313 research outputs found
Creationism in Europe: facts, gaps and prospects
The purpose of the paper is threefold. First, we present and discuss the extant literature on creationism in Europe (the “facts”). Within this section, we offer a review of the literature as well as an overview of the most remarkable developments and events recorded therein. Second, we indicate which material is missing from the literature (the “gaps”) and signal which gaps we think should first be filled. And third, on the basis of a forthcoming international historical study, we outline the possible factors that affect the popularity of creationism in Europe (the “prospects”). We also sketch how a sustained study of European creationism can contribute to other research domains such as the study of cultural evolution and the relation between science and religion
The early life history of the clam <i>Macoma balthica</i> in a high CO<sub>2</sub> world
This study investigated the effects of experimentally manipulated seawater carbonate chemistry on several early life history processes of the Baltic tellin (Macoma balthica), a widely distributed bivalve that plays a critical role in the functioning of many coastal habitats. We demonstrate that ocean acidification significantly depresses fertilization, embryogenesis, larval development and survival during the pelagic phase. Fertilization and the formation of a D-shaped shell during embryogenesis were severely diminished: successful fertilization was reduced by 11% at a 0.6 pH unit decrease from present (pH 8.1) conditions, while hatching success was depressed by 34 and 87%, respectively at a 0.3 and 0.6 pH unit decrease. Under acidified conditions, larvae were still able to develop a shell during the post-embryonic phase, but higher larval mortality rates indicate that fewer larvae may metamorphose and settle in an acidified ocean. The cumulative impact of decreasing seawater pH on fertilization, embryogenesis and survival to the benthic stage is estimated to reduce the number of competent settlers by 38% for a 0.3 pH unit decrease, and by 89% for a 0.6 pH unit decrease from present conditions. Additionally, slower growth rates and a delayed metamorphosis at a smaller size were indicative for larvae developed under acidified conditions. This may further decline the recruit population size due to a longer subjection to perturbations, such as predation, during the pelagic phase. In general, early life history processes were most severely compromised at ,pH 7.5, which corresponds to seawater undersaturated with respect to aragonite. Since recent models predict a comparable decrease in pH in coastal waters in the near future, this study indicates that future populations of Macoma balthica are likely to decline as a consequence of ongoing ocean acidification
Deep-sea benthic communities and oxygen fluxes in the Arctic Fram Strait controlled by sea-ice cover and water depth
Arctic Ocean surface sea-ice conditions are linked with the deep
sea benthic oxygen fluxes via a cascade of interdependencies across
ecosystem components such as primary production, food supply, activity of the
benthic community, and their functions. Additionally, each ecosystem
component is influenced by abiotic factors such as light availability,
temperature, water depth, and grain size structure. In this study, we
investigated the coupling between surface sea-ice conditions and deep-sea
benthic remineralization processes through a cascade of interdependencies in
the Fram Strait. We measured sea-ice concentrations, a variety of different
sediment characteristics, benthic community parameters, and oxygen fluxes at
12 stations of the LTER HAUSGARTEN observatory, Fram Strait, at water depths
of 275–2500 m. Our investigations reveal that the Fram Strait is bisected
into two long-lasting and stable regions: (i) a permanently and highly
sea-ice-covered area and (ii) a seasonally and low sea-ice-covered area.
