Ph.D. Candidate – Organismic and Evolutionary Biology
University of Massachusetts Amherst, Advisor – Theodore Castro-Santos
We propose to conduct genetic analyses on river herring to determine the species of 100 individuals. River herring refers to two species of anadromous fish: alewife and blueback herring. These fish have been identified as species of highest concern by NOAA due to declining populations in recent decades. The main causes for the population declines have been identified as overfishing and reduced access to spawning habitat. Moratoriums on harvest in all but two states have not resulted in significant recovery in most locations. Access to spawning habitat remains a considerable problem for the species. Restoring river herring runs into freshwater systems restores the natural nutrient transport between freshwater and marine ecosystems with the potential for improvements to freshwater productivity and ecosystem health.
Physical obstructions to rivers have resulted in an 85-95% reduction in available herring spawning habitat in Maine (the only state where these estimates are currently available). Early evidence suggests that restoration efforts may be disproportionately benefiting alewife. This may be due to species differences such as swimming performance or motivation, or due to seasonal differences as alewife typically enter river systems earlier than blueback herring. Physical conditions like temperature and flow change over the season, as well as ecological conditions such as predation pressure. To identify the cause of a potential discrepancy between alewife and blueback population restoration, studies need to be able to reliably distinguish between the two species, particularly during the middle of the season when there is overlap between late arrival alewife and early arrival blueback.
Scientists studying herring spawning success and fish passage rely almost entirely on visual ID to distinguish between alewife and blueback – a difficult task confounded by hybridization. In the proposed study we will:
1.Assess the reliability of river herring researchers in their current state to visually distinguish between alewife and blueback
2.Train the same researchers to identify river herring species using a photo database of fish of known species via genetic analyses prior to reassessment to quantify the potential to train researchers to visually distinguish between species
3.Conduct morphometric analyses on photographs of river herring to determine morphometric parameters that can be used to create a computer-based tool for visual identification of species
Link to student research
My Ph. D. dissertation research is focused on river herring passage performance at physical barriers in Wellfleet, MA prior to ecological restoration . The proposed study would represent an extension of my dissertation. The final product of this project will include the publication of a tool for visually identifying river herring species (whether by eye or by computer analysis of photographs) and that quantifies the reliability (or lack thereof) of a widely used method in river herring conservation.
The information from the genetic analyses will also provide additional information about basic river herring biology that will be included in my dissertation such as rate of hybridization, length-weight relationships, and age-length relationships of both alewife and blueback herring in the Herring River prior to restoration.
Contributions to Restotation
In addition to my research related to salt marsh restoration, I serve on the Board for SER-NE and have volunteered for outreach events for the Wellfleet Non-resident Taxpayer’s association, Cape Cod Sea Camps, Mass Audubon Wellfleet Bay, and the Town of Wellfleet educating the public about the Herring River salt marsh restoration and the importance of restoring river herring populations. I also co-founded an outreach blog that covers many life science topics, including ecological restoration.
M.S. Candidate – Natural Resources
University of New Hampshire, Advisor David Burdick
Salt marshes, valued for their ecosystem services such as flood control, carbon capture, and nutrient cycling (Costanza et al., 1998) are currently under threat of increased submergence and collapse due to sea level rise. Marshes build in elevation through below-ground growth of roots and rhizomes and the deposition of sediments on the marsh surface, but this growth is unable to keep pace with sea level rise in 58% of the marshes in the United States (Cahoon, 2015). Using marsh organ experiments, researchers have shown that plant growth is negatively impacted by higher sea level (Kirwan and Guntenspergen, 2015), but no one has shown how these reductions in plant growth relate to elevation change. The application of a thin layer of sediment to the marsh surface (thin-layer deposition) is a potential mitigation tool for elevation loss but its effects on plant growth and elevation gain are understudied. Using a novel application of the marsh organ, I will address two main objectives: 1) To determine the effect of higher sea levels on marsh-building processes 2) To determine the effectiveness of thin-layer deposition in restoring marsh elevation and resilience to sea level rise. I will construct two identical marsh organs in a tidal creek in the Great Bay, NH to determine the effects of flooding on plant growth and elevation change. Marsh organs consist of an array of PVC pipes at various heights to simulate five marsh elevations. For each elevation, two ‘pots’ will be planted with S. patens, two with S. alterniflora, and two will be un-vegetated. To investigate the effects of thin-layer deposition on plant growth and elevation change, I will add 3 cm of sand to the surface of an additional two pots at each elevation after planting. After one growing season (6 months), I will measure changes in below/above ground biomass and root volume. Changes in elevation will be measured in each pot using a miniature Surface Elevation Table (SET) (Cherry et al., 2009). Comparisons of biomass and elevation change between species, elevation, and thin-layer deposition treatments will be evaluated using ANOVA in JMP. In order to reach the largest possible audience, I plan to publish my results in a peer-reviewed journal and present at conferences through both oral and poster presentations.
Contributions to Restoration
Last summer, I assisted scientists from the Nature Conservancy in developing a protocol for culvert replacement in tidal creeks to allow for greater tidal flow in salt marshes. I am also a member of the Advocates for North Mill Pond (ANMP), a neighborhood association with the goal of restoring a tidal pond in Portsmouth, NH. My current project will help determine the effectiveness of thin-layer deposition in restoring marsh elevation to levels that can support natural vegetation.