Contact Us

The University of Texas
Marine Science Institute
750 Channel View Drive
Port Aransas, TX 78373
Phone: 361-749-6711

Maps & Directions

The fish ecology group at the Fisheries and Mariculture Laboratory (FAML) investigates a range of fundamental ecological questions. Our aim is to understand individual and population level processes that influence resilience of fishes in the face of changing environmental conditions. We conduct experiments in the laboratory to identify mechanisms driving ecological dynamics and investigate wild populations to assess variability in both individual traits and population fluctuations. To answer these questions, we employ state-of-the-art analytical techniques, such as geochemical markers in fish tissues and hard parts, as well as traditional ecological assessment methods. Much of this work with geochemical markers is done in close collaboration with investigators at the University of Texas Jackson School of Geosciences, which houses a range of analytical instrumentation including laser ablation ICP-MS and isotope ratio mass spectrometers.

Migration & Behavior

Individual variability in early life history traits and migratory movements can have profound effects on the structure and stability of populations. This variation can allow populations to persist in the face of environmental change by providing a portfolio of strategies that are best suited to different conditions. We investigate variation in these migratory and behavioral traits in a variety of projects:

DIADROMY

Many fishes move between fresh and marine waters at some stage of their lives. While the spectacular migrations of salmon receive much attention, the extent to which other species use low salinity and freshwater habitats is often poorly understood. We use high precision laser-based geochemical techniques to identify lifetime patterns of migrations across salinity gradients using microchemical compositions of fish hard parts such as their otoliths (“ear stones”). We therefore can quantify the presence, duration and frequency of these migrations to understand variation in migratory behavior and habitat requirements at various life history stages. We are currently using this method with a variety of species, including southern flounder (Paralichthys lethostigma) and common snook (Centropomus undecimalis) in the Gulf of Mexico and barramundi (Lates calcarifer) in northern Australia.

EARLY LIFE HISTORY

Mortality rates during the larval period are extremely high in marine fishes, normally more than 90%. Small variations in mortality rates during early life can have profound effects on year-class strength and population size. This is the foundation of our work in larval fish ecology, which seeks to understand the mechanisms of larval mortality and the effects of internal and external changes. We measure performance fish larvae in terms of ecologically meaningful traits or “survival skills,” such as the timing and magnitude of escape responses and foraging rate, and compare performance through ontogeny and in response to a variety of environmental and physiological conditions to understand how the capacity of larvae to survive is affected.

Trophic complexity

The function and positioning of fishes in marine food webs is an essential component of marine ecosystems dynamics. We aim to understand the importance of diet composition, quality, and nutrient cycling on the survivability and resilience of fishes, particularly those species that undergo ontogenetic niche shifts during their lifetime.

ESTUARINE & OCEANIC COUPLING

Fishes that migrate between the oceanic and estuarine habitats can act as conduits that transport nutrients and therefore provide external subsidies to local systems. Many of these movements take place at specific life history stages, for instance ontogenetic migrations from juvenile estuarine nursery habitats out to offshore habitats where adults may spawn. We are investigating the patterns of participation in estuarine and oceanic food webs using stable isotope tracers coupled with otolith chemistry and traditional mark-recapture techniques. Current study species in the Gulf of Mexico include Atlantic croaker (Micropogonias undulatus) and Atlantic tarpon (Megalops atlanticus). 

ADULT DIET & EGG QUALITY

To complement our eco-physiological studes on the role of certain fatty acids in larval escape responses (see Nutrition and Larval Success under Physiology), we are assessing temporal and geographic variability in the fatty acid profiles of field-collected red drum eggs.

Nursery habitats

The habitats in which fishes live during their earliest life history stages act as nurseries that can promote growth, development and survival. We examine the interplay between nursery habitat dynamics and fish performance at both the individual and population level in a variety of contexts.

HABITAT QUALITY

Estuaries serve as nurseries for a large number of species and yet they are subject to dramatic fluctuations in environmental conditions. Subtropical systems in particular experience significant shifts in salinity, dissolved oxygen and pH on time scales ranging from daily and seasonal to interannual and decadal. The ability of estuaries to serve as effective nurseries can change with these shifts in environmental parameters. We are using a combinatorial approach to assess fluctuations in habitat quality and the responses of individual fish and populations. This approach involves reconstructing temporal patterns in environmental fluctuation from geochemical proxies in stationary organisms (e.g. oysters, corals) in coastal habitats and comparing these time series to fluctuations in populations of both mobile and stationary fishes.

CONNECTIVITY

The field of fish connectivity has grown exponentially in the past decade, yet fundamental questions driving observed patterns remain. Although techniques such as otolith chemistry and genetic parentage analysis can identify sources and sinks of individual fishes, the mechanistic reasons behind the patterns are not clear. We are pursuing projects that ask to what extent biological and environmental qualities of nursery habitats promote or inhibit connectivity on local and regional scales. Unraveling the linkages between habitat quality parameters and connectivity patterns is essential for spatially explicit management strategies such as Marine Protected Areas.  

Investigators

More about our research:

 

 

sideart ecology1

sideart ecology2

sideart escape

sideart ecology4

sideart ecology3