Living rocks as vital natural sources | Why mussels room imperiled | Why perform we care? | Is there hope? | How can you help?


This is a woman Higgins eye pearlymussel with many of the covering buried and also the fleshy mantle flap exposed. The Higgins eye has evolved a ribbon-like mantle flap that, as soon as exposed above the shell, looks favor a minnow and serves together a attract to lure a potential fish host. Once the target fish approaches, she will certainly expell her larvae at the fish. The larvae attach to the fish"s gills or fins, and hitch a ride because that a couple of weeks while they continue their transformation into a youth mussel.

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Photo by Minnesota DNR; bernard Sietman

America"s Mussels, or clams, space a team of pets so inconspicuous they are often mistaken because that rocks. Laying ~ above the bottom of lakes, rivers, and also creeks, they hardly ever move and also eat through filtering water because that microscopic food particles. They can also reproduce there is no moving. The male disperses sperm and the water current carries it come the female wherein fertilization occurs. However throughout much of north America, and particularly in the Midwest, this rock-like creatures are sending an immediate message.

North America has actually the highest possible diversity that freshwater mussels in the world. And within north America, in the history the Midwest had some of the greatest numbers the mussels species. Currently, however, in the Midwest (Minnesota, Wisconsin, Iowa, Missouri, Illinois, Indiana and Ohio) more than fifty percent of the 78 known varieties are classified together Federally endangered, endangered or State species of special concern. No other team of animals in the Midwest is so gravely imperiled. To put this in perspective, The Nature Conservancy reports that around 70 percent that mussels in phibìc America space extinct or imperiled, compared to 16.5 percent of mammalian species and 14.6 percent that bird species.

Mussels room not in trouble simply due to the fact that they"re vulnerable creatures that room on their way out anyway. Although greatly sedentary, they deserve to move. Many varieties have adjusted to the constantly changing situations in streams and also rivers. They can likewise close their shells to avoid short term exposure to toxins or other unfavorable environmental conditions. Thus mussels are hard creatures that deserve to withstand harsh problems if those conditions are temporary. The fact that so numerous mussels space imperiled in the Midwest mirrors that there have been significant, long-term transforms to our lakes and also waterways. And also those changes have to be so dramatic the these aquatic pets have trouble surviving.


Although they deserve to be mistaken for rocks top top a river bottom, this collection of Missouri flow mussels reflects their beauty and also diversity.

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life Rocks as important Natural Resources

In the past, mussels were supplied by indigenous Americans in the building of tools and also utensils. Mussels were also crucial food source. After europe settlement, mussels were harvested for your shells to do pearl buttons. Through the early 1900"s, this multi-million dollar organization was in full swing along the Mississippi River. Since there to be no controls top top this industry, mussels were over-harvested and numbers of many species dwindled. This, in addition to the usage of plastic replacements, put an finish to the pearl button industry.

In the 1960"s, the Japanese cultured pearl industry started to expand. If tiny pieces of sand or mussel shell are placed into oysters lock surround the disturbance v a silicate, creating a pearl. Thousands of lots of live mussels room harvested from phibìc American rivers each year and also shipped to Japan where pieces of the shells are used as "seed pearls.". The demand and high price from this industry has actually resulted in increasing the events of illegal mussel harvesting.

Mussels play an important role in the aquatic ecosystem. Countless different type of wildlife eat mussels, consisting of raccoon, otters, herons, and also egrets. Mussels filter water because that food and thus room a purification system. They are usually present in groups called beds. Beds of mussels may selection in dimension from smaller sized than a square foot to plenty of acres; these mussels beds can be a tough "cobble" top top the lake, river, or present bottom which support other species of fish, aquatic insects and also worms.

Although your lives appear boring, their reproductive tactics are rather fascinating. After the masculine has dispersed sperm the is brought by currents to the female whereby fertilization occurs, the fertilized eggs are transformed right into a larval state inside the female. She then packages the larvae into an enticing lure that will entice a specific fish. Once the target fish approaches, she will expell her larvae at the fish. The larvae attach to the fish"s gills or fins, and also hitch a ride for a couple of weeks while they continue their change into a juvenile mussel. Once the transformation is complete, lock drop off of the unharmed fish, and begin their life together a young adult mussel. Not just is this an approach of reproduction interesting to biologists and also students the nature, the truth that mussels require specific types of fish to reproduce means that mussels room also good indicators the the wellness of their host fish populations.

