The pattern of colonization on the discs in Baltimore's Inner Harbor may follow a trend similar to that of a temperate abandoned farm field. At first, there will be a great diversity of weeds, wildflowers, small seedlings, and grasses. In time, the seedlings with rapid growth will begin to take over as small shrubs and sapling trees begin to appear. These plants will compete for space more efficiently and "weed out" their neighbors.
After a few seasons, the larger trees will dominate the landscape and the diversity may decline to a number of well-adapted species from the pooneering species that first emerged. This process is known as succession and occurs in many ecosystem populations. The succession of biofilms in the Inner harbor will be more rapid, and consists of species ranging from bacteria to invertebrate animals competing for limited space during the optimal time for growth.
Competition in the field is no less intense, only slower. The biofilm community on the disc will eventually become dominated by larger invertebrates--like mussels, barnacles, polychaete worms, and anemones--and limit the space of those species without the ability to compete effectively.
Here are some of the organisms you may encounter in this activity. Click one of the images below to see the corresponding gallery. Barnacles are sessile but most of this class are highly mobile using their 10 legs for movement. Barnacles are filter feeders using their legs to snare plankton from the water. The black-fingered mud crab is the largest of five species of mud crabs found in the Chesapeake Bay.
They have been seen on the biofilm discs as very small juveniles and are typically looking to prey upon barnacle and mussels on the discs. A free-living variety of marine annelid that builds burrows and is also highly mobile outside the burrow.
