The short version
Between 1987 and 1992, eelgrass in Waquoit Bay declined quickly. Fred Short and David Burdick of the University of New Hampshire mapped that loss from aerial photos and field checks, part of the bay at a time, and compared it with how built-up each part’s watershed was and how much nitrogen it received. The areas with more houses and more nitrogen lost their eelgrass faster. Tank experiments showed why: extra nitrogen feeds algae that block the light eelgrass needs. The authors describe theirs as the first study to tie housing development and nitrogen loading to eelgrass loss.
What the researchers did
The study combined mapping in the bay with experiments at the University of New Hampshire’s Jackson Estuarine Laboratory. (The full article is behind a paywall; this summary is based on its published abstract.)
- They used aerial photography, checked on the water, to map eelgrass in the Waquoit Bay National Estuarine Research Reserve and track how it changed from 1987 to 1992.
- They compared the loss in each sub-basin of the bay with the density of housing around it and the nitrogen it received, mostly through groundwater.
- In experimental tanks (mesocosms) at the Jackson Estuarine Laboratory, they grew eelgrass with excess nitrogen to see what happened.
- They also noted what was growing in and over the eelgrass beds in the bay as they declined.
What they found
- A fast decline. Over the five years studied, eelgrass acreage shrank steadily, and the beds that remained broke up into smaller, scattered patches.
- More houses, faster loss. Sub-basins with denser housing and higher nitrogen loading lost eelgrass more quickly.
- Algae do the damage. In the tanks, too much nitrogen fueled three kinds of algae: films growing on the eelgrass blades, seaweed, and floating microscopic algae. All three shade eelgrass and stress it.
- The same thing in the bay. Each of those three kinds of algae was seen taking over in parts of Waquoit Bay where eelgrass was failing.
- A call to act. The authors concluded that managers should limit development that adds nitrogen to groundwater and start taking steps to reverse the loss.
What it means for Waquoit Bay today
This paper, together with the work of Ivan Valiela’s group in the same years, built the case that nitrogen from homes in the watershed was driving the loss of Waquoit Bay’s eelgrass. That link is the foundation for the nitrogen limits Falmouth and Mashpee are working to meet today. For the bigger picture, see why Waquoit Bay lost its eelgrass and EPA’s 2002 risk assessment, which used later data to estimate how much nitrogen eelgrass can tolerate.
This summary is based on the abstract.
Read the paper
Short, F. T., & Burdick, D. M. (1996). Quantifying eelgrass habitat loss in relation to housing development and nitrogen loading in Waquoit Bay, Massachusetts. Estuaries, 19(3), 730–739. https://doi.org/10.2307/1352532
License: © 1996 Estuarine Research Federation, published by Springer. The article is not openly licensed and the full text is behind a paywall, so we link to the publisher’s page rather than host a copy; this summary is based on the published abstract. The card image is a title card made from the citation.
Drafted with AI assistance from the linked source.
