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Item Anthropogenic effects on the marine environment adjacent to Palmer Station, Antarctica(Antarctic Science, 2021-12-07) Palmer, Terence A.; Klein, Andrew G.; Sweet, Stephen T.; Montagna, Paul A.; Hyde, Larry J.; Wade, Terry L.; Pollack, Jennifer BeseresLocalized contamination from research-related activities and its effects on macrofauna communities in the marine environment were investigated at Palmer Station, a medium-sized Antarctic research station. Relatively low concentrations of polycyclic aromatic hydrocarbons (PAHs; 32–302 ng g-1) and total petroleum hydrocarbons (TPHs; 0.9–8.9 μg g-1) were detected in sediments adjacent to the sewage outfall and pier, where most human activities were expected to have occurred, and at even lower concentrations at two seemingly reference areas (PAHs 6–30 ng g-1, TPHs 0.03–5.1 μg g-1). Elevated concentrations of PAHs in one sample taken in one reference area (816 ng g-1) and polychlorinated biphenyls (353 ng g-1) and dichloro-diphenyl-trichloroethane (3.2 and 25.3 ng g-1) in two samples taken adjacent to the sewage outfall indicate spatial heterogeneity of localized sediment contamination. Limpet (Nacella concinna) tissues collected adjacent to Palmer Station had high concentrations of PAHs, copper, lead, zinc and several other metals relative to outlying islands. Sediment and limpet tissue contaminant concentrations have decreased since the early 1990s following the Bahía Paraíso spill. Natural sediment characteristics affected macrofaunal community composition more than contamination adjacent to Palmer Station, presumably because of the low overall contamination levels.Item Application of watershed analyses and ecosystem modeling to investigate land–water nutrient coupling processes in the Guadalupe Estuary, Texas(Ecological Informatics, 2009-08-07) Arismendez, Sandra S.; Kim, Hae-Cheol; Brenner, JorgeEstuarine nutrient enrichment is thought to be controlled by land use patterns in coastal watersheds. Hence, the objective of this work was to conduct a watershed analysis in two adjacent river basins with different land use characteristics to determine their influence on estuarine ecosystem response in the Guadalupe Estuary, Texas, U.S.A. All data sources for this study were available electronically on the Internet; the data were mined, managed, analyzed and transformed to simulate the estuarine ecosystem response to watershed-derived nutrient loads. Between 1992 and 2001, developed land use/land cover increased the most while forest cover decreased the most in both basins. Two hydrologic units nearest the coast were responsible for the greatest change in land cover. Nutrient concentrations and loads were significantly higher in the San Antonio River Basin than in the Guadalupe River Basin. Both river basins exhibited the highest flows ever recorded in 1992, however the magnitude of difference in loads between the two coastal hydrologic units for a wet and dry year was much greater in the Guadalupe River Basin (GRB) than in the San Antonio River Basin (SARB); this difference supports the concept that the GRB is a nonpoint source dominated system and SARB is a point source dominated system. There was a strong correlation between developed land use and nutrient concentrations in river water; the GRB had less developed land use and lower nutrient concentrations while the SARB had more developed land use and higher nutrient concentrations. Estuarine ecosystem response differed in the timing, duration and magnitude of DIN, phytoplankton and zooplankton when nitrogen loads from the Lower Guadalupe River were used as opposed to the Lower San Antonio. The two basins studied differ in their fundamental characteristics, i.e. precipitation, flow, human population density, etc., resulting in different drivers of nitrogen loading, point sources in the San Antonio River Basin and nonpoint sources in the Guadalupe River Basin, therefore, differing estuarine ecosystem responses.Item Aragonite saturation states in estuaries along a climate gradient in the northwestern Gulf of Mexico(Frontiers in Environmental Science, 2022-10-10) Hu, Xinping; Yao, Hongming; McCutcheon, Melissa R.; Dias, Larissa; Staryk, Corey J.; Wetz, Michael S.; Montagna, Paul A.In the northwestern Gulf of Mexico (nwGOM), the coastal climate shifts abruptly from the humid northeast to the semiarid southwest within a narrow latitudinal range. The climate effect plays an important role in controlling freshwater discharge into the shallow estuaries in this region. In addition to diminishing freshwater runoff down the coast, evaporation also increases substantially. Hence, these estuaries show increasing salinity along the coastline due to the large difference in freshwater inflow balance (river runoff and precipitation minus evaporation and diversion). However, this spatial gradient can be disrupted by intense storm events as a copious amount