Why room Mussels for this reason Imperiled?


One of the rarest mussels in phibìc America, the purple catspaw was once widespread in the southern portion of the Ohio river basin. When detailed in 1990, the was assumed to be functionally extinct. Phenomenally, in 1994 a breeding populace was uncovered in Killbuck Creek, Ohio.

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Visualize the Mississippi river (or the Ohio flow or any type of one that the countless rivers and also streams traversing ours countryside) as it should have showed up to the very first European explorers. The riverbanks to be forested, over there were plenty of sandbars, logjams were uncovered periodically, and also the water was completely totally free of man-made pollutants. Fish were most likely plentiful, and also if girlfriend sampled the sand and rocks on the bottom, friend would have found an abundance of insects, worms, and also other aquatic invertebrates. Then visualize the Mississippi or another waterway together it look at today. With these visualizations in mind, it"s not too complicated to believe that plenty of of the animals living in those rivers would have actually a tough time enduring today. But let"s look at the alters that have actually been made to our rivers and also streams and also how those transforms have affected mussels.


Many dams have been built on many of our rivers. Whether for hydropower, recreation, or navigation, dams room a physics barrier, i beg your pardon is a major threat come mussels. Part of the life bicycle of young mussels has attaching to the gills that a specific type of fish. These young mussels, which room actually larvae, are brought by the fish to different reaches of the river. At some point the larval mussel drops off the gills, floor on the bottom, and if it"s a suitable area, the mussel proceeds to grow. Together a sedentary animal, this is an excellent strategy because that populating lakes and also rivers. However, because dams space a obstacle to fish, they additionally prevent mussels in the upstream from relocating downstream, and vice versa.

The ebony shell (Fusconaia ebena) and elephant ear (Elliptio crassidens) mussels drastically examplify the affect of dams ~ above mussel distribution. Skipjack herring is the main fish host for these mussels. The skipjack stayed in the Mississippi flow watershed indigenous the pair Cities south to the Gulf that Mexico. It was in reality a migratory types in the upper Mississippi river watershed whereby it was recognized to generate in Lake Pepin and probably provided other locations in the watershed as well. But after a hydropower dam was put up on the Mississippi river at Keokuk, Iowa in 1913, the skipjack herring might no much longer migrate north of the dam. Thus, this varieties of fish to be extirpated indigenous the top Mississippi flow north of the dam in ~ Keokuk. Along with the extirpation that the skipjack, all (or most) reproduction of the ebony shell and elephant ear mussels, upstream the the dam, ceased. Individual live specimens that these types are still uncovered today in the top Mississippi watershed since these mussels are so long-lived and also were for this reason abundant prior to the dam. However, reproduction that these types no longer occurs north of the dam at Keokuk.

In addition to exhilaration as barriers to fish movement, dams influence mussels by changing the flow water atmosphere of rivers. The reservoir area upstream the a dam is a lakelike atmosphere in a segment of river. In most cases, riverine type of mussels cannot make it through in lakes. So all the mussel bed in the upstream reservoir area the the dam are eliminated. Depending upon the type of dam, releases indigenous the dam might not mimic natural conditions, rather unnaturally high release of water alternate with unnaturally short releases that water. The low water problems are particularly hostile to mussels (and most other type of wildlife in the river).

Sedimentation and Pollution

Agricultural production reasons eroding soil to operation off right into rivers and also lakes. Bridges are likewise sites that high erosion and sedimentation. Huge amounts that sediment entering streams and also rivers deserve to bury gravel and rocky bottoms and smother mussels. Numerous kinds of mussels can not live top top muddy or unconsolidated sandy bottoms, they require the river bottoms to it is in rock, gravel, or certain sands. The sediment in runoff often carries pesticides through it, which additional pollutes the water. Various other contaminants such together PCBs, mercury and lead room deposited in waterways from commercial plant discharges. A wide variety of various other toxic substances space released from commercial sites.

