Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.     

The influence of 70 and 120 kHz tonal signals on the behavior of harbor porpoises (Phocoena phocoena) in a floating pen

Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 or 120kHz with different signal durations, amplitudes and duty cycles (% of time sound is produced). Some signals were continuous, others were intermittent (duty cycles varied between 8% and 100%). The effect of each signal was judged by comparing the animals' surfacing locations and number of surfacings (i.e. number of respirations) during test periods with those during baseline periods. In all cases, both porpoises moved away from the sound source, but the effect of the signals on respiration rates was negligible. Pulsed 70kHz signals with a source level (SL) of 137dB had a similar effect as a continuous 70kHz signal with an SL of 148dB (re 1muPa, rms). Also, a pulsed 70kHz signal with an SL of 147dB had a much stronger deterring effect than a continuous 70kHz signal with a similar SL. For pulsed 70kHz signals (2s pulse duration, 4s pulse interval, SL 147dB re 1muPa, rms), the avoidance threshold sound pressure level (SPL), in the context of the present study, was estimated to be around 130dB (re 1muPa, rms) for porpoise 064 and around 124dB (re 1muPa, rms) for porpoise 047. This study shows that ultrasonic pingers (70kHz) can deter harbor porpoises. Such ultrasonic pingers have the advantage that they do not have a "dinner bell" effect on pinnipeds, and probably have no, or less, effect on other marine fauna, which are often sensitive to low frequency sounds.     

Anoxia over the western continental shelf of India: bacterial indications of intrinsic nitrification feeding denitrification

Studies on the Arabian Sea coastal anoxia have been of immense interest, but despite its ecological significance there is sparse understanding of the microbes involved. Hence, observations were carried out off Goa (15 degrees 30'N, 72 degrees 40'E to 15 degrees 30'N, 72 degrees 59'E) to understand the processes that mediate the changes in various inorganic nitrogen species in the water column during anoxia. Water column chemistry showed a clear distinct oxic environment in the month of April and anoxic condition in October. Our study based on microbial signatures indicated that oxygen deficit appeared as a well-defined nucleus almost 40 km away from the coast during the oxic period (April) and spreads there after to the entire water column synchronizing with the water chemistry. Striking results of net changes in inorganic nitrogen species in nitrification blocked and unblocked experimental systems show that denitrification is the predominant process in the water column consuming available nitrate ( approximately 0.5 microM) to near zero levels within approximately 72 h of incubation. These observations have been supported by concomitant increase in nitrite concentration ( approximately 4 microM). Similar studies on denitrification-blocked incubations, demonstrate the potential of nitrification to feed denitrification. Nitrification could contribute almost 4.5 microM to the total nitrate pool. It was found that the relation between ammonium and total dissolved inorganic nitrogen (DIN) pool (r=0.98, p<0.001, n=122) was significant compared to the latter with nitrite and nitrate. The occurrence of high ammonium under low phosphate conditions corroborates our observations that ammonium does not appear to be locked under low oxygen regimes. It is suggested that ammonium actively produced by detrital breakdown (ammonification) is efficiently consumed through nitrification process. The three processes in concert viz. ammonification, nitrification and denitrification appear to operate in more temporal and spatial proximity than hitherto appreciated in these systems and this gives additional cues on the absence of measurable nitrate at surface waters, which was earlier attributed only to efficient algal uptake. Hence we hypothesize that the alarming nitrous oxide input into the atmosphere could be due to high productivity driven tighter nitrification-denitrification coupling, rather than denitrification driven by extraneous nitrate.     

Habitat continuity effects on gradients of fish biomass across marine protected area boundaries

Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas.     

Modelling of sediment movement in the surf and swash zones

Under the action of marine currents, non-cohesive sediments evolve by bed-load, by saltation or suspension depending on their granulometry. Several authors have considered that the movement of sediment...     

Effects of cadmium, zinc and nitrogen status on non-protein thiols in the macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands, Belgium) and Thermaikos Gulf (N Aegean Sea, Greece)

Enteromorpha prolifera (Scheldt Estuary) and E. linza (Thermaikos Gulf) were incubated at three salinities with 100 and 200microgL(-1)Cd and Zn. The objective was to measure effects of Cd, Zn and nitrogen (N) status on the pools of metal-binding non-protein thiols: glutathione and phytochelatins, (gamma-glutamyl-cysteinyl)(n)-glycine (PC). In E. linza, ammonium pools were higher, but amino acid pools, total N and protein contents were lower than in E. prolifera. Reduced glutathione (GSH) pools were positively correlated with free glutamate and protein contents. In E. linza GSH pools increased and the ratio of reduced to oxidized glutathione (GSH:(GSH+0.5GSSG)), an indicator of oxidative stress, decreased with Cd contents, indicating Cd-induced glutathione oxidation. Total glutathione pools (reduced plus oxidized) ranged from 16nmolSgdwt(-1) in controls (at 0.5micromolCdgdwt(-1)) to 179nmolSgdwt(-1) (at 1.9micromolCdgdwt(-1)) at the highest cadmium dosage. Cadmium stimulated PC synthesis in E. prolifera which suggests that in N-rich algae, glutathione pools were high enough for PC synthesis. In both species GSH and protein increased with Zn contents, whereas GSH:(GSH+0.5GSSG) decreased, which would indicate Zn-induced oxidative stress; in E. linza, at the highest salinity the glutathione redox ratio decreased from 0.61 (at 2.9micromolZngdwt(-1)) to 0.26 (at 4.9nmolSgdwt(-1)) (at 0.5molCdgdwt(-1)). PCs were not synthesized in response to Zn, which may have resulted in Zn-induced GSH oxidation. The presence of both oxidative effects (Cd, Zn) and detoxification (Cd) could be identified by observing the responses of glutathione and PC pools to metal stress.     

