Center for Marine Sciences and Technology

Plastic debris is now ubiquitous in the marine environment affecting a wide range of taxa, from microscopic zooplankton to large vertebrates. Its persistence and dispersal throughout marine ecosystems has meant that sensitivity toward the scale of threat is growing, particularly for species of conservation concern, such as marine turtles. Their use of a variety of habitats, migratory behaviour, and complex life histories leave them subject to a host of anthropogenic stressors, including exposure to marine plastic pollution. Here, we review the evidence for the effects of plastic debris on turtles and their habitats, highlight knowledge gaps, and make recommendations for future research. We found that, of the seven species, all are known to ingest or become entangled in marine debris. Ingestion can cause intestinal blockage and internal injury, dietary dilution, malnutrition, and increased buoyancy which in turn can result in poor health, reduced growth rates and reproductive output, or death. Entanglement in plastic debris (including ghost fishing gear) is known to cause lacerations, increased drag—which reduces the ability to forage effectively or escape threats—and may lead to drowning or death by starvation. In addition, plastic pollution may impact key turtle habitats. In particular, its presence on nesting beaches may alter nest properties by affecting temperature and sediment permeability. This could influence hatchling sex ratios and reproductive success, resulting in population level implications. Additionally, beach litter may entangle nesting females or emerging hatchlings. Lastly, as an omnipresent and widespread pollutant, plastic debris may cause wider ecosystem effects which result in loss of productivity and implications for trophic interactions. By compiling and presenting this evidence, we demonstrate that urgent action is required to better understand this issue and its effects on marine turtles, so that appropriate and effective mitigation policies can be developed.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 268:245-264 (2004) - doi:10.3354/meps268245 Foraging ecology of the early life stages of four sympatric shark species Dana M. Bethea1,3,*, Jeffrey A. Buckel1, John K. Carlson2 1Department of Zoology, North Carolina State University, Center for Marine Sciences and Technology, 303 College Circle, Morehead City, North Carolina 28557, USA 2Southeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Panama City Laboratory, 3500 Delwood Beach Road, Panama City Beach, Florida 32408, USA 3Present address: Southeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Panama City Laboratory, 3500 Delwood Beach Road, Panama City Beach, Florida 32408, USA *Email: dana.bethea@noaa.gov ABSTRACT: Sharks may have an important role in marine ecosystems in relation to populations of fish and invertebrates at lower trophic levels. Fishery management plans stress the need for an ecosystem approach, but few quantitative studies on the foraging ecology of sharks have been published. Stomach contents and catch data of early life stages of Atlantic sharpnose Rhizoprionodon terraenovae, blacktip Carcharhinus limbatus, finetooth Carcharhinus isodon, and spinner sharks Carcharhinus brevipinna taken from fishery independent surveys in Apalachicola Bay, Florida, USA, were examined to test for overlap in resource use. Young-of-the-year Atlantic sharpnose sharks were found to feed mainly on shrimp, juveniles on sciaenids, and adults on clupeids. Young-of-the-year blacktip sharks were found to feed mainly on sciaenids, whereas juveniles fed on clupeids. The primary prey of young-of-the-year and juvenile finetooth and spinner sharks was clupeids. Eight of 10 prey size-selectivity tests showed neutral selection. Compared to relative prey sizes published for teleost piscivores, Atlantic sharpnose and finetooth sharks consume relatively small-sized prey while blacktip sharks consume relatively large prey. Regardless of maturity state and species, diet overlap was high for species-life stage combinations that are similar in size; however, species-life stages did not show significant habitat overlap. Prey categories shared by similar-sized species may not be limiting, although shark species may have alleviated competition pressure by partitioning the resource of time or space. KEY WORDS: Foraging ecology · Resource partitioning · Competition · Prey size-predator size relationships · Apalachicola Bay · Rhizoprionodon terraenovae · Carcharhinus limbatus · Carcharhinus isodon · Carcharhinus brevipinna Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 268. Online publication date: March 09, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 294:79-94 (2005) - doi:10.3354/meps294079 Hypoxia-induced habitat shifts and energetic consequences in Atlantic croaker and brown shrimp on the Gulf of Mexico shelf J. Kevin Craig1,2,*, Larry B. Crowder1 1Nicholas School of the Environment and Earth Sciences, Duke Center for Marine Conservation, 135 Duke Marine Lab Rd.,Beaufort, North Carolina 28516-9721, USA2Center for Marine Sciences and Technology, North Carolina State University, 303 College Circle, Morehead City, North Carolina 28557, USA *Email: kevin.craig@duke.edu ABSTRACT: Seasonal, summertime hypoxia (dissolved oxygen ≤ 2 mg l–1) has occurred over large areas (~1000 to 20000 km2) of the northwestern Gulf of Mexico shelf during several years since at least the mid-1980s, resulting in habitat loss for demersal species. To evaluate the effects of hypoxia-induced habitat loss on Atlantic croaker Micropogonias undulatus and brown shrimp Farfantepenaeus aztecus, we compared species’ spatial distributions and relationships to abiotic factors (temperature, dissolved oxygen, salinity) across years differing in the spatial extent of hypoxia. Analysis of 14 yr of fishery-independent research trawl and environmental data (July) indicated that hypoxia-induced shifts in spatial distribution result in considerable shifts in the temperature and oxygen conditions that croaker and brown shrimp experience. Croaker, which typically occupy relatively warm, inshore waters, remain in the warmest waters inshore of the hypoxic region but also are displaced to cooler offshore waters. Brown shrimp, which are typically distributed more broadly and further offshore, shift to relatively warm inshore waters as well as cooler waters near the offshore hypoxic edge. These shifts in the species’ spatial distribution are reflected in long-term decreases and increases in the mean temperatures occupied by croaker and brown shrimp, respectively, as well as increases in the variance in occupied temperatures for both species. Despite avoidance of the lowest oxygen waters, high densities of croaker and brown shrimp occur in areas of moderately low oxygen concentration (35 to 60% air saturation, 1.6 to 3.7 mg l–1) near the offshore hypoxic edge. Because temperature and dissolved oxygen are important abiotic factors that impact metabolic scope, these shifts in spatial distribution during severe hypoxia may impact organism energy budgets. High croaker and shrimp densities near the hypoxic edge likely have implications for trophic interactions as well as the harvest of both target (brown shrimp) and nontarget (croaker) species by the commercial shrimp fishery. KEY WORDS: Hypoxia · Micropogonias undulatus · Farfantepenaeus aztecus · Gulf of Mexico · Bioenergetics · Abiotic factors · Spatial distribution · Edge effects Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 294. Online publication date: June 09, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Widespread and persistent organochlorine (OC) contaminants, such as polychlorinated biphenyls (PCBs) and pesticides, are known to have broad-ranging toxicities in wildlife. In this study we investigated, for the first time, their possible health effects on loggerhead sea turtles (Caretta caretta). Nonlethal fat biopsies and blood samples were collected from live turtles for OC contaminant analysis, and concentrations were compared with clinical health assessment data, including hematology, plasma chemistry, and body condition. Concentrations of total PCBs (Sigma PCBs), Sigma DDTs, Sigma chlordanes, dieldrin, and mirex were determined in 44 fat biopsies and 48 blood samples. Blood concentrations of Sigma chlordanes were negatively correlated with red blood cell counts, hemoglobin, and hematocrit, indicative of anemia. Positive correlations were observed between most classes of OC contaminants and white blood cell counts and between mirex and Sigma TCDD-like PCB concentrations and the heterophil:lymphocyte ratio, suggesting modulation of the immune system. All classes of OCs in the blood except dieldrin were correlated positively with aspartate aminotransferase (AST) activity, indicating possible hepatocellular damage. Mirex and Sigma TCDD-like PCB blood concentrations were negatively correlated with alkaline phosphatase (ALP) activity. Significant correlations to levels of certain OC contaminant classes also suggested possible alteration of protein (increasing blood urea nitrogen, decreasing albumin:globulin ratio), carbohydrate (decreasing glucose), and ion (increasing sodium, decreasing magnesium) regulation. These correlations suggest that OC contaminants may be affecting the health of loggerhead sea turtles even though sea turtles accumulate lower concentrations of OCs compared with other wildlife.

