares (ha) in 1996 to approximately 375 ha in 2022. An excess of nitrogen is a known stressor of eelgrass as it causes eutrophication, or the growth of algae, which blocks light and disrupts photosynthesis of eelgrass. From 2018-2020, Wastewater treatment facilities (WWTFs) around Great Bay upgraded to comply with Environmental Protection Agency (EPA) regulation limiting the amount of total nitrogen output permitted. By 2020, three WWTFs that discharge into Great Bay reduced their nitrogen output to Great Bay by 80%.
While the point-source nitrogen pollution directly from WWTFs declined, eelgrass in Great Bay continued to disappear. Mikulis and her co-authors raised three potential reasons:
1) Eelgrass hasn’t had the time to recover yet. Some eelgrass recoveries from similar nitrogen-reduction projects have taken up to 10 years;
2) Non-point sources of nitrogen continue to be high and come from general watershed runoff. These non-point sources are harder to regulate as they are a cumulation of many tiny sources such as fertilizer used on lawn or agricultural fields, pet waste, or malfunctioning sewer systems;
3) The combination of high nutrient loads and rapid loss of eelgrass have created an unfavorable environment for eelgrass re-growth.
Mikulis digs into this last consideration with a complex model of nitrogen and phosphorus inputs to the Bay and outputs from the Bay to determine how nutrients behave in eelgrass habitat. Her work demonstrated that dissolved forms of nutrients are being retained in the Bay while particulate forms of these nutrients, including total suspended solids (TSS), are being flushed out of the Bay.
Mikulis and her co-authors suggest that one process retaining dissolved nutrients and producing particulate nutrients might be that dissolved nutrients imports from freshwater runoff are incorporated in plant and algal biomass in the Bay. This plant-bound nitrogen may be flushed from the estuary through drifting leaves or seaweed, or may be incorporated into the decomposition process and stored in sediment. Curiously, though eelgrass continued to decline during the study period, the retention of dissolved nutrients in the Bay remained consistent, suggesting that some other primary producer such as algae or seaweed was responsible for this uptake of dissolved nutrients. The growth of algae or seaweed is a detriment to eelgrass populations as these floating organisms can block light from reaching rooted eelgrass.
Another process producing particulate nutrients could be sediment resuspension. Eelgrass roots are important for securing sediment in the Bay’s floor. As eelgrass communities die back, the sediment is more susceptible to wave energy and is resuspended into the water column, causing turbidity, or a lack of clear water. With excess turbidity, light cannot penetrate deep into the water, which leaves photosynthetic organisms without the ability to use sunlight for growth and reproduction. This increase in turbidity correlates with the increase in total suspended solids (TSS) being generated and exported from the Bay.
Mikulis’s paper is a demonstration that biogeochemical cycling is a critical mechanism for the health or decline of eelgrass communities, and that by better understanding the details of this cycling, we as stewards of the Bay can make more informed decisions about how to promote healthy ecosystems. In fact, the work Mikulis completed as part of her MAD fellowship and Masters thesis enabled her to integrate with the estuarine stewardship community and identify further lines of inquiry regarding nutrient cycling and eelgrass health, such that she had a desire to “see it through” and continued for four more years studying this system for her Ph.D. Throughout her six years in Great Bay, Mikulis cultivated data analysis and seagrass ecology skills, but credits her development of science communication skills and conquering her fear of public speaking to the MAD program, which emphasizes communicating science in a non-technical manner.
Upon reflection of her recently-published paper, Mikulis comments, “We know a lot about seagrass loss. Very few stressors correlate directly, suggesting that ecosystems are really complicated, natural resource management is complicated, and requires a suite of regulatory and non-regulatory levers to manage declining ecosystems like eelgrass meadows.” To the members of the public who are interested in promoting the health of Great Bay, she suggests getting involved in the NERRs! Great Bay NERR heavily involves the public in our work across all sectors: research, education, training, and stewardship. Individuals can volunteer with our research team to collect data around the Bay, can volunteer with the education team to teach elementary students about the Bay, can join training programs such as the Changemakers, can attend public events such as Bayview lectures, and can educate themselves about small actions to help the Bay through products such as the Caring for Our Marshes guide.
Access Dr. Anna Mikulis’s paper, “Biogeochemical Stressors and Ecological Response in a Nitrogen-Impaired New England Estuary” at the author-shared link here.
Information about the Hollings Fellowship and the Margaret A. Davidson Fellowships can be found at the associated links.
Explore volunteer opportunities at Great Bay here.
– Lauren White, Biologist