With navigation on countless rivers and industrial complexes located on riverbanks, over there is always a hazard of an oil or toxic chemical spill. Also, numerous public and private septic solution empty into our waterways. In the 1970s, NO live mussels were found in the lower fifteen miles of the Minnesota and also the Mississippi Rivers, indigenous the Twin cities to Lake Pepin. The was referred to as a mussel desert. Negative water high quality was the factor that these areas could not assistance mussels. Since that time, sampling shows that water top quality is improving. In fact, a current mussel inspection north of Lake Pepin documented the presence of good numbers the individuals and numbers of types of mussels.


This higgins eye pearlymussel, an threatened species, was taken from the Mississippi river laden through zebra mussels.

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Exotic Species

Exotic types are one ever-increasing danger to our native plants and also animals. For indigenous mussels, infestation the zebra mussels has had near catastrophic effects. Many likely, zebra mussels were introducted right into the good Lakes inadvertently, indigenous ballast water dumping by large ocean-going vessels from Europe. Native the an excellent Lakes, barges and boats spread adults and larvae into the Illinois and Mississippi Rivers.

They rise in numbers faster than non-native mussels and also attach to virtually any tough surface, including native mussels. They reproduce so fast and also in together abundance that the aboriginal mussels" movement, feeding, and reproductive actions are stifled. One mussel was uncovered to have over 10,000 zebra mussels ~ above it.

Why perform We Care?

Monitors the aquatic health: the existence of diverse and reproducing populaces of mussels indicate a healthy and balanced aquatic system which means good fishing, good water top quality for waterfowl and other wildlife species, as well as insurance that our water is safe. Conversely, once mussel populations are at risk, that indicates problems for various other fish and also wildlife species, and people too. Ecological value: mussels are herbal filters, feeding on algae, plankton, and also silts, they assist purify the aquatic system. Mussels space also an essential food source for many types of wildlife including otters, raccoon, muskrat, herons, egrets, and also some fish. financial value: freshwater mussels have been and continue to it is in a significant economic resource; first in the button industry and now in the cultured pearl industry. Mussels from north American type the cell core of the cultured pearl industry in Asia.Education and aesthetic value: the study of mussels, their organic history, and also habitat requirements gives interesting and important lessons on the interconnectedness of the aquatic system and also how species adapt to their ecosystem. cultural value: Mussels played critical role in the social history of prehistoric and recent native peoples the the Ohio and Mississippi flow basins. They were provided as food and the shells were supplied for ornamentation, tools, and as a commodity because that trade. Indian shell middens (the piles the shells that indigenous Americans have actually left behind) extend for miles along sites of old villages and encampments follow me the Mississippi and Ohio Rivers. Biodiversity: Mussels have, and hopefully will certainly continue, to play an important role in our aquatic ecosystems. Considering that less than 20 mussel types are uncovered in many other countries of the world, our phibìc American rivers and also streams are truly "rich" v close to 300 species!! Mussels execute not obtain cancer. Researchers desire to know why and also mussels might have extr values later on that us cannot currently predict. The ns of any type of of these types will certainly have consequences on how the aquatic ecosystem functions.

Is over there Hope?

Passage and implementation that the Endangered varieties Act and the Clean Water plot has contributed to the recovery of some species. The Endangered types Act offers protection of present mussel areas containing threatened and endangered types and has supported efforts to recuperate endangered mussels. Enforcement the the Clean Water Act has actually resulted in improved water high quality which has enabled recolonization of mussels and fish in part areas.

How deserve to You Help?

To protect mussels the complying with things can be done.

Conserve power in an effort to border the building of brand-new hydroelectric strength plants. help control floor erosion through planting trees and plants to protect against runoff the soil right into freshwater areas. Eliminate aquatic weeds from boat trailers and motors before using again to protect against the spread of things such together zebra mussels. Execute NOT throw weeds earlier into the water.Help support watershed management programs by calling her local source management agency. Support and follow zebra mussel quarantine, inspection, and decontamination programs.

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