NOAA Great Lakes Environmental Research Laboratory Predator-Prey Interactions in the Gulf of Mexico Project

Sponsors:
Florida Sea Grant (Florida Sea Grant web site)
National Marine Fisheries Service, Marine Fisheries Initiative-MARFIN

Rationale: The Sustainable Fisheries Act of 1996 (+ read act posted on NMFS web site)and the amended Magnuson-Stevens Fishery Conservation and Management Act (+ read act posted on NMFS web site) elevated habitat and conservation as priorities in federal fisheries management. The importance of habitat in individual growth processes, population dynamics, predator-prey dynamics, etc. has long been accepted, but, in most cases such habitat relationships have not been known with sufficient mechanistic and quantitative detail to aid the evaluation of proposed management options. Gag grouper (Mycteroperca microlepis) is one such fishery. Gag grouper is among the most valuable

fishes in the SE United States (1998 ex-vessel value=$4 million; commercial landings=1.76 million lbs., recreational landings = 3.8 million lbs.). The gag fishery is presently under intense management scrutiny and is a priority for federal fisheries research related to essential fish habitat. To date, experimental studies of reef habitat have determined that juvenile-to-adult gag prefer large patch reefs but grow better on small ones. Our project simply asks why? Is it a supply-demand issue (e.g., per capita prey availability) mediated by habitat or is it complicated by density-dependent interactions (e.g., interference, social behavior) that either decrease consumption rates (i.e., decrease foraging efficiency) or increase metabolic costs at high gag densities? (Fig. 1) Answers to such questions are essential if we are to predict the effects of management options involving reef habitat and fish densities.

Conceptual model of habitat-mediated predator-prey interactions and predator growth rate where H is non-consumable habitat (patch reef size), NPREY is prey density (pelagic planktivorous fishes), NPRED is predator density (gag grouper), C is predator consumption rate, R is predator energetic costs and G is predator growth rate. Parentheses represent functions (hypotheses) that define linkages between boxes. (A) Prey density as a function of habitat NPREY = NPREY(H) (note- NPREY may also be dependent on predator consumption). (B) Predator density as a function of habitat NPRED = NPRED(H). (C) Predator-prey interactions, resulting in predator consumption, as a function of prey density and predator density C = C(NPREY(H), NPRED(H)). (D) Predator density dependent energy expenditure R = R(NPRED(H)). (E) Predator growth rate as a function of prey density and predator density as determined through predator consumption and predator energetic costs and mediated through habitat- G = G(C(NPREY(H),NPRED(H)), R(NPRED(H)).

Objective: Our overall objective is to quantify the linkages between essential habitat, prey fish availability (anchovies, sardines, scad, herring) and gag grouper growth and condition on shallow patch reefs (experimental and natural) in the eastern Gulf of Mexico using an energy-balanced bioenergetics approach (growth = food ingested minus metabolic expenditures) and hydroacoustics.

Methodology: Hydroacoustic surveys will quantify pelagic prey fish at replicate patch reefs. Visual censusing will quantify gag grouper densities at the sites. Food consumption will be determined by integrating: a) diel feeding pattern; b) food evacuation rates from stomachs; c) diet composition; d) original weight of ingested prey; e) conversion of prey weight consumed to gross energy consumed; and f) calculation of daily gross energy intake for gag using an appropriate consumption model. Gag lengths and weights will be measured, and relative weights calculated. Otolith analyses, supplemented with mark re-capture, will estimate recent growth. An energy-balanced bioenergetics approach will determine if growth is governed by food availability or density-dependent metabolic costs. All this will be done in the context of a large-scale experimental reef system containing patch reef habitat of various sizes, and allow direct comparisons to natural reef habitat.

