Experiments with Marine Settlers

The investigations described below enable students to investigate the unique living community of a marina, while watching for the arrival of the exotic tunicate, Ciona savignyi.

Biologist hanging rope in the water

Children making experimental materials

(Above photo: Port Townsend Marine Science Center Summer Camp)

The world below a floating dock is a fascinating place to explore. Since floating docks rise and fall with the tides, this environment is never left high and dry. Because of this, floating docks are home to a unique group of animals and plants, some of whom are never found on beaches or pilings where water recedes twice each day. All of the experiments that follow make use of objects suspended from floats rather than from fixed docks.

Barnacle larva Nearly all animals and plants living on a float arrive there as microscopic larvae drifting in the water as plankton. This animal, called a nauplius, will attach to a dock and grow up to be a barnacle.

When settling organisms are reproducing, there is enormous competition among their larvae for places to settle. Objects placed in the water during the spring quickly attract larval organisms that develop into adults over the summer.

Close-up of organisms attached to rope

Nearly all marine organisms that colonize docks and pilings begin their reproductive period in April and May. The most rapid growth will be seen during the summer months of July and August. Ropes and settling plates placed in the water during the winter will still accumulate settlers, but you may need a microscope to see them. Teachers interested in trying these activities with their classes may want to have students begin the experiment during the previous school year and follow them up in the fall. Ropes and settling plates can also be left in the water several years to observe successional changes over a longer period.

 

Investigation 1: What organisms will attach to a hanging rope?

 Biologist counting attached organisms
Investigation 2: What settling surfaces do organism prefer?  Tray with variety of test objects
Investigation 3: What other environmental factors influence where the settlers will live?  Floating dock

Catalog of Dock Fouling Species

Links to Sites on Invasive Species

 For Teachers

Exotic Tunicates Home Page