Watershed Watch: Cunliffe Pond


Map of the ponds within Roger Williams Park (inset shows location of RWP within Rhode Island). We monitor Cunliffe Pond.

Today Brown geology grads, undergrads, and postdocs celebrated our third successful season with the URI Watershed Watch program. The WW, coordinated by the URI cooperative extension, monitors about 120 RI water bodies on a weekly basis from May to October, all through the volunteer efforts of RI citizens. The long-term data (>20 years for some lakes) are used to assess restoration efforts, pollution impacts, climate change impacts, etc. Full information can be found at the URI-WW website.

Using the foldable boat, aka the ‘coin purse’, our crew has now monitored Cunliffe Pond for three years.

Specific measurements we make include, on a weekly basis: temperature, secchi depth, dissolved oxygen; on a biweekly basis: chlorophyll a; and three times per year: bacteria coloforms, phosphate, ammonium, nitrate, and cyanobacteria abundance. Here are some data highlights from our sampling effort, as well as some photos from the most recent sampling season.

Surface water temperature, measured weekly, shows a nice seasonal progression from May through October. Warmest temperatures are approximately 28 °C.

Secchi depth information also reveals a seasonal progression. We noticed abundance submerged aquatic vegetation and clear water in May (high secchi), which was replaced by phytoplankton in June-August (low secchi, high chlorophyll a). Cyanobacteria (mostly anabaena) blooms were evident in mid-summer, but dissipated in the fall.

Dissolved oxygen levels were variable, but generally lower during mid-summer due to higher water temperatures, and greater respiration related to high algae biomass. DO never dropped to critical levels for the bass population in the pond.

Brown geology undergraduate, Allison Cluett, measures the secchi depth from the canoe.

Visiting scholar Carolynn Harris volunteering to measure dissolved oxygen concentration using a Hach kit. Here she is adding starch color indicator.

Geology post-doctoral fellow Sarah Ivory prepares to deploy the water sampler.

Supplies for filtering phytoplankton from water samples. The filters are then frozen and sent to URI for analysis of chlorophyll a content.