A mechanistic approach reveals non linear effects of climate warming on mussels throughout the Mediterranean sea

There is a dire need to forecast the ecological impacts of global climate change at scales relevant to policy and management. We used three interconnected models (climatic, biophysical and energetics) to estimate changes in growth, reproduction and mortality risk by 2050, for three commercially and ecologically important bivalves at 51 sites in the Mediterranean Sea. These results predict highly variable responses (both positive and negative) in the time to reproductive maturity and in the risk of lethality among species and sites that do not conform to simple latitudinal gradients, and which would be undetectable by methods focused only on lethal limits and/or range boundaries.

L’effetto del food supply sul budget energetico di tre bivalvi in Mediterraneo

The impact of climate change on Mediterranean intertidal communities: losses in coastal ecosystem integrity and services

As has been shown for other ecosystems, the ecological and socio-economic impacts of climate change on Mediterranean intertidal habitats are highly variable in space and time. We conducted field and laboratory measurements of cellular, ecophysiological and behavioural responses of selected intertidal invertebrates (mussels, gastropods and sponges) and completed a literature review to determine what is known of socioeconomic consequences of these biological changes. Results suggest significant gaps in our knowledge that may impede a complete understanding of likely impacts (physical, biological, and socioeconomic) and that sufficient data for such an analysis is available only for mussels. A…

The effect of the quality of diet on the functional response of Mytilus galloprovincialis (Lamarck, 1819): Implications for integrated multitrophic aquaculture (IMTA) and marine spatial planning

Abstract The integrated multi-trophic aquaculture (i.e., IMTA) is a practice combining organisms with different trophic levels with the final purpose of transforming the continuous waste of food by targeting species into nutrient input for other non-target species. This practice very often involves filter feeders, such as bivalves, by the use of which bioenergetics budgets are strongly influenced by the quality and quantity of different foods. However, to date, scant information is available, to really understand the rebounds of food availability on the growth performances of these harvested biomasses in the natural environment. By choosing the mussel Mytilus galloprovincialis as a model, t…

Functional traits, mechanistic bioenergetics and microclimatic downscaling of marine ectotherms

The functional trait-based approach to investigate life history traits in marine invertebrates to predict effects of global climate change on ecosystems

Moving beyond mortality: a metabolic framework for exploring effects of climate change on intertidal mussel bed zonation

Predictive mechanistic bioenergetics to model habitat suitability of shellfish culture in coastal lakes

Quantitative tools based on mechanistic modelling of functional traits able to enhance the sustainability of aquaculture and most other human activities (i.e. reducing the likelihood of detrimental impacts optimising productions), are especially important factors in the decision to site aquaculture facilities in coastal lakes, ponds and lagoons and, in the case of detrimental impact, to adopt mitigation measures. We tested the ability of mechanistic functional trait based models to predict life history traits of cultivable shellfish in shallow coastal lakes. Dynamic Energy Budget (DEB) models were run to generate spatially explicit predictions of Mytilus galloprovincialis life history (LH) …

Low temperature trumps high food availability to determine the distribution of intertidal mussels Perna perna in South Africa

Explanations of species distributions often assume that the absence of a species is due to its inability to tolerate an environmental variable. Recent modelling techniques based on the dynamic energy budget (DEB) theory offer an effective way of identifying how interacting environmental parameters influence distributions through non-lethal effects on growth and development. The mussel Perna perna is an abundant ecosystem engineer around the coasts of Africa, South America and the Arabian peninsula, with an unexplained 1500 km lacuna in its distribution on the west coast of South Africa. We used a DEB approach to explain its distribution in southern Africa and test the hypothesis that this l…

Parameterisation of bivalve functional traits for mechanistic eco-physiological dynamic energy budget (DEB) models

