Alewife (Alosa pseudoharengus) Contributions to Lake Phosphorus Budgets: Implications for Management
Date of Award
4-4-2022
Document Type
Open Access Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Karen Wilson
Second Advisor
Chris Maher,
Third Advisor
Theresa Theodose
Abstract
As human-made dams are removed and fish passage at dams is improved in
support of restoration efforts, anadromous alewives (Alosa pseudoharengus) gain
access to historic spawning grounds. As they migrate to spawn, adult alewives import
marine derived nutrients to lakes and impoundments. Young of year alewives (juveniles)
export nutrients as they emigrate to the sea. These nutrients support primary
production and are incorporated into freshwater food webs. However, many lakes in
New England are mesotrophic or eutrophic. Additional nutrients, specifically
phosphorus (P), may exacerbate water quality issues. To examine these issues, I
compared outputs ofan alewife nutrient and population model to background lake P
data from seven lakes in New England. My objective was to provide a nutrient analysis
as an example for stakeholders, communities and organizations considering dam
removal or improved fish passage and the restoration of alewife populations. Results
demonstrated that alewives' impact on P levels was minimal under most scenarios. In
2017, alewives contributed less than 5% of mean epilimnetic Pin four of seven lakes
studied (China Lake, Highland Lake, Tagus Pond, and Pawtuckaway Lake). Alewives
contributed more Pin Warwick and Webber Ponds, which translated to 3.6-11.19% of
mean summer epilimnetic total phosphorus (TP) in Warwick Pond and 8.67 - 23.86% in
Webber Pond. In Carr Pond, however, alewives contributed 11.43 -93.67% of summer
epilimnetic TP, which is potentially a large portion of the in-lake P budget. Alewife P
import increased as adult escapement increased, and eventually adult import
outweighed juvenile export, relative to lake size. Although the scale of P contributed by
alewife was not extensive in the majority of the study lakes, it could be instructive to
include alewife derived Pas part of the flux of nutrients in management documents
such as total maximum daily load (TMDL) reports.
Recommended Citation
Farley Thurrell, Meg "Rue" MS, "Alewife (Alosa pseudoharengus) Contributions to Lake Phosphorus Budgets: Implications for Management" (2022). Student Scholarship. 10.
https://digitalcommons.usm.maine.edu/bio-students/10
