James B. McClintock

University of Alabama at Birmingham, Birmingham, Alabama, United States

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Publications (226)537.09 Total impact

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    ABSTRACT: Ocean acidification has been hypothesized to increase stress and decrease shell calcification in gastropods, particularly in cold water habitats like the western Antarctic Peninsula (WAP). There is limited information on how calcified marine benthic invertebrates in this region will respond to these rapidly changing conditions. The present study investigated the effects of elevated seawater temperature and decreased pH on growth (wet mass and shell morphometrics), net calcification, and proximate body composition (protein and lipid) of body tissues in two common benthic gastropods. Individuals of the limpet Nacella concinna and the snail Margarella antarctica collected from the WAP were exposed to seawater in one of four treatment combinations: current ambient conditions (1.5°C, pH 8.0), near-future decreased pH (1.5°C, pH 7.8), near-future elevated temperature (3.5°C, pH 8.0), or combination of decreased pH and elevated temperature (3.5°C, pH 7.8). Following a 6-week exposure, limpets showed no temperature or pH effects on whole body mass or net calcification. Despite no significant differences in whole body mass, the shell length and width of limpets at elevated temperature tended to grow less than those at ambient temperature. There was a significant interaction between the sex of limpets and pH. There were no significant temperature or pH effects on growth, net calcification, shell morphologies, or proximate body composition of snails. Our findings suggest that both gastropod species demonstrate resilience to initial exposure to temperature and pH changes predicted to occur over the next several hundred years globally and perhaps sooner along the WAP. Despite few significant impacts of elevated temperature or decreased pH, any response to either abiotic variable in species with relatively slow growth and long lifespan is of note. In particular, we detected modest impacts of reduced pH on lipid allocation in the reproductive organs of the limpet N. concinna that warrants further study.
    No preview · Article · Dec 2015 · ICES Journal of Marine Science
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    ABSTRACT: The Antarctic fish fauna from outer continental shelf/upper slope depths is under-sampled compared to that of the inner shelf, and there are limited quantitative data available on absolute abundance and taxonomic change with depth. A photographic survey of demersal fishes was conducted along a depth-gradient of 400–2099 m on the outer shelf and upper slope west of Anvers Island, Palmer Archipelago. A total of 1490 fishes were identified at least to the family level. Notothenioids composed 52.7% of absolute abundance and non-notothenioids 47.3%. The most abundant families were Nototheniidae (39.4%), followed by Macrouridae (28.9%), Zoarcidae (16.9%), and Channichthyidae (12.1%). The most abundant species were the notothenioids Lepidonotothen squamifrons (30.5%) and Chionobathyscus dewitti (11.7%), and the non-notothenioid Macrourus spp. (29.5%). The absolute abundance of all fishes peaked at 400–599 m. Depths of maximum abundance were 400–599 m for L. squamifrons , 700–1499 m for Macrourus spp., and 900–1499 for C. dewitti . At 700–999 m the abundance shifted from primarily notothenioids to the non-notothenioids Macrourus spp. and zoarcids. Fishes of the outer shelf and upper slope are not provincialized like those of the inner shelf and are circum-Antarctic.
    Full-text · Article · Oct 2015 · Antarctic Science
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    ABSTRACT: Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010‒2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼4.5 individuals × 1,000 m−2 within a depth range of 1,100‒1,500 m (overall observed depth range 841–2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids—echinoderms and mollusks—were abundant on the upper slope (550–800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore.
    Full-text · Article · Sep 2015 · Proceedings of the National Academy of Sciences
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    Full-text · Dataset · Jul 2015
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    ABSTRACT: Assessments of benthic coastal seawater carbonate chemistry in Antarctica are sparse. The studies that have been performed have generally been short in duration, during the austral spring/summer, under sea ice, or offshore in ice-free water. Herein we present multi-frequency measurements for seawater collected from the shallow coastal benthos on a weekly schedule over one-year (May 2012 – May 2013), daily schedule over three months (March – May 2013), and semidiurnal schedule over five weeks (March – April 2013). A notable pH increase (max pH = 8.62) occurred in the late austral spring/summer (November - December 2012), coinciding with sea ice break out and subsequent increase in primary productivity. We detected semidiurnal variation in seawater pH with a maximum variation of 0.13 pH units during the day and 0.11 pH units during the night. Daily variation in pH is likely related to biological activity, consistent with previous research. We calculated the variation in dissolved inorganic carbon (DIC) over each seawater measurement frequency, focusing on the primary DIC drivers in the Palmer Station region. From this, we estimated net biological activity and found it accounts for the greatest variations in DIC. Our seasonal data suggest that this coastal region tends to act as a carbon dioxide (CO2) source during austral winter months and as a strong sink during the summer. These data characterize present-day seawater carbonate chemistry and the extent to which these measures vary over multiple time scales. This information will inform future experiments designed to evaluate the vulnerability of coastal benthic Antarctic marine organisms to ocean acidification.