2005 Plans

This year, we will focus on objective 1-- estimate annual variability in daily ration, prey fish abundance, and gag abundance, growth and condition as a function of patch reef size. We will locate and map various reef habitats along a gradient of reef architectures in the Steinhatchee River and the Suwannee River regions in the northeastern Gulf of Mexico (Fig. 1). To locate reefs, we will use existing records of reef habitat from surveys conducted by Lindberg, Murie and Frazer over the past 18 years, and also rely on personal communication with fishers, researchers, and other organizations to provide sampling sites with the widest possible range of reef architectures. At each reef location, divers will measure cavity volume, vertical relief (profile) in both the upward (e.g., pinnacle structure, ledge) and downward (e.g., sinkhole) directions, and size. In addition, presence absence of pelagic prey fish schools and a general description of bottom flora and fauna will be noted. Cavity volume will be estimated by measuring internal dimensions and making the appropriate calculations. Vertical relief will be determined by measuring from the sand substrate to the top or bottom of the feature, with direction of relief indexed by “- ” for down (e.g., sinkhole) or “+” for up (e.g., pinnacle or ledge). For reef size (m2), divers will first estimate a general geometry (e.g., square, oval, etc) and the appropriate dimensions will be measured and area calculated. In addition, we will survey the immediate area surrounding each reef with sidescan sonar (Edgetech dual frequency –100, 350KHz system) for a second measure of reef size and to locate and map nearby reef habitat (e.g., habitat mosaics). Sidescan data will be processed using SonarWeb (http://www.chesapeaketech.com/) for bottom mapping and reef area estimates.

Reef architecture will be categorized using multivariate statistics (e.g., principle components analysis, multidimensional scaling) to identify clusters of similar reef types. Each cluster will be classified as a particular reef architecture type. We expect that certain well-known reef formations will emerge from this analysis, such as reef pinnacles, ledge formations, low-relief hard-bottom, sand veneer with sparse hard bottom patches, and sink holes. Information on reef size and classification will be incorporated into a GIS framework. We expect to locate and quantify a sufficient number of reef sites to provide a gradient of reef architectures with sufficient replication (e.g., N = 40-60 sites, n = 4-6 sites per reef type per study region) for a stratified random sampling design for Objectives 2 and 3.

Figure 1. Study areas in the northeastern Gulf of Mexico, adjacent to the Steinhatchee River (northern rectangle) and Suwannee River (southern rectangle). The southern area contains much of the Suwannee Regional Reef System, while the northern area includes a planned large-scale reef project.

2004 Accomplishments

Objective 1: To estimate annual variability in daily ration, prey fish abundance, and gag abundance, growth and condition as a function of patch reef size.

Objective 1A: Daily Ration (Consumption):
In total, 290 gag were captured for food habit analysis in August to November of 2002 and 2003, with 153 gag sampled from 4-cube arrays (55 from 25-m spaced arrays and 98 from 225-m spaced arrays) and 137 gag collected off of 16-cube arrays (54 from 25-m spaced arrays and 83 from 225-m spaced arrays). Overall, the proportion of gag with stomach contents on 25-m spaced 4-cube arrays, 225-m spaced 4-cube arrays, or 225-m spaced 16-cube arrays were not significantly different from one another (73%, 68%, and 67% respectively). In contrast, the proportion of gag on 25-m spaced 16-cube arrays that had recently fed (85%) was significantly greater than gag sampled from other array types. Overall, 92-100% of all gag had consumed pelagic baitfishes during the summers of 2002 and 2003, on all arrays irrespective of cube size or spacing. These baitfishes included tomtate (Haemulon aurolineatum), scaled sardine (Harengula jaguana), Spanish sardine (Sardinella aurita), and round scad (Decapterus punctatus). Gag from 225-m spaced arrays, both 4-cube and 16-cube, while having fed primarily on round scad, tomtate, scaled sardine, and Spanish sardine, had also consumed a variety of non-baitfish species, such as blue runner, pinfish, pigfish, sand diver, white grunt, and squid. In general, the number of prey species consumed by gag on 225-m spaced arrays, regardless of cube size, was higher than gag sampled from 25-m spaced arrays.

Average daily consumption (% body weight) and average daily gross energy consumption (cal/g body weight) was not different between gag on 25-m 4-cube arrays, 225-m 4-cube arrays, 25-m 16-cube arrays or 225-m 16-cube arrays (Kruskal-Wallis: P=0.206 and P=0.356, respectively). In general, there was a trend for gag from 4-cube arrays to have consumed less prey, and hence less gross energy, than gag from 16-cube arrays (1.58% of their body weight versus 2.16%, respectively).

These results contrasted slightly the consumption results from R/LR-B-49. The relative proportions of energy rich prey trended higher in 2002-2003 than in 2000-2001. Also, in 2000-2001 the energy consumption by gag on 4-cube arrays trended higher than on 16-cube arrays, whereas in 2002-2003 the trends were reversed.

