A dynamic subtropical coastal hotspot of benthic foraminifera in the Southeastern Mediterranean indicates early-stage tropicalization.

Due to ongoing ocean warming, subtropical environments are becoming accessible to tropical species. Among these environments are the vermetid reefs of the Southeastern Mediterranean (SEM). In the last decades, these valuable coastal habitats witnessed the proliferation of numerous alien species of tropical origin.

Taming the terminological tempest in invasion science.

Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions.

Cross-basin and cross-taxa patterns of marine community tropicalization and deborealization in warming European seas.

Ocean warming and acidification, decreases in dissolved oxygen concentrations, and changes in primary production are causing an unprecedented global redistribution of marine life. The identification of underlying ecological processes underpinning marine species turnover, particularly the prevalence of increases of warm-water species or declines of cold-water species, has been recently debated in the context of ocean warming. Here, we track changes in the mean thermal affinity of marine communities across European seas by calculating the Community Temperature Index for 65 biodiversity time series collected over four decades and containing 1,817 species from different communities (zooplankton, coastal benthos, pelagic and demersal invertebrates and fish).

Co-occurrence of native and invasive macroalgae might be facilitated under global warming.

Climate change is driving compositional shifts in ecological communities directly by affecting species and indirectly through changes in species interactions. For example, competitive hierarchies can be inversed when competitive dominants are more susceptible to climate change. The brown seaweed Fucus vesiculosus is a foundation species in the Baltic Sea, experiencing novel interactions with the invasive red seaweed Gracilaria vermiculophylla, which is known for its high tolerance to environmental stress.

Ocean acidification impairs seagrass performance under thermal stress in shallow and deep water.

Despite the effects of ocean acidification (OA) on seagrasses have been widely investigated, predictions of seagrass performance under future climates need to consider multiple environmental factors. Here, we performed a mesocosm study to assess the effects of OA on shallow and deep Posidonia oceanica plants. The experiment was run in 2021 and repeated in 2022, a year characterized by a prolonged warm water event, to test how the effects of OA on plants are modulated by thermal stress.

Invasive Fish and Sea Urchins Drive the Status of Canopy Forming Macroalgae in the Eastern Mediterranean.

Canopy-forming macroalgae, such as , increase the three-dimensional complexity and spatial heterogeneity of rocky reefs, enhancing biodiversity and productivity in coastal areas. Extensive loss of canopy algae has been recorded in recent decades throughout the Mediterranean Sea due to various anthropogenic pressures. In this study, we assessed the biomass of fish assemblages, sea urchin density, and the vertical distribution of macroalgal communities in the Aegean and Levantine Seas.

Superior growth traits of invaded (Caribbean) versus native (Red sea) populations of the seagrass .

Unlabelled: The seagrass is native to the Red Sea. It invaded the Mediterranean over the past century and most of the Caribbean over the last two decades. Understanding the main drivers behind the successful invasiveness of has become crucial.

Parasitism enhances gastropod feeding on invasive and native algae while altering essential energy reserves for organismal homeostasis upon warming.

Marine bioinvasions are of increasing attention due to their potential of causing ecological and economic loss. The seaweed Gracilaria vermiculophylla has recently invaded the Baltic Sea, where, under certain conditions, it was found to outcompete the native alga Fucus vesiculosus. Parasites of grazers and temperature are among the potential factors which might indirectly modulate the interactions between these co-occurring algae through their single and combined effects on grazing rates.

An invasive herbivorous fish (Siganus rivulatus) influences both benthic and planktonic microbes through defecation and nutrient excretion.

Direct and indirect impacts by invasive animals on plants and other animals through predation and competition have been evidenced in many ecosystems. For instance, the rabbitfish Siganus rivulatus, originating from the Red Sea, is now the most abundant species in costal habitats of South-Eastern Mediterranean Sea where it overgrazes algae. However, little is known about its impacts on microbes through release of metabolic wastes and feces.

Anthropogenic disruptions to longstanding patterns of trophic-size structure in vertebrates.

Diet and body mass are inextricably linked in vertebrates: while herbivores and carnivores have converged on much larger sizes, invertivores and omnivores are, on average, much smaller, leading to a roughly U-shaped relationship between body size and trophic guild. Although this U-shaped trophic-size structure is well documented in extant terrestrial mammals, whether this pattern manifests across diverse vertebrate clades and biomes is unknown. Moreover, emergence of the U-shape over geological time and future persistence are unknown.

Heat sensitivity of first host and cercariae may restrict parasite transmission in a warming sea.

To predict global warming impacts on parasitism, we should describe the thermal tolerance of all players in host-parasite systems. Complex life-cycle parasites such as trematodes are of particular interest since they can drive complex ecological changes. This study evaluates the net response to temperature of the infective larval stage of Himasthla elongata, a parasite inhabiting the southwestern Baltic Sea.

An integrated assessment of the Good Environmental Status of Mediterranean Marine Protected Areas.

Local, regional and global targets have been set to halt marine biodiversity loss. Europe has set its own policy targets to achieve Good Environmental Status (GES) of marine ecosystems by implementing the Marine Strategy Framework Directive (MSFD) across member states. We combined an extensive dataset across five Mediterranean ecoregions including 26 Marine Protected Areas (MPAs), their reference unprotected areas, and a no-trawl case study.