of precipitation leads to river flooding, which can cause temporary freshening of these systems in extreme cases, in addition to freshwater-induced ephemeral stratification. We examined estuarine water aragonite saturation state (Ωarag) data collected between 2014 and 2018, covering a period of contrasting hydrological conditions, from the initial drought to multiple flooding events, including a brief period that was influenced by a category 4 hurricane. Based on freshwater availability, these estuaries exhibited a diminishing Ωarag fluctuation from the most freshwater enriched Guadalupe Estuary to the most freshwater-starved Nueces Estuary. While Ωarag values were usually much higher than the threshold level (Ωarag = 1), brief freshwater discharge events and subsequent low oxygen levels in the lower water column led to episodic corrosive conditions. Based on previously obtained Ωarag temporal trends and Ωarag values obtained in this study, we estimated the time of emergence (ToE) for Ωarag. Not only did estuaries show decreasing ToE with diminishing freshwater availability but the sub-embayments of individual estuaries that had a less freshwater influence also had shorter ToE. This spatial pattern suggests that planning coastal restoration efforts, especially for shellfish organisms, should emphasize areas with longer ToE.Item Assessment of a brown tide impact on microalgal benthic communities in Baffin Bay (Texas) in 1990 using a primary production simulation model(Oceanolgica ACTA, 1995) Montagna, Paul A.; Blanchard, Gerard F.A primary production simulation mode! was used to assess the effect of a brown tide (Chrysophytes) on benthic microalgal photosynthesis. This model is based on the assumption that photosynthesis of microphytobenthos is primarily determined by irradiance at the sediment-water interface and by the photophysiological response of microalgae to changes of this irradiance. So, irradiance recordings at the sediment-water interface were used as the forcing variable. The simulation indicates that before the introduction of the brown tide, primary production of microphytobenthos was physically controlled. Light levels, bence primary production rates, were very variable (<1-132 mg C m-2 d-1, CV= 80 %) because wind-induced resuspension generates turbidity within the water column. During the chrysophyte bloom, the mean production rate of microphytobenthos dramatically decreased by two orders of magnitude (0.25-1.31 mg C m-2 d-1, CV = 46 %) due to shading by the planktonic compartment. Simulations further indicate that the indirect effects of this light reduction (decrease of P-1 parameters and biomass) bad a higher impact on microphytobenthic production rates than its direct effect (reduction of light energy at the surface of the sediment). As a result, the collapse of rnicrophytobenthic productivity could partially explain the observed decrease of macrofaunal abundance in Baffin Bay, since microphytobenthos is an important food source for benthic invertebrates.Item Baseline nutrient dynamics in shallow well mixed coastal lagoon with seasonal harmful algal blooms and hypoxia formation(Marine Pollution Bulletin, 2015-06-11) Turner, Evan L.; Paudel, Bhanu; Montagna, Paul A.Weekly inorganic nutrient and chlorophyll-a concentrations were measured to establish baseline conditions in Corpus Christi Bay, Texas during seasonal hypoxia and harmful algal bloom (HAB) formation. Two fixed stations along the southern shoreline were sampled weekly for a continuous year at the same time each day. Weekly shoreline observations were found to be statistically similar to quarterly observations in the bay center, but with a greater power to detect seasonal trends. Dissolved Oxygen (DO) < 4 mg/L was measured in June, 2012 along the southern shoreline of Corpus Christi Bay, which places lower DO conditions west of previous estimates. During a bay-wide HAB event in November of 2011 no changes were observed in any of the nutrient or chlorophyll-a observations. This study documents a baseline of nutrients and chlorophyll-a in Corpus Christi Bay during a dry (average salinity > 36 PSU) year.Item Blomberg, B.N., B. Lebreton, T.A. Palmer, G. Guillou, J. Beseres Pollack, and P.A. Montagna. 