Objective 1B: Prey fish abundance:
The mean index of prey availability to gag showed no significant difference between 4-cube reefs (n = 42, mean = 1.49) and 16-cube reefs (n = 37, mean = 1.65, p = 0.2013). Mean relative pelagic fish density was significantly lower on 4-cube reefs (n = 73, mean = 0.0006) than on 16-cube reefs (n = 62, mean = 0.0013, p < 0.0001). Mean school volume showed no significant differences between 4-cube (n = 73, mean = 53.9 m3) and 16-cube reefs (n = 63, mean = 51.5 m3, p = 0.3984). Mean relative pelagic fish abundance was significantly lower on 4-cube reefs (n = 73, mean = 0.025) than on 16-cube reefs (n = 62, mean = 0.052, p = 0.0139). Although statistically significant, given the high level of replication, these small differences between reef treatments are likely not biologically significant.

Objective 1C: Gag abundance, growth and condition: Overall, 16-cube reefs had a significantly higher average abundance of gag <60cmTL than did the 4-cube reefs (p=0.0118). The 16x225m arrays averaged 147.63 gag per array; which was significantly greater than the 4x25m arrays (p=0.0481, 96.50 gag per array) and the 4x225m arrays (p=0.0036, 64.50 gag per array). The 16x25m arrays averaged 109.03 gag per array, which was more than the 4-cube arrays but not significantly so.

In 2002, gag from 4x225m arrays had an average relative weight of 98.28%, which was significantly greater than the 4x25m arrays (p=0.0015, 92.75%), the 16x25m arrays (p=0.0033, 93.87%), and the 16x225m arrays (p=0.0424, 95.50%). The other treatments were not significantly different from one another. In 2003, none of these reef treatments were significantly different from another. Similarly, no significant differences were detected in marginal growth increments between the reef treatments, or between 2002 and 2003.

In comparison to previous studies in the same experimental system, gag abundance was as much as 40% lower by 2003. Concurrently, previously documented reef treatment effects on incremental growth and condition disappeared, consistent our previously confirmed hypothesis that gag density regulates growth and condition.

Objective 2: To quantify, in-situ, relative metabolic rates of gag as a function of gag size, gag density, water temperature and reef size using electron transport system (ETS) enzyme assay technique.

The ETS enzyme assay was adapted for use with large fish. Tissue samples for the complete experimental design were collected during both 2002 and 2003, i.e., 76 and 106 samples, respectively. The 2003 samples were all processed and statistically analyzed, while the 2002 samples are 75% processed and will be completed soon. For 2003, ETS activity was not significantly affected by reef treatments when gag length (cm TL) (p=0.4810) or total gag abundance (p=0.6962) was used as a covariate. Given some results from Objective 1C, the 2003 gag <60cm were compared between just the 4x225 and 16x225 treatments, and no difference in ETS activity was detected (p=0.5870). The lack of significant differences in 2003 is consistent with the absence of relative weight differences among reef treatments that year, in contrast to earlier years when gag abundance was higher and relative weights differed.

Objective 3: To quantify experimentally the O2 consumption, hence the energy expenditure, of gag as a function of their activity (e.g., hovering, swimming velocity) and to use this information to calibrate the ETS.

A prototype Blazka respirometer (Blazka et al. 1960) has been constructed and modified for use with gag grouper ranging in size from 42-62 cm total length. A re-circulating holding facility has also been modified for use in maintenance of gag and for use in the respirometer. Methods of collecting, transporting and maintaining gag in captivity have been finalized, including treatment information on any pathologies encountered. Gag can be housed successfully in 680 L recirculating seawater tanks at a summer temperature of 30°C. Trials of swimming respirometry have been conducted in the modified-Blazka respirometer (257 L volume) following the general procedures of Beamish (1970). Flow velocities in the respirometer are able to be maintained at 0-80 cm/s, and can be measured at the beginning and end of each run using a solid state flow meter (Marsh-McBirney) affixed in the center of the tunnel, behind the fish. These flow velocities correspond to hovering at ~10 cm/s to burst swimming at 80 cm/s. Temperature in the respirometer is measured by a Physitemp thermocouple. Oxygen consumption is measured using a polarographic micro-electrode with an A/D computer interface (Strathkelvin 928). Estimates of oxygen consumption rate (VO2) at the desired water velocity can be measured by linear regression of the depletion of oxygen from the respirometer over a portion of the experiment trial where the fish is swimming in a stable manner for at least 15 minutes.

