A study of the impact on energy levels in Lake Havasu after the invasion of Quagga/Zebra mussels from the Great Lakes.
Research results have shown that invasive mussels cannot survive well in the southern reaches of the Lower Colorado River. The Yuma area near the Colorado River has thousands fewer adult mussels per unit of measurement than Lake Havasu and Lake Mead.
Quagga Mussel adults were found in Lake Mead early in January 2007 and by middle January in Lake Havasu. From Lake Mead downstream on the Lower Colorado River the invasive (non-native) mussels are present to the Yuma area but Mexican officials have claimed they have not found them in their waters. The number of mussels is greater in Lake Mead then in Lake Havasu but there are fewer muzzles per unit area in the Colorado River near Yuma, Arizona than many areas upstream. There are several reasons for this difference.
The invasive species of bivalve mollusk found in the Lower Colorado River is known as the Quagga Mussel. This species is very similar to the Zebra Mussel which is another non-native animal that has spread to many waterways in the Eastern United States since it invaded the Great Lakes in the 1970’s and 1980’s. Experts on these species believe from existing evidence that the Quagga Mussels that have shown up in the Western States early in this century entered the Lower Colorado River from a boat trailered from the MidWest. The first adult Quagga Mussels were found in Boulder Basin on Lake Mead by National Park Service divers on January 6, 2007 and California divers found adult Quagga Mussels in Lake Havasu on January 18, 2007.
It is most likely that the mussels entered the Lower Colorado River as larvae or villagers and it was a few years earlier that the mussels were accidentally introduced and had time to mature to the adult stage by the above dates when adult specimens were documented. There are still no Quagga Mussels in Lake Powell on the Upper Colorado River because this species cannot swim or travel upstream without some help mostly as a result of human activity.
Our research was centered on Lake Havasu for 2 years. Our crew collected plankton samples which included larvae (villagers), along with the native zooplankton historically found in this body of water. We collected fish to study which the species consuming larvae and adult Quagga Mussels.
RESULTS OF THE STUDY; The species of fish that had villagers in there intestinal tracts were 1. Redear Sunfish and 2. Threadfin Shad. The plankton surveys showed different levels of zooplankton and villagers at each of the collection stations throughout the study as a result of temperature, season of the year and other physical conditions of the Lake Havasu Reservoir. For example,the water in the reservoir is the source of drinking water for millions of residents of Southern California and as a result the water is drawn out of the Lake and replaced from upstream in as little as 17 days on occasion. The water chemistry may prove to be a limiting factor in future research. The farther south you study the Lower Colorado River populations of invasive mussels, the less successful these populations are in colonization. The Yuma area of the Lower Colorado River has only a few (10 to 20 adult mussels) when compared with Lake Havasu with hundreds of adults per unit area and Lake Mead with thousands of adults measured in the same size units.
Chemistry, salinity, temperature, calcium concentration, sandy lake bottom versus rocky substrate are all factors that make the Lower Colorado River less suitable habitat conditions for these invasive (non-native)Quagga/Zebra mussels based on our research. Much study is still needed to complete the picture of mussels in the western waters in the near future.