Mechanistic models such as those based on dynamic energy budget (DEB) theory are emergent ecomechanics tools to investigate the extent of fitness in organisms through changes in life history traits as explained by bioenergetic principles. The rapid growth in interest around this approach originates from the mechanistic characteristics of DEB, which are based on a number of rules dictating the use of mass and energy flow through organisms. One apparent bottleneck in DEB applications comes from the estimations of DEB parameters which are based on mathematical and statistical methods (covariation method). The parameterisation process begins with the knowledge of some functional traits of a tar…

Life history traits to predict biogeographic species distributions in bivalves

Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provid…

Functional role of biofouling linked to aquaculture facilities in Mediterranean enclosed locations

Biofouling is generally considered a serious threat for human coastal activities such as aquaculture, and the ecological role of fouling organisms associated with fish-farm cages remains one of the most debated topics in the ecological field. However, although biofouling may cause significant problems related to human health, environmental impact and financial losses, in the past decade there has been an increasing interest in developing methods to promote the growth of biofouling on artificial structures as a strategy to mitigate human impacts and reduce the organic enrichment caused by net-cage fish farming. Here we investigated the filtration activity of biofouling assemblages colonizing…

The estimation of DEB parameters for the invasive intertidal bivalve, Brachidontes pharaonis

Predicting biological invasions in marine habitats through eco-physiological mechanistic models: a case study with the bivalveBrachidontes pharaonis

Aim 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 bioenergetics models to link functional traits to population dynamics: a study case with a marine bivalve

Can Septifer virgatus survive in a warming world? A Dynamic Energy Budget model approach

Dynamic Energy Budget model parameter estimation for the bivalve Mytilus californianus: Application of the covariation method

Dynamic Energy Budget (DEB) models serve as a powerful tool for describing the flow of energy through organisms from assimilation of food to utilization for maintenance, growth and reproduction. The DEB theory has been successfully applied to several bivalve species to compare bioenergetic and physiological strategies for the utilization 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 domin…

Dynamic Energy Budget parameters of Brachidontes pharaonis, a lessepsian bivalve in the Mediterranean Sea.

Dynamic Energy Budget (DEB) models are used for describing the flow of energy through organisms. The most important and powerful aspect of DEB theory is that inter-specific differences can be captured in the same model by comparison of parameter values. However, estimation of these parameters is complicated and can often not be done with direct empirical measurements alone. Here, we present DEB parameter estimates obtained by combining both experimental and literature data for the filter feeder Brachidontes pharaonis, which is considered one among the 100 worst invasive marine species in the Mediterranean Basin. We utilize a statistical procedure based on the covariation method to obtain pa…

Thinking beyond organism energy use: a trait-based bioenergetic mechanistic approach for predictions of life history traits in marine organisms

The functional trait-based bioenergetic approach is emergent in many ecological spectra, from the conservation of natural resources to mitigation and adaptation strategies in a global climate change context. Such an approach relies on being able to exploit mechanistic rules to connect environmental human-induced variability to functional traits (i.e. all those specific traits defining species in terms of their ecological roles) and use these to provide estimates of species life history traits (LH; e.g. body size, fecundity per life span, number of reproductive events). LHs are species-specific and proximate determinants of population characteristics in a certain habitat. They represent the …

Intertidal oyster and mussel beds in a global warming perspective. Trade offs and microclimatic downscaling

Estimation of dynamic energy budget parameters for the Mediterranean toothcarp (Aphanius fasciatus)

Organisms adopt different sets of physiological, behavioural and morphological trade-offs in order to cope with natural environmental fluctuations. This has consequential rebounds on ecological processes and population dynamics. Such aspects become crucial for sex-dimorphic species, where sex-specific growth variation could mirror different tactics both in energy acquisition and investment between maximum female and male body size with cascading effects on population demography. To date, different approaches have been used in order to understand the causes of individual growth rate changes in ectotherm indeterminate growers, most of which failed. Here, we propose the use of a mechanistic mo…

Modelli meccanicistici biofisici e bioenergetici DEB per la predizione della nicchia ecologica dei sospensivori bentonici in Mediterraneo in un contesto di climate change

