Final answer:
Zebra mussels are introduced into isolated lakes through ballast water from ships and by clinging to boats and trailers. To prevent their spread, cleaning boats and treating ballast water are effective methods.
Step-by-step explanation:
Zebra mussels are invasive species that have been introduced into isolated lakes primarily through the discharge of ballast water from ships. This ballast water, taken from one region and released into another, often contains various living organisms, including zebra mussel larvae. Zebra mussels can also hitchhike on recreational boats and trailers, clinging to the submerged surfaces and being transferred from one body of water to another.
To prevent the spread of zebra mussels into isolated lakes, one viable method involves thoroughly cleaning and decontaminating boats and equipment before they are moved between different water bodies. Implementing strict regulations and guidelines for the treatment of ballast water before it is discharged can also help prevent the introduction of zebra mussels to new environments.