Invasive species are a concern in many parts of the world, but nowhere is the threat more evident than in the state of Alaska. With 30-40 thousand miles of pristine coastline and commercial fisheries worth billions of dollars annually, introductions to Alaskan waters have the potential for great impact, both environmentally and economically. Fouling invertebrates have proven to be some of the worst salt water invaders all around the world. They are most often transported to new areas by ballast water and by towing structures from one location to the other. One of the most notorious marine fouling creatures is the sea squirt, or tunicate.
The main goal of our invasive species monitoring is to determine which species might be the most likely to come into our area, and where they are most likely to settle. Surveying those target areas on a regular basis will hopefully result in early detection and better odds of eradication before those invaders are firmly established.
Around Kachemak Bay we survey beaches on low tides, heavily encrusted boats or infrastructure as they come into the area or before they are moved to new locations, and anchor lines in Cook Inlet near the Nikiski terminal. Lessons from the lower forty-eight have taught us that moving floating infrastructure around is one of the leading causes of spreading ocean invasive species. Many times harbors are the first place for invasives to settle. Because of this we also hang settling plates in the Homer and Seldovia boat harbors and check to see what has grown on them three times a year. We have been monitoring for invasive species since 2006 and thankfully, although a few have been a few identified from our bay, they have not proven to be multiplying or even easy to find.
- What is a tunicate?
Tunicates are simple animals that are commonly found attached to rocks in the coastal ocean. If you spend time around harbors and marinas you are likely to have seen them attached to docks and pier pilings. Tunicates have a swimming larval stage, but during their adult stage most species are permanently attached to a substrate. They may be solitary (single animals, like humans) or colonial (living attached to one another, like corals). Both solitary and colonial tunicates have sac-like bodies and feed by filtering water. Water is drawn in through an incurrent siphon and expelled through an out current siphon. The siphons will sometimes expel water when touched, hence the nickname “sea squirts.”
- Learn more about invasive tunicates in Alaska:
- Identification Guides
- Learn more about settling plates
- KBNERR Tunicate Reports
In collaboration with the Smithsonian Environmental Research Center’s (SERC) iTunicate Network, KBNERR looks for invasive tunicates by monitoring settling plates in Homer and Seldovia harbors as well as conducting surveys on beaches and dock structures.