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MSI Public Lecture Series
Dr. Scott Nunez
The University of Texas Marine Science InstituteThursday, February 16th,
2006 at 7:00 PM
The
University of Texas Marine Science Institute, Visitor Center Auditorium
"The
Mystery of the Medina Lake Sharks"
Medina Lake, a freshwater reservoir formed by a dam constructed in 1911-1912,
seems an inappropriate place to go shark fishing. Medina Lake feeds a second
dammed lake from which the narrow Medina River flows, eventually making its way
to the Gulf of Mexico about 200 miles away. So when two Atlantic sharpnose
sharks were caught in Medina Lake last summer, there was some suspicion
regarding their origin. A few marine sharks, such as the bull shark, can adapt
to fresh water. The bull shark is common in tropical coastal waters worldwide
and has been caught in a number of freshwater rivers, including the Mississippi
(USA), Ganges (India), San Juan (Nicaragua), Euphrates (Iraq), and Amazon
(Brazil). The reasons behind these freshwater forays are not entirely clear.
How bull sharks and other freshwater elasmobranchs (sharks, skates and
rays) physiologically accomplish these freshwater migrations is perhaps more
intriguing than why they make them. Moving from high salinity to fresh
water represents quite a physiological challenge, a little like humans adapting
to life on Mars. Dr. Nunez will discuss recent findings regarding what makes
freshwater elasmobranchs special and whether people should be afraid to swim in
Medina Lake. Dr. Nunez is an
Assistant Professor at the University of Texas Marine Science Institute.
Research in his molecular endocrinology laboratory focuses on how sharks and
stingrays adapt to different salinities. Elasmobranchs share with humans many
of the same biochemical and hormonal systems that govern salt and water
balance. Therefore studies of freshwater sharks promise practical revelations,
such as the identification of novel regulatory pathways as yet undiscovered in
mammals. To
learn more about Dr. Nunez’s research go to:
http://www.utmsi.utexas.edu/staff/nunez.htm
Modified:: Tuesday February 07, 2006