Monday, March 14, 2016

Whale Fall Ecosystems

When whales die and sink to the bottom, their carcass, called a whale fall, provides a concentrated food source and environment for organisms of the deep sea.  First, scavengers will consume the outer layer of tissue and detritus provides the surrounding sediment with nutrients for a year or more.  The skeleton, however, can support communities of organisms for decades.  It can serve as a hard substrate for invertebrate colonization while microbes can live off of the energy released by chemical reactions.  In all, these whale fall ecosystems can form an all new food web in the deep sea.

The study that I used for my blog post on the sperm whale fall ecosystems proved that over a course of three years (2003-2005), a plethora of species called the dead whale home.  The species mentioned in the paper were those of mollusks, polychaetes and crustaceans.  The amounts of each were documented in the paper with mollusks being the most abundant.  Epifaunal species were collected using a suction sampler while infaunal were collected using a scoop sampler.  One idea that I would like to research further is that of the shell sizes of the mollusks.  The paper mentions that one species’ shell size started large and slowly decreased while the other species’ shell size demonstrated the opposite effect.  The paper did not mention why this occurred.

An interesting idea that I will be researching is that of shallow water falls versus deep sea falls.  One paper that I have found discusses how twenty five deceased whales and the associated fauna found with them indicate the presence of a shallow water whale fall community.  In fact, the study shows that shallow water and deep sea falls differ from one another because taphonomic pathways (what happens to animals when they die and decompose) vary more on the shelf.  Therefore, shallow water whale carcasses may not go through the same pathways as those of the deep sea.

I would also like to discuss in my presentation what sorts of organisms are able to utilize the whale carcass.  I have mentioned mollusks, polychaetes and crustaceans, which do seem to be the majority of the organisms that thrive in the ecosystem.   Studies have been done to identify kinds of microbes that thrive in this habitat and how their presence is proof the sulfide-based ecosystem that the whale carcasses provide.  Moreover, new species of polychaete worms have been discovered inside of whale bones.  An example is Capitella iatapiuna , which was just discovered in February of this year.  I have come across several papers stating that new species have been discovered thanks to these whale falls.  Furthermore, I have found plenty more information regarding the ecosystems, but I have not been able to read them all.  The papers that are listed are only just a few of the studies that I have come across.

Web sites:

Articles: (symbiosis in the two species of mussel shells.  May provide why shell sizes differ)

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