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  • 1
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Ambient UV radiation has substantially increased during the last decades, but its impact on marine benthic communities is hardly known. The aim of this study was to globally compare and quantify how shallow hard-bottom communities are affected by UV during early succession. Identical field experiments in 10 different coastal regions of both hemispheres produced a consistent but unexpected pattern: (i) UV radiation affected species diversity and community biomass in a very similar manner, (ii) diversity and biomass were reduced to a larger extent by UVA than UVB radiation, (iii) ambient UV levels did not affect the composition of the communities, and (iv) any UV effects disappeared during species succession after 2–3 months. Thus, current levels of UV radiation seem to have small, predictable, and transient effects on shallow marine hard-bottom communities.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reproductive period and life-history parameters were investigated for the hoplonemertineAmphiporus lactifloreus found on the tidal flats of the island of Sylt in the northern Wadden Sea. Every six weeks 20 individuals were collected and then histologically examined to determine the development stage of their reproductive organs.A. lactifloreus reproduces in the late autumn, its peak reproduction being in the second half of November. Individuals from all size classes 〉20 mm body length produced gametes. Individuals of the cohorts that reproduced in the late autumn of 1992 persisted and grew until July 1993, indicating thatA. lactifloreus is an iteroparous species. The length of relaxed individuals was significantly correlated with their length under anaesthetized conditions, but the regression changed significantly after the reproductive period. Length under ‘relaxed’ conditions was significantly correlated with weight (wet weight, dry weight, and ash-free dry weight); these relationships did not vary significantly before or after the reproductive period. Our results show that important life-history data of intertidal nemertines can be obtained without time-consuming histological studies. On the basis of these findings, recommendations for future studies on the population biology of intertidal nemertines are given. Regular length measurements of nemertines under ‘relaxed’ conditions are proposed as a useful tool for tracking the growth and survival of annual cohorts of intertidal nemertines.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 365 (1997), S. 241-250 
    ISSN: 1573-5117
    Keywords: soft-bottom ; intertidal ; chemoreception ; predation ; Nemertea ; Lineus viridis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nemertines can be important predators on tidal flats.They have been found to be preferentially active atnight low tides. To understand the role of these (andother) predators, it is important to understand howthey find their prey on tidal flats. Fieldobservations revealed that the nemertine Lineusviridis feeds on post-spawn Nereis virens inthe spring. Field experiments demonstrated that theplacement of post-spawn or freeze-thawed N.virens on tidal flats can elicit a foraging responseof L. viridis. Nemertines came to the sedimentsurface in large numbers and crawled toward the prey.Comparative experiments showed that more nemertineswere attracted to the sediment surface at day lowtides than at day high tides. More nemertines wereattracted at night low tides than at day low tides.Numbers of active nemertines on tidal flat areaswithout prey were always much lower than on tidal flatareas with prey. In an experimental flume in thelaboratory, starved nemertines were attracted to preyat current velocities of about 2 cm s-1.Regardless of whether it was a simulated high tide orlow tide in the flume, successful nemertines requiredabout 30 min to cover a distance of 50 cm betweenthe starting point and the prey. It is concluded thatthe high activity of nemertines during night low tidesis due in part to the enhanced probability of locatingprey, but is also influenced by prey behavior andpotential competitors. Predatory nemertines such asL. viridis easily cover relatively largedistances of 5–10 m in the field, and may thuseffectively influence the small-scale distribution oftheir potential prey on tidal flats. It is proposed totake the activity pattern, mobility and foraging rangeof predators into account when examining their role inmarine soft-bottom assemblages.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5117
    Keywords: Scrobicularia plana ; Tetrastemma fozensis ; intertidal ; parasites ; pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bivalve Scrobicularia plana, which iscommonly found on tidal flats in northwestern Europe,has disappeared from many locations during the pasttwo decades. Its local disappearance has beensuspected to be a result of pollution, but otherfactors such as parasites have also been discussed. The occurrence of Tetrastemma fozensis, a smallhoplonemertine inhabiting the mantle cavity of S. plana,was examined in bivalves from six differentestuaries in northern Spain. The bivalves are easilycollected, and the nemertines leave the bivalves whenplaced in a small jar with seawater for 72 h. Regularexaminations at 6–10 wk intervals of S. planafrom the estuary of Plencia revealed that thepercentage of bivalves containing nemertines T. fozensisdecreased during the summer months, but wasabove 70% during the rest of the year. In mostestuaries about 40–60% of the bivalves containednemertines, but in March 1994, 100% of the bivalvesfrom the estuary of Hendaye were hosts for nemertines.Nemertines were not found in S. plana from thehighly polluted estuary of Bilbao in either March orSeptember 1994. The number of nemertines withinindividual bivalves was positively correlated with thesize of the bivalves in locations where the percentageof bivalves containing nemertines was above 75%. Inone estuary where the nemertines disappeared almostcompletely from the bivalves between March 1994 andSeptember 1994, parasitic copepods appeared withinsome bivalves in September 1994. The ecology of thenemertine T. fozensis still remains largelyunknown, but we suspect that the nemertines may bebeneficial for their hosts.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 355 (1997), S. 11-19 
