View Past Projects
The aereal extent of seagrass meadows has declined globally during the last several decades, with major losses of seagrasses reported along the Atlantic and Gulf coasts of the United States. The positive correlation between the area covered by seagrass and the production of valuable finfish and shellfish has led to a large number of studies designed to elucidate the causes of seagrass declines. Worldwide, the destruction and the loss of critical seagrass habitat are being attributed to both natural and human-induced disturbances. In many cases, deteriorating water quality, especially resulting from excessive nutrient inputs and turbid runoff, has been associated with seagrass loss. Reversing seagrass loss in these cases usually requires large scale changes in land use and water treatment.
Seagrass Restoration via Birdstakes
An increasing threat to seagrass is mechanical damage from motor vessel operation in shallow waters. This is a growing problem in most coastal areas as these areas are more frequently used for recreational activities. In Florida, and elsewhere in the Gulf of Mexico, physical damage by motor vessels is one of the most common human impacts to seagrass beds. Motor vessels are implicated in seagrass bed damage in a number of ways, including anchoring, propeller scarring, and large excavations caused by hull groundings. In 1995 it was estimated that 173,000 acres of seagrass beds in Florida were moderately to severely damaged by boat propellers and hull groundings (Sargent et al. 1995). Fortunately, reversing the seagrass loss in many of these cases can be done on a relatively small scale with public education and restoration (Kirsch et al. 2005; Hall et al. 2006).
Cost-effective techniques are needed to facilitate early intervention for the prevention of scar erosion to enhance seagrass restoration. Our fertilization technique utilizes a novel approach by providing nutrients derived from the feces of sea birds which are encouraged to roost on perches installed at the restoration site (Kenworthy et al. 2000, Hall et al. 2006). The bird roosting stakes are constructed of 1 in. PVC pipe with pressure treated 2 x 2 x 8 inch blocks glued to the top of the stakes. The stakes are pressed into the sediment so they are not submerged at high tide. Seabirds, primarily cormorants, terns, pelicans and blue herons, roost on the stakes and defecate nutrient rich feces which act as a passive fertilizer delivery system putting nutrients into the water and sediment surrounding the stakes.
1) The Nature Conservancy (Big Lagoon) 2011- 2012 – “Restoring turtlegrass (Thalassia testudinum) meadows after propeller damage using bird roosts as a passive fertilizer delivery system along the Northern Gulf Coast
2) Fish and Wildlife Service 2009-2011 – “Restoring turtlegrass (Thalassia testudinum) meadows after propeller damage using bird roosts as a passive fertilizer delivery system along the Northern Gulf Coast”
3) The Nature Conservancy (Rabbit Island) 2009-2011- “Seagrass Restoration and Protection in Florida and Alabama”
4) Gulf of Mexico Foundation (Robinson Island) 2006-2008 - Robinson Island Restoration and Protection
Seagrass Restoration via Seeds
Shoalgrass (Halodule wrightii) is known to produce copious amounts of seeds in the Gulf of Mexico, with estimates as high as 3000 seeds m-2 in some areas (McMillian 1981) with seeds shown to remain viable for as long as 3 years and 10 months (McMillan 1991). This suggests that substantial seed banks may exist and that seeds buried in local sediments remain viable for periods of nearly four years. To date, there is no study of which we are aware that has determined shoalgrass seed reserves in the northern Gulf. However, a recent paper has documented that around 8% of shoalgrass core samples near Bayou La Batre, Alabama contained developing fruits (McGovern and Blankenhorn 2007), thereby providing evidence that sexual reproduction is occurring in local stands of shoalgrass.
The primary goal of the proposed research is to determine whether there is a sufficient seed reservoir for both SAV species that could be harvested with minimal damage to existing meadows, and, if so, whether restoration by seed planting is a locally viable SAV restoration strategy in the northern Gulf of Mexico and Mobile Bay. The proposed work is largely unproven to date, but the critical need to develop alternative restoration techniques, instead of the highly damaging and usually ineffective transplant methods, means that new and innovative approaches to restoration must be developed and tested.
1) ADCNR – SAV Restoration of Halodule wrightii and Vallisneria americana via seed propagation
Recovery of seagrass and recolonization after losses are rare, and destruction of seagrass habitat may have long-term consequences for sediment stability and production of economically important finfish and shellfish (Williams and Heck 2001). For this reason, many coastal states with substantial seagrass resources assess the distribution and abundance of seagrass meadows annually.
We are carrying out an annual monitoring program, beginning in summer 2011, using a tiered monitoring approach to survey the seagrass resources in the Mississippi and Florida portions of the Gulf Islands National Seashore. The protocol is based on a hierarchical design in which “Tier I” monitoring includes aerial surveys, phtointerpretation, mapping and ground truthing. “Tier II” includes rapid assessment of the overall abundance and distribution of seagrasses, and “Tier III” includes long-term detailed monitoring at selected locations. Our effort is specifically for Tier II and Tier III work that is conducted during the summer when seagrass biomass reaches its annual maximum. Because Tier II monitoring is focused on seagrass percent cover and species composition, it has added value in providing ground-truthing data for Tier I as it becomes available from state or federal agencies. Tier III data are useful for evaluating the likely factors involved in explaining observed changes in seagrass maximum depth distribution, percent cover or species composition.