I modelli meccanicistici basati sull’analisi dei tratti funzionali comportamentali (e.g. preferenze alimentari), fisiologici (e.g. vulnerabilità alla temperatura) e morfologici (e.g. forma e colore) che concorrono nell’ottimizzazione dell’incoming energetico del singolo organismo sono una soluzione pratica per fornire previsioni accurate sull’abbondanza degli organismi di una specie in un mondo in continuo cambiamento (Araujo & Rahbek 2006). Tale approccio è definito come ecomeccanica e ha rappresentato la base sulla quale costruire questo progetto di tesi. L’integrazione dei più recenti modelli biofisici e bioenergetici ha permesso di evidenziare tanto le strategie di gestione ed allocazio…

L’effetto della mitilicoltura posta a valle di allevamenti di specie ittiche riduce il carico organico

L’utilizzo del mussel cleaning che sfrutta le caratteristiche fisiologiche dei molluschi filtratori per la mitigazione degli impatti derivanti da reflui particellati di origine antropica, ed in particolare delle attività di piscicoltura, è stato introdotto di recente in diversi paesi europei. Tale procedura si basa sull’ipotesi che la filtrazione operata da elevate biomasse di molluschi eduli posti nei pressi degli impianti di pescicoltura possa ridurre il carico organico in eccesso proveniente dal surplus di mangime fornito ai pesci allevati e che in certa parte inutilizzato tende a sedimentare al di sotto delle gabbie di allevamento. In questo studio abbiamo analizzato in due periodi diff…

Testing the effects of temporal data resolution on predictions of the effects of climate change on bivalves

a b s t r a c t The spatial-temporal scales on which environmental observations are made can significantly affect our perceptions of ecological patterns in nature. Understanding potential mismatches between environmen- tal data used as inputs to predictive models, and the forecasts of ecological responses that these models generate are particularly difficult when predicting responses to climate change since the assumption of model stationarity in time cannot be tested. In the last four decades, increases in computational capacity (by a factor of a million), and the evolution of new modeling tools, have permitted a corresponding increase in model complexity, in the length of the simulations,…

Eco-physiological response of two marine bivalves to acute exposition to commercial Bt-based pesticide

Microbial products based on the entomopathogenic bacterium Bacillus thuringiensis (Bt) are among the most common biopesticides used worldwide to suppress insect pests in forests, horticulture and agricultural crops. Some of the effects of commercial Bt have been recorded for terrestrial and freshwater non-target organisms but little research is available on marine fauna. Nevertheless, due to the contiguity of agro-ecosystems and coastal habitats, marine fauna may be highly influenced by this control method. We studied the effect of a commercial Bt product on the physiological and ecological responses and the energy budget of two of the most frequent marine intertidal bivalves in the Mediter…

A bioenergetics framework for integrating the effects of multiple stressors: Opening a 'black box' in climate change research

Climate change is already impacting marine ecosystems across a range of scales, from individual physiology, to changes in species interactions and community structure, and ultimately to patterns in geographic distribution. Predicting how marine ecosystems will respond to environmental change is a signifi cant challenge because vulnerability to climatic and non-climatic stressors is highly variable, and depends on an organism’s functional traits, tolerance to stressors, and the environment in which it lives. We present a mechanistic approach based on biophysical and dynamic energy budget models that integrates the cumulative effects of multiple environmental stressors (temperature and food) …

An energy budget for the subtidal bivalve Modiolus barbatus (Mollusca) at different temperatures

Clearance rates, respiration rates and food absorption efficiencies of the commercially interesting subtidal bivalve Modiolus barbatus were measured at different temperatures under laboratory conditions and scope for growth calculated. Clearance rates were highest at temperatures from 20 °C to 28 °C, whereas respiration rate was maximal at 9 °C and minimal at 26 °C. Highest mean values of absorbed energy occurred at 20 °C and 26 °C. Scope for growth trend had negative values at 9 °C, 15 °C and 28 °C and positive values at temperatures 20 °C and 26 °C. The profitable thermal window for M. barbatus to have energy sufficient for growth and reproduction corresponded to <5 months per year. Seawa…