The next step in the ETS-calibration procedure is to maintain gag at set activity levels for a minimum of 7-10 days. After this period of time, the individual gag can be placed in the respirometer and maintained at the same activity level via water velocity. Its oxygen consumption can then be measured. The fish will be removed and an ETS sample taken. The relationship between the oxygen consumption and the value of the ETS assay will be used as a calibration tool for the ETS method. Respirometry trials are underway testing O2 consumption as a function of gag swimming activity and temperature. When those are completed the ETS calibration will be done using the same apparatus.

Objective 4: To test our hypothesis that the energy budget of gag (combination of consumption and metabolic rate increase in activity), and thus growth and condition, varies as a function of reef habitat.

This objective is not yet quantitatively completed, and must await the completion of Objectives 2 and 3. Nevertheless, the results to date confirm our working model of how reef habitat affects gag growth and condition by the consistency of results from this and previous projects in the same system. Our working model holds that (A) reef shelter limits local densities of gag, which in turn regulates growth and condition, and that (B) the extent to which this operates: (1) varies with the overall abundance of gag, due to density-dependent habitat selection and individual growth dynamics, and (2) varies with the regional productivity or trophic status of the system. Parts A and B1 of this working model were confirmed by previous studies, and both parts A and B are currently being explored for natural hard-bottom habitat in a 3-year MARFIN project just getting underway. By reference our conceptual model (see above), we now know that the relationship between H and G varies over time, that gag abundance either varies over a longer time scale or is showing a declining trend, that the availability of pelagic planktivorous fishes (Nprey) does not explain observed differences in G, that C varies in its minority components among reef types and over time, and that R may or may not differ among reef types.

In recent years, we found that gag had lower abundance than in earlier years in the same system, and that the reef treatment effects on gag abundance, relative weight and incremental growth were diminished compared to earlier years, or simply not manifested under the current conditions. This should be expected for treatment effects due to density dependent processes when densities are low.

The diets of gag in the current study trended toward more energy rich prey, consistent with what would be expected with reduced gag densities. However, the relative weights of gag were substantially less than in previous years when gag abundance was higher and reef treatment effects were more strongly manifested. This suggests that regional productivity during the current project might also have been lower than in previous years, although we cannot test this with the data at hand. If that was so, it further suggests that the overall abundance of gag and regional productivity co-vary in ways that require longer-term, broader-scale studies to test and to model quantitatively.

2003 Accomplishments

Objective 1: To estimate annual variability in daily ration, prey fish abundance, and gag abundance as a function of patch reef size.

Daily ration (consumption): A total of 149 gag grouper have been sampled for stomach contents, 72 from 16-cube reef sites and 77 from 4-cube reef sites. Stomach contents of gag grouper from the two reef types are being analyzed currently for prey species composition and prey size measurements (~90% completed). Potential prey species, especially baitfish species, have been collected for back-calculation regressions. Currently, regression analysis is being used for ten major species (including portunid crabs and squid) to determine fish size-otolith size (or carapace or pen size) and fish size-caloric density in order to back-calculate the prey consumption by the gag grouper. Daily food consumption, and hence daily gross energy intake, will be calculated when stomach contents are finalized.

Prey fish abundance: A total of 108 patch reefs representing 18 reef sites (with replication) were sampled with fisheries acoustics from June to Oct, with most intense sampling occurring in July and September. Digital signal processing of these acoustics data are currently underway.

Gag abundance: A census of gag on all 22 of the Suwannee Regional Reef System sites was done from 29 May through 06 August 2002. The system-wide census was done because early counts on reefs specific to this project suggested an overall decline of gag numbers from previous years.

Previous analysis determined that there were no differences in abundance of gag on 4-cube published (fished) and 4-cube unpublished reefs; this census supported those findings (p=0.4805), therefore the 4-cube published and unpublished reefs were combined for analysis of spacing effects. Spacing effects were analyzed between 25m and 225m reefs for the 4-cube, 16-cube published, and 16-cube unpublished reef arrays. Results of ANOVA (but not yet ANCOVA incorporating natural hard bottom) showed no significant differences in the number of gag between reef arrays with 25m spaced patches and 225m spaced patches. This was true for 4-cube (p=0.3351), 16-cube published (p=0.228), and 16-cube unpublished reefs (p=0.5099).

