1,721,021 research outputs found
Using temperature and food density to predict growth and reproduction of intertidal marine invertebrate ectotherms and the repercussion on biodiversity.
No full textHeart beat rate: a physiological response to thermal stress in blue mussels species.
No full textNon-native species often have ecological impacts on invaded communities. The
quanti#cation of features of invaders and recipient ecosystems facilitating and/or
interfering with successful invasion remains a challenge because of several factors may
in!uence the success of invasions. Among them, life history strategies (e.g., reproductive
potential, body size), ability to avoid predators, disease resistance and physiological
compensatory mechanisms to adapt to changing habitats are among the most important
factors. The latter has been often invoked as the key to success for many intertidal
invasive invertebrates and have been suggested as key indicators of invasibility rate
and the ultimate distribution on worldwide coastal intertidal habitats. The physiological
ability to adapt to cycling thermal stress conditions is one important aspect of these
species to thrive of intertidal habitats. The present study reports on the physiological
e"ect of thermal stress both at low tide and high tide of Mytilus galloprovincialis, a
Mediterranean species which is an invader in Northern American intertidal habitats and
M. trossulus, a sibling species. Heart beat rate (HBR) of the species was measured in high
tide standard condition (12°C, 28 ‰ of salinity) and at 4 di"erent body temperatures
(20°, 25°, 30°, 35°C) during low tide condition (aerial exposure). HBR of M. trossulus,
during high tide condition was signi#cantly higher (23.66 ± 2.52 beat*min-1, p<0.001)
than that of M. galloprovincialis (19.62 ± 0.26 beat*min-1); this is consistent with the
evolutionary adaptation to a lower habitat temperature (temperature compensation)
in the former species. During low tide conditions at di"erent body temperatures,
mussels of the two species showed similar behaviour. Both species increase quickly
their HBR after emersion, showing a tachycardia typical of initial emersion condition
than HBR fell sharply to bradycardia up to the time which mussels are re-immersed in
water
Predicting biological invasions in marine habitats through eco-physiological mechanistic models: a case study with the bivalve Brachidontes pharaonis
Full text linkAim We used a coupled biophysical ecology (BE)-physiological mechanistic
modelling approach based on the Dynamic Energy Budget theory (DEB,
Dynamic energy budget theory for metabolic organisation, 2010, Cambridge
University Press, Cambridge; DEB) to generate spatially explicit predictions of physiological performance (maximal size and reproductive output) for the invasive mussel, Brachidontes pharaonis.
Location We examined 26 sites throughout the central Mediterranean Sea.
Methods We ran models under subtidal and intertidal conditions; hourly
weather and water temperature data were obtained from the Italian Buoy
Network, and monthly CHL-a data were obtained from satellite imagery.
Results Mechanistic analysis of the B. pharaonis fundamental niche shows that
subtidal sites in the Central Mediterranean are generally suitable for this invasive bivalve but that intertidal habitats appear to serve as genetic sinks.
Main conclusions A BE-DEB approach enabled an assessment of how the
physical environment affects the potential distribution of B. pharaonis. Combined with models of larval dispersal, this approach can provide estimates of the likelihood that an invasive species will become established
Dynamic Energy Budget model parameter estimation for the bivalve Mytilus californianus: Application of the covariation method
Full text linkDynamic Energy Budget (DEB) models serve as a powerful tool for describing the flow of energy through organ-
ismsfrom assimilation offoodtoutilization for maintenance,growth andreproduction.The DEB theoryhas been
successfully applied to several bivalve species to compare bioenergetic and physiological strategies for the utili-
zation of energy. In particular, mussels within the
Mytilus edulis
complex (M. edulis,M. galloprovincialis
, and M. trossulus) have been the focus of many studies due to their economic and ecological importance, and their
worldwide distribution. However, DEB parameter values have never been estimated for Mytilus californianus
,a species that is an ecological dominant on rocky intertidal shores on the west coast of North America and
which likely varies considerably from mussels in the M. edulis complex in its physiology. We estimated a set of
DEB parameters for M. californianus
using the covariation method estimation procedure and compared these