    Full-text · Article · Jul 2015 · Polar Research
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    Kathryn M Schoenrock · Charles D Amsler · James B Mcclintock · Bill · J Baker
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    ABSTRACT: Many species of macroalgae along the western Antarctic Peninsula have a high coverage of filamentous algal endophytes. A previous field study showed that endophyte presence negatively impacts growth and survival in some Antarctic algae, but can have no impact on others. We examined nine species of common macroalgal hosts from the area surrounding Palmer Station, Antarctica, to examine fine-scale impacts of endophyte presence on host physiology. Physiological parameters were selected based on their potential to influence fitness of host algae. These included photosynthetic parameters, thallus toughness and susceptibility to grazers in those species previously known to be chemically defended. We found that few macroalgal hosts are impacted by the presence of endophytes and that these impacts are not consistent across all physiological parameters. Iridaea cordata and Pachymenia sp. were the only species among the nine examined that demonstrated physiological stress in the presence of endophytes. Out of four species in a previous study, I. cordata was also the most heavily impacted by endophyte presence.
    Full-text · Article · Jul 2015 · European Journal of Phycology
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    C.J. Brothers · J.B. McClintock
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    ABSTRACT: Anthropogenic climate change is causing a global increase in sea-surface temperatures with some of the largest increases expected in the subtropical regions of the Northern Hemisphere. Populations of the sea urchin Lytechinus variegatus in the Gulf of Mexico are especially vulnerable as they are already living near the upper limit of their thermal tolerance and cannot migrate further north to escape rising seawater temperatures. In regular echinoids, neuromuscular-mediated behaviors including the covering and righting responses, and the Aristotle's lantern reflex can be employed as organismal level “indicators” of well-being under these near-future conditions. Individuals of the regular sea urchin L. variegatus were collected in Eagle Harbor, FL and held in the laboratory under a 12L:12D light cycle at both 28 °C (current summer seawater temperature) and 32 °C (predicted near-future summer seawater temperature) for acute (one day) and chronic (ten day) exposures. Covering and righting responses and Aristotle's lantern reflexes were measured. Individuals chronically exposed to 32 °C covered themselves with less material than did individuals acutely exposed to either 28 °C or 32 °C. They also righted less frequently and had lantern reflexes less often than individuals in the other acute or chronic temperature treatments. Moreover, although individuals acutely exposed to 28 °C and 32 °C covered their tests more during daylight periods, individuals chronically exposed to these temperatures did not, indicating that these individuals had an impaired ability to cover in response to increased light levels. Our results suggest that near-future elevated seawater temperatures may impair important neuromuscular-mediated behaviors that could negatively impact population and community dynamics.
    Full-text · Article · Jun 2015 · Journal of Experimental Marine Biology and Ecology
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    ABSTRACT: A dense aggregation of skate egg cases was imaged during a photographic survey of the sea floor along the western Antarctic Peninsula in November 2013. Egg cases were noted in a narrow band between 394 and 443 m depth. Although some skate species in other oceans are known to utilize restricted areas to deposit eggs in great numbers, such nurseries have not been described in the Southern Ocean. © 2015 The Fisheries Society of the British Isles.