2017. Does reef structure affect oyster food resources? A stable isotope assessment. Marine Environmental Research 127: 32-40. doi: /10.1016/j.marenvres.2017.03.003(Marine Environmental Research, 2017) Blomberg, Brittany N.; Lebreton, Benoit; Palmer, Terence A.; Guillou, Gael; Pollack, Jennifer Beseres; Montagna, Paul A.As ecosystem engineers, oysters create and maintain structured habitat and can influence trophodynamics and benthic-pelagic coupling in the surrounding landscape. The physical reef structure and associated biotic parameters can affect the availability of food resources for oysters. Oysters and potential composite food sources d suspended particulate organic matter (SPOM) and surface sediment organic matter (SSOM) d were assessed using a dual stable isotope (d13C, d15N) approach at three reef types (natural, restored, and unconsolidated) seasonally for two years to determine if changes in physical and/ or biotic parameters affected the relative availability and/or use of food resources by oysters. SPOM was more depleted in 13C ( 24.2 ± 0.6‰, mean ± SD) than SSOM ( 21.2 ± 0.8‰). SPOM composition is likely dominated by autochthonous phytoplankton production, while SSOM includes trapped phytoplankton and benthic microalgae. SSOM was used by oysters in increasing proportions relative to SPOM over time at all reef types. This temporal trend is likely due to increased oyster biomass over time, promoting enhanced microphytobenthos growth through feedback effects related to oyster biodeposits. Structural differences between reef types observed in this study had no effect on food resource availability and use by oysters, indicating strong bentho-pelagic coupling likely due to shallow depths as well as strong and consistent winds. This study provides insights for restoration of oyster reefs as it highlights that food resources used by oysters remain similar among reef types despite changes in abiotic and biotic parameters among habitats and over time.Item Cervinia langi n. sp. and Pseudocervinia magna (Copepoda: Harpacticoida) from the Beaufort Sea (Alaska, U.S.A.)(Transactions of the American Microscopy Society, 1979) Montagna, Paul A.Two species of the family Cerviniidae have been collected from the Beaufort Sea off the coast of Alaska. Pseudocervinia magna (Smirnov, 1946) and Cervinia langi n. sp. were found in association. Lang (1936, 1948) described the new species as a variant of Cervinia synarthra Sars, 1911. However, C. langi is consistent and unique in the setation of its swimming legs and in details of the mandible and maxilliped. A key to the species and a table of salient morphological characters of the genus Cervinia are given. Appendages from the cephalothorax of P. magna are also figured, and its taxonomic position is discussed.Item Characterizing the role benthos plays in large coastal seas and estuaries: A modular approach(Journal of Experimental Marine Biology and Ecology, 2006-02-15) Tenore, Ken R.; Zajac, Roman N.; Terwin, Jeff; Andrade, Francisco; Blanton, Jack; Boynton, Walter; Carey, Drew; Diaz, Robert; Holland, A. Fred; Lopez-Jamar, Eduardo; Montagna, Paul A.; Nichols, Fred; Rosenberg, Rutger; Queiroga, Henrique; Sprung, Martin; Whitlatch, Robert B.Ecologists studying coastal and estuarine benthic communities have long taken a macroecological view, by relating benthic community patterns to environmental factors across several spatial scales. Although many general ecological patterns have been established, often a significant amount of the spatial and temporal variation in soft-sediment communities within and among systems remains unexplained. Here we propose a framework that may aid in unraveling the complex influence of environmental factors associated with the different components of coastal systems (i.e. the terrestrial and benthic landscapes, and the hydrological seascape) on benthic communities, and use this information to assess the role played by benthos in coastal ecosystems. A primary component of the approach is the recognition of system modules (e.g. marshes, dendritic systems, tidal rivers, enclosed basins, open bays, lagoons). The modules may differentially interact with key forcing functions (e.g. temperature, salinity, currents) that influence system processes and in turn benthic responses and functions. Modules may also constrain benthic characteristics and related processes within certain ecological boundaries and help explain their overall spatio-temporal variation. We present an example of how benthic community characteristics are related to the modular structure of 14 coastal seas and estuaries, and show that benthic functional group composition is significantly related to the modular structure of these systems. We also propose a framework for exploring the role of benthic communities in coastal systems using this modular approach and offer predictions of how benthic communities may vary depending on the modular composition and characteristics of a coastal system.Item Comparative biomass structure and estimated carbon flow in food webs in the deep Gulf of Mexico(Deep-Sea Research II, 2008-10-22) Rowe, Gilbert T.; Wei, Chihlin; Nunnally, Clifton; Haedrich, Richard; Montagna, Paul A.; Baguley, Jeffrey G.; Bernhard, Joan M.; Wicksten, Mary; Ammons, Archie; Briones, Elva Escobar; Soliman, Yousra; Deming, Jody W.A budget of the standing stocks and cycling of organic carbon associated with the sea floor has been generated for seven sites across a 3-km depth gradient in the NE Gulf of Mexico, based on a series of reports by co-authors on specific biotic groups or processes. The standing stocks measured at each site were bacteria, Foraminifera, metazoan