What’s Monitored

Looking at microbiotic organisims - rock photo by Darienne Mc Namara


Macroinvertebrates Group 4: sensitive to pollution

Isopods or sow bugs
(Order Isopoda) are scavengers and they are known to eat a variety of plant and animal material. They are generally found under leaves or other materials in small streams and in some ponds and lakes. They obtain most of their oxygen through the thin "skin" on their legs that are attached to their abdomen.


Bloodworm Midge LarvaeThe Bloodworm Midge Larvae is identical to the non-red Midge Larvae except for the Bloodwood Midge Larvae's red color. Both the Bloodworm and non-red Midge Larvae (Order Diptera) feed on a variety of food sources and different types are known to be herbivores, carnivores, omnivores, and detritivores. Most Bloodworm Midge Larvae live within the stream for a year or less, and emerge as adults through most of the year (except in the coldest months). It's these organisms' red color that allows them to be classified in Group 4, rather than in Group 3 with the other midges. Their red color is due to the fact that they have hemoglobin within them. In humans, it is the hemoglobin within our blood that carries oxygen throughout our bodies. Thus, these organisms have the ability to carry oxygen within their bodies, and thus need to rely less upon dissolved oxygen in the water for their oxygen supply.


Tubifex wormTubifex worms are tube builders that eat decaying plant and animal materials, filamentous algae, and diatoms. They live on or in the substrate of various waterbodies. Like other Group 4 organisms, they have the ability to withstand low levels of dissolved oxygen in the water, and like the bloodworms, may also have hemoglobin in their bodies to hold and supply them with oxygen. They may also wiggle their bodies in the water to aerate it, thus helping to make more oxygen available to them.


Pouch snails (Order Gastropoda) are similar to orb and gilled snails (Group 3), in that they are found in numerous types of aquatic environments and eat primarily algae and decaying plant materials. Unlike orb and gilled snails, pouch snails have been known to eat decaying animal materials as well. Pouch snails breathe in a similar fashion to orb snails, using a lung to store oxygen. These snails have been reported to live for 48 hours in water without any oxygen. Unlike the orb snails, it is not believed that the pouch snails come to the surface of the water for oxygen either. Instead, scientists believe that these snails can fill their lung with water and obtain oxygen through it as if it were a gill.

LeechLeeches (Class Hirudinea, which has three Orders) are well-known for their interest in sucking blood from warm-blooded organisms, but most types of leeches are scavengers or predators, not blood-suckers. They obtain their oxygen through their skin, and some have been observed using their suckers to hold onto a solid surface and then undulating their body in the water, likely to aid in respiration. Some types of leeches can survive for several days without oxygen, which explains why these organisms are considered tolerant to pollution.














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