Coffin Box Bryozoans are Smothering our Kelp Beds

Coffin box bryozoans are tiny invertebrates called bryozoan (Membraipora membrancea). They are called coffin boxes due to their formation of large rectangular shaped boxes which are in the shape of coffins as they live in large colonies. As an individual they are only around 1 cm each (Figure 1) however within the colonies they reach sizes up to 10cm or more which creates sheets over the kelp (Figure 2). They are active filter feeders and the biggest threat they produce is towards our kelp beds due to their quick spreading over kelp which steals nutrients and light from the kelp beds (Chapman, 2002).

                                   

Figure 1: Indivual organism, 1 cm                   Figure 2: Large coffin box colony on a native kelp (DFO).
in size (DFO).                                         

They are native to the Pacific Ocean within North America and were introduced to the gulf of Maine in 1920. Now they are found from northern New York up to the Labrador Sea since 2002.

Kelp beds are important because they create a source of food for various marine animals from fish to other inverts. They are so harmful to kelp because these bryozoans can cover entire kelp and prevent photosynthesis from by blocking light, prevent it from reproducing and releasing spores and can affect the growth rate as we and all these factors can cause to die and severely impact the future population of this population (Chapman, 2002).

Figrue 3: Distribution of Coffin Box in Newfoundland and Labrador (DFO).

They spread by the release of larvae which is then carried by the water currents. Also human activity such as boating is another method which can carry these colonies to new areas as seen in Figure 4. Therefore regular cleaning of the boat bottom should be done to prevent the spreading of the organism and various others much like the previous one mentioned (golden star tunicate). As seen in Figure 3 you can see how much they have been distributed all around the island (Caines, 2010).

Figure 4: Bottom of a boat covered in kelp that has been covered in coffin box colonies (DFO).

For more information about Newfoundland’s problem with Membraipora membrancea please visit http://www.nfl.dfo-mpo.gc.ca/e0018292.

With respect to Newfoundland’s waters there have been a number of scientific initiatives to understand these bryozoans better. A conservation effort and awareness in our province is in the rudimentary processes and DFO has begun an outreach program to educate the public – especially of those in the shipping and fishing industries. The program includes reporting sightings and ensuring that boats’ hulls and fishing gear are frequently and adequately cleaned. Research at DFO, MUN and elsewhere is being done to further understand the problem (DFO, 2011).

Similarly, internationally there is still little more being done about the spread of Membraipora membrancea along northern coastal regions. However a major problem with this invader is that it is difficult to identify. The studies that have been completed look to further identify, understand and impede the damages done by this invader. However, there is a need for further studies and improved techniques (Grosholz, 2002). One of the major problems with this species, along with most invasives, is that policies and regulations are not recognizing or progressing as quickly as the threat of the invaders (Bax et al., 2003), which is indeed the case with the coffin box bryozoans in Newfoundland waters.

Refernces:

Bax, N., Williamson, A., Aguero, M., Gonzalez, E., and Greeves, W. 2003. Marine invasive alien species: a threat to global biodiversity. Marine Policy. 27: pp. 313-323.

Chapman, A. S., R. E. Scheibling, and A. R. O. Chapman. 2002. Species introductions and changes in the marine vegetation of Atlantic Canada. Pages 133–148 in R.Claudi, P. Nantel, and E. Muckle-Jeffs, eds. Alien invaders in Canada’s waters, wetlands, and forests. Natural Resources Canada, Canadian Forest Service, Ottawa.

Caines, S. and P. Gagnon. 2010. Population dynamics of the invasive bryozoan Membranipora membranacea along subarctic and temperate longitudinal and latitudinal gradients. Newfoundland and Labrador Aquatic Invasive Species Workshop. St. John’s, NL

Department of Fisheries and Oceans. 2011. Aquatic Invasive Species: Coffin Box in Newfoundland and Labrador Waters. Retrieved from: http://www.nfl.dfo-mpo.gc.ca/folios/00604/docs/membranipora_coffin_box-eng.pdf

Grosholz, Edwin. 2002. Ecology and evolutionary consequences of coastal invasions. Trens in Ecology and Evolution.  17( 1). Pp. 22-27.