    Full-text · Article · Apr 2015 · Journal of Fish Biology
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    Full-text · Conference Paper · Apr 2015
  • C. J. Brothers · J. Harianto · M. Byrne · J. B. Mcclintock

    No preview · Conference Paper · Apr 2015
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    ABSTRACT: Gastropod assemblages associated with eight common macroalgae from the hard-bottom subtidal communities near Palmer Station, western Antarctic Peninsula, were investigated in order to establish a species inventory and determine abundance, distribution, and diversity. Four different sites within the area were sampled. Using SCUBA, selected algae were gently removed from the substrate and enclosed in a fine mesh bag. Shortly thereafter, all epibionts were removed and preserved. Twenty-one different gastropod taxa were identified, two of which not to species level. A total of 3486 individuals were quantified with Skenella umbilicata the numerically dominant, followed by Laevilacunaria antarctica and Eatoniella calignosa. Most individuals (86 %) were
    Full-text · Article · Mar 2015 · Polar Biology
  • Julie B. Schram · James B. McClintock · Charles D. Amsler · Bill J. Baker
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    ABSTRACT: As mean global temperatures continue to rise, regional seawater temperature measurements have revealed that some geographic areas are warming faster than others. One region that is experiencing particularly rapid warming is the western Antarctic Peninsula. Previous studies investigating direct effects of warming on Antarctic marine invertebrates have established that small increases in temperature can have significant impacts on aspects of behavior, physiology, and growth rates in these largely stenothermal organisms. To investigate how warming may impact feeding preferences of an ecologically important mesograzer on macroalgae of the Antarctic Peninsula, we examined the impacts of exposure to acute elevated temperature on the ecologically important omnivorous amphipod Gondogeneiea antarctica (Chevreux) at Palmer Station, Antarctica (64°46′S, 64°03′W) in April–May 2011. Amphipods were exposed to 1.5 °C (mean monthly upper summer temperature) or 3.5 °C (representative of current transient summer temperature peaks and projected mean for 2100) for a 24 h period. These amphipods were then used in choice-feeding assays with artificial food containing chemical extracts from six species of sympatric macroalgae known to produce feeding deterrents. We found that during acute exposure to elevated temperature (+2.0 °C), amphipods lost their feeding preferences in assays with artificial foods containing lipophilic (one macroalga), hydrophilic (three macroalgae), or combined lipophilic/hydrophilic (one macroalga) extracts. Our findings suggest that increased frequency in transient peaks and longer-term upward trends in ambient summer seawater temperature have the potential to alter feeding preferences in a common mesograzer that could influence macroalgal communities that dominate benthic communities along the western Antarctic Peninsula.
    No preview · Article · Feb 2015 · Marine Biology
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    ABSTRACT: This study examines climate change impacts (increased temperature and pCO2) on canopy-forming Desmarestia anceps and D. menziesii from the western Antarctic Peninsula during the austral summer–winter of 2013. These are ecologically important species that play a role functionally equivalent to kelp forests in this region. Two-way factorial microcosm experiments with treatments reflecting near-future ocean conditions were run with these species and include increased temperature alone (3.5 °C × pH 8.0), reduced pH alone (1.5 °C × pH 7.6), and both factors combined (3.5 °C × pH 7.6). Phlorotannin concentration, chlorophyll a concentration, growth, and photosynthetic parameters (slope to saturation of photo centers (α), saturating irradiance (E k), maximum electron transport rate (ETRmax), and maximum quantum yield of photosystem II (F v/F m)) were used to assess the physiological responses of the individuals to the different climate change treatments. Few significant impacts were observed: In D. menziesii, E k at the midpoint (after 39 days) was significantly higher in the 3.5 °C × pH 7.6 treatment and phlorotannin concentration was significantly higher in the 1.5 °C × pH 7.6 treatment than others at the end point of the experiment (79 days). All individuals in the experiment grew quickly through the midpoint, but growth declined thereafter. The photosynthetic apparatus of these species acclimated to microcosm conditions, and photo-physiological parameters changed between initial, midpoint, and end point measurements. Results indicate that D. menziesii is the more sensitive of the two species and that climate change factors can have a synergistic effect on this species. However, neither species responds negatively to climate change factors at the level of change used in this study, though the observed shifts in phlorotannin concentration and photosynthetic characteristics may have an unforeseen impact on the community dynamics in this geographic area.
