No. 05–Fouling Organisms

For eleven years I hauled five gallon buckets of water from the docks at Beaufort’s down town marina to the old North Street Aquarium. Early on I began a casual observance of all the “stuff” growing on the dock floats and bottoms of boats in the slips there. Years of observation since have led to the conclusion that no single mind can wrap itself around the incredibly intricate, complex, theory smashing, counter intuitive, ever changing world of surface water fouling organisms.

Fouling organisms are aquatic flora and fauna that attach to and grow upon hard objects below water. We humans have given the name “fouling” because they reduce the speed of our boats and render marine equipment useless if left too long submerged and unused. In fact, the wide variety of self attaching species are essential to the higher life forms that depend on them for food and habitat.

Encrusting organisms inhabit all the worlds oceans, coastal waters and estuarine systems. Waters that lack hard vertical bottom structure and therefore the encrusting organisms that would colonize it are virtual marine deserts. Sport fishing prospects in the state’s offshore waters are being enhanced by a continuing program of artificial reef building. Black sea bass and other favored game species are taking up residence in and around recently deposited New York City subway cars.

Once fully colonized, offshore structure remains rather stable with regard to the variety and distribution of encrusting organisms and the many other species they play host to. This is due to the fact that the surrounding environment is itself largely stable. The near surface colonies of the downtown marina are anything but stable however. A great number of factors play a role in determining which species may be found and how they are distributed through the mini-ecosystem.

Seasonal factors play a large role with regard to water temperature, length of day and spawning habits. Long term general climatic conditions are also a factor. The recently ended five year draught brought a whole series of observations that were a radical departure from conditions of the pre-draught marina ecosystem.

One species of Hydroid (a brown branching colonial animal that looks like a plant) had virtually disappeared from the floats by the end of the first year of the draught. Along with it went a species of amphipod commonly known as skeleton shrimp. Unfortunately, skeleton shrimp were the only easily obtainable food source for the sea horses at the old aquarium. We do not currently have sea horses at the Estuarium because the hydroid and skeleton shrimp have yet to return in sufficient numbers to assure a sustainable harvest.

Under normal conditions there is a seasonal rhythm to float colonization with different species in dominance at different times of the year. It will be interesting to see how long it takes for the pre-draught rhythm to return.

With future columns we will continue to delve into the interesting world of incrusting organisms and meet some of the more intriguing creatures that make up that commonly. overlooked world.