USE OF BENTHIC MACROINVERTEBRATES TO ASSESS WATER QUALITY
USE OF BENTHIC MACROINVERTEBRATES TO ASSESS WATER QUALITY IN BOLIN CREEK David Lenat Consulting Services
• AQUATIC MACROINVERTEBRATES • AQUATIC INSECTS • BENTHIC MACROINVERTEBRATES • BENTHOS
What are benthic macroinvertebrates? • Invertebrates (animals without backbones) that live on the stream bottom and are visible with the naked eye, such as aquatic insects, crustaceans, worms, clams, and snails
Why use Benthos? • Found in all aquatic habitats • Easily and inexpensively collected • Most life cycles are about one year in length in temperate stream systems • Integrate a wide array of potential pollutant types • Important in the diets of fish
Aquatic Macroinvertebrates Groups • • • Ephemeroptera – mayflies Plecoptera – stoneflies EPT Trichoptera – caddisflies Odonata – damsel and dragonflies Coleoptera – beetles Megaloptera – Dobson and Alderflies Diptera – True flies Oligochaeta – Aquatic worms Crustacea – Crayfish, amphipods, Isopods Mollusca – Snails and clams
Stonefly Mayfly Caddisfly
Caddisfly Cases
Caddisfly
METHODS • Based on NC DWQ Standard methods – Standard 10 -sample qualitative – Qual 4 (4 samples) – EPT (4 samples, EPT only) – Taxa classified as Rare, Common or Abundant
METRICS • Total Taxa Richness • EPT Taxa Richness (DWQ criteria) – Higher number indicates better WQ • Biotic Index (DWQ Criteria) – Weighted Mean of Tolerance values (0 -10) – Lower number indicates better WQ – Range about 4. 5 -9. 0
Bioclassifications • Excellent • Good-Fair • Poor
Existing Data • NC Division of Water Quality - 1993 Present • Watershed Assessment and Restoration Project (WARP) - Report 2003 • Carrboro - Environmental Consultants 2000 -2007 • Carrboro - LCS - 2008 -2009
Factors Unique to Bolin Cr • Ecoregion – Slate Belt, Triassic • Drought – Extreme low flows in recent years, sometime with complete loss of water
Mean Monthy Flow at Morgan Cr near White Cross (cfs) Month: Year May June July Aug Sept Oct Nov 2002 0. 03 0. 04 0. 01 0. 04 6 4 15 2003 7 6 3 2 2 2 5 2004 0. 7 5 7 2 4 3 2005 2 0. 7 0. 3 0. 2 0. 01 0. 2 0. 6 2006 0. 7 1. 7 5 0. 08 0. 5 1. 9 16 2007 1. 8 0. 6 0. 2 0. 000 0. 008 0. 003 2008 2 0. 4 1. 6 5 15
Sampling Goals • Determine present water quality in Bolin Creek and tributaries. • Look for trends over time. • Look at effects of land management. • Look for any areas of higher water quality within the watershed.
PRESENT WATER QUALITY? • Winter (Dec 2008) – Good-Fair all sites – Low EPT taxa richness, but some intolerant species abundant • Summer (July 2009) – Good-Fair at sites 1 and 4, Fair at sites 2 and 3
TRENDS OVER TIME (Winter and Spring Data) • SR 1777 (#2) – – – – April 1993 March 1998 April 2000 December 2000 February 2001 March 2001 December 2008 EPT Rating � 28* 26* 30* 18 17 16 10 Good-Fair Not Rated Good-Fair
TRENDS OVER TIME (Winter and Spring Data) • Estes/Village (#4) – – – – April 1993 February 1998 December 2000 February 2001 March 2002 December 2008 EPT Rating � 26* 26 9 6 10 7 10 Good Fair Good-Fair
EFFECTS OF LAND MANAGEMENT • Baldwin Park area • Dry Gulch • Toms Creek
SEARCH FOR AREAS OF HIGHER QUALITY • Smallest streams, esp. seeps and springs • Dependent on geology, land use, and groundwater inputs • If areas of higher values found, give higher level of protection? • In 2009, sampled upper Bolin Creek(Lloyd-Andrews farmstead); Jones Creek (Twin Creeks); unnamed tributaries (Seawall School Rd. ) • At this time, 2 areas along Seawell School Road
Rhynchelmis bolinensis?
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