Warm up 9/20-0/21 What is the only natural lake in Texas? Why does a thermocline form? What is eutrophication?

Benthic Macroinvertebrate groups Shredders- eat course particulate organic material Scrapers- eat algae and other substances off rocks Collectors- filter fine particulate organic material out of the water Predators- eat other living organic material Piercers- pierce open tissue of a plant or animal and inject enzyme to break down tissue

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

Benthic Macroinverts and their groups Caddisfly: collectors and/or shredder Water boatman: piercer Helgrammite (dobsonfly): predator Water strider: predator Dragonfly Nymph: predator Water penny: scraper Midge: collectors, scrapers, shredders, or predators Mayfly nymph: scraper Stonefly nymph: predator and/or shredder Mayfly Nymph: collector Blackfly larva: collectors Damselfly nymph: predator Tubificid worm: collector