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At least 793 records · Page 44Linked to original sources
PubMed1984

Rhythms of locomotion and oxygen consumption in the estuarine amphipod Corophium volutator (Crustacea: Amphipoda).

The estuarine amphipod Corophium volutator exhibits an endogenous circatidal rhythm of swimming activity, with maxima occurring just after the expected time of high water, under constant laboratory conditions. Oxygen uptake by Corophium is also subject to modulation across the tidal cycle. The period of highest oxygen uptake occurs during the ebb tide, in phase with the period of maximum swimming activity. A second increase in oxygen uptake during the early flood tide is thought to reflect either in-burrow activity or a previously described rhythm of emergence. This being so, this aspect of the animal's respiratory metabolism may be regulated by an autonomous oscillator independent of that governing the animal's swimming behaviour.

Activity Cycles↗
PubMed1997

Dueling hypotheses: circatidal versus circalunidian battle basics.

The circalunidian-clock hypothesis is a formulation describing the means by which the tide-associated rhythms of intertidal organisms are generated. The postulate was described in a 1995 article in this journal (12:299-310). A recent paper published here (13:153-62) by Prof. Ernest Naylor challenges the validity of this hypothesis and presents an alternate he calls the "circatidal/circadian clock hypothesis." His paper first presents a model of his idea and then expresses the model's action in an unusual type of plot of his own invention. From the latter's display, he concludes it describes all the properties used as supporting evidence for the circalunidian-clock idea and thus discredits that hypothesis. Here, I present my analysis of his model and discuss its usefulness to the field. I find that his Naylor plot does not represent his model, and that his hypothesis mainly explains only data he has obtained for his favorite research subject, the crab Carcinus. I built a model similar to his and show that it produces a compact plot nothing like the one he reported. Finally, I believe that the circalunidian-clock hypothesis-which was not at all endangered by the Naylor paper-is clearly the best explanation at this time for the control of organismic tide-associated rhythms.

Activity Cycles↗
PubMed2004

Effect of intertidal exposure on Vibrio parahaemolyticus levels in Pacific Northwest oysters.

Interest in Vibrio parahaemolyticus (Vp) increased in the United States following Vp-associated gastroenteritis outbreaks in 1997 and 1998 involving the West Coast and other areas. The present study evaluated multiple aspects of Vp ecology in the Pacific Northwest with three objectives: (i) to determine the effect of low-tide exposure on Vp levels in oysters, (ii) to determine the relationship between total and pathogenic Vp, and (iii) to examine sediments and aquatic fauna as reservoirs for pathogenic Vp. Samples were collected from intertidal reefs along Hood Canal, Wash., in August 2001. Fecal matter from marine mammals and aquatic birds as well as intestinal contents from bottom-dwelling fish were tested. Total and pathogenic Vp levels in all the samples were enumerated with colony hybridization procedures using DNA probes that targeted the thermolabile direct hemolysin (tlh) and thermostable direct hemolysin (tdh) genes, respectively. The mean Vp densities in oysters were four to eight times greater at maximum exposure than at the corresponding first exposure. While tdh-positive Vp counts were generally < or = 10 CFU/g at first exposure, counts as high as 160 CFU/g were found at maximum exposure. Vp concentrations in sediments were not significantly different from those in oysters at maximum exposure. Pathogenic (tdh positive) Vp was detected in 9 of 42 (21%) oyster samples at maximum exposure, in 5 of 19 (26%) sediment samples, but in 0 of 9 excreta samples. These results demonstrate that summer conditions permit the multiplication of Vp in oysters exposed by a receding tide.

Animals↗
PubMed1998

Possible natural circaseptan rhythm in the beach beetle Chaerodes trachyscelides white.

Activity rhythms in groups of captive beach beetles (Chaerodes trachyscelides White) have been recorded in an actograph over a period of 29 days. Under constant illumination and when no sand was provided for the beetles to burrow in abnormal behaviour occurred. With sand and in constant darkness a strictly nocturnal activity period with apparently circaseptan components superimposed was observed. The beetles in their natural habitat are confined to the debris zone where they feed on washed up seaweed and this debris zone moves up and down depending on the heights of the tides. Circaseptan elements in the beetles' activity may act as adaptations to the weekly alternations between spring- and neap-tides.

Animals↗
PubMed1979

Bottom line on the top people--by Speakman.

