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At least 703 records · Page 39Linked to original sources
PubMed2002

Imidacloprid residues in Willapa Bay (Washington State) water and sediment following application for control of burrowing shrimp.

Pesticides have been used in the Willapa Bay estuary in western Washington State to control the exotic invasive plant species Spartina alterniflora (cordgrass) and the native species of burrowing shrimp (Callianassa sp.; Upogebia sp.) that affect oyster production. Carbaryl, the only registered insecticide for control of burrowing shrimp, has not been extensively studied in the Willapa Bay. However, carbaryl use has been severely restricted, and alternatives likely to have less severe environmental impacts are being sought. Imidacloprid applied directly to exposed sediments when the tide is out is efficacious for burrowing shrimp control but lacks studies of its behavior in the estuary. For this study, imidacloprid dissipation was monitored as the tide was rising in Willapa Bay. Over 99% of applied material dissipated from small plots within 24 h, but residues near the analytical detection limit were found in sediments 28 days later. At a distance of 152 m along a transect from the plot in the direction of tidal flow, imidacloprid residues in water peaked within 10 min after initiation of tidal flow. Within 30 min, imidacloprid residues were not detected, nor were residues detected in the water any time over the next month after application. Carbaryl residues in water were also monitored, and they exhibited the same rise and fall at the 152 m distance from the experimental plot as did the imidacloprid residues. However, carbaryl levels significantly above the detection limit were still present in water over the next month after application. The rapid dissipation of imidacloprid from water was hypothesized to be due to extensive dilution by the tide. The hypothesis was tested in batch equilibration sorption studies with radiolabeled imidacloprid and Willapa Bay sediment. Sorption distribution coefficients were <1 mL/g, and hysteresis was not observed during two desorption cycles, suggesting that imidacloprid was widely dispersed to extremely low levels soon after application.

Adsorption↗
PubMed2000

Significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data

How and where the ocean tides dissipate their energy are long-standing questions that have consequences ranging from the history of the Moon to the mixing of the oceans. Historically, the principal sink of tidal energy has been thought to be bottom friction in shallow seas. There has long been suggestive evidence, however, that tidal dissipation also occurs in the open ocean through the scattering by ocean-bottom topography of surface tides into internal waves, but estimates of the magnitude of this possible sink have varied widely. Here we use satellite altimeter data from Topex/Poseidon to map empirically the tidal energy dissipation. We show that approximately 10(12) watts--that is, 1 TW, representing 25-30% of the total dissipation--occurs in the deep ocean, generally near areas of rough topography. Of the estimated 2 TW of mixing energy required to maintain the large-scale thermohaline circulation of the ocean, one-half could therefore be provided by the tides, with the other half coming from action on the surface of the ocean.

Journal Article↗
PubMed2004

Mass and volume contributions to twentieth-century global sea level rise.

The rate of twentieth-century global sea level rise and its causes are the subjects of intense controversy. Most direct estimates from tide gauges give 1.5-2.0 mm yr(-1), whereas indirect estimates based on the two processes responsible for global sea level rise, namely mass and volume change, fall far below this range. Estimates of the volume increase due to ocean warming give a rate of about 0.5 mm yr(-1) (ref. 8) and the rate due to mass increase, primarily from the melting of continental ice, is thought to be even smaller. Therefore, either the tide gauge estimates are too high, as has been suggested recently, or one (or both) of the mass and volume estimates is too low. Here we present an analysis of sea level measurements at tide gauges combined with observations of temperature and salinity in the Pacific and Atlantic oceans close to the gauges. We find that gauge-determined rates of sea level rise, which encompass both mass and volume changes, are two to three times higher than the rates due to volume change derived from temperature and salinity data. Our analysis supports earlier studies that put the twentieth-century rate in the 1.5-2.0 mm yr(-1) range, but more importantly it suggests that mass increase plays a larger role than ocean warming in twentieth-century global sea level rise.

Journal Article↗
PubMed1989

Matrix-isolation of H-induced free radicals from purines in acidic glasses.