Several laboratory and field studies indicate that organochlorine contaminants (OCs), such as polychlorinated biphenyls (PCBs) and pesticides, modulate immune responses in rodents, wildlife, and humans. In the present study we examined the effects of OCs on immunity in free-ranging loggerhead sea turtles (Caretta caretta). Mitogen-induced lymphocyte proliferation responses, lysozyme activity, and OC concentrations were measured from blood samples. Mitogens chosen in the lymphocyte proliferation assay were phytohemagglutinin (PHA) and concanavalin A (ConA) for T-lymphocyte stimulation, and lipopolysaccharide (LPS) and phorbol 12,13-dibutyrate (PDB) for B-lymphocyte stimulation. Lysozyme activity was significantly and negatively correlated with whole-blood concentrations of 4,4 -dichlorodiphenyldichloroethylene (4,4 -DDE) and the sum of chlordanes. Lymphocyte proliferation responses stimulated by PHA, LPS, and PDB were significantly and positively correlated with concentrations of the sum of PCBs measured in whole blood. LPS- and PDB-induced proliferation were also significantly and positively correlated with 4,4 -DDE blood concentrations. These correlative observations in free-ranging turtles suggest that current, chronic exposure to OCs may suppress innate immunity and enhance certain lymphocyte functions of loggerhead sea turtles. To further test this hypothesis, lymphocyte proliferation was measured after in vitro exposure of peripheral blood leukocytes from 16 turtles to Aroclor 1254 (0-13.5 microg/mL) or 4,4 -DDE (0-13.4 microg/mL). Both contaminants increased PHA- and PDB-induced proliferation at concentrations below those that affected cell viability. Moreover, the concentrations that enhanced PDB-induced proliferation in vitro were similar to concentrations measured in turtles with the highest proliferative responses. The similarities between the in vitro experiments and the correlative field study suggest that OC exposure modulates immunity in loggerhead turtles.