Within the Fram Strait ecosystem, sea-ice concentration and water depth are
two independent abiotic factors, controlling the deep-sea benthos. Sea-ice
concentration correlated with the available food and water depth with the
oxygen flux. In addition, both abiotic factors sea-ice concentration and
water depth correlate with the macrofauna biomass. However, at water depths
> 1500 m the influence of the surface sea-ice cover is minimal
with water depth becoming more dominant. Benthic remineralization across
the Fram Strait on average is ∼ 1 mmol C m−2 d−1. Our data
indicate that the portion of newly produced carbon that is remineralized by
the benthos is 5 % in the seasonally low sea-ice-covered eastern part of
Fram Strait but can be 14 % in the permanently high sea-ice-covered
western part of Fram Strait. Here, by comparing a permanently sea-ice-covered
area with a seasonally sea-ice-covered area, we discuss a potential scenario
for the deep-sea benthic ecosystem in the future Arctic Ocean, in which an
increased surface primary production may lead to increasing benthic
remineralization at water depths < 1500 m.</p
Carbon and nitrogen turnover in the Arctic deep sea: in situ benthic community response to diatom and coccolithophorid phytodetritus
In the Arctic Ocean, increased sea surface temperature and sea ice retreat
have triggered shifts in phytoplankton communities. In Fram Strait,
coccolithophorids have been occasionally observed to replace diatoms as the
dominating taxon of spring blooms. Deep-sea benthic communities depend
strongly on such blooms, but with a change in quality and quantity of
primarily produced organic matter (OM) input, this may likely have
implications for deep-sea life. We compared the in situ responses of Arctic
deep-sea benthos to input of phytodetritus from a diatom
(Thalassiosira sp.) and a coccolithophorid (Emiliania
huxleyi) species. We traced the fate of 13C- and
15N-labelled phytodetritus into respiration, assimilation by
bacteria and infauna in a 4-day and 14-day experiment. Bacteria were key
assimilators in the Thalassiosira OM degradation, whereas
Foraminifera and other infauna were at least as important as bacteria in the
Emiliania OM assimilation. After 14 days, 5 times less carbon and
3.8 times less nitrogen of the Emiliania detritus was recycled
compared to Thalassiosira detritus. This implies that the
utilization of Emiliania OM may be less efficient than for
Thalassiosira OM. Our results indicate that a shift from
diatom-dominated input to a coccolithophorid-dominated pulse could entail a
delay in OM cycling, which may affect benthopelagic coupling.</p
San Francisco Bay Area corporate history : a selected annotated bibliography
Human activities, among which dredging and land use change in river basins,
are altering estuarine ecosystems. These activities may result in changes in
sedimentary processes, affecting biodiversity of sediment macrofauna. As
macrofauna controls sediment chemistry and fluxes of energy and matter between
water column and sediment, changes in the structure of macrobenthic
communities could affect the functioning of an entire ecosystem. We assessed
the impact of sediment deposition on intertidal macrobenthic communities and
on rates of an important ecosystem function, i.e. sediment community oxygen
consumption (SCOC). An experiment was performed with undisturbed sediment
samples from the Scheldt river estuary (SW Netherlands). The samples were
subjected to four sedimentation regimes: one control and three with a
deposited sediment layer of 1, 2 or 5 cm. Oxygen consumption was measured
during incubation at ambient temperature. Luminophores applied at the
surface, and a seawater–bromide mixture, served as tracers for bioturbation
and bio-irrigation, respectively. After incubation, the macrofauna was
extracted, identified, and counted and then classified into functional groups
based on motility and sediment reworking capacity. Total macrofaunal
densities dropped already under the thinnest deposits. The most affected
fauna were surficial and low-motility animals, occurring at high densities in
the control. Their mortality resulted in a drop in SCOC, which decreased
steadily with increasing deposit thickness, while bio-irrigation and
bioturbation activity showed increases in the lower sediment deposition
regimes but decreases in the more extreme treatments. The initial increased
activity likely counteracted the effects of the drop in low-motility, surficial
fauna densities, resulting in a steady rather than sudden fall in oxygen
consumption. We conclude that the functional identity in terms of motility
and sediment reworking can be crucial in our understanding of the regulation
of ecosystem functioning and the impact of habitat alterations such as
sediment deposition
A multi-parent recombinant inbred line population of C. elegans allows identification of novel QTLs for complex life history traits
Background
The nematode Caenorhabditis elegans has been extensively used to explore the relationships between complex traits, genotypes, and environments. Complex traits can vary across different genotypes of a species, and the genetic regulators of trait variation can be mapped on the genome using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) derived from genetically and phenotypically divergent parents. Most RILs have been derived from crossing two parents from globally distant locations. However, the genetic diversity between local C. elegans populations can be as diverse as between global populations and could thus provide means of identifying genetic variation associated with complex traits relevant on a broader scale.
