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Diatoms from two macro-tidal mudflats in Chignecto Bay,Upper Bay of Fundy,New Brunswick,Canada 总被引:1,自引:1,他引:0
M.?Trites I.?KaczmarskaEmail author J.M.?Ehrman P.W.?Hicklin J.?Ollerhead 《Hydrobiologia》2005,544(1):299-319
Mudflat research is dispersed among several fields (ecology, sedimentology), each with its own focus and methodology. Consequently, although the volume of mudflat literature is considerable, our understanding of mudflat ecology remains fragmented. For example, little is known about the structure of microbial communities outside Western Europe. Here we present the first North American specific composition and densities of live mudflat diatoms and relate them to properties of their environment on two closely located flats. The two flats (Daniel’s and Buck’s) were similar until the mid–1980s. After this time the biological and sedimentary environment on Buck’s Flats began to change and resulted in a precipitous decline of the keystone invertebrate Corophium volutator (Pallas). The specific diatom composition on each of the two flats examined was still very similar. Tychoplanktonic diatoms were numerically dominant on both flats. The flats differed significantly in the relative contribution of epipelic diatoms, which were about an order of magnitude greater on Buck’s Flats. CCA analysis suggests that very few of these species exist within their optimal habitat. Some of the differences appeared small, but were statistically and biologically significant. Daniel’s Flats sediments had a 30% larger mean grain size, less water and organic carbon compared to Buck’s Flats sediments. Buck’s Flats had more variable depths of the oxygenated layer, often with anoxic inclusions throughout. Daniel’s Flats supported more C. volutator, while Buck’s Flats contained greater densities of diatoms. The importance of preserving environmental conditions (sedimentary and biotic) prevailing on flats such as Danielȁ9s Flat in order to foster populations of Corophium at a level necessary to support foraging migratory shorebirds is also discussed. 相似文献
2.
D. A. Scruton C. J. Pennell C. E. Bourgeois R. F. Goosney L. King R. K. Booth W. Eddy T. R. Porter L. M. N. Ollerhead K. D. Clarke 《Hydrobiologia》2008,596(1):225-239
Microalgal biofilms are associated with considerable variability in the properties of natural sediments, yet little effort
has been made to isolate micro-scale spatial and temporal changes in sediment properties caused by the growth of a biofilm.
Understanding the changes associated with biofilm growth and quantifying the time scales over which these changes occur is
important for developing suitable experimental designs and for understanding how biofilms mediate sediment properties and
processes. The development of a microphytobenthic biofilm and associated changes in the sediment was investigated over 45 days
in the laboratory. The biogeochemical properties of the sediment: bulk density, water content, chlorophyll a concentration and colloidal carbohydrate concentration were measured on a sub-millimetre scale in the top 2 mm. The erosion
threshold was measured with a Cohesive Strength Meter (CSM). Biofilm development was rapid, with changes in the properties
occurring after 1 day and a visible film forming after just 3 days. The largest changes in sediment properties tended to occur
in the surface 200 μm through time, with some variables also showing a differing response with depth. There were significant
changes in water content, chlorophyll a concentration, colloidal carbohydrate concentration and erosion threshold in the surface 2 mm, with a general trend to increase
with time. Bulk density was highly variable and did not show a consistent pattern of change with time. Erosion threshold was
positively correlated with water content, chlorophyll a and colloidal carbohydrate in the surface 200 μm and these were also positively correlated with each other. Low Temperature
Scanning Electron Microscopy (LTSEM) images revealed changes in the surface sediment structure and the formation of a thick
multi-layer biofilm. The rapidity of biofilm growth and development and the associated changes to the sediment should be considered
when designing experiments that investigate biofilms and properties of sediments and/or that involve biocide treatments or
disturbance to the sediment. 相似文献
3.
