1,720,965 research outputs found
Population biology and larval ecology of the sea urchin Centrostephanus rodgersii (Agassiz 1863) in New Zealand under the influence of Global Climate Change
No full textDetecting drivers of Ostreopsis blooms through modellistic approach
No full textBlooms of toxic dinoflagellates belonging to the genus Ostreopsis in coastal areas are a topic of increasing interest due to the potential hazard that these species might pose to marine organisms and to human health, and the consequent negative effect on tourism, fishery and aquaculture economy. For the last 15 years, blooms of Ostreopsis species have been observed in temperate and tropical coastal waters in both the northern and southern hemispheres. Despite their ecological, sanitary and economic relevance, particularly in touristic areas, Ostreopsis bloom dynamics are still poorly known and the mechanisms of bloom development are unclear, particularly in terms of which environmental/meteorological variables trigger bloom events.
These mechanisms are investigated by modeling the concentration of Ostreopsis cf ovata in seawater in response to an array of environmental and meteorological variables. The best model among multiple linear regressions, generalized linear models, mixed models and generalized linear mixed models is chosen according to its Akaike Information Criterion. This model allows us to define a microalgal bloom event, considering the magnitude of the increase of cells concentration in seawater over time.
This definition is in turn applied within a meta-analysis framework to discriminate between bloom and non-bloom conditions and detect which environmental/meteorological variables are driving the bloom event on a global scale.
A foreseeable future application of the chosen model is in the field of forecasting Ostreopsis bloom events from a coastal management point of view. This tool would represent one of the major achievements in the framework of M3-HABs, a EU funded project (ENPI-CBCMED program) coordinated by CoNISMa aimed at developing a pan-Mediterranean strategy for monitoring, modeling and implementing mitigation measures to manage Ostreopsis blooms along Mediterranean coasts
How does embryonic and larval thermal tolerance contribute to the distribution of the sea urchin Centrostephanus rodgersii (Diadematidae) in New Zealand?
No full textGrowth, morphometrics and size structure of the Diadematidae sea urchin Centrostephanus rodgersii in northern New Zealand
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The thermal tolerance of crown-of-thorns (Acanthaster planci) embryos and bipinnaria larvae: implications for spatial and temporal variation in adult populations
No full textA novel application of an adaptable modeling approach to the management of toxic microalgal bloom events in coastal areas
No full textHarmful algal blooms have been increasing in frequency in recent years, and attention has shifted from describing to modeling and trying to predict these phenomena, since in many cases they pose a risk to human health and coastal activities. Predicting ecological phenomena is often time and resource consuming, since a large number of field collected data are required. We propose a novel approach that involves the use of modeled meteorological data as input features to predict the concentration of the toxic benthic dinoflagellate Ostreopsis cf. ovata in seawater. Ten meteorological features were used to train a Quantile Random Forests model, which was then validated using field collected concentration data over the course of a summer sampling season. The proposed model was able to accurately describe Ostreopsis abundance in the water column in response to meteorological variables. Furthermore, the predictive power of this model appears good, as indicated by the validation results, especially when the quantile for predictions is tuned to match management requirements. The Quantile Random Forests method was selected, as it allows for greater flexibility in the generated predictions, thus making this model suitable as a tool for coastal management. The application of this approach is novel, as no other models or tools that are adaptable to this degree are currently available. The model presented here was developed for a single species over a limited geographical extension, but its methodological basis appears flexible enough to be applied to the prediction of HABs in general and it could also be extended to the case of other ecological phenomena that are strongly dependent on meteorological drivers, that can be independently modeled and potentially globally available
Impacts of near future sea surface pH and temperature conditions on fertilisation and embryonic development in Centrostephanus rodgersii from northern New Zealand and northern New South Wales Australia
No full textOceans are warming and becoming more acidic. While higher temperature and lower pH can have negative effects on fertilisation and development of marine invertebrates, warming may partially ameliorate the negative effect of lower pH. This study determined the effect of warming (3 °C) and decreased pH (0.3, 0.5, 1.1 units below ambient) on fertilisation and development in two populations of the sea urchin Centrostephanus rodgersii, one at its northern range limit (Coffs Harbour, New South Wales NSW, 30°27′S, 153°14′E) and the other one in New Zealand where the species may be a recent arrival (Mokohinau Islands, 35°56′S, 175°9′E). Both populations were sampled in August 2011. The two populations exhibited a differential response to temperature, while pH affected them similarly. Fertilisation was robust to pH levels forecast for 2100, and it was only slightly reduced at pH values forecast for 2300 (i.e. ≈5 and ≈8 % for the northern NSW and the New Zealand populations, respectively). Decreased pH (pH = 7.6) reduced the percentage of succeeding developmental stages. Progression through cleavage and hatching stages was faster at +3 °C in the New Zealand population but not in northern NSW urchins, while for the NSW population, there was a positive interaction between temperature and pH at hatching. Gastrulation was negatively affected by an extreme pH 7.0 treatment (60–80 % reduction) and least affected by increased temperature. The percentage of abnormal embryos at gastrulation increased significantly at +3 °C treatment in the northern NSW population. Predicted future increases in temperature may facilitate further expansion of the geographical range of C. rodgersii in New Zealand, with a minimal effect of concurrent reduced pH
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
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