    Full-text · Article · Feb 2015 · Marine Biology
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    Kathryn M Schoenrock · Charles D Amsler · James B Mcclintock · Bill J Baker
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    ABSTRACT: Endophytic organisms are known to have varied effects on their host organism in terrestrial and marine environments. In previous studies on marine algae, these symbioses range from innocuous to path-ogenic depending on the host and endophyte species. The present study further assessed a pathogenic relationship between filamentous algal endophytes and a red algal host from the western Antarctic Peninsula. We analyzed endophyte presence (appearance of fila-mentous thalli) in the three life history stages of Iri-daea cordata and potential impacts on fertility in the fertilized female gametophytes (carposporophytes) and tetrasporophytes. We found that endophytes proliferate throughout significantly more thallus area in tet-rasporophyte and unfertilized gametophyte hosts than in carposporophyte hosts, but there was no correlation between endophyte cover and fertility in these individuals. This study also provides a demographic analysis of I. cordata populations surrounding Palmer Station, Antarctica, showing that these populations are hap-loid dominated (∼78% of individuals). The differential presence of filamentous algal endophytes indicates that endophyte pathogenicity indirectly has greater effect on tetrasporophytes and unfertilized gametophytes than on the carposporophytes, which house the products of sexual recombination.
    Full-text · Article · Feb 2015 · Botanica Marina
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    Roberta C. Challener · Lisa L. Robbins · James B. McClintock

    Full-text · Article · Jan 2015 · Marine and Freshwater Research
  • Roberta C. Challener · Stephen A. Watts · James B. McClintock
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    ABSTRACT: Land-based aquaculture facilities experience occasional hypercapnic conditions due to the accumulation of the metabolic waste product carbon dioxide. Pre-gonadal Lytechinus variegatus (horizontal diameter = 20 mm) were exposed to control (608 μatm pCO2, pH 8.1) or hypercapnic conditions (1738 μatm pCO2, pH 7.7) in synthetic seawater for 14 weeks. Sea urchins exposed to hypercapnic conditions exhibited significantly slower growth (reduced dry matter production), primarily due to reduced test production. Higher fecal production rates and lower ash absorption efficiency (%) in individuals exposed to hypercapnic conditions suggest the ability to process or retain dietary carbonates may have been affected. Significant increases in neutral lipid storage in the gut and increased soluble protein storage in the gonads of individuals exposed to hypercapnic conditions suggest alterations in nutrient metabolism and storage. Furthermore, organic production and energy allocation increased in the lantern of those individuals exposed to hypercapnic conditions. These results suggest chronic exposure to hypercapnic conditions alters nutrient allocation to organ systems and functions, leading to changes in somatic and reproductive production.
    No preview · Article · Nov 2014 · Marine behaviour and physiology
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    ABSTRACT: The threat that ocean acidification (OA) poses to marine ecosystems is now recognized and U.S. funding agencies have designated specific funding for the study of OA. We present a research framework for studying OA that describes it as a biogeochemical event that impacts individual species and ecosystems in potentially unexpected ways. We draw upon specific lessons learned about ecosystem responses from research on acid rain, carbon dioxide enrichment in terrestrial plant communities, and nitrogen deposition. We further characterize the links between carbon chemistry changes and effects on individuals and ecosystems, and enumerate key hypotheses for testing. Finally, we quantify how U.S. research funding has been distributed among these linkages, concluding that there is an urgent need for research programs designed to anticipate how the effects of OA will reverberate throughout assemblages of species. ■ INTRODUCTION Rising atmospheric CO 2 is linked to global warming and changes to terrestrial ecosystems. 1 In the oceans, increasing CO 2 alters surface seawater chemistry by decreasing ocean pH and calcium carbonate saturation state. 2,3 Collateral changes in biological systems are already apparent 4 and further alterations are expected. While there is no clear boundary between the role of CO 2 in Earth's climate and its role in seawater chemistry, the term ocean acidification (OA) is used to refer to the subset of changes in ocean chemistry that propagate from the addition of anthropogenic CO 2 to seawater. On time scales shorter than centuries, the primary concern with OA is a potential reconfiguration of marine ecosystems. 5
    Full-text · Article · Sep 2014 · Environmental Science & Technology
  • Ruth E. McDowell · Charles D. Amsler · James B. McClintock · Bill J. Baker
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    ABSTRACT: Marine macroalgae can release reactive oxygen species (ROS) upon wounding and grazing. Here we address the potential role of ROS in herbivore defense. We performed feeding assays in the presence of varying concentrations of hydrogen peroxide (H2O2), a common type of ROS. H2O2 inhibited feeding by a marine amphipod grazer, Gondogeneia antarctica, over broad levels of concentration, and its potency was strongly dependent on its rate of decay in natural seawater. Because it is possible that the inhibitory levels of H2O2 are encountered in the vicinity of a sympatric macroalgal wound, we suggest that H2O2 has the potential to act as a direct anti-grazing defense in marine ecosystems. Since some sympatric macroalgae release a burst of non-H2O2 ROS, we also performed experiments to evaluate the role of these naturally-produced ROS on sympatric grazers. The presence of wounded Ascoseira mirabilis (which releases a burst of non-H2O2 ROS after wounding) during a feeding assay inhibited feeding of G. antarctica compared to the presence of intact A. mirabilis. These data are consistent with a role for ROS as a direct anti-herbivore defense in nature. However, the data are also consistent with hypotheses that involve other putative activated anti-grazing defenses.
