SEMINAR: REMINDER-- MBF602 STUDENT SEMINAR *TODAY* @ 12 NOON---ELIZABETH MARTIN-COUNCILL & DWIGHT EBANKS

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

 

 ****PLEASE NOTE THERE IS NO MBF FACULTY SEMINAR SCHEDULED FOR THIS FRIDAY****

MBF Student Seminar Series

 

Elizabeth Martin-Councill

Advisor: Dr. David Die

“A comparative theoretical study of age-structured

fish subpopulations”

Many species of harvested fish undergo changes in reproductive strategies and behaviors as a consequence of fishing pressure or changes in habitat.  Many of these changes occur in subpopulations where management efforts are disproportional across large spatial scales or where the habitat of the population in a particular area is altered.  This project provides a new way of modeling such populations where subpopulations are reproductively isolated and shows how using a comparative approach, we can understand the mechanics that dictate the age structure of these populations.  The model derived in this study is a discrete-time Leslie process, the components of which are functional response curves. Here, I present a brief overview of the derivation of the model with underlying assumptions, solvability, and a brief analysis of the solution.  I also present a simplified hypothetical two-stage model of a fish population in which both mature and immature individuals are present.  The results of this model show detailed intra-year dynamics that can be used to estimate age structure within the year.  Finally, I present an outline of the ongoing research being done on this project as it applies to harvested marine fishes, particularly Atlantic Tarpon, Bluefin Tuna, Swordfish, and Skipjack tuna.

 

Dwight Ebanks

Advisor: Dr. Nelson Ehrhardt

“The influence of increased aquatic CO₂ on the respiration in early life stages of cobia, Rachycentron canadum,

and mahi mahi, Coryphaena hippurus”

Projected increases in atmospheric CO₂ and the resulting decrease in oceanic pH over the course of the 21^st century warrant studies on the effects of these abiotic environmental changes on marine teleosts.  The goal of my research is to assess the impact of projected changes in CO₂ on the early development and physiological dynamics of cobia, Rachycentron canadum, and mahi mahi, Coryphaena hippurus.  Both fish are widely distributed pelagic marine teleosts, which, at 26 °C typically hatch in ca. 24 and 36 h, respectively.  Respiration rates of cobia spermatozoa, fertilized eggs, and yolk-sac larvae for the year 2100 projected CO₂ level (800-870 ppm) were assessed.  Preliminary analysis of individual respiration rates displayed an increase at the elevated CO₂ level relative to current day values for both spermatozoa (0.65 to 1.55 pmol O₂/h/spermatozoa) and yolk-sac larvae (12.5 to 16.3 µmol O₂/h/larva).  However, the individual respiration rate for fertilized eggs decreased from 4.25 to 1.86 µmol O₂/h/egg at the year 2100 projection. Respiration rates for mahi mahi eggs increased from 2.6 to 3.0 nmol O₂/h/egg (448 to 1147 ppm) followed by a decrease to 2.7 nmol O₂/h/egg at 1590 ppm CO₂ with an increase to 2.8 nmol O₂/h/egg at 1765 ppm CO₂.  Embryo development studies will be conducted in the near future.  

 

FRIDAY, FEBRUARY 24, 2012

12:00pm

RSMAS campus, S/A 103

Pamela Harris
Administrative Assistant
Marine Biology and Fisheries
Rosenstiel School of Marine and 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/