Multiple stressors facilitate the spread of a non‐indigenous bivalve in the Mediterranean Sea

Abstract

Aim: The introduction of non-indigenous species (NIS) via man-made corridors connecting previously disparate oceanic regions is increasing globally. However, the environmental and anthropogenic factors facilitating invasion dynamics and their interactions are still largely unknown. This study compiles and inputs available data for the NIS bivalve Brachidontes pharaonis across the invaded biogeographic range in the Mediterranean basin into a species distribution model to predict future spread under a range of marine scenarios.Location: Mediterranean Sea.Methods: A systematic review produced the largest presence database ever assembled to inform the selection of biological, chemical and physical factors linked to the spread of B. pharaonis through the Suez Canal. We carried out a sensitivity analysis to simulate current and future trophic and salinity scenarios. A species distribution model was run to determine key drivers of invasion, quantify interactive impacts arising from a range of trophic states, salinity conditions and climatic scenarios and forecast future trajectories for the spread of NIS into new regions under multiple-parameter scenarios (based on the main factors identified from the systematic review).Results: Impacts on invasion trajectory arising from climate change and interactions with increasing salinity from the new opening of the canal were the primary drivers of expansion across the basin, the effects of which were further enhanced by eutrophication. Predictions of the current distribution were most accurate when multiple stressors were used to drive the model. A habitat suitability index developed at a subcontinental scale from model outputs identified novel favourable conditions for future colonization at specific locations under 2030 and 2050 climatic scenarios.Main conclusions: Future expansion of B. pharaonis will be enhanced by climatefacilitated increased sea temperature, interacting with increasing pressures from salinity and eutrophication. The spatially explicit risk output maps of invasions represent a powerful visual product for use in communication of the spread of NIS and decision-support tools for scientists and policymakers. The suggested approach, the observed distribution pattern and driving processes can be applied to other NIS

Predicting shifting sustainability trade‐offs in marine finfish aquaculture under climate change

“…On this basis, stakeholders could identify and implement proactive, site‐specific management strategies tailored to target species. Once such relationship is spatially‐contextualized and mapped, it represents, in practice, the quantitative informational baseline that scientists, policy‐makers, and stakeholders need to produce management strategies and plans that will also adapt to the combined multiple pressures of climate change (Kearney & Porter, ; Pacifici et al., ; Payne et al., ; Sarà, Porporato, Mangano, Mieszkowska, ; Shelton, ).…”

Estimation of fitness from energetics and life‐history data: An example using mussels

“…Here we describe a modeling approach that combines energetic and life‐history information to investigate the effects (on fitness) of multiple physical drivers of energetic cost and intake, as well as differential allocation of resources to growth, metabolism, reproduction, and nonliving structures, using mussels as a model system. We developed this model for a generic small mussel, starting from the invasive mussel Brachidontes pharaonis model in the Mediterranean (Sarà, Porporato, Mangano, & Mieszkowska, ) for which published data were available for most of the energetic parameters (Sarà, Palmeri, Rinaldi, Montalto, & Helmuth, ). Where data were not available for this species, we used published information from other mussel species to test the model.…”

The role of two non-indigenous serpulid tube worms in shaping artificial hard substrata communities: case study of a fish farm in the central Mediterranean Sea

“…Within fouling communities, more attention has been paid to sessile NIS, including a various array of solitary and colonial marine invertebrates (e.g. ascidians, bryozoans, bivalve molluscs, tube-building polychaete worms, sponges, barnacles and sea anemones; Wallentinus & Nyberg 2007, Lezzi et al 2018, Sarà et al 2018a). These organisms not only shape local metabolic and trophic interactions, by altering the physical or biological environment in the system, they can exert a strong habitat-modifying effect, making it more suitable for some species and less so for others (Stachowicz et al 2002, Floerl et al 2004, Sarà et al 2018a.…”

“…ascidians, bryozoans, bivalve molluscs, tube-building polychaete worms, sponges, barnacles and sea anemones; Wallentinus & Nyberg 2007, Lezzi et al 2018, Sarà et al 2018a). These organisms not only shape local metabolic and trophic interactions, by altering the physical or biological environment in the system, they can exert a strong habitat-modifying effect, making it more suitable for some species and less so for others (Stachowicz et al 2002, Floerl et al 2004, Sarà et al 2018a. NIS habitat modifications might have a pronounced ecosystem impact and may cause changes in ecosystem goods and services (Wallentinus & Nyberg 2007, Sarà et al 2018b.…”

“…MSFD Descriptor 2; ICES 2016, Zenetos et al 2017. To effectively deal with risk and impact evaluations on local biodiversity and ecosystem functioning, scientists, legislators, stakeholders and policy makers have pointed out the need for (1) an improved NIS database, (2) integrated checklists and databases based on geo-referenced occurrence and (3) proactive monitoring programmes and modelling exercises (Molnar et al 2008, Hewitt et al 2009, Sarà et al 2018a. To date, the MSFD (EC 2008), among other descriptors, includes the 'impacts of non-indigenous invasive species at the level of species, habitats and ecosystems', acknowl-edging the critical role of vectors in biological invasions and considering the importance of managing the pathways of invasion to guarantee Good Environmental Status.…”