Aquatic Organisms by LeAnne Yenny

Benthic Macroinvertebrates Used as bioindicator organisms The presence or absence of these organisms in a stream can be used to reveal the overall ecological quality of the water. Generally, unpolluted waters support a greater variety of freshwater macros than polluted water.

Life Cycles Incomplete metamorphosis (3 stages) Eggs to Nymph to Adult Include mayflies, stoneflies, dragonflies, damsalflies, true bugs Complete metamorphosis (4 stages) Eggs to Larva to Pupa to Adult Include flies, beetles, caddisflies, dobsonflies

Functional Feeding Groups Based on their feeding methods and adaptations They are an important part of the food web They are a primary link between the base of the food chain and the larger animals such as fish

Shredders The first group of macroinvertebrates to break down the detritus (leaves that have started to decompose). Includes craneflies, some caddisflies, stoneflies, sowbugs, and scuds. They break the detritus down into fine particles.

Collectors Drifting downstream the fine particles become food for the collectors. They use various methods of either filtering or gathering of fine particles. Filterers use fan-like filaments near the mouth to capture food particles. Includes some mayflies, midges, and net-spinning caddisflies.

Grazers (also called Scrapers) Feed on the algae that grow on the surface of rocks. Includes some caddisflies, the water penny (a beetle), and certain midges and mayflies.

Predators The shredders, collectors, and grazers are a food source for the predators. Includes dobsonfly, dragonfly. Predators have large powerful mouth parts for grasping prey.

1. Bacteria + Leaves. = Detritus (slimy. leaves) 2. Shredders break 1. Bacteria + Leaves = Detritus (slimy leaves) 2. Shredders break down leaves 3. Collectors filter and gather leaf parts 4. Grazers eat algae 5. Predators feed on all macros

Water Quality Indicators Each macroinvertebrate belongs in a Taxa - a group indicating the level of pollution tolerance

Taxa 1 Includes: Caddisfly (Trichoptera) Stonefly (Plecoptera) Water Penny Riffle Beetle Mayfly (Ephemeroptera) Gilled Snail Dobsonfly

STONEFLY LARVA STONEFLY ADULT Order: Plecoptera

ADULT MAYFLY MAYFLY LARVA Order: Ephemeroptera

CADDISFLY LARVA ADULT CADDISFLY Order: Tricoptera

Can you tell the difference? Mayfly emerger Caddis comparison Stonefly nymph

Taxa 2 Includes: Crayfish Sowbug Scud Alderfly Larva Fishfly Larva Damselfly Watersnipe Fly Crane Fly Beetle Larva Dragonfly Clam

Taxa 3 Includes: Aquatic Worm Midge Fly Larva Blackfly Larva Leech Pouch Snail Pond Snail Other Snails

Questions?