H.(D.)-atoms produced by photo-oxidation (lambda = 254 nm) of Fe2+ in acidic glasses (6 mol dm-3 H2SO4/H2O or D2SO4/D2O) at 77K were allowed to react with the purine bases adenine, guanine, hypoxanthine and xanthine as well as with ribo- and deoxyribosides (-tides) of adenine and guanine by annealing to 110-130 K. The ensuing free radicals were studied by electron spin resonance (ESR) spectroscopy at 77 K. Individual radical species were assigned by simulation of patterns isolated from thermal annealing studies up to 180 K. It is shown that H.-atom reaction with the bases produces C2- and C8-addition radicals for adenine and C8-addition species for guanine. Guanine is also photo-oxidized directly in the glass, producing a cation or its deprotonated successor species. In the nucleosides (-tides) of both bases, H. atoms were found to abstract hydrogen from carbon sites C1', C2' or C3', and C5' for ribosides and C1', C2', and C5' for deoxyribosides (-tides), respectively.

Adenine↗
PubMed2001

Sea level rise during past 40 years determined from satellite and in situ observations.

The 3.2 +/- 0.2 millimeter per year global mean sea level rise observed by the Topex/Poseidon satellite over 1993-98 is fully explained by thermal expansion of the oceans. For the period 1955-96, sea level rise derived from tide gauge data agrees well with thermal expansion computed at the same locations. However, we find that subsampling the thermosteric sea level at usual tide gauge positions leads to a thermosteric sea level rise twice as large as the "true" global mean. As a possible consequence, the 20th century sea level rise estimated from tide gauge records may have been overestimated.

Journal Article↗
PubMed2003

Coral reef death during the 1997 Indian Ocean Dipole linked to Indonesian wildfires.

Geochemical anomalies and growth discontinuities in Porites corals from western Sumatra, Indonesia, record unanticipated reef mortality during anomalous Indian Ocean Dipole upwelling and a giant red tide in 1997. Sea surface temperature reconstructions show that although some past upwelling events have been stronger, there were no analogous episodes of coral mortality during the past 7000 years, indicating that the 1997 red tide was highly unusual. We show that iron fertilization by the 1997 Indonesian wildfires was sufficient to produce the extraordinary red tide, leading to reef death by asphyxiation. These findings highlight tropical wildfires as an escalating threat to coastal marine ecosystems.

Animals↗
PubMed2000

Sources of Escherichia coli in a coastal subtropical environment.

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil E. coli concentrations. The ability of E. coli to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coli concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments.

Bacteriological Techniques↗
PubMed2004

Transport of the harmful bloom alga Aureococcus anophagefferens by oceangoing ships and coastal boats.

It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species Aureococcus anophagefferens (brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of Aureococcus (>22 ppt) and the low salinity of the residual ballast water (approximately 2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute Aureococcus. During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were sampled. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well sample. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of Aureococcus.

DNA, Ribosomal↗
PubMed2002

Different responses of Ross River virus to climate variability between coastline and inland cities in Queensland, Australia.

AIMS: To examine the potential impact of climate variability on the transmission of Ross River virus (RRv) infection, and to assess the difference in the potential predictors of RRv incidence in coastline and inland regions, Queensland, Australia. METHODS: Information on the RRv cases notified between 1985 to 1996 was obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australia Bureau of Statistics, respectively. The function of cross correlations was used to compute a series of correlations between climate variables (rainfall, maximum temperature, minimum temperature, relative humidity, and high tide) and the monthly incidence of RRv disease over a range of time lags. Time series Poisson regression models were performed to adjust for the autocorrelations of the monthly incidences of RRv disease and the confounding effects of seasonality, the case notification time, and population sizes. RESULTS: The cross correlation function shows rainfall, maximum temperature, minimum temperature, and relative humidity at a lag of 1-2 months and high tide in the current month were significantly associated with the monthly incidence of RRv in the coastline region. Relative humidity and rainfall at a lag of two months was also significantly associated with the monthly incidence of RRv in the inland region. The results of Poisson regressive models show that the incidence of RRv disease was significantly associated with rainfall, maximum temperature, minimum temperature, relative humidity, and high tide in the coastline region, and with rainfall and relative humidity in the inland region. There was a significant interaction between climate variables and locality in RRv transmission. CONCLUSIONS: Climate variability may have played a significant role in the transmission of RRv. There appeared to be different responses of RRv to climate variability between coastline and inland cities in Queensland, Australia. Maximum temperature appeared to exhibit a greater impact on the RRv transmission in coastline than in inland cities. Minimum temperature and relative humidity at 3 pm inland seemed to affect the RRv transmission more than at the coastline. However, the relation between climate variables and RRv needs to be viewed within a wider context of other social and environmental factors, and further research is needed.