Monitoring toxic organochlorine (OC) compounds is an important aspect in wildlife studies, especially in protected species such as sea turtles. The goal of this study was to determine whether blood OC concentrations can predict those in adipose tissue of sea turtles. Blood offers many benefits for monitoring OCs. It can be collected nondestructively from live turtles and can be sampled repeatedly for continuous monitoring. Organochlorine concentrations in blood may better represent the exposure levels of target tissues, but blood concentrations may fluctuate more than those in fatty tissues following recent dietary exposure or lipid mobilization. Paired fat and blood samples were collected from 44 live, juvenile loggerhead sea turtles and 10 juvenile Kemp's ridley sea turtle carcasses. Organochlorines were analyzed using gas chromatography with electron capture detection and mass spectrometry. Lipid-normalized OC concentrations measured in the blood significantly correlated to levels found in the fat samples of both species. This result suggests that sea turtle blood is a suitable alternative to fatty tissues for measuring OCs because blood concentrations reasonably represent those observed in the paired fat samples. However, blood OC concentrations calculated on a wet-mass basis were significantly and inversely correlated to lipid content in the fat samples. Therefore, caution should be used when monitoring spatial or temporal trends, as OC levels may increase in the blood following mobilization of fat stores, such as during long migrations, breeding, or disease events.

Ocean soundscapes convey important sensory information to marine life. Like many mid-to-low latitude coastal areas worldwide, the high-frequency (>1.5 kHz) soundscape of oyster reef habitat within the West Bay Marine Reserve (36°N, 76°W) is dominated by the impulsive, short-duration signals generated by snapping shrimp. Between June 2011 and July 2012, a single hydrophone deployed within West Bay was programmed to record 60 or 30 seconds of acoustic data every 15 or 30 minutes. Envelope correlation and amplitude information were then used to count shrimp snaps within these recordings. The observed snap rates vary from 1500-2000 snaps per minute during summer to <100 snaps per minute during winter. Sound pressure levels are positively correlated with snap rate (r = 0.71-0.92) and vary seasonally by ~15 decibels in the 1.5-20 kHz range. Snap rates are positively correlated with water temperatures (r = 0.81-0.93), as well as potentially influenced by climate-driven changes in water quality. Light availability modulates snap rate on diurnal time scales, with most days exhibiting a significant preference for either nighttime or daytime snapping, and many showing additional crepuscular increases. During mid-summer, the number of snaps occurring at night is 5-10% more than predicted by a random model; however, this pattern is reversed between August and April, with an excess of up to 25% more snaps recorded during the day in the mid-winter. Diurnal variability in sound pressure levels is largest in the mid-winter, when the overall rate of snapping is at its lowest, and the percentage difference between daytime and nighttime activity is at its highest. This work highlights our lack of knowledge regarding the ecology and acoustic behavior of one of the most dominant soniforous invertebrate species in coastal systems. It also underscores the necessity of long-duration, high-temporal-resolution sampling in efforts to understand the bioacoustics of animal behaviors and associated changes within the marine soundscape.

