SEMINAR: MBF602 STUDENT SEMINAR *FRIDAY* 4/6 @ 1pm---Rolando Santos & Steven Saul

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

 

MBF Student Seminar Series

 

Rolando O. Santos

Advisor: Dr. Diego Lirman

“Temporal and Spatial Dynamics Submerged Aquatic Vegetation Seascape in Biscayne Bay”

Habitat loss and fragmentation, which affect the ecosystem function and connectivity, have become important subjects of research in ecology.  Previous work has documented patterns of fragmentation of submerged aquatic vegetation (SAV) seascapes associated with water management practices that regulate freshwater discharges into littoral areas of Biscayne Bay. Due to the ecological importance of SAV communities, which serve as nursery habitats for fisheries species, it is important to identify temporal and spatial trends in SAV seascape loss and fragmentation. A historical change-analysis of SAV seascape characteristics of western Biscayne Bay was conducted here using aerial photographs from the 1930s to the present time. To assess the influence of water management practices on the SAV seascapes over decadal scales, fragmentation patterns were compared between areas adjacent and distant to freshwater canals. When SAV seascape metrics were compared between nearshore (0-200m from shore) and offshore (200-500m from shore) habitats, nearshore regions showed a linear increase in fragmentation over time. While SAV seascapes in areas distant from canals showed, on average, higher fragmentation levels, areas adjacent to canals presented larger variability and fluctuations in spatial changes (i.e., area losses and gains). These results suggest the most dynamic spatial changes in SAV seascapes have occurred closer to shore and freshwater canals. These findings provide historical baseline conditions of the spatial dynamics of SAV seascapes that can be used to document future impacts of management projects as part of the Comprehensive Everglades Restoration Plan.

 

Steven Saul

Advisor: Dr. David Die

“An Individual-Based Spatial Model to Evaluate the Effect of Fisher Behavior on Catch per Unit Effort”

Fisher’s decisions can influence the effectiveness of management measures as such decisions can allow fishers to dissipate the benefits of regulation.  Furthermore, these decisions determine the spatial and temporal locations of fishery-dependent observations.  In most stock assessments such observations are used to infer the abundance of fish populations and are essential in our efforts to understand the dynamics of fish stocks.  In order to understand some of the ways that fisher behavior can influence our perception of abundance, an individual-based spatial model of the reef fish fishery off of the West Coast of Florida was developed.  Results from the simulation model demonstrate that catch per unit effort (CPUE) is not always proportional to stock biomass and that CPUE standardization using our current statistical methodologies is not always effective at extracting relative biomass trends from CPUE.  Furthermore, although most stock assessments assume the spatial distribution of biomass across a management area to be stationary, simulation results show that changes in the spatial distribution of biomass can result from harvest occurring in particular locations and not randomly.  Such interaction between the spatial distributions of fishing effort and biomass can lead to situations where relative abundance indices derived from fishery dependent data provide a biased perception of trends in stock biomass.

 

 

Friday, April 6, 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/