    ISSN: 1573-5117
    Keywords: extended parental care ; soft-bottoms ; predation ; protection ; recruitment ; amphipoda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In intertidal soft-bottoms, epibenthic predation isone of the most important post-recruitment processes.Small juveniles are particularly susceptible topredation, and they often settle in the highintertidal where predation pressure is relatively low.Growth conditions in the high intertidal are, however,only suboptimal compared to the low intertidal.Juvenile amphipods Leptocheirus pinguis usuallyremain in their mother‘s burrow for extended timeperiods growing to average sizes of 4–6 mm during thisextended parental care. In laboratory experiments,more juvenile amphipods survived in controls than inpredator additions. In the predator treatments, mostadult amphipods survived while many juvenilesdisappeared. Medium-sized juveniles (6–10 mm size)that had already established their own burrowsemigrated in large numbers from the predatortreatments whereas most of the adult females remainedas residents in these trays. Juvenile L. pinguissurvived periods where they are most susceptible toepibenthic predation in the protected burrows of theirmother. Extended parental care enables juvenileamphipods to recruit immediately into the adulthabitat with a good survival chance. It ishypothesized that some small soft-bottom infauna findprotection in the burrows of other infauna,medium-sized infauna is most likely to engage inescape reactions, whereas large infauna build theirown, deep, burrows, safe from epibenthicpredators.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5117
    Keywords: algal holdfasts ; Peracarida ; reproduction ; dispersion ; benthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the colonisation process of islands, newly immigrating species often arrive as single individuals. Islands that have received single colonisers may subsequently harbour large populations of a species, while other islands may completely lack this species. Exchange between islands is limited, thereby strongly affecting evolutionary processes. While this concept is widely used in the context of oceanic islands or habitat patches on the mainland, it is rarely used to explain and examine the distribution patterns of marine invertebrates. Benthic marine organisms inhabiting patches with island-like features may also be restricted in their movements between patches. Once established in a patch, it may be more favourable to remain there rather than moving to another patch. Juveniles of species with direct development may recruit to the island patch of their parents. Herein, we examined the peracarid fauna in patches that have island-like features, i.e. kelp holdfasts. The number of peracarid species within an individual holdfast increased with its size. Similarly, the number of individuals per holdfast increased with holdfast size. However, several peracarid species showed a strongly aggregated distribution pattern, being highly abundant in some holdfasts and almost completely absent in others. Our results suggest that these aggregations of conspecifics may be a consequence of the peracarid reproductive biology: fully developed juveniles emerge from the female's marsupium and recruit to the immediate vicinity of their mother, showing little or no tendency to emigrate towards other patches. At present, while it is not known how long peracarid aggregations within kelp holdfasts persist, our data suggest that some juveniles may remain with the natal holdfast and possibly reproduce therein. It is concluded that, during certain time periods, reproduction rates of peracarids in a holdfast may exceed their migration rates between holdfasts.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5117
    Keywords: algal mats ; soft-bottom infauna ; community ; mud flats ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of benthic infauna to green algal mats is commonly examined in either small-scale short-term experiments or large-scale long-term data sets that are averaged over large areas. In this study, we used a small-scale approach to study long-term effects caused by the recurring appearance of green algal mats in the early 1990's on a New England mud flat. Algal mats frequently covered the inner parts of the mud flat, where algae persisted for 6 months between July and December, and were incorporated into the sediment after the growth season. These inner parts of the mud flat differed from the outer parts, where green algae never occurred. Between 1979 and 1996, infaunal numbers increased ten-fold at the 37 stations in the inner part, but not at the 19 stations in the outer part of the mud flat. Detritus-feeding annelids primarily contributed to the numerical increase of infaunal colonizers; grazing gastropods and amphipods, and suspension- and filter-feeding bivalves showed no change. The recurring development and deposition of green algae in the inner part of the mud flat resulted in a localized yet persistent change in the infaunal community. The results suggest that it is necessary to follow the fate of algal mats after the growth season. We propose that effects on infaunal colonizers are most severe and long-lasting where decaying algal mats finally become incorporated into the sediment. Brood protecting annelids are most likely to benefit from detrital material provided by moderately dense algal mats.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2017-06-07
    Description: Schizophrenia is a devastating disease that arises on the background of genetic predisposition and environmental risk factors, such as early life stress (ELS). In this study, we show that ELS-induced schizophrenia-like phenotypes in mice correlate with a widespread increase of histone-deacetylase 1 (Hdac1) expression that is linked to altered DNA...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 9
    Publication Date: 2013-06-01
    Print ISSN: 0141-1136
    Electronic ISSN: 1879-0291
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Elsevier
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  • 10
    Publication Date: 2003-08-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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