Objective 2: To quantify, in-situ, relative metabolic rates of gag as a function of gag size, gag density, water temperature and reef size using electron transport system (ETS) enzyme assay technique.

Total of 91 Gag were sampled for ETS. At least 2 samples per fish were taken in the field and immediately frozen in Liquid Nitrogen. In some cases, up to 5 samples were taken from the fish. Each sample was then divided into at least 2 sub-samples. In some cases, up to 5 sub-samples were taken from each sample. A total of 42 samples (196 sub samples) have been processed.

Much of the time was focused on testing the assumptions of the ETS assay technique for large fishes. These tests included determining the appropriate location on the fish to take tissue samples, the potential biases associated with flash freezing tissue in liquid nitrogen, tissue sample size and homogeneity of tissue sizes between fish, and pH affects during the assay procedure. As a result of this effort, the ETS procedure as outlined in the literature has been modified for application to large fish. Testing of the procedure will continue for the next month to test differences in tissue type- red vs. white muscle such that the procedure can be optimized to improve accuracy and precision.

To date, we have established that the assay can be used on large fish in general, and on Gag Grouper specifically. Insufficient samples are processed to test for differences between reef habitat sizes. The next several months will be used to finish testing of the procedure and processing the remaining tissue samples collected during the past summer.

Objective 3: To quantify experimentally the O2 consumption, hence the energy expenditure, of gag as a function of their activity (e.g., hovering, swimming velocity) and to use this information to calibrate the ETS.

A prototype Blazka respirometer has been constructed and modified for small fish. Two additional and larger respirometers are in the planning/construction stage. A re-circulating holding facility has been modified for use with the respirometers. Small gag have been introduced into the system and are under acclimation. Completion of the larger respirometers and oxygen consumption trials for various activity states are slated for February 2003.

Objective 4: To test our hypothesis that the energy budget of gag (combination of consumption and metabolic rate increase in activity), and thus growth and condition, varies as a function of reef habitat.

Parameter estimates for the bioenergetic model are being developed as described under objectives 1-3, above. The synthesis of these parameters, as a quantitative test of our hypothesis, is a year two activity.

Previous Project Accomplishments

OBJECTIVE 1: To test the hypothesis that availability of pelagic prey fish to gag, in total or per capita, differs as a function of patch reef size.

No consistent differences in pelagic prey fish density (0-10.7 fish m-2) existed as a function of patch reef size, suggesting that reef habitat of the size and complexity used in this study does not determine the density of forage fish at reef sites. Available analytical software did not allow estimation of abundance per school of pelagic prey fish, so we cannot yet test for differences in absolute prey abundance between reef types. This is forthcoming. Significant year and month differences in pelagic prey fish densities reflect the inter-annual variability and changes over the course of a summer. Pelagic prey fish were consistently present above study reefs during all sampling periods, with frequencies of occurrence at 100% in 2000 and 98-99% in 2001. Prey fish availability, as measured by the density of forage fish at a reef divided by the number of gag grouper on the reef, differed by reef size. The 4-cube reefs had greater prey availability than 16-cube reefs. Highest mean density per capita was found on a 4-cube array (0.22 fish/m2/gag), and the lowest mean density per capita was also found on 4-cube array (0.02 fish/m2/gag). Nevertheless, the mean pelagic density per capita of gag was higher on 4-cube reefs (0.11 fish/m2/gag) than on 16-cube reefs (0.05 fish/m2/gag).

OBJECTIVE 2: To test the hypothesis that gross energy consumption (food consumption) by gag differs between patch reefs of contrasting size.

Prey consumed by gag grouper from 4-cube and 16-cube arrays were predominantly pelagic planktivorous fishes. Gag on 4-cube arrays consumed a greater diversity of prey than those on 16-cube arrays (17 versus 8 species), whereas the diet of gag on 16-cube arrays contained relatively more portunid crabs than gag on 4-cube arrays (24% versus 7% by energy).