Adult↗
PubMed1982

Variation in fecal pollution indicators through tidal cycles in the Fraser River estuary.

Daily fluctuations in fecal pollution indicators in the Fraser River estuary were examined by sampling through 24 h at four sites; water levels, currents, and salinities were observed simultaneously. Fecal coliforms were measured on shipboard using the membrane filter technique, and coprostanol and cholesterol were extracted using hexane and analyzed by gas chromatography. Maximum concentrations of fecal sterols and coliforms occurred after high tide at the station upstream of major sewage outfalls and on the ebb or at low tide at the stations downstream of major sewage outfalls. Fecal coliform counts were highly correlated with coprostanol and cholesterol levels at sites near sewage treatment plants. Coprostanol was highly correlated with cholesterol except where concentrations approached detection limits. In receiving waters, fecal coliform counts but not sterol concentrations were reduced by chlorination of sewage treatment plant effluents during the summer months. We concluded that, dependent on the objectives of a future monitoring program, samples should be collected either randomly in time such that the seasonal or annual mean includes tidal variability or systematically during the ebb tide to assess contributions to bathing beaches and shellfish harvesting areas. Fecal sterols deserve consideration as potentials indicators of fecal contamination from chlorinated sewage effluents.

British Columbia↗
PubMed2000

Clustering behavior of hermit crabs (Decapoda, Anomura) in an intertidal rocky shore at São Sebastião, southeastern Brazil.

The clustering behavior and cluster composition of hermit crabs as well as the patterns of shell utilization of clustered and scattered individuals were studied. This study was conducted in the intertidal region of Grande Beach, São Sebastião, southeastern Brazil. Samples were taken both in randomized transects and 1 m2 quadrats during low tide periods. Crabs were counted, measured (shield length), and sexed. Shells were identified and had their adequacy and condition (physical damage and incrustation) recorded. Clusters occurred mainly in air exposed areas and were dominated or composed only by Clibanarius antillensis. Other species like Paguristes tortugae, Pagurus criniticornis, and Calcinus tibicen were also present in these clusters, but in small numbers. Only one monospecific aggregation composed by individuals of P. criniticornis was recorded in tide pools. Almost all crabs were inactive, despite some that were submerged in tide pools. Most of the individuals of C. antillensis were clustered (70.88%). Scattered individuals were larger than clustered ones and occupied mainly shells of Tegula viridula, which seemed to be the most adequate shell to the crabs. Clustered individuals used less incrusted shells than isolated ones. In general, clustering in Grande Beach presented the same patterns of size and sex distribution, and shell utilization than others already studied, with the exception of the smaller cluster size registered in this area.

Animals↗
PubMed2005

Cladocerans (Branchiopoda) of a tropical estuary in Brazil.