to parameter values from other bivalve species. Model parameters were used to compare sensitivity to environ-
mental variability among species, as a
first examination of how strategies for physiologically contending with
environmental change by M. californianus
may differ from those of other bivalves. Results suggest that based
on the parameter set obtained,
M. californianus has favorable energetic strategies enabling it to contend with a range of environmental conditions. For instance, the allocation fraction of reserve to soma (
κ ) is among the highest of any bivalves, which is consistent with the observation that this species can survive over a wide
range of environmental conditions, including prolonged periods of starvatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Combining heat-transfer and energy budget models to predict local and geographic patterns of mortality in Mediterranean intertidal mussels
No full textRecent studies have emphasised that organisms can experience physiological stress well within their
geographic range limits. Developing methods for mechanistically predicting the presence, absence and
physiological performance of organisms is therefore important because of the ongoing effects of climate
change. In this study, we merged a biophysical–ecological (BE) model that estimates the aquatic (high
tide) and aerial (low tide) body temperatures of Mytilus galloprovincialis with a Dynamic Energy Budget
(DEB) model to predict growth, reproduction and mortality of this Mediterranean mussel in both intertidal
and subtidal environments. Using weather and chlorophyll-a data from three Mediterranean sites along
the Italian coasts, we show that predictions of sublethal and lethal (acute) stress can potentially explain
the observed distribution (both presence and absence) of mussels in the intertidal and subtidal zones,
and the maximum size of animals in the subtidal zones. Importantly, our results suggest that different
mechanisms limit the intertidal distribution of mussels, and that these mechanisms do not follow a simple
latitudinal gradient. At the northernmost site (Palermo), M. galloprovincialis appears to be excluded from
the intertidal zone due to persistent exposure to lethal aerial temperatures, whereas at the southernmost
sites (Porto Empedocle and Lampedusa) sublethal stress is the most important driver of mussel intertidal
distribution. Our predictions provide a set of hypotheses for future work on the role of climate change in
limiting intertidal distribution of mussels in the Mediterranean
Predicting patterns of stress and mortality in intertidal invertebrates: applications of biophysical ecology in a changing world
No full textBackground, Questions and Methods
Recent studies have emphasized that local and geographic patterns of species distributions can be set by a variety of factors related to weather and climate, including exposure to lethal environmental conditions, indirect effects on consumers and competitors, and sublethal effects of physiological stress on growth and reproduction. Predicting where, when and with what magnitude these impacts are most (and least) likely to occur is imperative if we are to effectively plan for (i.e. adapt to) the effects of climate change.

We developed a series of methods for translating patterns of environmental “signals” into organismal responses in intertidal ecosystems. Importantly, “organismal climatologies” – long term patterns of organism temperature measured using in situ biomimetic sensors - show distinct differences from patterns based on environmental temperature (air or water temperature). Similarly, we explored the use of dynamic energy budget models, linked to heat budget models of animal temperature, to examine temporal and spatial patterns of sublethal stress and growth. 

Results and Conclusions
Comparisons of four different metrics of stress- seasonal averages, extreme temperatures, number of “stressful days” (>32°C) and return time of stress events – show that temporal and spatial patterns of sublethal stress do not always track patterns of lethal exposure. In other words, simply knowing average temperature often tells us very little about exposure to extremes and vice versa. These results are consistent with the idea that extreme events can occur during the temporal synchrony of multiple “normal” events- for example low wave splash, extreme low tides and high solar radiation. Results also suggest that the combination of heat budget models with dynamic energy budgets are potentially an effective way to predict spatial patterns of intertidal organisms, but that we still need more physiological data regarding the role of aerial body temperature in driving growth and reproduction.

Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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