Although trends in average daily food consumption and average daily gross energy consumption indicated that gag from 4-cube arrays consumed greater quantities of prey than gag from 16-cube arrays (e.g., 22 versus 11 cal/g body weight, respectively), the differences were not significant either between reef array sizes or between sublegal-sized and legal-sized gag.

OBJECTIVE 3: To confirm prior experimental results showing differences in gag growth and condition between patch reefs of contrasting size, and to estimate those differences concurrent with Objectives 1 and 2 in order to perform Objective 4.

Mean overall abundance of gag was 132% higher on 16-cube than on 4-cube reefs. Mean abundance of gag >50 cm was 221% higher on 16-cube reefs Mean abundance of gag <50 cm was 97% higher on 16-cube reefs.

While our data from 2001 support the differences between 16-cube and 4-cube reefs, we found no differences in gag abundances between published and unpublished reefs. This was true of the total abundances as well as the abundances of legal sized gag. Additionally, abundances of gag on unpublished reefs were drastically reduced from 1997 numbers and were close to the abundances of published reefs. Total numbers of gag were significantly higher on 16-cube patches than on 4-cube patches; this is consistent with results from 1997. An overall reduction from 850 to 685 individuals was observed from1997-2001. This translates to a 20% reduction in gag abundance. The bulk of this reduction was from 16-cube unpublished reefs. The overall abundance of gag on all 16-cube patches in 2001 is 38% lower than in 1997; concurrently, the overall abundance of gag on all 4-cube patches increased by 29%.

The condition factors of relative weight and girth both indicated that gag from 4-cube reefs were in better condition, this being most evident in gag greater than 50 cm. These results are consistent with results from 1997. In 1997 there was a marginal interaction effect between fishing pressure and patch reef size on relative weight. This interaction was not apparent in 2001. Mean relative weights in 2001 were lower than in 1997 for all reef types. Mean relative weight on 4-cube reefs decreased from 111.75 in 1997 to 97.53 in 2001, a 13% reduction. Mean relative weight on 16-cube reefs decreased from 108.10 in1997 to 95.65 in 2001, a 12% reduction.

OBJECTIVE 4: To characterize gag bioenergetics by integrating habitat, prey fish abundance, daily food consumption of gag, and gag growth from Objectives 1-3 to determine: a) whether habitat-related differences in growth and condition can be explained entirely by differences in pelagic prey fish availability and gross energy consumption, or b) whether it is necessary to further hypothesize differences in metabolic expenditures (e.g., density-dependent activity levels) to explain observed differences in gag production (growth).

Gag abundance and relative weights were lower in this study than in a 1996-97 study in the same experimental reef system, and the differences between 4- and 16-cube patch reefs were not as pronounced as documented earlier. Prey fish densities did not differ between reef types. Diet composition of gag differed somewhat between the 4- and 16-cube reefs, and the energy intake was slightly but not significantly greater on 4-cube reefs. It is unlikely that observed differences in prey availability and gross energy consumption explain the observable differences in gag growth and condition, which vary inter-annually. However, existing results are too variable for quantitative bioenergetic comparisons, given the slight differences observed and the sample sized obtained to date. Expansion of this dataset through follow-up studies should allow those tests in the future.

Products

Lindberg, W.J. T.K. Frazer, K.P. Portier, F. Vose, J. Loftin, D. Murie, D.M. Mason, B. Nagy, M. Hart. Factors Regulating Density and Performance of Gag Grouper: Density-Dependent Habitat Selection for Shelter. Ecological Applications. (Submitted 2004)

Butler, M., D.M. Mason, W.J. Lindberg, D. Murie, D.C. Parkyn. Application of the ETS enzyme assay to large marine fishes. Journal of Experimental Marine Biology and Ecology. (Submitted 2004)

Lindberg, W., D.M. Mason, D. Murie. 2003. Bioenergetic Response of Gag Grouper to Reef Habitat Configuration. Interim Report to Florida Sea Grant. 4pp.

Mason, D.M., W.J. Lindberg, D.J. Murie, B. Nagy, M. Butler. Reef habitat quality and fish performance: a bioenergetics perspective. Special session- “New Perspectives in Fish Energetics: A Return to Academic Nursery Grounds”. 134th Annual Meeting of the American Fisheries Society. Madison WI. August 21-26, 2004.