The Speakman review, that long-awaited probe into top posts in the NHS, is about to burst upon an impatient world. Alison Hyde has been taking a look at its contents. Speakman proposes 24 steps in appraising top jobs. He has some good tidings for area administrators and not so good tidings for works officers: the first are what he considers the supremos of the service and the second he places a poor third in the area ratings.

Administrative Personnel↗
PubMed1999

Vertical migration behaviour of diatom assemblages of Wadden Sea sediments (Dangast, Germany): a study using cryo-scanning electron microscopy.

The vertical migration behaviour of diatom assemblages inhabiting Wadden Sea sediments near Dangast (Germany) was investigated using cryo-scanning electron microscopy. The diatom assemblages were dominated by small Navicula species. Intertidal sediments which were located at different distances from the high tide level or stayed submerged even throughout low tides were chosen. Samples were prepared and cryofixed in the field. Sampling was restricted to three sets: (i) before the onset of vertical migration, (ii) 3 to 5 h after the onset of vertical migration, and (iii) before the area became flooded again or just prior to dusk. The diatom assemblages inhabiting the different types of sediments did not always show the same response. When the tidal cycle exposed the sediment surfaces during the night cell densities increased in the early morning hours with the onset of light. Later on, although the photon flux density was still increasing, cell densities stayed constant or decreased before the water flooded the areas around noon. In experiments in which the water drained off around noon and the areas became exposed throughout the entire afternoon, cell densities increased even up to dusk when the photon flux density had dropped to values below 20 microM photons m-2 s-1. In an experiment in which the last sampling occurred at 10.15 pm, when the photon flux density had already declined below 10 microM photons m-2 s-1, cell densities had decreased to lower values. This was ca. 1 h before the area was flooded again. Finally, cryo-scanning electron microscopy revealed frequently occurring micro-patches of diatom assemblages which could be differentiated into typical areas of lower and higher cell densities further complicating the pattern of light or water cover induced movements.

Cryoelectron Microscopy↗
PubMed2001

Lysis of Gymnodinium breve by cultures of the green alga Nannochloris eucaryotum.

Laboratory cultures of Florida's red tide organism, Gymnodinium breve, were killed by the green alga Nannochloris eucaryotum. Studies involved organism-organism interaction as well as organism-cell-free culture (N. eucaryotum) interaction. Both studies demonstrated that N. eucaryotum adversely affected Florida's red tide organism. The lysis has been attributed to compounds called APONINs (apparent oceanic naturally occurring cytolins). N. eucaryotum crude APONIN was extracted from cell-free cultures, partially purified and fractionated. The fractions were bioassayed against G. breve, and 'fingerprints' of the deleterious fractions were obtained.

Animals↗
PubMed1999

[Marine toxins].

The consumption of seafood, which is contaminated by toxines of red tides, is a common cause of disease in tropic regions. The most important diseases, which are caused by red tides are Paralytic Shellfish Poisoning (PSP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Amnesic Shellfish Poisoning (ASP), Ciguatera Fish Poisoning (CFP).

Americas↗
PubMed2000

Does damming of the Colorado River affect the nursery area of blue shrimp Litopenaeus stylirostris (Decapoda: Penaeidae) in the Upper Gulf of California?

After damming the Colorado River the freshwater flow was reduced to 1% of its virgin flow to the Upper Gulf of California (UGC). The ecological effects need to be properly documented. The UGC is the nursery area for Litopenaeus stylirostris, the most profitable fishery in the zone. In order to know the relative abundance of L. stylirostris postlarval stage we conducted a sampled survey every 14 days in 1993, 1994 and 1997, plus an intensive sampling during a complete tide cycle in July 1995 and 1996. We did 10 min trawls each hour during the flood tide. Relative abundance of postlarvae was higher (p < 0.05) in those years when freshwater flow reached the UGC.

Animals↗
PubMedDate not supplied

Riding the wave: what health care can learn from other industries.

Many staffing challenges face 21st century health-care employers. If a rising tide lifts all ships, then tidal surges and currents also affect all ships. Recruitment and retention represent two major human resources issues facing employers. Economic downturns, the rising cost of postsecondary education, competition for the best graduates, reduced desire to accept relocations, forced overtime and shift work, and the graying of the workforce are some of the challenges faced by employers. Another challenge is the lack of loyalty in today's business world. Corporations and nonprofits both show reduced loyalty to employees, who, in turn, limit their willingness to remain loyal to one employer. Competition for a shrinking pool of workers results in employees being more selective about where to begin their careers and being less loyal once they arrive. These factors negatively affect productivity and make it increasingly imperative for employers to understand how best to recruit and to retain the most talented workers they can find. Health care and other industries should be prepared for the surging tides of change.