1) National Park Service- “Monitoring Seagrass Resources of the Gulf Islands National Seashore”
Habitat Connectivity of Nearshore Seagrass Beds and Offshore Fishing Grounds
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. But only a handful of studies have
attempted to determine how many of the juveniles of a species move successfully from putative
nursery habitats to adult habitats (e.g., Gillanders et al. 1996, Kraus and Secor 2005). The
evidence that supports successful movement of seagrass or wetland-associated juveniles to adult
habitats is largely indirect, both because such movement data are difficult to obtain and because
there has been a dearth of communication between benthic ecologists (who study nearshore
ecosystems) and fisheries biologists (who monitor adult stocks).
The nursery habitats for a species are those that are the most likely to contribute to future populations. This contribution should be a function of both the size and number of individuals added to adult populations, because both of these factors affect survival, growth, and reproductive success in the adult 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. Both the gray snapper (Lutjanusgriseus) and the gag grouper (Mycteroperca microlepis) are most commonly found in seagrass meadows
as early and late juveniles, while adults of both species are associated with hard substrates such as hard bottoms and coral reefs (Starck and Schroeder 1971; Rutherford et al. 1989, Koening and
Coleman 1998b). In addition, the elemental compositions of the otoliths of both species have been studied, and it is known that different populations of both juvenile gray snapper and gag can be identified by the unique chemical signatures in their otoliths (Lara et al. 2003, Hanson et al.2004).
1) USA Habitat Connectivity 2006 – 2009 “Estimating the relative importance of northern Gulf nursery habitats to adult fish populations: studies of gray snapper (Lutjanus griseus) and gag grouper (Mycteroperca microlepis)”
2) NOAA MARFIN – “Nursery origins of adult gag grouper, gray snapper, and lane snapper from the northern Gulf of Mexico: onshore-offshore connectivity of reef fishes and contribution of seagrass meadows to fishery production”
Climate-mediated ichthyofaunal shifts in the northern Gulf of Mexico: implications for estuarine ecology and nearshore fishery production.
Recent increases in global temperatures are expected to drive concurrent changes in the composition and ecology of terrestrial and marine communities worldwide. Thererefore, information on the effects of climate change on marine ecosystems has been repeatedly identified as being critical for the proper implementation of adaptive, ecosystem-based management. However, few studies have quantitatively linked effects of climate change with shifts in regional fishery production. Recently, Fodrie et al. (2010, Global Change Biol) quantified changes in fish assemblages within seagrass meadows of the northern GOM between the 1970s and 2000s, and found that several tropical snapper, grouper and parrotfish species have become significantly more abundant over the last 30+ years. For instance, Lutjanus synagris (lane snapper) was entirely absent three decades ago, but is now the 8th most abundant seagrass-associated fish. L. griseus (gray snapper, now 7th most abundant), Mycteroperca microlepis (gag grouper, now 17th most abundant) and Nicholsina usta (emerald parrotfish, now 23rd most abundant) have also greatly increased.
Coastal seagrass meadows are well known to provide critical nursery habitat for many juvenile fishes and crustaceans that ultimately recruit offshore to highly valuable fisheries (Heck et al. 2003, MEPS). Therefore, there is a pressing need to explore how the changes documented by Fodrie et al. (2010) might affect seagrass nursery habitats in the northern GOM, as well as the very large fishery production that is ultimately and inextricably linked to this iconic nearshore habitat. Doing so is a necessary first step that will assist in the wise management of Essential Fish Habitat as climate continues to evolve.
Therefore, we are addressing the following 2 overarching questions: 1) how have climate-related changes affected the contribution of seagrass nurseries to economically valuable adult populations of snappers and groupers, as well as to endemic red drum and spotted sea trout; and 2) how are food webs in seagrass nursery habitats functioning in response to increases in tropical fish species? To answer these questions we are using both observational (population level) and manipulative (food-web level) approaches.
1) MSU/NGI Estuarine Ecology (Species Shift) –“ Climate-related ichthyofaunal shifts in the northern Gulf of Mexico: implications for estuarine ecology and nearshore fisheries.”
Shoreline Stabilization via Oyster Reef Restoration
Coastal and shoreline habitats like salt marshes, oyster reefs, and seagrass meadows protect coastal lands from waves and storms, provide shelter and food for many marine organisms, and supply food, occupation, and recreation for human societies. Unfortunately, many of these habitats are also among the most degraded and threatened habitats in the world because of their sensitivity to sea level rise, storms, and increased human utilization. Many previous efforts to protect shorelines have involved the introduction of hardened structures, such as seawalls, rocks, or bulkheads to dampen or reflect wave energy. A major concern in implementing bulkheads and seawalls for coastal property protection is that many nearshore habitats are damaged and destroyed because erosive wave energies are reflected back into the water body, instead of absorbed or dampened. Mobile Bay, like many other coastal areas, is highly developed with a large and increasing proportion of the shorelines armored by bulkheads and seawalls.