Results
To investigate the effect of local genetic variation on heritable traits, we developed a new RIL population derived from 4 parental wild isolates collected from 2 closely located sites in France: Orsay and Santeuil. We crossed these 4 genetically diverse parental isolates to generate a population of 200 multi-parental RILs and used RNA-seq to obtain sequence polymorphisms identifying almost 9000 SNPs variable between the 4 genotypes with an average spacing of 11 kb, doubling the mapping resolution relative to currently available RIL panels for many loci. The SNPs were used to construct a genetic map to facilitate QTL analysis. We measured life history traits such as lifespan, stress resistance, developmental speed, and population growth in different environments, and found substantial variation for most traits. We detected multiple QTLs for most traits, including novel QTLs not found in previous QTL analysis, including those for lifespan and pathogen responses. This shows that recombining genetic variation across C. elegans populations that are in geographical close proximity provides ample variation for QTL mapping.
Conclusion
Taken together, we show that using more parents than the classical two parental genotypes to construct a RIL population facilitates the detection of QTLs and that the use of wild isolates facilitates the detection of QTLs. The use of multi-parent RIL populations can further enhance our understanding of local adaptation and life history trade-offs
Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management
The goal of ecosystem-based marine spatial management is to maintain marine ecosystems in a healthy, productive and resilient condition; hence, they can sustainably provide the needed goods and services for human welfare. However, the increasing pressures upon the marine realm threaten marine ecosystems, especially seabed biotopes, and thus a well-planned approach of managing use of marine space is essential to achieve sustainability. The relative value of seabed biotopes, evaluated on the basis of goods and services, is an important starting point for the spatial management of marine areas. Herein, 56 types of European seabed biotopes and their related goods, services, sensitivity issues, and conservation status were compiled, the latter referring to management and protection tools which currently apply for these biotopes at European or international level. Fishing activities, especially by benthic trawls, and marine pollution are the main threats to European seabed biotopes. Increased seawater turbidity, dredged sediment disposal, coastal constructions, biological invasions, mining, extraction of raw materials, shipping-related activities, tourism, hydrocarbon exploration, and even some practices of scientific research, also exert substantial pressure. Although some first steps have been taken to protect the European sea beds through international agreements and European and national legislation, a finer scale of classification and assessment of marine biotopes is considered crucial in shaping sound priorities and management guidelines towards the effective conservation and sustainability of European marine resources
Organism-sediment interactions govern post-hypoxia recovery of ecosystem functioning
Hypoxia represents one of the major causes of biodiversity and ecosystem functioning loss for coastal waters. Since eutrophication-induced hypoxic events are becoming increasingly frequent and intense, understanding the response of ecosystems to hypoxia is of primary importance to understand and predict the stability of ecosystem functioning. Such ecological stability may greatly depend on the recovery patterns of communities and the return time of the system properties associated to these patterns. Here, we have examined how the reassembly of a benthic community contributed to the recovery of ecosystem functioning following experimentally-induced hypoxia in a tidal flat. We demonstrate that organism-sediment interactions that depend on organism size and relate to mobility traits and sediment reworking capacities are generally more important than recovering species richness to set the return time of the measured sediment processes and properties. Specifically, increasing macrofauna bioturbation potential during community reassembly significantly contributed to the recovery of sediment processes and properties such as denitrification, bedload sediment transport, primary production and deep pore water ammonium concentration. Such bioturbation potential was due to the replacement of the small-sized organisms that recolonised at early stages by large-sized bioturbating organisms, which had a disproportionately stronger influence on sediment. This study suggests that the complete recovery of organism-sediment interactions is a necessary condition for ecosystem functioning recovery, and that such process requires long periods after disturbance due to the slow growth of juveniles into adult stages involved in these interactions. Consequently, repeated episodes of disturbance at intervals smaller than the time needed for the system to fully recover organism-sediment interactions may greatly impair the resilience of ecosystem functioning.
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