The study was conducted in the Capibaribe river estuary in Recife (Brazil) to assess the role played by cladocerans in a eutrophic environment. Samplings were carried out monthly at 4 fixed stations along the estuary from July 1987 to June 1988. Collections were made with a plankton net of 65 micrometers mesh size. Six cladocerans species were registered: Penilia avirostris, Diaphanosoma spinulosum, Chlydorus barroisi, Ceriodaphnia rigaudi, Ilyocryptus spinifer, and Moina micrura. The most frequent species was Moina micrura with 49%. The only true marine species was Penilia avirostris, which was registered at station 1 (close to the river mouth), during high and low tide and in the dry season. The Cladocera average density decreased from 329 ind.m'3 (August 1987, high tide) to 2 ind.m(-3) (March 1988, high tide) due to the high load of organic and chemical pollution received by the estuary. At all stations, D. spinulosum, M. micrura, and C. barroisi occurred with a wide distribution, mainly during the rainy season. C. rigaudi and I. spinifer were rare, occurring only during the rainy season. Cladocerans played an important role in the food webs of the plankton community of the Capibaribe tropical estuary and the dominance of a few small species indicated a hypereutrophic environment. A high level of disturbance was indicated by the decline in diversity of specialized species and the increase in abundance of opportunistic species like M. micrura.

Animals↗
PubMed2005

A histological investigation of the maturation of the acorn worm, an inhabitant of the Sea of Japan, and a suggestion about the relationship between synchronized spawning/spermiation and the tidal level.

One species of Hemichordata, Balanoglossus misakiensis, is then acorn worm originally reported from the intertidal zone of the Miura Peninsula on the Pacific Ocean side of Japan. We histologically examined the reproductive cycle of the population of this species, which inhabits only the sublittoral zone in the Sea of Japan. Testes and ovaries began to develop at the beginning of May 2003 and were almost mature in the latter half of June in males and in the first half of July in females in the same year. Subsequently, spermiation and spawning followed in the latter half of July in males and in the first half of August in females. Progress in maturation appeared to be related to increases in the water temperature. Although some experiments were conducted in aquariums to identify the conditions responsible for the synchronization of the occurrence of spontaneous spawning/spermiation, no clues were obtained. During the experiments, however, 11, 2, and 4 individuals out of the 67 used achieved spawning/spermiation on separate days. The occurrence of spawning/spermiation in the laboratory corresponded to the latter half of the switch from high tide to low tide on those days. Also in the field, it was known that they released the gametes according to this specific schedule. Therefore, it was suggested that, in the Japan Sea population of this species, the tide level may be a condition for synchronized spawning/spermiation.

Animals↗
PubMed1975

Health hazards of bivalve-mollusk ingestion.

Bivalve mollusks (oysters, clans, and mussels) filter large quantities of water unselectively and thereby may concentrate a variety of aquatic contaminants pathogenic for man within edible shellfish viscera. The recognized bacterial disease associated with ingestion of contaminated bivalves include typhoid fever (not presently a public health problem), Vibrio parahemolyticus gastroenteritis, and Vibrio chloerae infection. The major known shellfish-associated viral diseases are viral hepatitis and possibly viral gastroenteritis. The ingestion of bivalves that have fed on the toxic species of dinoflagellates that produce red tides may be responsible for an uncommon and very rarely fatal illness, paralytic shellfish poisoning. Outbreaks of airborne respiratory irritation in populations exposed to red tides may be the most common public health problem associated with red tides. The health hazards resulting from industrial, agricultural, and oil pollution of bivalves in coastal waters and the hazard from improper handling of bacterially contaminated mollusks remain to be defined.

Animals↗
PubMed1999

Towards management of mosquitoes at Homebush Bay, Sydney, Australia. I. Seasonal activity and relative abundance of adults of Aedes vigilax, Culex sitiens, and other salt-marsh species, 1993-94 through 1997-98.

The mosquitoes associated with 2 saline wetlands at Homebush Bay, Sydney, Australia, were investigated over 5 consecutive seasons. Twenty-one species were collected in adult traps at the 2 sites but the saline wetlands supported larvae of only 4 species: Aedes alternans, Aedes camptorhynchus, Aedes vigilax, and Culex sitiens. Of these, Ae. vigilax and Cx. sitiens were the most common, and their peak abundances generally occurred during February and April, respectively. Both wetlands were influenced by tides and rainfall-runoff, and a lack of regular tidal exchange in the mangroves and inadequate drainage of the saltmarsh provided potential habitat. Populations of Ae. vigilax and Cx. sitiens at the Newington site were greater than those at the Bicentennial Park site, because of more extensive habitat at the former, but were diminished by irregular ground-based applications of temephos during the middle 3 years of the study. Populations at the Bicentennial Park site, not subjected to the larvicide, were typically smaller but more consistently related to influences of tide and rainfall through the 5 seasons. During the final season, populations of both species in both wetlands were enhanced by exceptional tide penetration and rainfall. Helicopter applications of Bacillus thuringiensis israelensis larvicide were employed at both sites and effectively suppressed populations of both pest species. For future management, provision of full tidal exchange and water recirculation to reduce the area of water impounded within the mangroves and retained in depressions on the marshes should significantly suppress the pest populations and relieve reliance on control agents.

