Our Research

The FEED lab will focus on topics such as fish life history, phenology, and habitat in the context of their management as living resources. All topics will include aspects of engaging and educating fishery stakeholders in the northern Gulf of Mexico.

Estuarine Life-History using Otolith Chemistry

Otoliths, or “ear stones”, are anatomical features of bony fishes that aid a fish as it moves in three dimensional space through the water column. The growth of otoliths mirrors the somatic growth of the fish. For fish that live in temperate environments, growth is driven by season – with rapid growth in the summer and slow growth in the winter. These periods of variable growth result in rings (like those in trees) inside of the otolith which allow us to age fish based on the number of pairs of rings. Additionally, otoliths incorporate the chemistry of the environment that the fishes occupy making them reliable indicators for changes in movement as fishes move through water with different chemistry (for example fresh water and salt water).

Sex Specific Differences in Habitat Usage for Spotted Sea Trout in a Dynamic Estuary:

Spotted seatrout inhabit estuaries throughout their life history and have been observed to exhibit sex specific habitat usage in telemetry studies and gillnet surveys (Callihan et al. 2013, 2015). Although telemetry studies and gillnet surveys provide excellent sources of information they are temporally and spatially limited. Through otolith microchemistry we are able to identify temporal patterns in habitat usage as it relates to salinity throughout an individuals complete life history. These patterns are then able to be related to age, growth, sex, and seasonality. Quantifying these patterns informs Essential Fish Habitat for this highly sought after game species.

Healthy Habitats and Healthy Fisheries

Healthy fisheries rely on healthy habitats. Fish do not live in a bubble – they rely on a wide variety of resources to survive and thrive, including food and refuge from predators. Healthy habitats provide these resources to faunal communities in many ways, several of which are poorly or misunderstood. Our lab focuses on the interactions between the community and relative abundance of fish across multiple marine and estuarine habitats.

Impacts of Estuarine Habitat Restoration on Fish and Invertebrate Communities in Coastal Louisiana:

To combat estuarine saltmarsh loss throughout Louisiana, restoration projects have been conducted to rebuild the marsh protect the marsh from further eroding. Following these projects, our lab seeks to understand now the local abundance and community of fish and invertebrate species may change in these now-altered habitats. We use numerous fisheries independent sampling gear types (i.e. longlines, gillnets, throw traps, seines) to get a thorough picture of species dynamics across a range of feeding types, body sizes, and habitat use in the ecosystem.

Hydrology, Inundation, and Nursery Habitat in Restored Coastal Marshes:

Coastal marsh restoration aims to rebuild wetlands that provide essential nursery habitat for fish and invertebrates, but creating marsh does not always guarantee suitable habitat. The timing, duration, and frequency of flooding influence how organisms access the marsh, while prolonged inundation can lead to hypoxia and other stressful environmental conditions. This project investigates how hydrology, inundation patterns, and water quality vary across restored marshes in coastal Louisiana and how these factors influence nekton communities. By pairing continuous environmental monitoring with seasonal fisheries sampling, this research evaluates whether restored marshes are functioning as productive nursery habitats and identifies the environmental conditions that promote ecological success.

Phenology of Fish Movement and Fishery Recruitment

Phenology is the rhythm of the natural world. As the year moves on, we see ecological and biological changes driven by seasonal changes in temperature, weather, and light. Evolutionary, marine fish have developed cues on when to move and spawn based on these changes in seasons. However, as the climate on our planet changes, migratory and reproductive cues tied to temperature and weather may come at a different time than they have historically. These differences in timing may alter the behavior of fish and result in ecological match and mismatches resulting in population-level effects. Our lab works to understand the role that phenology plays in the life histories of marine fish and how environmental changes may alter those life histories. Recently, our lab has begun to focus on the phenology of recruitment of estuarine fishes, and how over decades the phenology of some species have changed – and others have stayed the same.

Movement Ecology of Fishes

Understanding movement ecology is essential for understanding how marine and coastal fishes use habitats, access critical resources, and respond to changing environmental conditions. By identifying movement patterns, migration routes, and habitat connectivity, researchers can better assess the impacts of human activities, habitat loss, and climate change on fish populations. This knowledge supports effective conservation strategies, sustainable fisheries management, and the protection of ecologically important habitats throughout the region.

Movement Ecology of Estuarine Fishes in Restored Habitats:

Restored marshes and living shorelines are designed to enhance habitat for estuarine fishes, but little is known about how fish actually use these restored environments. This project uses acoustic telemetry to track the movements of estuarine fishes and quantify habitat use, residency, and connectivity among restored shorelines and surrounding habitats. By linking fish movement patterns with environmental conditions and habitat characteristics, this research provides insight into how restoration influences the behavior of mobile species and helps determine whether restored habitats function as important feeding, refuge, or nursery areas for coastal fisheries.

Study of Harmful Algal Blooms

Many coastal regions within the U.S. are impacted by an array of algal toxins, with production of multiple toxin classes overlapping in space and time. Algal toxins, also known as phycotoxins, are potent toxins produced by marine and freshwater microalgae (dinoflagellates, diatoms, and cyanobacteria) during blooms. Impacts to humans include amnesic, diarrhetic, hepatotoxic, and azaspiracid shellfish poisoning, symptoms of which range from gastrointestinal distress to neurological impairment. Impacts on estuarine organisms include reduced growth rates and documentations of large mortality events.

Persistence and trophic transfer of algal toxins in benthic-pelagic coupled food webs

Freshwater and marine phycotoxins converge, as tributaries carrying upstream harmful algal blooms (HABs) empty into productive transition zones that harbor other toxigenic species associated with higher salinities. These freshwater and marine phycotoxins have the potential to co-accumulate in primary consumers of ecological and commercial values, and higher trophic level species. The food-web dynamics and toxicokinetics responsible for the accumulation and persistence of toxins are largely unknown, especially in the benthic-pelagic coupled food webs of Gulf Coast estuaries. To understand the co-accumulation of marine and freshwater phycotoxins, current research in Barataria Bay, LA includes seasonal collection of water, sediments, and estuarine organisms to quantify phycotoxins across feeding strategies, habitats, and trophic levels between benthic and pelagic food webs. Additional research includes an intense, focused field study to assess the persistence of phycotoxins in the water column, sediments, and estuarine organisms. Documenting and quantifying phycotoxin patterns in Barataria Bay, LA will inform management strategies and enhance ability to respond to future HAB outbreaks.