J. Mar. Sci. Eng.2015, 3(3), 509-519; doi:10.3390/jmse3030509 - published 29 June 2015 Show/Hide Abstract
Abstract: Although algal symbionts can become a source of reactive oxygen species under stressful conditions, symbiotic planulae of the coral Pocillopora damicornis are highly tolerant to thermal stress compared with non-symbiotic planulae of Acropora tenuis. As a first step to understand how P. damicornis planulae attain high stress tolerance, we compared the respiration rate and temperature dependence between symbiotic planulae of P. damicornis and non-symbiotic planulae of A. tenuis, as well as between larvae and adult branches within each species. Larvae and adult branches of both species had similar temperature dependency of respiration rate, with the temperature coefficient (Q10) values of about 2. Planula larvae of P. damicornis had a significantly lower respiration rate than that of A. tenuis larvae at 25–30 °C, but not at 32 °C, whereas adult branches of P. damicornis had a significantly higher respiration rate than that of A. tenuis branches at all temperatures. Thus, P. damicornis larvae appear to be capable of reducing their respiration rate to a greater extent than A. tenuis larvae, which could partly explain why P. damicornis larvae had high survivorship under thermal stress, although other antioxidant or photoprotective mechanisms should be investigated in the future.
J. Mar. Sci. Eng.2015, 3(3), 492-508; doi:10.3390/jmse3030492 - published 25 June 2015 Show/Hide Abstract
Abstract: Accurate and efficient species-based marine habitat assessment is in great demand for the marine environment. Remote sensing techniques including airborne light detection and ranging (LiDAR) derived bathymetry can now be used, in concert with suitable ground truthing, to produce marine habitat maps over wide areas. Hydrodynamic conditions, e.g., current speeds and wave exposure influence habitat types through direct impact on marine organisms, as well as influence on sediment transport and, hence, substrate type. Habitat classification and mapping was carried out using both LiDAR derivatives and hydrodynamic parameters derived from numerical modelling at a location off the coast of Port Hedland in the Pilbara region of Western Australia, 1660 km north of Perth. Habitat classes included seagrass, algae, invertebrates, hard coral, and areas where there is no evident epibenthos. The inclusion of the hydrodynamic parameters significantly increased the accuracy of the classification by 7.7% when compared to using LiDAR derivatives alone.
J. Mar. Sci. Eng.2015, 3(2), 466-491; doi:10.3390/jmse3020466 - published 23 June 2015 Show/Hide Abstract
Abstract: Mangroves serve as either sinks or sources for inorganic and organic nutrients and can mitigate anthropogenic nutrient pollution, control the production in adjacent systems, and prevent eutrophication. To better understand the nutrient dynamics in a subtropical mangrove, we employed a three-way approach in the Nanliu River Estuary, southern China: Pore water profiles and sediment incubations revealed benthic early diagenesis as well as sediment–water exchange of dissolved nutrients and oxygen, while tidal sampling of estuarine and mangrove water identified source and sink functions of the entire mangrove forest. Fluxes of oxygen during incubations were always directed into the sediment, indicating heterotrophy of the system. There was a net uptake of dissolved inorganic nitrogen, mainly caused by nitrate influx, while ammonium and nitrite showed variable flux direction. Despite high pore water concentrations, phosphate and silica showed net uptake. Fluxes of dissolved organic carbon were generally low except for high efflux in the dark following a storm event. Due to the combination of small forest area and strong anthropogenic nutrient input, the net sink function for dissolved nitrogen and phosphorus provides no significant buffer against the eutrophication of coastal waters.
J. Mar. Sci. Eng.2015, 3(2), 444-465; doi:10.3390/jmse3020444 - published 23 June 2015 Show/Hide Abstract
Abstract: Thermal tolerance tests on Acropora millepora, a common Indo-Pacific hard coral, have shown that adult corals can acquire increased thermal tolerance by shuffling existing type C to type D Symbiodinium zooxanthellae when subjected to increased seawater temperatures. We report here dimethylsulphoniopropionate (DMSP) concentrations in A. millepora and examine links between DMSP concentrations, zooxanthellae clade, and bleaching tolerance. DMSP analysis on native and transplanted corals from three locations in the Great Barrier Reef indicated that the lower thermal tolerance in type C zooxanthellae coincided with variable DMSP concentrations, whilst the more thermal tolerant type D zooxanthellae had more stable areal DMSP concentrations as seawater temperatures increased. Our results suggest this increased thermal tolerance in type D zooxanthellae may reflect the ability of these coral symbionts to conserve their antioxidant DMSP levels to relatively constant concentrations, enabling the coral to overcome the build-up of oxygen free radicals in the cytoplasm of A. millepora. A conceptual diagram illustrates how the antioxidants DMS (P) participate in the bleaching process by scavenging oxygen free radicals and form DMSO, thus moderating coral bleaching and increasing thermotolerance.
J. Mar. Sci. Eng.2015, 3(2), 428-443; doi:10.3390/jmse3020428 - published 19 June 2015 Show/Hide Abstract
Abstract: This paper describes storm surge simulations made for Sandy (2012) for the Metropolitan New York (NYC) area using the Advanced Circulation (ADCIRC) model forced by the Weather Research and Forecasting (WRF) model. The atmospheric forecast uncertainty was quantified using 11-members from an atmospheric Ensemble Kalman Filter (EnKF) system. A control WRF member re-initialized every 24 h demonstrated the capability of the WRF-ADCIRC models to realistically simulate the 2.83 m surge and 4.40 m storm tide (surge + astronomical tide) above mean lower low water (MLLW) for NYC. Starting about four days before landfall, an ensemble of model runs based on the 11 “best” meteorological predictions illustrate how modest changes in the track (20–100 km) and winds (3–5 m s−1) of Sandy approaching the New Jersey coast and NYC can lead to relatively large (0.50–1.50 m) storm surge variations. The ensemble also illustrates the extreme importance of the timing of landfall relative to local high tide. The observed coastal flooding was not the worst case for this particular event. Had Sandy made landfall at differing times, locations and stages of the tide, peak water levels could have been up to 0.5 m higher than experienced.
J. Mar. Sci. Eng.2015, 3(2), 412-427; doi:10.3390/jmse3020412 - published 3 June 2015 Show/Hide Abstract
Abstract: We studied genotype by environment interaction (G × E) for body weight (BW) of Atlantic cod (Gadus morhua L.) from the National cod breeding program in Norway. Records of 13,811 fish in a nucleus farm (NUC) and two test farms (PENorth, PESouth) in year-class (YC) 2007, and for 9149 fish in NUC and one test farm in YC 2010 were available. Heterogeneity of variances and heritabilities ( ) were estimated using a univariate animal model with environmental effects common to full-sibs (full-model). Genetic correlations ( ) between farms were estimated using a multivariate full-model and a reduced-model (without ) for each YC. Heterogeneity of was observed in both YC 2007 (0.10 to 0.16) and YC 2010 (0.08 to 0.26). The estimates of between NUC and test farms were relatively high for both models (0.81 ± 0.19 to 0.96 ± 0.17) and (0.81 ± 0.08 to 0.86 ± 0.04), suggesting low re-ranking of genotypes. Strong re-ranking of genotypes between PESouth and PENorth may be less important because most cod producers are situated close to the breeding nucleus. In conclusion, G × E between NUC and test farms were low and at present there is no need for separate breeding programs for BW in cod.