1,721,032 research outputs found
Detecting 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
Management of harmful benthic dinoflagellates requires targeted sampling methods and alarm thresholds
No full textConcern regarding Benthic Harmful Algal Blooms (BHABs) is increasing since some harmful benthic species have been identified in new areas. In the Mediterranean basin, the most common harmful benthic microalgae are Ostreopsis cf. ovata and Prorocentrum lima, which produce palytoxin-like compounds and okadaic acid respectively, and the need to implement monitoring activities has increased. However, a general agreement on appropriate strategies (e.g. sampling season, definition of alarm thresholds, etc.) is still lagging behind, especially for P. lima, whose proliferation dynamics are still poorly known
Table S1 from The multiple roles of β–diversity help untangle community assembly processes affecting recovery of temperate rocky shores
No full textLocation and environmental data for experimental site
Assessing the neurotoxic effects of Ostreopsis cf. ovata by using microelettrode array based platform
No full textIn the last decade, the occurrence of harmful Ostreopsis cf. ovata blooms has increased both in frequency and in geographic distribution. This resulted in adverse impacts on public health and the
economy and has become a global concern. Until now, the data required for the evaluation of real toxicological hazard related to naturally occurring phenomena, such as algal blooms, require time
and resources. Existing data are mainly derived on in vivo mouse assay and are related to acute effects of palytoxin without considering that the toxicity of the dinoflagellates is due to a mixture of
biotoxins whose composition is not only strongly species dependent, but may also differ according to region of occurrence, specific environmental conditions and biological cycles.
In this study, we investigated for the first time the effect of cultured O. cf. ovata cells and their naturally released toxins mixture in the growth medium on rat cortical neuronal networks grown on
multi-electrode arrays (MEA). By means of the multiparametric analysis of neuronal network activity, the approach revealed different toxicological characteristics of the cellular component and
the algal conditioned growth medium, highlighting the higher toxic potential of the first treatment. Overall, the high sensitivity, the rapidity and the throughput make MEA-based method a valuable
tool to be used to facilitate the toxicity evaluation of marine toxic algae in due time and at regulatory level
Effects of ocean acidification and diet on thickness and carbonate elemental composition of the test of juvenile sea urchins
No full textContinuous anthropogenic CO2 emissions to the atmosphere and uptake by the oceans will cause a reduction of seawater pH and saturation state (U) of CaCO3 minerals from which marine calcifiers build their shells and skeletons. Sea urchins use the most soluble form of calcium carbonate, high-magnesium calcite, to build their skeleton, spines and grazing apparatus. In order to highlight the effects of increased pCO2 on the test thickness and carbonate elemental composition of juvenile sea urchins and potential differences in their responses linked to the diet, we performed a laboratory experiment on juvenile Paracentrotus lividus, grazing on calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea, Dictyota dichotoma) macroalgae, under different pH (corresponding to pCO2 values of 390, 550, 750 and 1000 matm). Results highlighted the importance of the diet in determining sea urchin size irrespectively of the pCO2 level, and the relevance of macroalgal diet in modulating urchin Mg/Ca ratio. The present study provides relevant clues both in terms of the mechanism of mineral incorporation and in terms of bottom-up processes (algal diet) affecting top-down ones (fish predation) in rocky subtidal communities
Colonization Processes and the Role of Coralline Algae in Rocky Shore Community Dynamics
No full textRecovery from disturbance is an important attribute of community dynamics. Temperate rocky shores will expe- rience increases in both the type and intensity of impacts under future expected global change. To gauge the community response to these potential changes in the disturbance regime it is important to assess space occu- pancy and the temporal dynamics of key species over the recovery process. We experimentally disturbed repli- cated 1 m2 plots in the lower intertidal at 5 sites along the Ligurian rocky coast (North-western Mediterranean) and assessed early succession processes over 18 months. To identify colonisation processes and role of key spe- cies in affecting species richness on recovery trajectories, we monitored species composition at the cm-scale along fixed transects within the plots. Our results highlighted the role of a limited number of taxa in driving the recovery of species richness across sites, despite site variation in community composition. Settlement of new propagules and overgrowth were the principal pathway of space occupancy. We detected an important role for coralline algae, particularly the articulated Corallina elongata, in promoting the colonisation of a diverse range of colonists. The present study highlights the important role played by calcifying coralline macroalgae as substrate providers for later colonists, favouring recovery of biodiversity after disturbance. This pivotal role may be compromised in a future scenario of elevated cumulative disturbance, where ocean acidification will likely depress the role of coralline algae in recovery, leading to a general loss in biodiversity and community complexit
Cascading Effects of Ocean Acidification in a Rocky Subtidal Community
No full textTemperate marine rocky habitats may be alternatively characterized by well vegetated macroalgal assemblages or barren grounds, as a consequence of direct and indirect human impacts (e.g. overfishing) and grazing pressure by herbivorous organisms. In future scenarios of ocean acidification, calcifying organisms are expected to be less competitive: among these two key elements of the rocky subtidal food web, coralline algae and sea urchins. In order to highlight how the effects of increased pCO2 on individual calcifying species will be exacerbated by interactions with other trophic levels, we performed an experiment simultaneously testing ocean acidification effects on primary producers (calcifying and non-calcifying algae) and their grazers (sea urchins). Artificial communities, composed by juveniles of the sea urchin Paracentrotus lividus and calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea var stricta, Dictyota dichotoma) macroalgae, were subjected to pCO2 levels of 390, 550, 750 and 1000 matm in the laboratory. Our study highlighted a direct pCO2 effect on coralline algae and on sea urchin defense from predation (test robustness). There was no direct effect on the non-calcifying macroalgae. More interestingly, we highlighted diet-mediated effects on test robustness and on the Aristotle’s lantern size. In a future scenario of ocean acidification a decrease of sea urchins’ density is expected, due to lower defense from predation, as a direct consequence of pH decrease, and to a reduced availability of calcifying macroalgae, important component of urchins’ diet. The effects of ocean acidification may therefore be contrasting on well vegetated macroalgal assemblages and barren grounds: in the absence of other human impacts, a decrease of biodiversity can be predicted in vegetated macroalgal assemblages, whereas a lower density of sea urchin could help the recovery of shallow subtidal rocky areas affected by overfishing from barren grounds to assemblages dominated by fleshy macroalgae
Reef Check chronicles: A comprehensive analysis of 19 Years of Maldives coral reef history and impacts response
No full textclimate change all around the world. Over an 19-year period, comprehensive coral reef monitoring was conducted
throughout the Maldivian central atolls using the Reef Check protocol. The study aims to explore the
combined impact of varying degrees of human pressures with climate change effects, and their implications for
reef recovery. By categorising reefs based on island management, inhabited, uninhabited, and resort, we
examined the benthic community composition and the fish and macro-invertebrate communities, revealing
significantly different environmental responses between oceanic and lagoon reefs. Reefs near inhabited and
resort islands, subject to higher human pressures, exhibited greater impacts during the 2016 bleaching event.
However, some oceanic reefs demonstrated notable post-bleaching recovery. Uninhabited islands, with lower
human impact, showed faster post-bleaching recovery. Recognising these distinctions at the reef management
level can inform policymakers in crafting targeted management and regulation for safeguarding natural environments,
particularly amidst climate change-induced threats
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