USE OF BENTHIC MACROINVERTEBRATES TO ASSESS WATER QUALITY IN BOLIN CREEK David Lenat Lenat Consulting Services

AQUATIC MACROINVERTEBRATES AQUATIC INSECTS BENTHIC MACROINVERTEBRATES BENTHOS

benthic macroinvertebrates? 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 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 EPT

Mayfly Stonefly 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

Bioclassifications Excellent Good Good-Fair Fair Poor

Existing Data NC Division of Water Quality Present Watershed Assessment and Restoration Project (WARP) - Report 2003 Carrboro - Environmental Consultants Carrboro - LCS

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 MayJuneJulyAugSeptOctNov

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) EPT Rating –April *Good –March *Good –April *Good –December Good-Fair –February Not Rated –March Good-Fair –December Good-Fair

TRENDS OVER TIME (Winter and Spring Data) Estes/Village (#4) EPT Rating –April *Good –February Good –December 20009Fair –February 20016Fair –March Fair –March 20027Fair –December 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?