Diffusion of Innovation↗
PubMed2002

[Study on the molecular biology of hemorrhagic fever virus in Xinjiang].

OBJECTIVE: To explore the relationship between the structure and function at molecular level and the routes of transmission of Xinjiang hemorrhagic fever (XHF) virus. METHODS: S genes of five XHF virus strains were cloned, sequenced and compared with that of other Crimean-Congo hemorrhagic fever virus strains. RESULTS: It was found that S genes of the five viruses had 1,672 nuclei tides, while ORF of them including 1,449 nuclei tides and coded with a protein of 482 amino acid. The nucleotides homology of Chinese isolates (93.0%-99.5%) was obviously higher than that of any other S genes strains identified in other countries'. Phylogenetic tree showed that all Chinese isolates clustered into one branch and could be further divided into another three groups. CONCLUSION: The sequential difference of S genes was not totally related to the host, areas and time of the viruses isolated.

Genes, Bacterial↗
PubMed2003

[Nutrient elements in the atmospheric wet deposition in Changjiang River estuary].

In order to study the effects of atmospheric wet deposition on red tide, five kinds of nutrient elements were measured with 64 rainwater samples collected at Shengsi Archipelago from May 2000 to April 2001. The results showed that there were obvious differences between monthly average concentrations, due to the different resource and precipitation. The variation of seasonal fluxes suggested that the wet deposition might cause red tide except in winter. The annual concentrations of NO3-N, NH4(+)-N, NO2(-)-N, PO4(3-)-P and SiO3(2-)-Si were 20.23, 30.14, 0.11, 0.045 and 3.43 mumol.L-1, respectively, and their annual fluxes were 2.67 x 10(8), 3.98 x 10(8), 0.014 x 10(8), 0.0059 x 10(8) and 0.45 x 10(8) mol, respectively. Compared with river input, they were much more smaller.

China↗
PubMed2003

[Response of Prorocentrum minimum growth to zinc limitation].

Studies on the growth and physiological response of red tide alga Prorocentrum minimum to three Zn2+ levels were showed that the specific growth rate and biomass were limited in low Zn(2+)-grown cells (1.4 pmol.L-1, which were 0.40 d-1 and 51,100 cell.ml-1 respectively. The specific growth rate was not significantly different when the Zn2+ concentration in medium was increased over 24.4 pmol.L-1, but there was a slight decrease in biomass; however, both specific growth rate and biomass were much higher than those in low Zn(2+)-grown cells. It was also showed that chlorophyll a synthesis was limited due to Zn2+ deficient, and therefore, the cells became light saturated at higher irradiance under Zn-limited condition. Light-saturated photosynthetic rates (Pm) and photosynthetic efficiency (alpha) increased significantly with increasing Zn2+ concentrations. It was concluded that Zn2+ concentration might be one of the key factors affecting red tide blooms in eutrophication environment.

Biomass↗
PubMed2003

[Inhibition and elimination of chlorine dioxide on Phaeocystis globosa].

Different densities of red tide organism, Phaeocystis globosa (ST strain) were exposed to different concentrations of chlorine dioxide. The results showed that chlorine dioxide could effectively kill and control the algae. When the algae, in the density of 2.35 x 10(9) cells.L-1, was exposured to ClO2 above 0.74 x 10(-2) mmol.L-1, it was inhibited, and eliminated under ClO2 concentration above 2.96 x 10(-2) mmol.L-1. When the density of algae was 2.35 x 10(9), 1.18 x 10(9), 4.70 x 10(8) and 1.18 x 10(8) cells.L-1, the concentration of chlorine dioxide which could kill the algae efficiently in 96 h was 2.96 x 10-2, 2.22 x 10-2, 1.48 x 10-2 and 0.59 x 10-2 mmol.L-1, respectively. Under the same rate of inhibition or elimination, the higher the density of algae was, the lower the concentration of chlorine dioxide was to effectively control the growth of algae cell, ClO2 could be considered as a potential algaecide to control red tide.

Chlorine Compounds↗
PubMed2004

Long-term temporal-spatial dynamics of marine coastal water quality in the Tolo Harbor, Hong Kong, China.