meiofauna, macrofauna, invertebrate megafauna, and demersal fishes. Sediment community oxygen consumption (SCOC) by the sediment-dwelling organisms was measured at each site using a remotely deployed benthic lander, profiles of oxygen concentration in the sediment pore water of recovered cores and ship-board core incubations. The long-term incorporation and burial of organic carbon into the sediments has been estimated using profiles of a combination of stable and radiocarbon isotopes. The total stock estimates, carbon burial, and the SCOC allowed estimates of living and detrital carbon residence time within the sediments, illustrating that the total biota turns over on time scales of months on the upper continental slope but this is extended to years on the abyssal plain at 3.6 km depth. The detrital carbon turnover is many times longer, however, over the same depths. A composite carbon budget illustrates that total carbon biomass and associated fluxes declined precipitously with increasing depth. Imbalances in the carbon budgets suggest that organic detritus is exported from the upper continental slope to greater depths offshore. The respiration of each individual “size” or functional group within the community has been estimated from allometric models, supplemented by direct measurements in the laboratory. The respiration and standing stocks were incorporated into budgets of carbon flow through and between the different size groups in hypothetical food webs. The decline in stocks and respiration with depth were more abrupt in the larger forms (fishes and megafauna), resulting in an increase in the relative predominance of smaller sizes (bacteria and meiofauna) at depth. Rates and stocks in the deep northern GoM appeared to be comparable to other continental margins where similar comparisons have been made.Item Comparing fixed-point and probabilistic sampling designs for monitoring the marine ecosystem near McMurdo Station, Ross Sea, Antarctica(Antarctic Science, 2008-05-16) Morehead, Sally; Montagna, Paul A.; Kennicutt II, Mahlon C.Fixed-point and probabilistic sampling designs were compared to investigate which design best detected known contamination gradients in the marine ecosystem adjacent to McMurdo Station, Antarctica. The fixed-point sampling design included transects along historical contamination and physical disturbance gradients. The probabilistic sampling design used randomly selected hexagons spaced at 50 m intervals. In both designs, 15 stations were sampled over a small area (~1 km2) that extended from Winter Quarters Bay to Cape Armitage. Sediment quality triad components (sediment chemical contaminants, sediment toxicity, and a benthic index of biotic integrity) were measured to indicate chemical, toxicological, and biological effects. There were higher correlations between sediment quality triad components for the fixed-point sampling design than for the probabilistic design. The fixed-point design was better at detecting the intensity of alteration because disturbance of the marine ecosystem at McMurdo Station is localized within a small area. Based on these results, a limited fixed-point design with nine stations detected no significant change in macrofaunal community structure over a four year period from 2000–2004. However, the macrofaunal assemblages present in the contaminated portions of Winter Quarters Bay are indicative of a disturbed benthic community that has been subject to organic enrichment and toxic chemical exposure.Item Comparing performance of five nutrient phytoplankton zooplankton (NPZ) models in coastal lagoons(Ecological Modelling, 2014-02-07) Turner, Evan L.; Bruesewitz, Denise A.; Mooney, Rae F.; Montagna, Paul A.; McClelland, James W.; Sadovski, Alexey; Buskey, Edward J.Modeling nutrient cycle dynamics in the open ocean based on the well-known interactions among nitrogen, phytoplankton, and zooplankton (NPZ) is well-established. Difficulty arises in applying this methodology to multiple coastal systems because of differences among geography, water chemistry, microbial interactions, weather patterns, and sedimentary nutrient cycling. Current trends in ecological modeling are toward more complex modeling relationships and mathematical functions. Four published NPZ models and a new model are compared based on their varying number of equations, mathematical complexity, and required parameters. The new model adapts NPZ interactions to shallow estuary systems by adding a benthic consumption component as a nutrient producer consumer (NPC) system. Each model is calibrated and validated for two bays in the western Gulf of Mexico: San Antonio Bay, TX, USA, and Copano Bay, TX, USA. Daily riverine nutrient inputs are used as the model driver while historical measurements are used for calibration and validation. The five models are compared for their ability to simulate the observed bay response of primary production in both locations. The new model simulates