Van Cortlandt Lake and

Tibbetts Brook Biodiversity

There is clear evidence to show that changes in water quality are coupled with changes in the biological organization of aquatic communities. Unfortunately the diversity and distribution of most of the organisms associated with freshwater in urban habitats are largely unknown, such as here in NYC (Mcintyre 2000). The Friends of Van Cortlandt Park with the help of volunteers and school groups, hope to gain a better understanding of the invertebrate community living in Tibbetts Brook and Van Cortlandt Lake. In addition we will be using our water monitoring data to understand the drivers of aquatic macro-invertebrate abundance and species diversity.

Contact Alex Byrne, Environmental Educator at if interested in data or opportunities to sample.


FVCP Teams up with the DEC to explore Freshwater Biodiversity

In August of 2016 The Friends of Van Cortlandt Park teamed up with DEC WAVE Project water quality biologists and local naturalists in order to conduct a survey for Benthic Macro Invertebrates (BMI) in Tibbetts Brook. BMI organisms are good proxies in determining the level of impact on freshwater streams due to their sensitivity to changes in dissolved oxygen, water pH, nutrient levels and ion concentration. Presented here are results of the organisms sampled identified to order and family. Also included is the assessment calculations performed by the DEC. Special thanks to the DEC WAVE Program and our awesome group of volunteer naturalists.


Tibbetts Brook Site Results

Locations: Along South County Trail parallel to Saw Mill river pkwy

Coordinates: 40.9079,-73.8842 (S1)  & 40.9138, -73.8835 (S2) 

Collection Date: Fri Aug 05 2016


Macro-invertebrate Sample:

  • (Mollusca)  Pelecypoda (S1,S2)
  • (Mollusca) Planorbidae (S2)
  • (Crustacea) Amphipoda (S1,S2)
  • (Diptera)  Simuliidae (S1,S2)
  • (Wormlike) Hirudinea (S1,S2)
  • (Wormlike) Oligochaeta (S1,S2)
  • (Trichoptera)  Hydropsychidae (S1,S2)
  • (Diptera) Chironomidae (S1,S2)
  • (Coleoptera) (S1)


Assessment Results: (S1)

WAVE Assessment Result: Possibly Impaired

Izaak Walton League Assessment: Fair (13 out of 27)

Assessment Results: (S2)

WAVE Assessment Result: Possibly Impaired 

Izaak Walton League Assessment: Poor (12 out of 27)





WAVE Notes From the Field

  • Substrate (Sediment) plays a large role in determining diversity with more complex substrates ( rocks, pebbles, sand and silt) providing more habitat and increasing diversity.
  • Observed unusual amounts of algae and discoloration in the water near a large pipe at one of our sampling sites which led to Yonkers engineers discovering damages to the integrity of the pipe as well as 3 illegal connections.
  • Determined that the lake and brook are occupied by two different assemblages with a much higher diversity of snails and true bugs (Hemiptera) located within the lake.


Current Projects

  • Generating a species list of BMI for Tibbetts Brook and Van Cortlandt lake (Coming Soon).
  • Summarizing and comparing our 2016 WAVE data to a 1998 DEC survey of BMI.
  • Using statistical models in order to determine the chemical parameters most responsible for driving BMI diversity and abundance.
  • Acquiring Permits to create a reference collection in collaboration with associates from the American Museum of Natural History.


Suggested Reading

McIntyre, Nancy E. “Ecology of urban arthropods: a review and a call to action.” Annals of the Entomological Society of America 93.4 (2000): 825-835.