Lindburg, William, J., Doran M. Mason, Debra Murie, Thomas Frazer, Kenneth Portier, Brian Nagy, Mary Hart, Mark Butler and Doug Marcinek. 2004. Processes important to reef fish conservation and fisheries management: Density-dependent habitat selection, trophic coupling and individual growth dynamics. 4th World Fisheries Congress. May 2 - 6, 2004, Vancouver, British Columbia, Canada.

Butler, Mark, Doran M. Mason, Debra J. Murie, William J. Lindberg. 2004. Adaptation of the electron transport System assay for In-Situ estimation of metabolic rates of gag grouper. 4th World Fisheries Congress. May 2 - 6, 2004, Vancouver, British Columbia, Canada.

Nagy, Brian, Douglas M. Marcinek, Doran M. Mason, Debra J. Murie, William J. Lindburg. 2004. Reef Size Mediated Pelagic Fish Distributions in the Gulf of Mexico. 4th World Fisheries Congress. May 2 - 6, 2004, Vancouver, British Columbia, Canada.

Mason, D.M. Integration of technologies for understanding the functional relationship between reef habitat and fish performance. NOAA Atlantic Oceanographic Meteorological Laboratory. Miami, FL. March 16, 2004

Mason, D.M. Habitat-mediated predator production dynamics on reefs. University of Minnesota-Duluth. March 5, 2004.

Mason, D.M., B. Nagy, M. Butler, S. Larsen, D.J. Murie, and W.J. Lindberg. 2003. Technological approaches for understanding the functional relationship between reef habitat quality and fish abundance and performance. 56th Gulf and Caribbean Fisheries Institute Conference, Tortola, British Virgin Islands, November 10-14, 2003.

Butler, M., D.M. Mason, W.J. Lindberg, D. J. Murie. Adaptation of the Electron Transport System assay for the in-situ estimation of metabolic rates of Gag Grouper. 133rd AFS Annual Meeting, Quebec City, Quebec, Canada, August 10-14, 2003.

Nagy, B., M.W. Butler, D.M. Marcinek, D.M. Mason, D.J. Murie, and W.J. Lindberg. Reef Size Mediated Pelagic Fish Distributions on an Artificial Reef System in the Gulf of Mexico. 133rd AFS Annual Meeting, Quebec City, Quebec, Canada, August 10-14, 2003.

Murie, D.J., J. Debicella, P. O'Day, W. Lindberg, D. Marcinek, M. Butler, and D.M. Mason. Comparison of Gross Energy Consumption of Gag Grouper between Patch Reefs of Contrasting Size in the Gulf of Mexico. 133rd AFS Annual Meeting, Quebec City, Quebec, Canada, August 10-14, 2003. (Poster)

Mason, D.M. Habitat-mediated predator production dynamics in the Gulf of Mexico. NOAA/NOS, Center for Coastal Environmental Health and Biomolecular Research, Charleston, South Carolina. June 13, 2003.

Mason, Doran M. Habitat-mediated predator production dynamics in the Gulf of Mexico. Institute of Fisheries Research - University of Michigan Fall seminar series. November 1, 2002.

Mason, D.M., W.J. Lindberg, D. Murie, and B. Nagy. A bioenergetics-based formalization of habitat-mediated predator-prey interactions and predator growth response on coastal reefs. Southern Division American Fisheries Society 9th Midyear Meeting. Jacksonville, Florida. February 2001

Nagy, B. D.M. Mason, and W.J. Lindberg. Pelagic fish distributions on an artificial reef system in the Gulf of Mexico. Southern Division American Fisheries Society 9th Midyear Meeting. Jacksonville, Florida. February 2001.

Mason, D.M. Habitat-mediated predator-prey interactions in the Gulf of Mexico. Public seminar, NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI. October 2001.

Nagy, B., M.W. Butler, D.M. Marcinek, D.M. Mason, D.J. Murie, and W.J. Lindberg. 2002. Reef Size Mediated Pelagic Fish Distributions on an Artificial Reef System in the Gulf of Mexico. 132nd AFS Annual Meeting, August 18-22, 2002. Baltimore, MD. (Poster)

Habitat-Mediated Predator-Prey Interactions in the Eastern Gulf of Mexico Research Project

2005 Plans

2004 Accomplishments

2003 Accomplishments

Previous Project Accomplishments

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