SEMINAR: MBF STUDENT SEMINAR --TOMORROW @ 1PM-- DWIGHT EBANKS & KRISTINE STUMP

[Pam Harris <pharris@rsmas.miami.edu>]

 

MBF Student Seminar Series

 

Dwight Ebanks

Advisors: Dr. Nelson Ehrhardt & Dr. Daniel Benetti

 

“The influence of increased CO2 on the respiration and development of cobia, Rachycentron canadum during embryonic stages”

Projected increases in atmospheric CO2 and the resulting decrease in oceanic pH over the course of the 21st century warrant studies on the effects of these abiotic environmental changes on marine teleosts.  The goal of my research was to assess the impact of projected changes in CO2 on the early physiological dynamics and development of cobia, Rachycentron canadum.  Cobia are widely distributed marine teleosts, which typically hatch in ca. 24 h.  Respiration rates of cobia embryos for the year 2100 CO2 level (800-870 ppm) as forecasted by IPCC and beyond (≈2900 ppm) were assessed.  Utilizing pooled data for the respirometer methodology, the embryo respiration rate decreased from 3.9 to 3.2 nmol O2/h/egg at the year 2100 projection but it was not significant (Mann-Whitney U(9) =114, p = .677). When using pooled data for the biological oxygen demand bottle method, regression analysis t(2) = .48, p = .677 did not show a statistically significant difference across the CO2 levels examined (39, 577, 100, 2923 ppm). Embryonic development after 9 and 19 hrs exposure to elevated levels of CO2 (876, 949, 957 ppm) were not significantly different.  These results on pH effects suggest early life history stages of cobia may be resistant to near future CO2 levels.

 

 

Kristine Stump

Advisor: Dr. John McManus

“Effects of habitat degradation in a Lemon Shark nursery:

Community characterization before and after a disturbance”

The lemon shark, Negaprion brevirostris, is a large coastal species that uses nursery habitats throughout its range.  In Bimini, Bahamas, mangrove-fringed shorelines serve as nursery grounds for hundreds of juvenile N. brevirostris, providing both protection from predation and ample foraging.  Recently, a significant portion of nursery habitat was destroyed during construction of a resort.  Clear-cutting of mangrove forests and filling of wetlands impact not only nursery-bound neonate and juvenile N. brevirostris, but also the resources upon which they rely.  To describe community diversity and structure, near-shore seining was conducted to quantify prey communities in both the disturbed and a nearby intact control nursery between 2009 and 2011.  These data were compared to data collected prior to habitat degradation, from 2000 to 2003, using identical methods, in both nurseries.  ANOSIM results showed no significant differences in abundance, biomass or occurrence of taxa in the control nursery, while significant differences were found for all three in the disturbed nursery.  Species richness decreased significantly in the disturbed nursery, while no such change was seen in the control.  Declines found in mean abundance of most taxa, including those important in N. brevirostris diet, can have impacts on the growth, survival, habitat use and home range of the nursery-bound sharks in this insular system. 

 

FRIDAY, FEBRUARY 8, 2013

1:00pm

RSMAS campus, S/A 103

Pamela Harris

Marine Biology and Fisheries

Rosenstiel School of Marine & Atmospheric Science

University of Miami

4600 Rickenbacker Causeway/SLAB-118

Miami, FL 33149

(305) 421-4176

fax - (305) 421-4600

pharris@rsmas.miami.edu  

 

http://www.rsmas.miami.edu/academics/divisions/marine-biology-fisheries/