Invasive Species Driving Bird Kills

     With the introduction of non-native mussels, fish and aquatic plants, and the steady number of algal blooms in the Great Lakes, native birds are being affected by build-ups of botulinum toxin somewhere in the food chain, causing alarming die-offs.  

     And scientists have a pretty good idea how it's happening; zebra and quagga mussels, invasive species from Eurasia, filter water; clarity increases, sunlight penetrates deeper and the cladaphora algae thrive for a while; after the algae die, oxygen levels deplete, nutrient levels rise, and the water becomes an excellent place for botulinum toxins to grow. Then, scientists believe, gobies--bottom feeders-- ingest food contaminated with the toxin which tends to concentrate in their skin, fat and organs; birds then eat the gobies, and ultimately some die, and that is the occurrence scientist hope they can prevent.