Scruton D. A. Clarke K. D. Ollerhead L. M. N. Perry D. McKinley R. S. Alfredsen K. Harby A. 《Hydrobiologia》2002,483(1-3):71-82
Neodiaptomus songkhramensis n. sp. from 86 temporary waters in the vicinity of Song Khram River in northeast Thailand is described and figured. It was found during May and June (rainy season) in Sakon Nakhon, Nakhon Pranom and Udon Thani Provinces. The new species usually co-occurs with 1–5 other diaptomids; the most frequently co-occurring species are Neodiaptomus blachei, Tropodiaptomus oryzanus, Neodiaptomus yangtsekiangensis, Dentodiaptomus javanus and Eodiaptomus phuphanensis. 相似文献
4.
Eva C. Enders Keith D. Clarke Curtis J. Pennell L. M. Neil Ollerhead David A. Scruton 《Hydrobiologia》2007,582(1):231-242
Winter habitat use and activity patterns of juvenile Atlantic salmon and brown trout were analysed in a comparative study
between Passive Integrated Transponder (PIT) technology, radio telemetry and underwater observation by snorkelling. Two study
periods were conducted in Stoney River, Newfoundland, Canada. During Study period I, 49 juvenile Atlantic salmon (fork length:
11.0–18.0 cm) and 7 brown trout (11.0–17.3 cm) were tagged with PIT tags and/or radio transmitters in late winter of 2004.
During Study period II, 18 juvenile Atlantic salmon (fork length: 12.0–18.4 cm) and 23 brown trout (10.9–20.8 cm) were tagged
and tracked twice a day at 10:00 h and 22:00 h on five consecutive days in late winter of 2005. From the 56 fish released
during Study period I, on average 19.6 ± 6.0% of the PIT tagged fish and 99.3 ± 2.2% of the radio tagged fish were relocated
during any given survey. Over the Study period II, 39% of fish emigrated from the study site. PIT technology had an efficiency
of 39.2 ± 14.1% to detect the remaining fish. In contrast, radio telemetry relocated on average 96.9 ± 6.5% of the tagged
fish whereas by snorkelling on average only 4.1 ± 5.6% of the tagged fish were observed. PIT telemetry may however be more
efficient in smaller, less heterogeneous streams. The advantage of PIT technology over radio telemetry is clearly that it
is relatively less costly permitting higher numbers of individuals to be tagged and there is no limit in the operational life
of the transponder. In winter, juvenile salmonids preferred low flow velocity and no preferences were observed for any specific
water depth over the range of available water depths. Fish selected preferentially boulder habitat over other substrates in
the environment. Habitat utilisation did not differ between day and night. The use of winter preference indices may be important
for future habitat modelling. 相似文献
5.
Kernel Density Surface Modelling as a Means to Identify Significant Concentrations of Vulnerable Marine Ecosystem Indicators 总被引:1,自引:0,他引:1
Ellen Kenchington Francisco Javier Murillo Camille Lirette Mar Sacau Mariano Koen-Alonso Andrew Kenny Neil Ollerhead Vonda Wareham Lindsay Beazley 《PloS one》2014,9(10)
The United Nations General Assembly Resolution 61/105, concerning sustainable fisheries in the marine ecosystem, calls for the protection of vulnerable marine ecosystems (VME) from destructive fishing practices. Subsequently, the Food and Agriculture Organization (FAO) produced guidelines for identification of VME indicator species/taxa to assist in the implementation of the resolution, but recommended the development of case-specific operational definitions for their application. We applied kernel density estimation (KDE) to research vessel trawl survey data from inside the fishing footprint of the Northwest Atlantic Fisheries Organization (NAFO) Regulatory Area in the high seas of the northwest Atlantic to create biomass density surfaces for four VME indicator taxa: large-sized sponges, sea pens, small and large gorgonian corals. These VME indicator taxa were identified previously by NAFO using the fragility, life history characteristics and structural complexity criteria presented by FAO, along with an evaluation of their recovery trajectories. KDE, a non-parametric neighbour-based smoothing function, has been used previously in ecology to identify hotspots, that is, areas of relatively high biomass/abundance. We present a novel approach of examining relative changes in area under polygons created from encircling successive biomass categories on the KDE surface to identify “significant concentrations” of biomass, which we equate to VMEs. This allows identification of the VMEs from the broader distribution of the species in the study area. We provide independent assessments of the VMEs so identified using underwater images, benthic sampling with other gear types (dredges, cores), and/or published species distribution models of probability of occurrence, as available. For each VME indicator taxon we provide a brief review of their ecological function which will be important in future assessments of significant adverse impact on these habitats here and elsewhere. 相似文献
6.