To test the hypothesis that elemental composition of otoliths (sagittae) could be influenced by differences in natural prey type, young‐of‐the‐year bluefish Pomatomus saltatrix were captured immediately after their migration from oceanic waters into mid‐Atlantic Bight estuaries and fed either shrimp, Crangon septemspinosa and Palaemonetes spp. or fish Menidia menidia under similar temperature and salinity regimes in two separate 60 day experiments. Unlimited rations of fish and shrimp prey were provided in the first experiment which led to differences in bluefish growth rate between the two prey treatments; fish prey was limited in the second experiment to ensure that growth rates of bluefish in the two prey treatments were similar. Concentrations of seven elements in bluefish otoliths were determined using solution‐based inductively coupled plasma mass spectrometry (ICPMS). There was no significant effect of diet on five of the seven elements examined (Na, Mg, K, Ca and Mn). The levels of Sr and Ba in the otoliths of shrimp‐fed bluefish, however, were significantly higher than fish‐fed bluefish in both experiments. Concentrations of Ba in shrimp‐fed bluefish otoliths were double that found in fish‐fed bluefish. The results suggest that diet can explain some of the variation in otolith chemistry previously attributed to physical and chemical properties of the water.

During summer of 2001, venous blood gases were determined in loggerhead sea turtles (Caretta caretta) captured by trawl (n = 16) in coastal waters of South Carolina and Georgia (USA) as part of a sea turtle census program and captured in pound nets (n = 6) in coastal North Carolina (USA) during a study of sea turtle population biology. Trawls were towed for 30 min, so turtles captured were forcibly submerged for < or = 30 min. Pound nets are passive gear in which fish and sea turtles are funneled into a concentrated area and removed periodically. Sea turtles in pound nets are free to surface and to feed at will. Blood was obtained from the dorsal cervical sinus as quickly as possible after landing on the boat (range 2-10 min trawl, 1-2 min pound net) and at 30 min after landing just prior to release. Blood gases including pH, partial pressures of O2 and CO2 (pO2, pCO2), and lactate were measured within 10 min. Instrument measurements for pH, pO2, and pCO2 made at 37 C were corrected to cloacal temperature and HCO3- was calculated from temperature-corrected pH and pCO2. Venous blood pH and bicarbonate were higher, and pO2 and lactate were lower from pound net-captured turtles compared to trawl captured turtles at the initial sampling time. In pound net turtles, pH and bicarbonate declined and lactate increased during 30 min on deck. In trawled sea turtles, venous blood pH increased and pCO2 and pO2 decreased during the 30 min on deck. Both capture systems caused perturbations in blood gas, acid-base, and lactate status, though alterations were greater in trawl captured turtles.

Field anesthesia is often necessary for both invasive and noninvasive procedures on wild animals. We describe basic principles of safe anesthetic delivery, monitoring, and recovery for application in procedures involving free-ranging wildlife. For invasive procedures, the potential for immediate and lasting pain must be addressed and appropriate analgesia provided. In situations where the minimum standard of safe anesthesia and effective analgesia cannot be provided, the investigator and approving bodies should rigorously evaluate the risk to the patient against the value of the data obtained. This document is intended to serve as a resource for Institutional Animal Care and Use Committees, biologists, veterinarians, and other researchers planning projects that involve free-ranging wildlife in field conditions.

Characterization of a population of green turtles inhabiting the northeastern Gulf of Mexico was made possible by the mortality of a subset of > 4500 sea turtles that stranded during a mass cold stunning event in Florida, USA, during January 2010.In total, 434 dead, stranded green turtles Chelonia mydas were evaluated through necropsy and skeletochronological analysis to characterize morphology, sex, body condition, disease status, age structure, and growth patterns.Standard straightline carapace lengths ranged from 18.1 to 78.5 cm (mean ± SD = 36.3± 10.4 cm) and did not significantly differ from those of stranded green turtles that survived this event.Prevalence of fibropapilloma (FP) was low, at 6%, and sex ratio was significantly biased toward females (2.45F:1M).Age estimates ranged from 2 to 22 yr (mean ± SD = 9 ± 4 yr) and female age distribution was significantly greater than that of males.Mean stage durations, as calculated through sum mation of size class-specific growth rates and fitting smoothing spline models to length-at-age data, were similar and ranged from 17 to 20 yr.Generalized additive models and generalized additive mixed models were used to assess the potential influence of discrete and continuous covariates on growth rates.Somatic growth was significantly influenced by size, age, and calendar year; however, no effect of sex, FP status, or body condition was found.Increased understanding of population parameters will improve population models for the species and can also serve as a reference for assessing potential effects of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico.