    No preview · Article · Sep 2014 · Journal of Experimental Marine Biology and Ecology
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    ABSTRACT: Whale falls provide a substantial, nutrient-rich resource for species in areas of the ocean that may otherwise be largely devoid of food. We report the discovery of a natural whale fall at 1430 m depth in the cold waters of the continental slope off the western Antarctic Peninsula. This is the highest latitude whale fall reported to date. The section of the carcass we observed—the tail fluke—was more complete than any previously reported natural whale fall from the deep sea and in the early stages of decomposition. We estimate the entire cetacean to measure 5 to 8 m in length. The flesh remained almost intact on the carcass but the skin was missing from the entire section except for the end of the fluke, clearly exposing blubber and soft tissue. The absence of skin indicates rapid and homogenous loss. The dominant macrofauna present were crustaceans, including most prominently the lithodid crab Paralomis birsteini, and zoarcid fish typical of the ‘mobile-scavenger' successional stage. The density of mobile macrofauna was greatest on the carcass and declined to background levels within 100 m, indicating that they were attracted to the whale fall. This whale fall offers an important opportunity to examine the decomposition of a carcass under deep-sea conditions at polar latitudes.
    Full-text · Article · Aug 2014 · Deep Sea Research Part A Oceanographic Research Papers
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    ABSTRACT: Warming seawater temperatures and ocean acidification on the coastal western Antarctic Peninsula pose unique challenges to stenothermal marine invertebrates. The present study examines prospective sub-lethal effects of elevated temperature, pCO2, and resultant decrease in seawater pH, on righting behavior and maximal escape speeds for two common gastropods, the limpet Nacella concinna (Strebel) and mesogastropod snail Margarella antarctica (Lamy). Replicate individuals held in individual containers were exposed to four combinations of seawater temperature (1.5 °C — current average, 3.5 °C — projected average by 2100) and pH (pH 8.0 — current average, pH 7.8 — projected average by 2100 as a result of elevated pCO2 levels) for a period of 6 weeks. Following this chronic exposure, righting behavior, determined for the limpets as proportion to right over 24 h and for snails as time to right, as well as maximum escape speed following contact with a sea star predator were measured. We found no significant differences in proportions of limpets displaying the capacity to right among the four temperature–pH treatments. However, there was a significant temperature–pH interaction effect for mean righting times in snails, indicating that the effect of pH on the time to right is dependent on temperature. We found no significant effects of temperature or pH on mean maximal escape speed in limpets. Additionally, we observed a significant temperature–pH interaction effect for mean maximal escape speed in snails. These interactive effects make it difficult to make clear predictions about how these environmental factors may impact behavioral responses.
    No preview · Article · Aug 2014 · Journal of Experimental Marine Biology and Ecology

Publication Stats

5k Citations
537.09 Total Impact Points


  • 1988-2015
    • University of Alabama at Birmingham
      • Department of Biology
      Birmingham, Alabama, United States
  • 1986-2008
    • University of California, Santa Cruz
      • Institute of Marine Sciences
      Santa Cruz, California, United States
  • 1981-2008
    • University of South Florida
      • Department of Chemistry
      Tampa, Florida, United States
  • 1998
    • Florida Institute of Technology
      • Department of Chemistry
      Melbourne, Florida, United States
  • 1997
    • University of Naples Federico II
      • Department of Pharmacy
      Napoli, Campania, Italy
  • 1992
    • University of Alabama
      Tuscaloosa, Alabama, United States
  • 1990
    • Loyola University
      New Orleans, Louisiana, United States
  • 1983
    • Harvard University
      Cambridge, Massachusetts, United States
  • 1982
    • The University of Tampa
      Tampa, Florida, United States