Macroinvertebrates

What are macroinvertebrates? Aquatic- means they that live in water (at least part‐time) • Macro- means they can be seen without the aid of a microscope or other magnifying device • Invertebrates- are animals without backbones So…. Macroinvertebrates are organisms that do not have a backbone and are visible without a microscope.

Why care about aquatic macroinvertebrates? Macroinvertebrates are valuable indicators of the health of aquatic environments because they are benthic. • Benthic means they are typically found on the bottom of a stream or lake and do not move over large distances • Thus, they cannot easily or quickly move away from pollution or other environmental stresses.

What are some stresses? Different macroinvert species react differently to environmental stressors like – Pollution – Sediment loading – Habitat changes • Seeing the diversity and density of different macroinverts at a given site can create a picture of the environmental conditions of that body of water

Where do they get their energy? Organic matter from higher up in the water column that drift down. Most organisms are scavengers or detrivores detritus is non-living particulate organic material (as opposed to dissolved organic material). It typically includes the bodies or fragments of dead organisms as well as fecal material. Some use chemosynthesis. Convert carbon molecules and nutrients into organic materials

Intolerant vs. tolerant macroinverts If exposed to an environmental stressor (pollution, warming due to low flows, low dissolved oxygen due to algal blooms, etc.): – Intolerant macroinverts may die – Tolerant macroinvert species often inhabit spaces vacated by intolerant organisms, – The result is an entirely different population of organisms!

Macroinverts in healthy water bodies A healthy water body will typically contian a majority of intolerant macroinverts such as: – Mayflies (Ephemeroptera) – Stoneflies (Plecoptera) – Caddisflies (Tricoptera)

Macroinverts in stressed water ecosystems A body of water under environmental stress will contain a majority of macroinverts that are tolerant of these conditions, such as: – Leeches (Hirudinea) – Tubifex worms (Tubifex sp.) – Pouch Snails (Gastropoda)

So… Many species are able to tolerate certain types of pollution. Mayflies, stoneflies, and caddisflies are generally intolerant of pollution. If a large number of these insect types are collected in a sample, the water quality in the stream is likely to be good. If only pollution-tolerant organisms such as non-biting midges and worms are found, the water is likely to be polluted.

There are several reasons why macroinvertebrates are used as water quality indicators: They are sensitive to changes in the ecosystem. Many live in an aquatic ecosystem for over a year. They cannot easily escape changes in the water quality. They can be collected very easily from most aquatic systems with inexpensive or homemade equipment.

Common Stream Macroinvertebrates Mollusks – clams, mussels, snail, limpets Insects- stoneflies, mayflies, dragonflies, damselflies, true flies, beetles Crustaceans- crayfish, scuds, aquatic sow bugs Annelids- aquatic worms, leeches, planaria

Lifecycles Incomplete Metamorphosis (Egg – nymph - adult) Mayflies Stoneflies Dragonflies/Damselflies True bugs Complete Metamorphosis (Egg - larva - pupa -adult) Caddisflies Dobsonflies/alderflies Beetles True flies

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