Wave Interactions with Multiple Semi-Immersed Jarlan-Type Perforated Breakwaters

This study examines wave interactions with multiple semi-immersed Jarlan-type perforated breakwaters. A numerical model based on linear wave theory and an eigenfunction expansion method has been developed to study the hydrodynamic characteristics of breakwaters. The numerical results show a good agreement with previous analytical results and experimental data for limiting cases of double partially immersed impermeable walls and double and triple Jarlan-type breakwaters. The wave transmission coefficient C_T; reflection coefficient C_R, and energy dissipation coefficient C_E coefficients and the horizontal wave force exerted on the front and rear walls are examined. The results show that C_R reaches the maximum value when B/L = 0.46n while it is smallest when B/L=0.46n+0.24 (n=0, 1, 2,...). An economical triple semi-immersed Jarlan-type perforated breakwater can be designed with B/L = 0.25 and C_R and C_T ranging from 0.25 to 0.32 by choosing a relative draft d/h of 0.35 and a permeability parameter of the perforated front walls being 0.5 for an incident wave number kh nearly equal to 2.0. The triple semi-immersed Jarlan-type perforated breakwaters with significantly reduced C_R, will enhance the structure’s wave absorption ability, and lead to smaller wave forces compared with the double one. The proposed model may be used to predict the response of a structure in the preliminary design stage for practical engineering.     

Down-scaled regional ocean modeling system (ROMS) for high-resolution coastal hydrodynamics in Korea

A down-scaled operational oceanographic system is developed for the coastal waters of Korea using a regional ocean modeling system(ROMS).The operational oceanographic modeling system consists of atmospheric and hydrodynamic models.The hydrodynamic model,ROMS,is coupled with wave,sediment transport,and water quality modules.The system forecasts the predicted results twice a day on a 72 h basis,including sea surface elevation,currents,temperature,salinity,storm surge height,and wave information for the coastal waters of Korea.The predicted results are exported to the web-GIS-based coastal information system for real-time dissemination to the public and validation with real-time monitoring data using visualization technologies.The ROMS is two-way coupled with a simulating waves nearshore model,SWAN,for the hydrodynamics and waves,nested with the meteorological model,WRF,for the atmospheric surface forcing,and externally nested with the eutrophication model,CE-QUAL-ICM,for the water quality.The operational model,ROMS,was calibrated with the tidal surface observed with a tide-gage and verified with current data observed by bottom-mounted ADCP or AWAC near the coastal waters of Korea.To validate the predicted results,we used real-time monitoring data derived from remote buoy system,HF-radar,and geostationary ocean color imager(GOCI).This down-scaled operational coastal forecasting system will be used as a part of the Korea operational oceanographic system(KOOS) with other operational oceanographic systems.     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

2012年夏季楚科奇海浮游动物垂直迁移及上升流对其生物量的影响

The diel vertical migration(DVM) of zooplankton and the influence of upwelling on zooplankton biomass were examined using water column data of current velocity and mean volume backscattering strength(MVBS)collected by moored acoustic Doppler current profilers(ADCPs) deployed in the southeastern Chukchi Sea during the 5th Chinese National Arctic Research Expedition(CHINARE) in summer 2012, combined with the satellite observational data such as sea surface temperature(SST), wind, and chlorophyll a(Chl a). Hourly acoustic data were continuously collected for 49-d in the mooring site. Spectral analysis indicated that there were different migrating patterns of zooplankton, even though precisely classifying the zooplankton taxa was not available. The prevailing 24-h cycle corresponded to the normal DVM with zooplankton swimming upwards at sunrise and returning to deep waters at sunset. There was a clear DVM in the upper 17 m of the water column during the period with distinct day-night cycles, and no active DVM throughout the water column when the sun above the horizon(polar day), suggesting that light intensity was the trigger for DVM. Also there was a second migrating pattern with 12-h cycle. The upwelling event occurring in the northwest of Alaskan coastal area had important influence on zooplankton biomass at the mooring site. During the upwelling, the SST close to the mooring site dropped significantly from maximal 6.35°C to minimal 1.31°C within five days. Simultaneously, there was a rapid increase in the MVBS and Chl a level, suggesting the aggregation of zooplankton related to upwelling.