SEMINAR: MBF602 STUDENT SEMINAR TODAY @ 1PM---JESSICA WATSON & BILL HARFORD

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

On 1/26/2012 9:59 AM, Pam Harris wrote:

 

MBF Student Seminar Series

 

Jessica Watson

Advisors: Dr. Peter Ortner and Dr. Gary Hitchcock

“Trophic role, production, abundance and distribution of Appendicularians in the Florida Straits.”

Data on plankton trophic interactions as well as primary and secondary production in marine ecosystems are important to both ecosystem-based models utilized in fisheries management, as well as biogeochemical models, which incorporate biological processes for the fixation and sequestration of carbon.  Processes responsible for the extremely high rates of mortality among ichthyoplankton include advection of larvae to unfavorable environments and starvation.  Furthermore, previous studies have linked the availability of plankton prey and early growth of larval fish to recruitment success in marine fish.  Little is known about the patterns of secondary production in the lower latitudes of the ocean, and the oligotrophic region of the Florida Straits in particular.  Appendicularians, which are the preferred prey of larval snapper and larval tuna in the Florida Straits, have been found to be significant consumers of primary production.  Two of the objectives of my dissertation research are (1) to describe the spatio-temporal abundance and distribution of appendicularians in the Florida Straits from samples collected during the 2003-2004 Billfish Project, and (2) to determine whether the cyanobacteria Prochlorococcus and Synechococcus, which are important primary producers in this region, are egested or assimilated by appendicularians using grazing experiments and flow cytometry of fecal pellets.

 

 

Bill Harford

Advisor: Dr. Elizabeth Babcock

“Trophic modeling of Shortfin Mako (Isurus Oxyrinchus) and Bluefish (Pomatomus Saltatrix) interactions in the western North Atlantic Ocean”

  An ecosystem model of the western North Atlantic Ocean was constructed that emphasized predator-prey dynamics of shortfin mako (Isurus oxyrinchus) and bluefish (Pomatomus saltatrix). Modeling served to synthesize knowledge about food consumption rates and feeding habits into a framework which could be used to describe the dynamics of key trophic linkages. The model was used to investigate whether directed fishing for each member of this predator-prey linkage could result in indirect effects on (1) shortfin mako biomass and yield as a result of changes in shared bluefish resources; and, (2) bluefish biomass and yield as a result of changes in shortfin mako biomass. Model outcomes were suggestive of bottom-up organization of the modeled food web, including those interactions involving shortfin mako and bluefish. Comparison of model predictions with reference biomass time series indicated that fishing mortality and declines of a principal prey resource, bluefish, may have contributed to shortfin mako declines in recent decades. Preliminary exploration of fishing policies was suggestive of competition for shared bluefish resources between shortfin mako and bluefish fisheries, as increased catches of bluefish had deleterious effects on shortfin mako biomass and yield. Conversely, bluefish biomass and yield were relatively invariant to changes to shortfin mako catches. Sensitivity analysis indicated consistency in model outcomes across a variety of model configurations; however, outcomes were deemed sensitive to the magnitude of bluefish consumption by shortfin mako. The results of this study are consistent with the need to identify key trophic linkages in developing approaches to ecosystem-based fisheries management.

 

FRIDAY, JANUARY 27, 2012

1:00pm

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/