Aedes↗
PubMed2003

[Extinguishment of harmful algae by organo-clay].

Periodic and widespread algal blooms have caused a variety of problems for aquatic life and human activity throughout the world. Currently, the only remedial practice employed for removing algal blooms is to spread clay on the surface of the water. But, the algal removal efficiency by the crude minerals are not really ideal, and how to improve the capability of clays to remove algae is now the technological focus, which also is fatal to the practical value of clays. In this study, hexadecyltrimethyleamine bromide (HDTMAB), one kind of cationic organo-surfactants, was chosen to improve kaolin by surface sorption and cationic exchange, and was tested to remove Prorocentrum donghaiense, a red tide organism in Donghai Sea. The results indicated that organo-clay had an excellent ability to extinguish red tide organisms, even under the application of 0.01 g.L-1, and could subside more than 95% red tide organisms in 24 h. The efficient algae removal by organo-clay might be from the reversal of the surface electric charge on clay particles, the "net capture" by the long lipoid chains of HDTMAB, and the local high density of HDTMAB on particles surface, which could effectively kill algal cells.

Aluminum Silicates↗
PubMed2003

How do mangrove forests induce sedimentation?

The mangrove forests play a significant role as sediment traps. They reduce tidal flows and induce sedimentation of soil particles at low tide. However, there are no such processes taking place in the non-mangrove areas. Site of Avicennia-Rhizophora interphase is more efficient than Avicennia and or Rhizophora zones, in trapping the sediment by 30, 25 and 20% respectively at low tide as compared to high tide.

Ecosystem↗
PubMed2001

Planktonic primary production in a tidally influenced mangrove forest on the Pacific coast of Costa Rica.

The seasonal variation of planktonic primary productivity was measured during one year in the main channel in the interior part of the mangrove forest of the Estero de Morales (Estero de Punta Morales), a mangrove system located in the Golfo de Nicoya at the Pacific coast of Costa Rica. Samples were incubated at the surface, 0.5 m and 1.0 m depth and the "light and dark bottle technique" was employed. The annual gross primary productivity (PPg) was 457 and the net primary productivity (PPn) was 278 g C m(-2) a(-1). Daily PPg ranged from 0.29 to 3.88 and PPn from 0.12 to 2.76 g C m(-2) d(-1). The highest rates observed in May and September were due to red tide blooms. The seasonal variation of primary productivity inside the mangrove forest depends closely on the PP in the adjacent area of the upper Golfo de Nicoya. Obviously the PP was light-limited since the compensation depth in the ebb current was found at only 1 m depth. In the flood current it was somewhat deeper. The planktonic primary productivity inside the mangrove forest was completely restricted to the open channels. A simultaneous measurement demonstrated that PPn of the phytoplankton could not take place under the canopy of the mangroves. Additional studies on the time course of the oxygen concentration in the mouth of the main channel over 24 hrs demonstrated a relation between the O2 and the tidal curves. The ebb current had always lower O2 concentrations than the flood current, regardless of the time of the day. The difference to the foregoing high tide, however, was much smaller when the low tide occurred during the day. This indicates that under the canopy the net primary production and hence O2 liberation of the attached macro- and microalgae, together with the high PPn of the phytoplankton in the channels, helped the oxygen concentration not to decrease as far as during the night. Nevertheless it shows that the consumtion of organic material in the submersed part of the mangrove forest exceeds always its production.

Animals↗