Bioturbation in the Sea

Matthew and Jamie

What is Bioturbation?

• The reworking (mixing) of sediments and solutes by plants and animals.

• Bioturbation has been proposed as an additional and very significant pollutant transport process. Bioturbation may be responsible for a major, if not dominant, fraction of the chemical quantities released from sediments to the water column.

• Measured using a bioturbation index (BI).

Organisms Responsible for Bioturbation

• Mainly annelid worms, molluscs (bivalves and gastropods), crustaceans (amphipods), marine mammals and holothurians (sea cucumbers).

• These organisms may be burrowers or deposit feeders, such as the lug wormand soft-shelled clams.

Why do we care? (Benefits)

• It can produce trace fossils, which show evidence of organisms responsible for bioturbation.– The first trace fossils can be dated back to the

Cambrian period (~500 million years ago).• Used to predict depositional rates and

processes.– This is key information in determining clean up

plans for polluted areas.

Why do we care? (Benefits)

• Can enhance an areas productivity, by aerating the sediment , removing pollutants and wastes, and transporting nutrients back into the sediment.

• Also releases nutrients from the sediment into the water column, stimulating plankton growth.

Possible Negative Effects

• Can be responsible for the release of viruses and other pollutants from the sediment into the water column.

References• Dashtgard, S. E., Gingras, M. K. (2005). The temporal

significance of bioturbation in backshore deposits: Waterside beach, New Brunswick, Canada. PALAIOS, V. 20, p. 589–595

• Evolving thoughts (2010). ScienceBlogs. http://scienceblogs.com/evolvingthoughts/2007/01/in_the_mud_1.php

• Karleskint, G. (1997). Introduction to Marine Biology. Saunders College Publishing. Harcourt Brace & Company. ISBN, 0-03-074191-2.

• Thibodeaux, L. J., Bierman, V. J. (2003) The bioturbation driven chemical release process. The American Chemical Society. Env. Science and tech. p. 252 -258.