WATER’S MUSCLES: MUSSELS? By Maggie

WATER’S MUSCLES: MUSSELS?

Native mussels are the muscle of freshwater. The more of them you have, the greater the water body health is. Similarly to muscles’ dual roles as support and movement of the body, mussels fill specific roles and provide unique environmental services. Quite impressive for such a small creature!

FOOD WEB

Mussels are thoroughly ingrained in the food web of Wisconsin water bodies. These invertebrates are effective at filtering bacteria and plankton out of the water. They can then convert the nutrients into forms accessible to higher trophic levels.

COMMENSAL RELATIONSHIPS

Some species of mussel are also indubitably paired with certain fish species; reproduction for all mussels involves the young mussels, called glochidia, attaching to the fleshy parts of fish. Mother mussels have developed species-specific lures in order to attract the correct type of fish. For example, the Higgins’ eye mussel has developed a minnow-look-alike lure in order to attract bass and walleye. Once attached, the glochidia will grow and develop without harming the fish (commensalism).

QUALITY MONITORS

Like all living creatures, mussels require certain parameters in order to successfully live. Common across all species is the quality of water. The sensitive nature of mussels means they require habitats with pristine water in order to thrive. A large population of one or multiple species represents a high quality of water. Also, depending on the mussel species present and their requirements, information about the substrate and fish species in the water system can be gleaned.

HISTORY-KEEPERS

Individual mussels can be examined for better understanding of lake history. Mussels will grow rings on their shell during each year of life. Certain characteristics of the shell will also reveal hints about the water quality during that time. Being able to read these details will broaden the understanding of past lake history and dynamics.

POTENTIAL HARM

Unfortunately, since the conditions necessary for happy mussels are exceptionally pristine, anything that reduces the quality of water will negatively affect mussel populations. Some common sources of harm include pollution, invasive species, over harvesting, abundant silt and habitat change:

-Industries on moving water bodies will discharge some level of pollutant. Abundance and concentration will determine the extent of its impact on the overall water quality.

-Zebra mussels and other exotic species can out compete the natives since there are no natural predators and they can grow exponentially.

-Over harvesting has occurred in recent history with the growing interest of pearls for fashion purposes.

-Disturbance on the habitat can result in siltation, or excess fine soil being put into the system. A build up of silt can reduce the respiration capability of mussels.

-Dramatic habitat changes tend to be due to human intervention. Dams in particular cause flowing water to stagnate, which reduces the exposure of mussels to nutrients.

Due to such a wide range of harm, half of Wisconsin’s fifty-one mussel species are listed as threatened or endangered. Nature is extraordinary in the fact that it can undergo change to a certain extent without unraveling. We, as neighbors, need to understand how our actions impact the system and actively promote water body health. Water cannot afford to lose its muscles! 

* On August 25th, we have a new program: Native Mussel on the Manitowsih River Canoe Adventure! You can sign up now: https://www.z2systems.com/np/clients/nldc/event.jsp?event=36173& *