The long-term temporal and spatial dynamics of marine coastal water quality in Tolo Harbor, Hong Kong were explored. The Harbor is divided into three zones represented as Harbor, Buffer, and Channel Subzones. The time range for the study covers the period from the 1970s to the 1990s. The selected indicators for the comprehensive assessment of water quality consist of physical, chemical and biological aspects, including suspended solids(SS), Secchi disk depth(SD), 5-day biochemical oxygen demand(BOD5), total nitrogen (TN), total phosphorus(TP), faecal coliform, chlorophyll-a(Chl-a), and the number of red tide occurrences. The results indicated the presence of obvious temporal and spatial trends with regard to changes in water quality. Spatially, water quality in the Channel Subzone is the best, while that in the Harbor Subzone is the worst. On a temporal basis, the average trend from bad to good was 1980s > 1990s > 1970s as indicated by most of the selected water quality indicators. Water quality during the late 1980s reached its worst level with the lowest SD, the highest BOD5, TN, TP, Chl-a concentrations, and the number of red tide occurrences. These long-term temporal-spatial water quality trends were also found in other studies of the Tolo Harbor. The large quantity of pollutants produced as a result of increasing population, industrial and commercial actives, and urbanization and industrialization trends in both Shatin and Tai Po seem to be primarily responsible for the changes in marine coastal water quality.

Commerce↗
PubMed2004

Development of a predictive model for ross river virus disease in Brisbane, Australia.

This paper describes the development of an empirical model to forecast epidemics of Ross River virus (RRV) disease using the multivariate seasonal auto-regressive integrated moving average (SARIMA) technique in Brisbane, Australia. We obtained computerized data on notified RRV disease cases, climate, high tide, and population sizes in Brisbane for the period 1985-2001 from the Queensland Department of Health, the Australian Bureau of Meteorology, the Queensland Department of Transport, and Australian Bureau of Statistics, respectively. The SARIMA model was developed and validated by dividing the data file into two data sets: the data between January 1985 and December 2000 were used to construct a model, and those between January and December 2001 to validate it. The SARIMA models show that monthly precipitation (beta = 0.004, P = 0.031) was significantly associated with RRV transmission. However, there was no significant association between other climate variables (e.g., temperature, relative humidity, and high tides) and RRV transmission. The predictive values in the model were generally consistent with actual values (root mean square percentage error = 0.94%). Therefore, this model may have applications as a decision supportive tool in disease control and risk-management planning programs.

Alphavirus Infections↗
PubMed2003

Application and refinement of the WHO risk framework for recreational waters in Sydney, Australia.

Local adaptation of the World Health Organisation (WHO) Farnham approach to managing pathogen risk in recreational waters was readily achieved given the extensive microbiological beach data for Sydney, and a clear understanding of applying the 'Annapolis Protocol' sanitary survey component to beach classification. Daily enterococci counts were predicted by rainfall (>10 mm in 24 h or >5 mm over 4-5 days), or by wind direction/speed, sunlight and tide during dry periods. Quantitative microbial risk assessment models (maximum risk exponential model for gastroenteritis and adenovirus exponential model for respiratory illness) fitted the United Kingdom epidemiological data and show potential for use. Flexibility in interpreting what is important for local conditions is essential, illustrated by replacing the general descriptions in the Farnham report with more ridged values for stormwater-impacted beaches. Hence, a user-friendly format for bather risk management, based on key environmental predictors of faecal pollution (such as rainfall, wind direction and tide) should largely replace the need for regular and costly microbiological testing; providing risk estimates in real time and allowing immediate control measures, such as signage or temporary beach closures. Ongoing testing resources should be directed to understanding the source(s) of faecal contamination, comparing enterococci/enteric virus survival under warm Australian conditions and spot checks for recalibration of environmental factors.

Calibration↗
PubMed2003

Influence of Adyar river in the coastal waters of Chennai (Madras), Bay of Bengal.

The impact of the river Adyar which is influenced by industrial wastes and domestic sewage from the city of Chennai (Madras), on the hydrobiology of coastal water in the Bay of Bengal was evaluated. Reduction in pH, dissolved oxygen (DO), nitrite, nitrate, primary productivity and increase of ammonia, phosphate, silicate, heavy metals, biological oxygen demand (BOD), chlorophyll pigments, particulate organic carbon (POC), respiration, suspended solids, ATP, and bacteria in the mixing site during low tide indicated that the Adyar water was heavily polluted and ultimately affect the quality of coastal water near the vicinity of mixing zone. The effects are diluted or nullified as the distance increased from the mixing site due to heavy mixing and littoral current. During high tide, the flow was completely stopped and little or no effect was recorded. The light, water current and wave action are the important factors which minimize the pollution impacts in the receiving coastal water.

Ammonia↗