primary production closer to measured observations than other models because of the inclusion of benthic consumption dynamics. However, differences of equation complexity between NPZ models had no relationship to overall goodness of fit in study area. Models produced nearly identical results regardless of different relationships and mathematical formulas. Although every location is unique, this study shows that adding mathematical complexity may only provide marginal gains in practice while decreasing portability when extending NPZ models for the coastal zone.Item Comparison of sampling methods for deep-sea infauna(Limnology and Oceanography: Methods, 2016-11-21) Montagna, Paul A.; Baguley, Jeffery G.; Hsiang, Chein-Yi; Reuscher, Michael G.Sampling methods for benthic meiofauna and macrofauna assessments on the northern Gulf of Mexico continental slope and deep sea were compared. For meiofauna, a core with an inner diameter of 5.1 cm is recommended for yielding an appropriate sample size. Meiofauna are concentrated in the uppermost 2 cm sediment layer, so the top 3 cm are sufficient to sample. Macrofauna penetrate deeper and the top 10 cm are sufficient. Smaller sieves capture more organisms so 45 μm for meiofauna, and 300 μm for macrofauna, is recommended. On average, 88% of meiofauna were extracted in the Ludox fraction compared to the total of both Ludox and the sediment pellet. Box corers and multiple corers were compared for estimating macrofauna and meiofauna metrics. Multicorers are recommended for quantitative assessments, but box corers are useful for qualitative studies that require capturing more diversity. Box cores underestimate macrofauna abundance by 2.9 times. While the larger box core captures more species resulting in higher diversity estimates, it is low relative to the 24 times larger area sampled. The multicorer preserves vertical distribution. Because meiofauna are sampled from subcores, there is little difference between the two devices for estimating meiofauna metrics. Replicate multicore samples (i.e., deployments) do not add substantially to our understanding of the variance of species richness or abundance, thus to describe the spatial footprint of macrofauna community structure, it is recommended that resources should be used to sample more stations over a larger area rather than multiple replicates at fewer stations.Item Competition for dissolved glucose between meiobenthos and sediment microbes(Journal of Experimental Marine Biology and Ecology, 2003-03-31) Montagna, Paul A.Meiobenthos, small invertebrates inhabiting the surface layers of marine sediments, can absorb dissolved organic matter (DOM). Experiments were performed to test if meiobenthos can compete with sediment microbes for uptake of small amounts of [14C]glucose. Meiofaunal glucose uptake rates were measured by themselves and in the presence of sediment microbes. Glucose uptake by meiofauna was not inhibited by the presence of bacteria, nor did it appear that bacterial uptake was inhibited by meiofauna. Thus, there was no direct or interference competition. Uptake rates by 1 cm3 of sediment (bacteria) were four orders of magnitude greater than those of individual meiofauna, but on a biomass specific basis, meiofaunal uptake was in the same range if not higher than that of sediment bacteria. Thus, the potential for indirect or resource competition exists. Since bacterial biomass dominated the system studied, uptake of glucose was dominated by bacteria. The results support the hypothesis that in natural sediments, where the biomass of bacteria is higher than that of meiofauna, heterotrophic uptake is primarily a microbial process. However, resource competition between meiofauna and bacteria for DOM in sediments probably exists where bacterial biomass is low relative to meiofaunal biomass.Item Decomposition of Spartina alterniflora in different seasons and habitats of a Northern Massachusetts salt marsh, and a comparison with other Atlantic regions(Estuaries, 1980-03) Montagna, Paul A.; Ruber, ErnestPackets of freshly harvested liveSpartina alterniflora were placed on the marsh surface, in a tidal ditch, in a pool contacting sides and bottom, and in the center-bottom of the same pool in September 1972. Rates of loss were the same for all four sites through day 242. After that packets on the marsh surface decomposed slower. A second experiment was begun in July only at the marsh surface and pool side sites. These lost dry weight much more rapidly than packets started in September. Populations of bacteria, fungi, diatoms, flagellates, ciliates and nematodes within the packets peaked within 60 days then decreased proportionately with the loss of dry weight in packets through day 242. After this, bacterial numbers decreased more rapidly presumably in response to a qualitative change in the packet material. Populations of flagellates and ciliates also declined rapidly after day 300. This decline occurred