Music Music Zebra mussels arrived in the United States in the late 1980’s in the great lakes region. They were probably in the ballast water in a ship from the Middle East and when it was discharged into our fresh waters, they found a universe full of food and a void of predators. Zebra mussels spread rapidly throughout the great lakes and down the Illinois river, all the way to the Mississippi river.
These are zebra mussels and you can see by looking at this rock how they can colonize a rock. This same thing happens to water intake pipes. The zebra mussels get inside these pipes and they attach. Zebra mussels have bissel threads and they secrete these threads much like a spider secretes threads to make its web. They’re real sticky and real strong and they are able to hold on to things. Now one of the things that’s kinda peculiar to the zebra mussels is they like to build on top of each other. (BugMobile) The zebra mussels bissel threads allow them to cling to almost any surface, and that’s precisely what they do. Attach to any solid object, including each other. As they accumulate on machinery, they tend to interfere with its operation, whether it is a propeller, pump or water intake to a power plant or a supply intake to Erie’s fresh drinking water. Zebra mussels filter plankton out of the water and they out compete other animals at this level of the food chain, thus decreasing biodiversity. There incessant filtering makes the water clearer and this has dramatically increased underwater visibility. It has also increased the amount of light to greater depths and given rise too much heartier weeds and water plants close to the surface, which in turn impedes fishing and water skiing. Looking at the IPM pyramid, there is nothing that can be done culturally. They are very well established in their own world, under water. In terms of physical and mechanical tactics, little can be done to control the spread of Zebra Mussels, but we can undo some of the on done to man-made items, buy scraping them off and restoring the equipment to working order. In terms of biological control there is a very peculiar mixed blessing in the Round Goby.
Biological control of zebra mussels was limited basically we had a few species of fish such as carp and fresh water drum that would eat some zebra mussels but didn’t really do much in controlling them. About 1990 the fish called the Round Goby was probably brought to the great lakes the same way zebra mussels did, it probably came over in ballast water. The Round Goby is a small fish that eats zebra mussels. About 70% of its diet is zebra mussels. It has invaded the bottom of Lake Erie. It’s just covered with these fish and they really eat a lot of zebra mussels. That sounds like it’s a great idea that we finally have a predator that can eat zebra mussels, but there are some problems associated with this little fish.
(bugMobile) What’s that?
The problem with these gobies eating the eggs of some of these other fish is that they are eating the eggs of small mouth bass that the fishermen want to fish for. If the goby keep eating their eggs, there may no longer be as many small mouth bass around for these people to fish for. The gobies build nests, they lay eggs but after they lay the eggs, the male actually sits there and guards the nest to prevent other fish from coming in and eating their eggs. So, they are very prolific. In fact there are so many gobies on the bottom of the lake out here now so that when skin divers go down and swim over the bottom, they say it’s just like a moving carpet there are so many gobies on the bottom of the lake. One of the problems with gobies is that other fish eat gobies. We have the small mouth bass and yellow perch in Lake Erie that feed on goby. The problem with that is that gobies eat zebra mussels which contain a lot of contaminants. Since the zebra mussels have contaminants then the goby get these contaminants in their system and they pass it on up to the small mouth bass and yellow perch when they eat the gobies. When people eat the fish that eat the gobies that eat the zebra mussels then the contaminants that were in the zebra mussels end up in the people.
(BugMobile) When poisonous substances move up the food chain, that’s called Bio-magnification. The goby is just as invasive as the zebra mussel. The net effect between the action of these two invasive species is still a net loss in biodiversity. One might wish to believe that the goby is a biological control for the zebra mussel, but it wasn’t planned. The result is still a system out of balance.
Zebra mussels filter plankton out of water. There are a lot of species of fish out in the lake that are dependent upon these different types of plankton, when they are small fish, to feed on. Because the zebra mussles have filtered out a lot of this plankton, it has changed the species of fish that actually live in Lake Erie now and has actually lowered the abundance of fish that can live there because there’s not as much food left for these fish to feed on. Some of the other ways that round gobies are probably affecting biodiversity is because they eat other fish’s eggs. As they eat the eggs of the other fish, those fish don’t have the ability to reproduce as fast as round goby and are therefore eliminated from the lake. (BugMobile) There are limited chemical controls for zebra mussels in some instances. Since it’s a waterway, strong chemicals are out of the question. However in certain targeted areas such as the fresh water intake for Erie’s water supply a small pulse of relatively harmless diluted chlorine can be sent back out through the collection pipe and this prevents zebra mussels from attaching to the inside surface of the pipe. These aquatic invaders can pose a dramatic threat to Pennsylvania’s aquatic biodiversity. Just a few miles south of Lake Erie is Lake Edinboro. Now the first inland lake to have zebra mussels.
What PA sea grant is concerned about is transport of the zebra mussels to some of our inland lakes and waterways. Some of the ways the zebra mussels could be transported to our inland lakes are via their boats. The boats can have zebra mussels attached to their hulls if the boat was in the water for a long time. Could be attached to the prop of the boat, but also zebra mussels attach to aquatic vegetation. The reason this is a problem is because the aquatic vegetation can become attached to the boat, the prop or even the boat trailer as it’s backed into the water. This could then be transported to another lake if this vegetation is hanging on the boat, or if there are zebra mussels attached to the hull. When the angler or boater gets to the new lake, that he wants to go fishing or water skiing at, if he’s not careful to remove this vegetation or remove the zebra mussels from the hull of his boat, they can then be released into the water, the new lake or the new river that he’s backing his boat into. (BugMobile) Wow, you’d have to be pretty thick skinned not to be bothered by that zebra mussel story. Thanks Gary.
Well let’s head down toward home. Music "I Get Around" by the Beach Boys.