At last analysis in 1997, over 30% of the bay’s available coastline was armored with over 10-20 acres of intertidal habitat lost, a high percentage in this microtidal bay. A recent study found that historical armoring and marsh-edge losses have already had negative fisheries consequences, and projected further reductions of blue crab harvest if armoring continues. Recently, a growing initiative for sustainable shoreline protection has focused on balancing effective protection and habitat creation by a variety of new methodologies collectively termed “living-shorelines”. Wave-reducing breakwaters are becoming an increasingly common along sheltered coastlines and are proclaimed by many as a more responsible alternative to traditional shoreline armoring; however, their effectiveness or ecological impact is largely untested.
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.
1) USA Alabama Oyster Reef Restoration Program and Northern Gulf Institute (2006-2008) – “Restoring estuarine landscapes in Alabama coastal waters through creation of oyster reefs”
2) The Nature Conservancy/ Mobile Bay NEP (2008-2009) “ Shoreline stabilization and habitat restoration at Helen Wood Park, AL “
3) ADCNR Breakwater – “Dauphin Island Sea Lab Finfish and Shellfish Nursery Habitat Restoration Project”
4) TNC/NOAA-ARRA ( Stimulus) (2009-2012)-“Coastal Alabama Economic Recovery and Ecological Restoration Project: Creating jobs to protect shorelines, restore oyster reefs and enhance fisheries production”
Oyster Reef Restoration
Oyster production in Mobile Bay is influenced by several physical, chemical, and biological factors including water quality, storms, disease, predation, overharvest, and the occurrence of low oxygen (hypoxia) or no oxygen (anoxia) events in the near-bottom waters. Hypoxic and anoxic events frequently occur within Mobile Bay waters and can have profound impacts on numerous fisheries species.
During these events, the dissolved oxygen in the water column becomes low enough to stress many organisms, and occasionally this results in the mass shoreward movement of fish and mobile invertebrates, locally-termed “Jubilees”. These low oxygen events are equally stressful for many sessile invertebrates, such as oysters, that have no means to escape the poor water quality. This has posed a challenge for many restoration efforts since most attempts have focused on maximizing acreage at the sacrifice of reef height. Recent research has shown that taller oyster reefs (greater vertical relief) have higher oyster recruitment and persist longer than short reefs, especially in areas that experience prolonged periods of low oxygen. However, it was previously unclear how reef height could affect the entire oyster reef community.
The habitat and feeding grounds for many fish and invertebrates provided by oyster reefs are among the many ecosystem services they provide. Recently, restoring reefs for ecosystem benefits has become popular in many coastal systems like Mobile Bay. It is important that future efforts to create or restore oyster reef habitat understand how reef design (i.e. reef height) and reef location can influence not only the success for the oysters, but also the nearby community of fish and invertebrates.
1) USA Alabama Oyster Reef Restoration Program (2004-2007) –“Quantifying fisheries benefits of oyster reef restoration in Mobile Bay”
Ecosystem Services of Oyster Reefs
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.
1) USA Alabama Oyster Reef Restoration Program (2004-2008) “Ferry Marsh and Little Dauphin Island tidal creek reefs – Ecosystem Services Provided by Oyster Reefs: An Experimental Assessment”
Fisheries Oceanography of Coastal Alabama (FOCAL)
The Dauphin Island Sea Lab (DISL) initiated the Fisheries Oceanography of Coastal Alabama (FOCAL) program in November 2006 with the support of the Marine Resources Division (MRD) of the Alabama Department of Conservation and Natural Resources (ADCNR). The goal of FOCAL is to collect fisheries-independent data in support of ongoing DISL fisheries research and ADCNR management goals. Further, data are collected with respect to ecosystem-based fisheries management considerations to include:
1) information on the early stages of marine fishes (eggs and larvae) and their zooplankton predators and prey (seasonality, abundance, vertical distribution, across- shelf distribution and assemblage composition);
2) physical characterizations of the offshore, coastal and Mobile Bay environments (water column stratification, temperature, salinity, current velocity and direction); 3) seasonal-scale information on the benthic habitats and associated macrofauna on the Alabama shelf (abundance, distribution, seasonality and assemblage composition);
A secondary goal includes process studies to 1) test specific hypotheses about biological-physical coupling and 2) target specific taxa of interest.
Our current FOCAL study involves using red drum early life history indices to evaluate relationships between larval abundance at ingress to estuarine waters and postsettlement juvenile abundance in seagrass meadows of Mississippi Sound.
Deepwater Horizon Oil Spill Work
1) GUIS Oil Spill Seagrass Survey – “Potential Peterochemical Damage Assessment of Seagrass Resources of Gulf Islands National Seashore from Mississippi to Florida”
2) Baldwin Co. Prespill Beach Survey
3) MSU/NGI Rapid Oil Spill (2010- 2011) – “Potential impacts of the DwH oil spill on fishery resources: will there be reduced recruitment of economically important shrimp, crabs, and finfish in seagrass and marsh nursery habitats of the north central Gulf of Mexico?”
4) BP Oil Spill (2011)- “Impacts of the Deepwater Horizon oil releases on the functional integrity of salt marshes and seagrass meadows and associated fauna”