Simian Virus 40 (SV40) transformation of primary cultures of human mammary epithelial cells has yielded a cloned epithelial-like cell line and a representative, single-cell subclone. Although apparently homogeneous, both cloned cell lines can also yield small numbers of three other cell types. The more-elongated cell type can be obtained directly by replating cells from the medium of the epithelial-like cell cultures or by picking and culturing single cells to form representative lines. Immunofluorescent and immunocytochemical analysis of these cell lines growing on plastic or as tumor-nodules in nude mice for epithelial membrane antigens, various cytokeratins, various actins, laminin, Type IV collagen, the common acute lymphoblastic leukemia antigen (CALLA), and a 135-kDa glycoprotein confirm the epithelial nature of the epithelial-like cells and suggest a myoepithelial origin for the more-elongated cell type. Ultrastructural analysis largely confirms the results, although the myofilamental bundles can be scanty in the growing myoepithelial-like cells. The other two cell types are possibly related to the keratinizing and casein-secreting cells seen in the epithelial tumor-nodules before and after mating the mice, respectively. The myoepithelial-like cells produce 5- to 17-fold more laminin, Type IV collagen, CALLA, and the 135-kDa glycoprotein than the epithelial cells, and all of these antigens are preferentially found on myoepithelial cells in vivo. It is suggested that the SV40-transformed epithelial cell is an immortalized form of human mammary stem cell which can differentiate in culture and in vivo to myoepithelial-like cells. 相似文献
7.
Philip S. Rudland Gillian E. Ollerhead Angela M. Platt-Higgins 《In vitro cellular & developmental biology. Animal》1991,27(2):103-112
Summary Transformation of primary cultures of human breast cells with simian virus 40 and clonal selection has yielded single-cell-cloned,
epithelial cell lines, as well as myoepithelial-related cell lines. When grown on floating collagen gels, the epithelial cell
lines give rise to branching rays of cells, thick fingerlike protrusions, saclike structures, and degenerating areas. The
myoepithelial-related cell lines give rise only to the branching rays. Epidermal growth factor stimulates the production of
the thick protrusions, whereas cholera toxin stimulates the production of the degenerating areas. Immunocytochemical staining
of these cultures using reagents directed against the cell surface-extracellular matrix or the cellular cytoskeleton confirms
the epithelial and myoepithelial nature of the cells, and demonstrates that the degenerating areas are undergoing squamous
metaplasia. The fingerlike protrusions consist of cords of cells composed of inner, epithelial and outer, myoepithelial-related
cells sometimes surrounding a central lumen reminiscent of ducts. The saclike structures resemble alveoli. Ultrastructural
analysis confirms the identification of the basic cell types and also identifies indeterminate cells possessing features of
both epithelial and myoepithelial cells. It is suggested that the epithelial cell lines represent human mammary stem cells
that can undergo processes of morphogenesis and differentiation in vitro to form many of the three-dimensional structures
found within the breast.
This work was supported by the North West Cancer Research Fund and the Cancer and Polio Research Fund. 相似文献
8.
Activity patterns of juvenile Atlantic cod (Gadus morhua) in Buckley Cove,Newfoundland 总被引:1,自引:1,他引:0
Cote D. Ollerhead L.M.N. Gregory R.S. Scruton D.A. McKinley R.S. 《Hydrobiologia》2002,483(1-3):121-127
We monitored swimming speed of 2–3 year-old juvenile Atlantic cod (Gadus morhua) from August to December 1999, using a 2-D location finding acoustic telemetry system in a coastal area of Newfoundland, Canada. We concurrently monitored the locations of 22–41 individuals by triangulation using a fixed hydrophone array. We estimated average swimming speeds at intervals of 60–120 s and compared them over a 1 to 17 °C thermal range, three diel periods, and five substrates (sand, gravel, sand-sparse boulder, boulder, and kelp). However, cod did not exhibit a change in swimming speed over the temperature range studied. Increased activity and foraging rates (expressed as swimming speeds) were expected to increase at elevated temperatures due to increased metabolic demands. Activity did vary significantly with diel cycle and substrate. Swimming speeds were significantly lower at night during September and October. Results for August and November were inconclusive, while swimming speed was significantly lower during the day in December. We observed significantly reduced average swimming speeds in structurally complex substrates (e.g. rock, cobble and kelp) in September and October. Our results suggest that activity of juvenile cod in the wild does not vary with temperature as predicted from studies in the laboratory. Instead, activity varied with diel cycles and structural complexity, variables that influence an individual's ability to forage and seek refuge, potentially altering individual fitness. 相似文献
9.