Soundscape analysis is a potentially powerful tool in ecosystem monitoring. Ecoacoustic metrics, including the Acoustic Complexity Index (ACI) and Acoustic Entropy (H), were originally developed for terrestrial ecosystems and are now increasingly being applied to investigate the biodiversity, habitat complexity and health of marine systems, with mixed results. To elucidate the efficacy of applying these metrics to marine soundscapes, their sensitivity to variations in call rate and call type were evaluated using a combination of field data and synthetic recordings. In soundscapes dominated by impulsive broadband snapping shrimp sounds, ACI increased non-linearly with increased snapping rate (∼100–3500 snaps/min), with a percent range of variation (∼40–50%) that exceeds that reported in most studies. H, however, decreased only slightly (∼0.04 units) in response to these same snap rate changes. The response of these metrics to changes in the rate of broadband snapping was not strongly influenced by the spectral resolution of the analysis. For soundscapes dominated by harmonic fish calls, increased rates of calling (∼5–120 calls/min) led to decreased ACI (∼20–40% range of variation) when coarse spectral resolutions (Δf = 94 or 47 Hz) were used in the analysis, but ACI increased (∼20% range of variation) when a finer resolution (Δf = 23 Hz) was employed. Regardless of spectral resolution used in the analysis, H decreased (∼0.20 units) in response to increased rates of harmonic calling. These results show that ACI and H can be modulated strongly by variations in the activity of a single sound-producing species, with additional sensitivity to call type and the resolution of the analysis. Variations in ACI and H, therefore, cannot be assumed to track call diversity, and the utility of these metrics as ecological indicators in marine environments may be limited.

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum ( Sciaenops ocellatus ) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry – tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry – tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.

Abstract A major challenge in marine ecology is describing patterns of larval dispersal and population connectivity, as well as their underlying processes. We used a biophysical model to simulate dispersal of eastern oyster, Crassostrea virginica, larvae and connectivity among a network of 10 no‐take reserves in a shallow, wind‐driven estuary to assess the relative importance of spawning location, spawning date, larval behavior, larval mortality, and adult reproductive output to predicted dispersal and connectivity patterns. The location (i.e., natal reserve) and date of spawning relative to physical processes, particularly frequency of wind reversals, were the dominant drivers of dispersal and connectivity patterns. To a lesser extent, larval behavior (i.e., 3D vertical advection and ontogenetic depth regulation) and mortality modified dispersal and connectivity, whereas spatiotemporal variability in adult reproductive output was of minimal importance. Over a 21‐day larval duration, mean dispersal distance of passive surface particles ranged from 5 to 40 km. Reserves were too small (1 km2) relative to mean dispersal distances to promote extensive local retention (median 2%) and spaced too far apart (typically ~50 km) to promote extensive inter‐reserve connectivity (median 2%). Limited connectivity and local retention may preclude the network from being self‐sustainable, thereby limiting its long‐term conservation and management benefits. In reserve systems characterized by limited connectivity, management efforts should focus on increasing connectivity by increasing the number or size of reserves to realize the benefits of improved adult demographics within reserves.

Habitat suitability index (HSI) models provide spatially explicit information on the capacity of a given habitat to support a species of interest, and their prevalence has increased dramatically in recent years. Despite caution that the reliability of HSIs must be validated using independent, quantitative data, most HSIs intended to inform terrestrial and marine species management remain unvalidated. Furthermore, of the eight HSI models developed for eastern oyster (Crassostrea virginica) restoration and fishery production, none has been validated. Consequently, we developed, calibrated, and validated an HSI for the eastern oyster to identify optimal habitat for restoration in a tributary of Chesapeake Bay, the Great Wicomico River (GWR). The GWR harbors a high density, restored oyster population, and therefore serves as an excellent model system for assessing the validity of the HSI. The HSI was derived from GIS layers of bottom type, salinity, and water depth (surrogate for dissolved oxygen), and was tested using live adult oyster density data from a survey of high vertical relief reefs (HRR) and low vertical relief reefs (LRR) in the sanctuary network. Live adult oyster density was a statistically-significant sigmoid function of the HSI, which validates the HSI as a robust predictor of suitable oyster reef habitat for rehabilitation or restoration. In addition, HRR had on average 103-116 more adults m^−2 than LRR at a given level of the HSI. For HRR, HSI values ≥0.3 exceeded the accepted restoration target of 50 live adult oysters m^−2. For LRR, the HSI was generally able to predict live adult oyster densities that meet or exceed the target at HSI values ≥0.3. The HSI indicated that there remain large areas of suitable habitat for restoration in the GWR. This study provides a robust framework for HSI model development and validation, which can be refined and applied to other systems and previously developed HSIs to improve the efficacy of native oyster restoration.

