Research Highlights


Southern flounder

Populations of southern flounder (Paralichthys lethostigma) in Texas have declined dramatically over recent decades, pointing to the need to understand habitat requirements at critical early life history stages. This project will examine low-salinity habitat use and movements of post-settlement juveniles using a combination of stable isotope and elemental otolith signatures. This work focuses on southern flounder populations in the Nueces and Aransas-Copano bay systems in Texas.


Sectioned otolith

Juvenile flounder

Water sampling

This project is being carried out by Megan Nims as part of her Masters thesis research and is funded by Texas Sea Grant.


Barramundi

Variation in within-river habitat use and migration patterns is an important yet poorly understood component of diadromous life history patterns. This project focuses on the catadromous barramundi (Lates calcarifer) in the Victoria River, Northern Territory, Australia. This river is nearly 800 km long and unregulated, allowing a unique opportunity to assess habitat use and spawning frequency in a minimally-impacted system. We have used a combination of elemental and isotope ratios to track movement between fresh and marine habitats as well as specific regions within the river to comprehensively characterize habitat requirements. 

    

Barramundi habitat
 
Lasering otoliths

This work is in collaboration with Dr. Malcolm McCulloch (University of Western Australia) and Dr. Tim Dempster (University of Melbourne). 

Work from this project has been published in PLoS One (DOI: 10.1371/journal.pone.0018351)

GBR damselfish & coral skeletons 

Geochemical records in biogenic carbonate skeletons in hermatypic corals have long been used to reconstruct variation in environmental parameters such as temperature, salinity and nutrient availability. This project is investigating temporal variability in proxies such as Ba/Ca in otoliths of a site-attached damselfish species (Acanthochromis polyacanthus) and Porites coral skeletons from inshore and offshore locations on the Great Barrier Reef. Coupled with long-term water sample analyses, these records will allow us to investigate temporal variation in freshwater flood pulses and upwelling events in coral reef habitats.

Extracted coral core  X-ray of coral slice  Sailing on the GBR

This work is in collaboration with Dr. Mike Kingsford (James Cook University) and Dr. Malcolm McCulloch (University of Western Australia) and funded by the Australian Research Council.



American shad


Population mixing in the marine environment is notoriously difficult to quantify, and otolith natural tags have allowed unprecedented insight into stock-specific distributions. Anadromous fish species are ideal candidates for these investigations because freshwater chemical signatures tend to be geographically distinct at finer spatial scales than those in the marine environment. This ongoing work draws upon a large database of ground-truthed natal signatures from 20 natal rivers across the native range of American shad (Alosa sapidissima). These signatures are now being used to identify origins of immature migrants captured in marine environments and compare those with previous mark-recapture results from adult migrants.


American shad


Weir in Minas Basin


This work was done in collaboration with Dr. Simon Thorrold (Woods Hole Oceanographic Institution) and was funded by NSF.  Publications from this project can be found on the Lab Publications page.