SEMINAR: Re: MBF602 STUDENT SEMINAR *FRIDAY* 3/23 @ 1pm---Nathan Vaughan & Nancy Muehllehner

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

note the corrected date below
On 3/21/2012 5:04 PM, Pam Harris wrote:

MBF Student Seminar Series

 

Nathan Vaughan

Advisor: Dr. Jerald Ault

“Challenges in fitting annual non-equilibrium mortality estimates”

Since size of fish is a principal observation in fisheries monitoring, development of reliable length-based stock assessment methodologies has been of great interest for a long time in fisheries science, particularly for data-limited and tropical fisheries.  Previous research has been dedicated to the development of a zero-bias, non-equilibrium mortality estimator. Building upon the works of Ehrhardt & Ault (AE) and Gedamke & Hoenig (GH) with goal was achieved. Current model fitting approaches however are limited to a step change system applying large 3-5year blocks of equilibrium while maintaining a possibility of model selection through AIC ranking. To obtain the optimum benefit from this advanced estimator it would be ideal to develop a model fitting framework able to fit any mortality pattern that may be realistically expected. Through detailed stock simulation mortality scenarios of interest are highlighted; (1) the identification of sudden shifts (i.e. opening or closure of a fishery), (2) gradual mortality trending (i.e. increasing population size), or (3) unique anomalous events (such as a hurricane). Understanding the impact of these patterns and identifying them in real datasets will give us greater insight into the historical patterns driving stock structure as well as improve predictive power into the future. Through simulation model examples this presentation will focus on highlighting the unique challenges faced in attempting this approach, concluding with a proposed model fitting strategy which may provide a solution.  

 

Nancy Muehllehner

Advisor: Dr. Chris Langdon

“Symbiosis under Ocean Acidification: Coral-Zooxanthellae interactions from the field to the lab”

While much ocean acidification (OA) research focuses on the calcification response in biomineralizing organisms, recent attention has turned toward other important aspects of the biological response, such as marine symbioses.  In tropical stony corals, the root of their ability to calcify and survive lays in the symbiosis between the unicellular algae, Symbiodinium microadriaticum, and the scleractinian coral host cell, with up to 100% of daily carbon needs being provided to the host by its symbiont.  The effects of OA on zooxanthellae, both free-living and in symbiosis vary by symbiont clade (Brading et al., 2011) and across temperature stress (Anthony et al., 2008).  In collaborative work with Ross Cunning, I have found that symbionts respond uniformly in both the field, when exposed to decades-long acidification from CO2 vents in the South Pacific, and in the lab, after months-long acidification in our coral growth facility.  Symbiont density was found to be significantly reduced in 2 Pacific coral species in the field and declined consistently across CO2 levels in the lab along with chlorophyll a per cell in an Atlantic species.  These data indicate that the symbiont response to ocean acidification may play an influential role in determining the overall coral holobiont response to global climate change.

 

 

Friday, March 23, 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/