SEMINAR: MBF602 STUDENT SEMINAR: TODAY @ 1PM----KRISTINE STUMP & ROSS CUNNING

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

 

MBF Student Seminar Series

 

Kristine Stump

Advisor: Dr. John McManus

“Hunted hunters: an experimental test of the effects of

predation risk on juvenile lemon shark habitat use”

 The effects of predation on a species occur either directly, through consumption, or indirectly as risk effects.  Risk effects arise when prey alter their behavior in an attempt to decrease encounters, detection and/or capture.  Often, a perceived predation threat leads to risk effects which manifest as changes in habitat use by the prey species, and these effects can be significant and even greater in consequence than direct effects.  In Bimini, Bahamas, neonate and juvenile lemon sharks (Negaprion brevirostris) use mangrove-fringed shorelines as nursery areas in part due to the protection afforded from predators, namely larger conspecifics.  We investigated the small-scale use of mangrove structure by neonate and juvenile lemon sharks as an anti-predatory response to predation risks.  Controlled experimental trials were conducted on captive sharks to assess the degree of the sharks’ use of artificial mangroves when solitary, with a size-matched conspecific and with a potential predator (subadult conspecific).  Results showed a significant increase in use of artificial mangroves when in the presence of a potential predator as compared to when with a size-matched conspecific.  In addition, a significant negative correlation was found between body size and the use of artificial mangrove structure when in the presence of a potential predator, indicating that size is an important factor in anti-predatory behavior.  

 

Ross Cunning
Advisor: Dr. Andrew Baker
“The implications of areal versus cell-specific symbiont density measurements in the study of coral-algal symbioses”

  Most studies that quantify the dinoflagellate algal symbionts of reef corals (Symbiodinium spp.) have estimated symbiont densities by counting the number of algal cells isolated from a known surface area of coral tissue, producing an areal density measurement. In contrast, new real-time PCR techniques allow symbionts to be enumerated on a cell-specific basis by quantifying the total number of symbiont and host cells present in a DNA sample and calculating a symbiont to host cell ratio. This technique and its resulting cell-specific density measurements offer a number of advantages to researchers studying coral symbiont communities, but may produce results that are very different from those obtained by areal density measurements. In fact, I propose that the two metrics may reveal opposite but reconcilable trends in seasonal symbiont density changes. Here, I explore the differences between cell-specific and areal measurements of symbiont density and their implications for the study of symbiont community dynamics and coral bleaching. I argue that normalizing the number of symbionts in a coral to the number of host cells rather than a fixed unit area provides a more relevant description of the physiological status of the symbiosis.

 

 

WEDNESDAY, NOVEMBER 30, 2011

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/