Download Ryan Johnson

Ryan Johnson
Geo4300 Biogeography
Paper 6
10/10
Worm, Boris, Helike K. Lotze, and Ransom A. Myers. "Predator diversity hotspots
in the blue ocean." Proceedings of the National Academy of Sciences of the
United States of America 100.17 (2003): 9884-9888. Academic Search Premier.
EBSCO. Web. 12 Apr. 2011.
Biology Department, Dalhousie University, Halifax, NS, Canada
1) Research Problem
Predators are very important for biodiversity within the ocean. Data were
collected to identify ocean predator hotspots. Then it was determined if making
these areas conservation area would have positive effects on the diversity.
2) Background Information
Many large predators populations such as tuna, sharks, and turtles are being
driven to low levels. Large predators are very important to ocean diversity.
Removing a keystone species can have a top to bottom effect on the ecosystem.
Because of these concerns marine scientists are calling for large-scale protected
areas in the open ocean around these hotspots. These ideas have been used for
benthic diversity with the conservation of coral reefs.
3) Method
They used observations taken by US and Australian longline fisheries collected
between 1991 and 2000. Recorded the counts of tuna, billfishes, bony fish,
sharks, sea turtles, seabirds, and marine mammals. One of the worlds largest
and widespread fishing methods, and is useful for determining pelagic diversity
because they catch a wide range of species. The data are then expressed on
different cells on a map. The best data were expressed in the Atlantic, and was
used in a model. The model was used to determine weather closing off large
areas of ocean would have an effect on the species diversity.
4) Results
Species diversity was low in high latitudes, intermediate in tropical regions, and
peaked at intermediate latitudes. Diversity also peaked close to prominent
topographic features such as islands, shelf breaks, atolls, shelf’s breaks, and
seamounts. The model had several different results for different areas. So of the
high diversity areas that would be protected have a low catch rate for target fish
for fishing anyways so it has a positive effect on ocean diversity. But some high
diversity areas are high catch rate, and making them conservation areas will
cause over fishing in other areas.
Good report, but it is a little older than it should be. Nonetheless, given the
importance of the paper, its age won’t count.
QuickTime™ and a
decompressor
are needed to see this picture.
5) Weaknesses
Longline fishing only hooks larger species and doesn’t give a true extent of diversity. The
model of effects of conservation areas is completely theoretical and is not taken from
observations.
6) Conclusion
Creating these conservation areas have an overall positive effect on species diversity,
especially within the protected area and usually outside of it also.