in new packets at around this date as well. In a limited set of samples 12 taxa were analyzed for date or detritus-age dependent occurrence. Of these, eight were data dependent, two were dependent on packet age, and two could not be determined from the data.Item Deep-sea tardigrades in the northern Gulf of Mexico with a description of a new species of Coronarctidae (Tardigrada: Arthrotardigrada), Coronarctus mexicus(Journal of Zoological Systematics and Evolutionary Research, 2011-04-21) Romano III, Frank; Gallo, Maria; D'Addabbo, Rossana; Accogli, Gianluca; Baguley, Jeffrey; Montagna, Paul A.During May and June 2000, for the first time, benthic samples were collected from 43 stations in the northern Gulf of Mexico deep sea that included seven transects along the northern continental slope and abyssal plain ranging in depth from 625 to 3159 m. A total of 54 tardigrades (36 identified) were extracted from samples, ranging in depth from 625 to 3150 m. Collected tardigrades belong to five genera and represented eight species, Angursa bicuspis abyssalis (two specimens from 1401 and 2020 m depth), four species of Coronarctus (29 specimens from 625 to 3159 m depth), Euclavarctus convergens (one specimen from 2743 m depth), E. thieli (one specimen from 2635 m depth), Proclavarctus sp. (one specimen from 2600 m depth), Styraconyx sp. (two specimens from 1565 and 2600 m depth). The most abundant genus was Coronarctus (80.5% of identified species) and was present in most areas sampled with the exception of the central and Mississippi trough regions and comprised four species, Coronarctus laubieri (15 specimens), C. stylisetus (one specimen), C. disparilis (three specimens) and a new species C. mexicus (10 specimens). Tardigrades were mostly found in the western regions (NW, W, WC) and in deep waters, 2290 m average depth. Analyses of tardigrade and depth collected gave a slight positive correlation (R2 = 0.029), while analyses of tardigrade and degrees longitude resulted in a slight negative correlation (R2 = 0.022).Item Determining the effects of freshwater inflow on benthic macrofauna in the Caloosahatchee Estuary, Florida(Integrated Environmental Assessment and Management, 2015-08-14) Palmer, Terence A.; Montagna, Paul A.; Chamberlain, Robert H.; Doering, Peter H.; Wan, Yongshan; Haunert, Kathleen M.; Crean, Daniel J.Florida legislation requires determining and implementing an appropriate range and frequency of freshwater inflows that will sustain a fully functional estuary. Changes in inflow dynamics to the Caloosahatchee Estuary, Florida have altered salinity regimes that, in turn, have altered the ecological integrity of the estuary. The purpose of this current project is to determine how changes in freshwater inflows affect water quality, and in turn, benthic macrofauna, spatially within the Caloosahatchee Estuary and between multiyear wet and dry periods. Thirty-four benthic species were identified as being indicator species for salinity zones, and the estuary was divided into 4 zones based on differences in community structure within the estuary. Community structure had the highest correlations with water quality parameters that were common indicators of freshwater conditions resulting from inflows. A significant relationship between salinity and diversity occurs both spatially and temporally because of increased numbers of marine species as salinities increase. A salinity-based model was used to estimate inflow during wet and dry periods for each of the macrofauna community zones. The approach used here (identifying bioindicators and community zones with corresponding inflow ranges) is generic and will be useful for developing targets for managing inflow in estuaries worldwide. Integr Environ Assess Manag 2016;12:529–539. © 2015 SETACItem Direct and indirect effects of hypoxia on benthos in Corpus Christi Bay, Texas, U.S.A.(Journal of Experimental Marine Biology and Ecology, 2006-02-03) Montagna, Paul A.; Ritter, ChristineHypoxia (low oxygen conditions) has been found in the southeastern region of Corpus Christi Bay, Texas, U.S.A. every summer since 1988. The objectives of the current study were to determine direct and indirect effects of hypoxia on macrofauna. Direct physiological effects of hypoxia include reduction of benthic abundance, biomass, diversity, species richness and species evenness because of physiological intolerance. Indirect ecological effects of hypoxia include predation of emerging benthic fauna from the sediment. Macrofaunal community characteristics were compared vertically within sediments in caged and uncaged sediment samples in hypoxic and normoxic areas. Cage effects were determined with partial cages, which had reduced flow and no predator exclusion. Dissolved oxygen concentrations during the experiment was monitored in water column profiles and continuous measurement of bottom water in the hypoxic and normoxic areas. Hypoxia in Corpus Christi Bay in 1999 