Dempson JB Robertson MJ Pennell CJ Furey G Bloom M Shears M Ollerhead LM Clarke KD Hinks R Robertson GJ 《Journal of fish biology》2011,78(7):1976-1992
Atlantic salmon Salmo salar smolts (n = 181) from two rivers were surgically implanted with acoustic transmitters and released to determine migration route, residency time and survival in a 50 km long estuarine fjord located on the south coast of Newfoundland, Canada. Data obtained from automated receivers placed throughout the Bay d'Espoir fjord indicated that migrating smolts used different routes to reach the outer areas of the fjord. The duration of time that smolts spent in the immediate estuary zone also differed between the two localities (7 and 17 days) although the total time smolts were resident in the fjord was similar and extensive (40 days). Many smolts were resident for periods of 4-8 weeks moving back and forth in the outer part of the fjord where maximum water depths range from 300 to 700 m. Survival in the estuary zone was greater for smolts with prolonged residency in estuarine habitat. Overall smolt survival to the fjord exit was moderately high (54-85%), indicating that the initial phase of migration did not coincide with a period of unusually high mortality. 相似文献
10.
D. A. Scruton C. Pennell L. M. N. Ollerhead K. Alfredsen M. Stickler A. Harby M. Robertson K. D. Clarke L. J. LeDrew 《Hydrobiologia》2008,609(1):263-275
In insular Newfoundland, Canada, studies were conducted from 1999 to 2003 on the effects of ‘simulated’ hydropeaking power
generation on juvenile Atlantic salmon (Salmo salar). In 1999, Atlantic salmon parr were released into an experimental reach below a hydroelectric facility and flow was manipulated
over a range of discharge (1.0–4.2 m3 s−1) during a series of ‘experiments’ simulating hydropeaking in both summer and fall. Fish were implanted with radio transmitters,
manually tracked, precisely located (±1 m), habitat selection evaluated, and movement response determined. Experiments were
continued in 2002 and 2003 to contrast response of salmon between summer and winter, the magnitude of flow changes were greater
(0.7–5.2 m3 s−1) and changes were made more rapidly (instantly). As discharge was increased, velocity and depth use by parr increased, and
fish adapted behaviourally by increased contact with the substrate. Salmon parr also exhibited two distinct movement patterns
in the summer and fall of 1999 studies; high site fidelity or considerable movement during trials. Salmon were more mobile
during both static and dynamic flow conditions and throughout the diel cycle in the summer of 2002 experiment, and 2 fish
were stranded and died, the only time this happened in the four series of experiments. Within each experiment generally there
were no differences between movements at static high and low flows for day and night movements, with one exception, and night
time movements were always greatest, again with one exception. During dynamic flow changes, within each experiment, distances
moved during down ramping and up ramping were not significantly different except in the summer of 1999. Overall, comparing
between experiments for up and down ramping events, distances moved in the summer of 2002 were statistically higher than for
all other experiments. Not surprisingly, the home ranges of fish in the summer of 2002 were also the greatest while the smallest
home ranges were in the winter of 2003. Results suggest hydropeaking regimes may be energetically costly potentially affecting
over-winter survival which is related to energy reserves obtained during summer. Collectively these studies provide comprehensive
information on the response of juvenile Atlantic salmon parr to hydropeaking, on both diel and seasonal scales, and will assist
hydro producers and regulators design and operate hydropeaking regimes to minimize ecological impact.
Guest editors: R. L. Welcomme & G. Marmulla
Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries 相似文献
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