Abstract We examined diet, dietary niche width, diet overlap, and prey size–predator size relationships of blue marlins Makaira nigricans , dolphinfish Coryphaena hippurus , yellowfin tuna Thunnus albacares , and wahoos Acanthocybium solandri caught in the western North Atlantic Ocean during the Big Rock Blue Marlin Tournament (BRT) in 1998–2000 and 2003–2009 and dolphinfish captured outside the BRT from 2002 to 2004. Scombrids were important prey of blue marlins, yellowfin tuna, and wahoos; other frequently consumed prey included cephalopods (for yellowfin tuna and wahoos) and exocoetids (for yellowfin tuna). Dolphinfish diets included exocoetids, portunids, and conspecifics as important prey. Blue marlins and wahoos consumed relatively few prey species (i.e., low dietary niche width), while dolphinfish had the highest dietary niche width; yellowfin tuna had intermediate niche width values. Maximum prey size increased with dolphinfish size; however, the consumption of small prey associated with algae Sargassum spp. occurred across the full size range of dolphinfish examined. Most interspecific diet overlap values with dolphinfish were not significant; however, blue marlins, yellowfin tuna, and wahoos had significant diet overlap due to their reliance on scombrid prey. Prey types found in blue marlins, dolphinfish, and wahoos were more consistent among BRT years than prey found in yellowfin tuna. The prey of yellowfin tuna and wahoos collected during BRT years correlated with historic (early 1980s) diet data from North Carolina, the Gulf of Mexico, and the Bahamas. Based on principal components analysis, diets from several oceans clustered together for blue marlins, dolphinfish, yellowfin tuna, and wahoos. Although differences were found, the diets of each predator were largely consistent both temporally (e.g., over the past three decades in the Gulf Stream) and spatially (among oceans), despite potential effects of fishing or environmental changes.

As human impacts on marine ecosystems escalate, there is increasing interest in quantifying sub-lethal physiological and pathological responses of marine mammals.Glucocorticoid hormones are commonly used to assess stress responses to anthropogenic factors in wildlife.While obtaining blood samples to measure circulating hormones is not currently feasible for freeswimming large whales, immunoassay of fecal glucocorticoid metabolites (fGCs) has been validated for North Atlantic right whales Eubalaena glacialis (NARW).Using a general linear model, we compared fGC concentrations in right whales chronically entangled in fishing gear (n = 6) or live-stranded (n = 1), with right whales quickly killed by vessels (n = 5) and healthy right whales (n = 113) to characterize fGC responses to acute vs. chronic stressors.fGCs in entangled whales (mean ± SE: 1856.4 ± 1644.9 ng g -1 ) and the stranded whale (5740.7 ng g -1 ) were significantly higher than in whales killed by vessels (46.2 ± 19.2 ng g -1 ) and healthy whales (51.7 ± 8.7 ng g -1 ).Paired feces and serum collected from the live-stranded right whale provided comparison of fGCs in 2 matrices in a chronically stressed whale.Serum cortisol and corticosterone in this whale (50.0 and 29.0 ng ml -1 , respectively) were much higher than values reported in other cetaceans, in concordance with extremely elevated fGCs.Meaningful patterns in fGC concentration related to acute vs. chronic impacts persisted despite potential for bacterial degradation of hormone metabolites in dead whales.These results provide biological validation for using fGCs as a biomarker of chronic stress in NARWs.