occurred as transient events, many of which were of short duration (less than 1 h) and moderate intensity (around 2 mg l− 1). The macrobenthic community characteristics (i.e., abundance, biomass, species richness, diversity, and evenness) were directly affected by hypoxia as indicated by depressed levels and few deeper-dwelling organisms in the hypoxic area. Community structure was also different between the hypoxic and normoxic areas because of loss of species (presumably due to intolerance to low oxygen) in the hypoxic areas. Benthic invertebrates were found primarily in the surface in the hypoxic area, but there was no significant indication of indirect effects, i.e., increased predation pressure in the hypoxic area. The increased exposure to predation risk may be mitigated by predator avoidance of hypoxic areas. In conclusion, hypoxia in Corpus Christi Bay has negative direct effects on benthic organisms, but no indirect effects, such as increased predation pressure. The most significant finding is the interaction between hypoxia and vertical distributions of infauna, which drive hypoxia intolerant organisms to the surface and out of sediments.Item Disruption of grazer populations as a contributing factor to the initiation of the Texas brown tide algal bloom(Limnology and Oceanography, 1997) Buskey, Edward J.; Montagna, Paul A.; Amos, Anthony F.; Whitledge, Terry E.Disruption of grazer populations, or mismatches between phytoplankton blooms and population dynamics of their planktonic and benthic grazers, may play an important role in the initiation of some harmful algal blooms. The Laguna Madre of Texas has experienced a persistent, nearly monospecific phytoplankton bloom since January 1990 commonly referred to as the “brown tide.” Whole-water samples collected in the area where the bloom began reveal the pattern of bloom initiation and dispersion during the first few months of the bloom. Enumeration of microzooplankton from these same samples also reveals that protozoan grazer populations were depressed and nearly eliminated before the bloom began. Benthic biomass and species diversity also declined before the onset of the bloom. The disruption of planktonic and benthic grazers may have been due to extreme hypersaline conditions caused by an extended period of drought (salinities > 60%0). A massive fish kill caused by an abnormal period of below freezing temperatures released a pulse of nutrients into an already disturbed environment allowing this nuisance bloom to become established. Planktonic and benthic grazers have been unable to contribute to the demise of this bloom, which has persisted for >7 yr without interruption.Item Distribution of two species of the genus Nototanais spp. (Tanaidacea) in Winter Quarters Bay and waters adjoining McMurdo Station, McMurdo Sound, Antarctica(Polar Biology, 2015-06-16) Rhodes, Adelaide C.; Carvalho, Nayara F.; Palmer, Terence A.; Hyde, Larry J.; Montagna, Paul A.Nototanais is the most commonly found peracarid crustacean genus in Antarctic waters. The only two species in the genus, Nototanais dimorphus and Nototanais antarcticus, have been found to have overlapping circumpolar distributions in depths from 7 m to 585 m around Antarctica. However, only one species, N. dimorphus, has been recorded during yearly sampling from 2000 to 2010 at nine shallow (12–36 m) benthic pollution monitoring sites in Winter Quarters Bay and waters adjoining McMurdo Station, McMurdo Sound, Antarctica. These stations varied by depth, anchor ice formation and anthropogenic contamination. In 2011 and 2012, 1071 specimens of Nototanais spp. were collected and separated by species, gender and life stage. N. antarcticus was confirmed to co-occur with N. dimorphus at four of nine long-term monitoring sites. One station had no occurrences of either species. N. antarcticus was found in very low abundances in relation to N. dimorphus, indicating that individual species distributions may be modified by pollution and anchor ice, among other biological factors.Item Distributional notes of Harpacticoida (Crustacea: Copepoda) collected from the Beaufort Sea (Arctic Ocean)(1978) Montagna, Paul A.; Carey Jr., Andrew G.Forty-one species of large-size Harpacticoida have been sorted from Smith-McIntyre grab samples sieved through 1.00 and 0.2 mm aperture screens. Fifty-eight stations were occupied throughout the southwestern Beaufort Sea, ranging from Point Barrow, Alaska (USA) west, to Demarcation Point, the eastern border with Canada. The depth of the study area ranged from 5-3500 m. Harpacticus superflexus Willey and Stenhelia nuwukensis M. S. Wilson dominated the samples numerically. Though H. superflexus was ubiquitous, S. nuwukensis was restricted to a narrow range of shallow waters. The female to male ratio was 99:1. It is not known why there is such a preponderance of females, but sexually dimorphic characters may be absent or the smaller males may have passed through the sieve.