Nantucket Island, off the coast of Massachusetts, has a series of fresh-water and estuarine ponds which play an important role in the ecology of this maritime area. Many of the ponds are used primarily for contact recreation including boating, kayaking, fishing, sailing and swimming, and they also provide important habitat for a variety of waterfowl, including migrating and resident populations.
In 2005, Dr. Jim Sutherland, a collaborative co-investigator working with RPI-DFWI scientists since the mid-1980’s, retired from the NYS Department of Environmental Conservation after 30 years of service and re-located on Nantucket. Thereafter, Sutherland became active in local water quality research, receiving several grants to study local ponds including Head of Hummock Pond (HHP). HHP is a small kettle pond about 16 acres in size which exhibits severe water quality problems including elevated plant nutrient (nitrogen, phosphorus) levels and intense blooms of cyanobacteria. All nutrient samples collected from the ponds are shipped to the Keck Water Research Laboratory for analysis.
Extremely poor water quality in 2009 prompted a more intense water quality investigation of HHP during 2010. There also was concern about the predominance of cyanobacteria in HHP during 2009 and potential public health and safety issues associated with chronic blooms of these organisms. This concern is related to an accumulating body of evidence that links bloom toxins with the development of sporadic ALS disease in individuals who have resided in close proximity to affected ‘bloom’ ponds.
The Nantucket Land Council (NLC), a local 501 (c)(3) organization, provided the necessary funds to implement the 2010 HHP project. Sampling began in early April and continued through mid-November with the pond sampled about every 2 weeks (21 sample trips). The data and samples collected regularly from HHP included depth profiles of temperature and dissolved oxygen, Secchi depth transparency, water for the analysis of total phosphorus, a nitrogen series (nitrate, ammonia, total N), chlorophyll a, phycocyanin, microcystin (cyanobacteria neurotoxin), field measurements and a whole water sample which was preserved for phytoplankton ID, enumeration and biovolume measurements.
Based upon the 2010 results, HHP water quality can be described as ‘hyper-eutrophic’, with elevated levels of total phosphorus, total nitrogen and chlorophyll a. In addition, there was an extensive bloom of cyanobacteria on the pond from July through mid-to-late October, and the cyanobacteria neurotoxin, microcystin, was detected in the water column during this entire period.
Sutherland and the NLC submitted a grant application to a local funding entity for remediation work on HHP. The basis of the proposal work-plan is to interrupt the cyanobacteria bloom cycle and encourage growth of other forms of phytoplankton. The proposal was funded and a SolarBee® long-distance water circulation unit will be installed during April 2011 to prevent pond stagnation and nullify the buoyancy regulation competitive advantage of the cyanobacteria. Another season of monitoring on HHP during 2011 will evaluate the effectiveness of the circulation unit in alleviating the cyanobacteria blooms.