Abstract Central to ecology and resource management is knowledge of the spatiotemporal scales at which demographic rates vary and the ecological consequences of demographic variation, such as that due to density dependence. We quantified the spatiotemporal variation in eastern oyster Crassostrea virginica recruitment, density, growth, and survival and assessed density dependence within a network of no-take reserves in Pamlico Sound, North Carolina. From 2006 to 2008, average oyster recruitment and total density increased 15- and fivefold, respectively. The unprecedentedly high oyster densities in certain reserves (up to 6,500/m2 at the end of the study) modified demographic rates such that further density increases were regulated by density-dependent survival. Oyster demographic rates varied significantly among reserves at relatively small spatial scales (20 km). Certain reserves were the strong “recruiters,” others the fast “growers,” and yet others the high “survivors.” Cohort dynamics altered the demographic rank order such that the demographically “best” reserves varied intra- and interannually. From a management perspective, the prevalence of density-dependent survival suggests that the oysters in this system are habitat rather than recruitment limited, which may minimize the utility of stock enhancement programs. Addition of habitat (i.e., artificial reefs) should focus on reserves characterized by high recruitment but density-dependent growth and survival. This study (1) supports the efficacy of marine reserves in rapidly increasing the density and age–size structure of protected species, (2) highlights the need for spatially explicit demographic data to support multifaceted management objectives, and (3) when combined with evidence of reserve larval connectivity, provides support for applying metapopulation concepts to this reserve system. Received January 27, 2012; accepted July 11, 2012

Coastal areas provide nesting habitat for marine turtles that is critical for the persistence of their populations. However, many coastal areas are highly affected by coastal development, which affects the reproductive success of marine turtles. Knowing the extent to which nesting areas are exposed to these threats is essential to guide management initiatives. This information is particularly important for coastal areas with both high nesting density and dense human development, a combination that is common in the United States. We assessed the extent to which nesting areas of the loggerhead (Caretta caretta), the green (Chelonia mydas), the Kemp's ridley (Lepidochelys kempii), and leatherback turtles (Dermochelys coriacea) in the continental United States are exposed to coastal development and identified conservation hotspots that currently have high reproductive importance and either face high exposure to coastal development (needing intervention), or have low exposure to coastal development, and are good candidates for continued and future protection. Night-time light, housing, and population density were used as proxies for coastal development and human disturbance. About 81.6% of nesting areas were exposed to housing and human population, and 97.8% were exposed to light pollution. Further, most (>65%) of the very high- and high-density nesting areas for each species/subpopulation, except for the Kemp's ridley, were exposed to coastal development. Forty-nine nesting sites were selected as conservation hotspots; of those high-density nesting sites, 49% were sites with no/low exposure to coastal development and the other 51% were exposed to high-density coastal development. Conservation strategies need to account for ~66.8% of all marine turtle nesting areas being on private land and for nesting sites being exposed to large numbers of seasonal residents.

Abstract The concepts of metapopulation persistence and source‐sink dynamics are central and often untested tenets of marine reserve networks. Effective application of these concepts to marine reserves is limited by data on demographic rates within reserves and larval connectivity among reserves. Using a network of reserves established to restore eastern oyster (Crassostrea virginica) in Pamlico Sound, North Carolina, USA as our model system, we integrated empirically based demographic rates and regional hydrodynamic‐based connectivity estimates within a metapopulation model to (1) evaluate the potential for the reserve network to function as a self‐persistent oyster metapopulation, (2) determine the relative importance of demographics vs. connectivity on reserve source‐sink dynamics, (3) assess the efficacy of stock enhancement in promoting metapopulation persistence, and (4) evaluate whether application of a Few Large or Several Small reserves—a modification of the Single Large or Several Small concept—promoted greater metapopulation retention of larvae within the reserve network (i.e., local larval retention within reserves + larval connectivity among reserves). The reserve network failed to function as a self‐persistent metapopulation, despite exceptional demographic rates within reserves. When considering only larval supply from reserves, local retention and connectivity were insufficient to provide annual replacement (≥~0.25 recruits per adult). Accordingly, reserves contributed to the metapopulation primarily via production, not dispersal, of larvae and reserve source‐sink dynamics were influenced more by demographics within reserves, particularly adult growth and survival, than larval connectivity among reserves. Addressing recruitment limitation via stock enhancement was not effective at augmenting projected metapopulation declines. Several small reserves initially promoted greater metapopulation retention of larvae than a few large reserves, however, as the number or area of reserves increased, metapopulation retention was equivalent among designs, suggesting that Few Large and Several Small reserves may be the best network design. Marine reserves can be an effective restoration tool for improving demographic rates within reserve boundaries, but designation of multiple reserves does not guarantee a functional reserve network metapopulation. Both demographics and larval connectivity are important considerations to successful application of metapopulation concepts to the design of reserve networks.