Macroinvertebrate Mayhem Introduction

Macroinvertebrates – organisms that don’t have an internal skeleton and are large enough to be seen with your eyes.

Environmental Stressors (things that put stress on aquatic organisms) can affect the populations of macroinvertebrates.

• Runoff from cities and farms can contain: - chemical pollution - soil & sediment - insecticides - sewage - fertilizer • Alien species • Changes in stream flow and temperature

Aquatic macroinvertebrates can be an indicator of the quality of the aquatic environment.

• Some organisms can’t adapt to poor environmental conditions and may disappear. (Intolerant) • Some organisms can adapt to some extent to poor conditions, but not if conditions get too bad. (Facultative) • Some organisms can tolerate poor conditions and even serve as indicators of the poor water conditions. (Tolerant)

Caddisfly

Adults resemble small moths with long hair-like antennae. Adults only live long enough to mate and lay eggs, and have no mouthparts, since they don’t eat.

Caddisfly Larvae

• Important food source for fish • Can spin silk to make nets to catch food in flowing water • Use silk to make a case out of rocks, plant material, etc.

• Caddisfly larvae can’t tolerate low oxygen levels in water. (Intolerant)

Mayfly

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Adults are the only insects to hold their wings straight up when resting.

Like Caddisflies, adults only live long enough to mate and lay eggs, so they have no working mouthparts.

Mayfly Larvae

• Have feathery gills to get oxygen out of water, and sometimes wave them to get more oxygen.

• Important food source for fish and birds • Very sensitive to environmental pollutants. (Intolerant)

Stonefly

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Adults live near streams Adult males drum their abdomens on a tree branch to attract females.

Adults and nymphs are important food sources for fish.

Stonefly Nymph

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Moves by walking on rocks and hanging on with clawed feet.

Important food source for fish Very sensitive to amount of oxygen in water. (Intolerant) Undulates abdomen to try to get extra oxygen out of water.

Dragonfly

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Adults are very important predators and prey in the ecosystem.

Adults are the fastest flying insect, reaching speeds of up to 60 miles per hour.

Dragonfly Nymph

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Important predators and food source in the aquatic ecosystem.

Sensitive to environmental changes, including changes in turbidity, water flow, oxygen levels and vegetation, but can tolerate some environmental disruption. (Facultative)

• Dragonfly larvae have an extendible mouthpart called a “mask” with claws on the end to grab food.

• The dragonfly nymph expands and contracts its abdomen to move water over its internal gills, and can squeeze the water out rapidly for a short burst of underwater jet propulsion.

Damselfly

• Looks similar to a dragonfly, but usually smaller, and can fold its wings up over its back.

• Important predators and food source for birds.

Damselfly Nymph

• Important food source for fish and important predator of mosquitoes and flies, like dragonflies.

• Has three external gills at the end of its abdomen.

• Sensitive to environmental pollution & changes, but can adapt to some changes. (Facultative)

Midge

• Adult life cycle is short, as in Mayflies • Food source for other insects

Midge Larvae

• Breathes with feathery gills on abdomen • Important food source for fish and other aquatic insect larvae • Very tolerant of pollution and low oxygen (can float at the surface of the water to breath)

Rat-Tailed Maggot

• Actually the larva of a “flower fly” that looks like a honeybee • Adults are beneficial because they pollinate flowers while drinking nectar.

Rat-tailed Maggot

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Feeds on decomposing material in the water and other larvae.

Very tolerant of pollution & low oxygen because it has a breathing tube that can extend out of the water (looks like a tail)