Plastic and natural inorganic microparticles do not differ in their effects on adult mussels (Mytilidae) from different geographic regions.

Microplastics are ubiquitous in the marine environment and studies on their effects on benthic filter feeders at least partly revealed a negative influence. However, it is still unclear whether the effects of microplastics differ from those of natural suspended microparticles, which constitute a common stressor in many coastal environments. We present a series of experiments that compared the effects of six-week exposures of marine mussels to two types of natural particles (red clay and diatom shells) to two types of plastic particles (Polymethyl Methacrylate and Polyvinyl Chloride).

Mediterranean rocky reefs in the Anthropocene: Present status and future concerns.

Global change is striking harder and faster in the Mediterranean Sea than elsewhere, where high levels of human pressure and proneness to climate change interact in modifying the structure and disrupting regulative mechanisms of marine ecosystems. Rocky reefs are particularly exposed to such environmental changes with ongoing trends of degradation being impressive. Due to the variety of habitat types and associated marine biodiversity, rocky reefs are critical for the functioning of marine ecosystems, and their decline could profoundly affect the provision of essential goods and services which human populations in coastal areas rely upon.

Bright spots as climate-smart marine spatial planning tools for conservation and blue growth.

Marine spatial planning that addresses ocean climate-driven change ('climate-smart MSP') is a global aspiration to support economic growth, food security and ecosystem sustainability. Ocean climate change ('CC') modelling may become a key decision-support tool for MSP, but traditional modelling analysis and communication challenges prevent their broad uptake. We employed MSP-specific ocean climate modelling analyses to inform a real-life MSP process; addressing how nature conservation and fisheries could be adapted to CC.

Sea level rise can severely reduce biodiversity and community net production on rocky shores.

Sea level rise (SLR), driven by anthropogenic climate change, can be a major threat to coastal ecosystems. Among the most biologically diverse but SLR-threatened coastal ecosystems are rocky shores, especially in regions with a small tidal range. Nonetheless, the impacts of SLR on rocky shore biodiversity, community structure and ecosystem functions have rarely been studied.

Native biodiversity collapse in the eastern Mediterranean.

Global warming causes the poleward shift of the trailing edges of marine ectotherm species distributions. In the semi-enclosed Mediterranean Sea, continental masses and oceanographic barriers do not allow natural connectivity with thermophilic species pools: as trailing edges retreat, a net diversity loss occurs. We quantify this loss on the Israeli shelf, among the warmest areas in the Mediterranean, by comparing current native molluscan richness with the historical one obtained from surficial death assemblages.

Low diversity or poorly explored? Mesophotic molluscs highlight undersampling in the Eastern Mediterranean.

Mesophotic assemblages are the next frontier of marine exploration in the Mediterranean Sea. Located below recreational scuba diving depths, they are difficult to access but host a diverse array of habitats structured by large invertebrate species. The Eastern Mediterranean has been much less explored than the western part of the basin and its mesophotic habitats are virtually unknown.

A review of the combined effects of climate change and other local human stressors on the marine environment.

Climate change (CC) is a key, global driver of change of marine ecosystems. At local and regional scales, other local human stressors (LS) can interact with CC and modify its effects on marine ecosystems. Understanding the response of the marine environment to the combined effects of CC and LS is crucial to inform marine ecosystem-based management and planning, yet our knowledge of the potential effects of such interactions is fragmented.

Community dynamics and ecological shifts on Mediterranean vermetid reefs.

Mediterranean coastal ecosystems experience many local and global stressors and require long-term monitoring to detect and follow trends in community structure. Between 2009 and 2017, we seasonally and annually monitored the spatiotemporal community dynamics at 11 sites on the rocky shores of the southeastern Mediterranean, focusing on the understudied intertidal vermetid reef ecosystem. Marked seasonal trends were found in biodiversity, with the highest diversity in winter and spring.

Epiphytes provide micro-scale refuge from ocean acidification.

Coralline algae, a major calcifying component of coastal shallow water communities, have been shown to be one of the more vulnerable taxonomic groups to ocean acidification (OA). Under OA, the interaction between corallines and epiphytes was previously described as both positive and negative. We hypothesized that the photosynthetic activity and the complex structure of non-calcifying epiphytic algae that grow on corallines ameliorate the chemical microenvironmental conditions around them, providing protection from OA.

Uptake and incorporation of PCBs by eastern Mediterranean rabbitfish that consumed microplastics.

Two experiments were executed to assess the feasibility of Polychlorinated Biphenyls (PCBs) transfer to fish tissues via MPs as a vector. PCBs that occur in the marine environment were tested for their adsorption to four different MP types. PCB congeners showed the highest adsorption levels to Polypropylene homo-polymer.

Management priorities for marine invasive species.

Managing invasive alien species is particularly challenging in the ocean mainly because marine ecosystems are highly connected across broad spatial scales. Eradication of marine invasive species has only been achieved when species were detected early, and management responded rapidly. Generalized approaches, transferable across marine regions, for prioritizing actions to control invasive populations are currently lacking.

Ocean warming and tropical invaders erode the performance of a key herbivore.

Climate change and bioinvasions are two facets of global change that can act in tandem to impact native species and ecosystems. However, their combined effects on key species have rarely been studied. The Mediterranean Sea is a hot spot of both ocean warming and bioinvasions, where their impact can be tested together.