Benthic Macroinvertebrate and Pollution Tolerance What is benthic

Benthic Macroinvertebrate and Pollution Tolerance

What is benthic? • Means bottom dweller

Benthic Macroinverts and Water Quality • • Used as indicators of water quality Separated into four groups We count the number of species per group Most pollution tolerant group is weighted heavily (multiply by a larger number) • Least tolerant weighted most lightly (multiply by a smaller number) • The greater the number the more polluted the river

• Pollution tolerant organisms like clean water as well as intolerant organisms, but tolerant organisms can also survive in polluted places while those others can’t. • Example: You will find leeches and other worms (group 4) in clean water as well as polluted but stoneflies (group 1) are only found in clean water.

Group I: Pollution Intolerant • Need high levels of D. O. • Cannot survive in habitats affected by nutrient pollution • Mostly shredders or predators • Live in clean, cold stream. Found in riffles, why? • Canary of clean water: stonefly • Dobsonfly, alderfly and snipefly

Group II: Moderately Intolerant • More tolerant of nutrient enrichment and drops in D. O. • As algae increase, scrapers increase (water pennies and mayflies) • Greatest number of organisms, most diverse.

Group III: Fairly Tolerant • Organisms can accept low levels of D. O. • Mostly scavengers and collectors • Includes sow bugs, scuds, and right handed snail (gilled).

Group IV: Pollution Tolerant • Very tolerant of low D. O. and severe nutrient pollution. • Most have special adaptations for breathing oxygen at surface • left handed snail: breathes air from a pouch • Bloodworms (midge larva) have hemoglobin type blood to help them move oxygen through their body