The nearshore rocky habitat of Lake Erie, Ohio. Rocky nearshore habitats, such as this one at Put-in-Bay on South Bass Island, are attachment sites for invasive Zebra Mussels and shelter for invasive Round Goby. Both species were introduced to Lake Erie from ballast water release from cargo ships that came from the Caspian Sea in the 1980s and 1990s, respectively. They tend to outcompete native fish and mussels that use the same rocky habitats. The rocky shallow habitat also provides surfaces for submerged algae like Cladophora. This alga can grow in thick mats if too many nutrients (particularly phosphorus) enter the lake. Thus, it can be a nuisance.