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"Restoring estuarine landscapes in Alabama coastal waters through creation of oyster reefs"

Funding Agency: National Marine Fisheries Service
PI: Ken Heck
Co-PI: Sean P. Powers

This project is designed to examine the potential benefit of restoration of shallow subtidal oyster reefs on adjacent nearshore habitats located at Point aux Pines and in the vicinity of Alabama Port, by examining whether such habitats will (1) result in fisheries enhancement; and (2) facilitate the maintenance and expansion of other biogenic habitats, by addressing the following four objectives:

1. documenting changes in the physical setting of study sites resulting from the addition of oyster reefs.
2. quantifying oyster recruitment and adult density in created nearshore reefs.
3. quantifying primary and secondary producers within subtidal and intertidal habitats between created oyster reef and shoreline.
4. quantifying juvenile and adult fish and mobile invertebrate utilization of created oyster reefs and adjacent habitats.

Project status: Reefs were created in Summer and Fall 2007 and field work is ongoing.

"Estimating the relative importance of northern Gulf nursery habitats to adult fish populations: studies of gray snapper (Lutjanus griseus) and gag grouper (Mycteroperca microlepis)"

Halting the decline or facilitating the restoration of nearshore habitats will require an improved method of prioritizing where to spend limited time, money, and effort. One problem in setting priorities, however, is that the concept of nursery habitat has rarely been defined clearly, even in research studies that purport to test it. Most studies of the nursery-role concept have focused on seagrasses or wetlands and examined the effects of these habitats on one of three factors: the density, survival, or growth of juveniles. Generally, an area has been called a nursery if a juvenile fish or invertebrate species occurs at higher densities, avoids predation more successfully, or grows faster there than in other habitats. There are very few studies on movement patterns of individuals from potential nurseries to adult habitats, and this is a vital missing link in our understanding of nurseries. Movement of individuals is one of the most difficult variables to measure in ecology. Fortunately, vast improvements in technology -- archival data loggers, stable isotopes, genetic markers, and otolith microchemistry -- now enable researchers to track and infer movements.

Using two species of commercial/recreational significance, we will attempt to elucidate habitat connectivity of relevance to Alabama coastal fisheries by:

1. Quantifing the abundances and growth rates of juvenile gray snapper and gag found in nearshore seagrass meadows of the northcentral Gulf of Mexico. This will be accomplished by trawling to measure local abundances in seagrass meadows, and analyzing otolith growth bands to estimate growth rates.
2. Using the saggital otoliths of juvenile gray snapper and gag collected in 2006 and 2007, analyzed via Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA ICPMS), to create a “reference library” of characteristic trace element signals for potential nursery seagrass beds.
3. For 1- and 2-year-old individuals collected during 2007-2009, sample the rings deposited during the first year of the fish’s life that can be compared to the signals from 2006-2007 juveniles to infer the nursery habitat origin of each individual fish.
4. Coalesce data to determine the nursery “value” of seagrass beds in the northern Gulf in terms of contribution to overall fishery production for these species.

Project status:  Field work is ongoing.

"Robinson Island Restoration and Protection"

Project status:  Field work ended in August 2007.  Sample and data analysis is still ongoing.

"Ecosystem Services Provided by Oyster Reefs: An Experimental Assessment"

Funding Agency: National Marine Fisheries Service
PI: Ken Heck
Co-PI's: Just Cebrian, Sean P. Powers

Oyster reefs provide numerous important ecosystem services that are only now becoming well documented.  Through their filtration activities, oysters remove sediments, phytoplankton, and detrital particles, thereby reducing turbidity and improving water quality.  Thus, oysters and other suspension-feeding bivalves may counteract impacts of estuarine eutrophication.  Through their removal of organic particles in the water column, oysters divert energy to benthic food chains and depress pelagic energy flows that may lead to noxious sea nettles.  Oyster reefs also serve as important biogenic habitat for benthic invertebrates as well as fishes and mobile crustaceans.  This recognition of oyster reefs as providers of important ecosystem services, rather than merely a commodity to exploit, coupled with the dramatic depletion of oyster reefs in many estuaries of the southeast US has prompted increased efforts to restore and/or enhance oyster reefs in many estuarine systems. 
This project investigates and quantifies the potential of oyster reefs to positively change water clarity, benthic primary production and secondary production, and the nursery value of marsh creeks around Dauphin Island and Little Dauphin Island.  By employing a Before-After-Control-Impact Paired (BACI-P) design beginning in the Summer of 2004, we have begun to specifically address each point in the overall hypothesis. 

1.  quantify and monitor the abundance of water-column suspended solids, and nutrients imported into and exported out of the marsh creeks,
2.  quantify and monitor the abundance and productivity of phytoplankton, benthic micro- and macroalgae, and macrobenthos,
3.  quantify and monitor species number, densities and secondary productivities of infaunal and benthic macrofaunal communities,
4.  quantify and monitor relative abundances of juvenile and adult fish and mobile invertebrates.

Ultimately, the results of our study will assist in providing the conceptual and empirical basis to make realistic predictions of ecosystem benefits resulting from oyster reef restoration.

Project status:  Field work ended in August 2006.

Publications: Geraldi, N. R., S. P. Powers, K. L. Heck, Jr. and J. Cebrian. (In review). Can habitat restoration be functionally redundant for fish? Response of transient fish and crustaceans to oyster reef restoration in tidal creeks. Marine Ecology Progress Series.