Historical ecology of a biological invasion: the interplay of eutrophication and pollution determines time lags in establishment and detection

Metabolic scaling of an invasive mussel depends on temperature and chemical cues from an invasive predator

Metabolism drives various biological processes, potentially influencing the ecological success and evolutionary fitness of species. Understanding diverse metabolic rates is fundamental in biology. Mechanisms underlying adaptation to factors like temperature and predation pressure remain unclear. Our study explored the role of temperature and predation pressure in shaping the metabolic scaling of an invasive mussel species (Brachidontes pharaonis). Specifically, we performed laboratory-based experiments to assess the effects of phenotypic plasticity on the metabolic scaling by exposing the mussels to water conditions with and without predator cues from another invasive species (the blue crab, Callinectes sapidus) across various temperature regimes. We found that temperature effects on metabolic scaling of the invasive mussels are mediated by the presence of chemical cues of an invasive predator, the blue crab. Investigating temperature-predator interactions underscores the importance of studying the ecological effects of global warming. Our research advances our understanding of how environmental factors jointly impact physiological processes.

New records of non-indigenous species from the eastern Mediterranean Sea (Crustacea, Mollusca), with a revision of genus Isognomon (Mollusca: Bivalvia)

We report new data on non-indigenous invertebrates from the Mediterranean Sea (four ostracods and 20 molluscs), including five new records for the basin: the ostracods Neomonoceratina iniqua, Neomonoceratina aff. mediterranea, Neomonoceratina cf. entomon, Loxoconcha cf. gisellae (Arthropoda: Crustacea)-the first records of non-indigenous ostracods in the Mediterranean-and the bivalve Striarca aff. symmetrica (Mollusca). Additionally, we report for the first time Electroma vexillum from Israel, and Euthymella colzumensis, Joculator problematicus, Hemiliostraca clandestina, Pyrgulina nana, Pyrgulina microtuber, Turbonilla cangeyrani, Musculus aff. viridulus and Isognomon bicolor from Cyprus. We also report the second record of Fossarus sp. and of Cerithiopsis sp. cf. pulvis in the Mediterranean Sea, the first live collected specimens of Oscilla galilae from Cyprus and the northernmost record of Gari pallida in Israel (and the Mediterranean). Moreover, we report the earliest records of Rugalucina angela, Ervilia scaliola and Alveinus miliaceus in the Mediterranean Sea, backdating their first occurrence in the basin by 3, 5 and 7 years, respectively. We provide new data on the presence of Spondylus nicobaricus and Nudiscintilla aff. glabra in Israel. Finally, yet importantly, we use both morphological and molecular approaches to revise the systematics of the non-indigenous genus Isognomon in the Mediterranean Sea, showing that two species currently co-occur in the basin: the Caribbean I. bicolor, distributed in the central and eastern Mediterranean, and the Indo-Pacific I. aff. legumen, at present reported only from the eastern Mediterranean and whose identity requires a more in-depth taxonomic study. Our work shows the need of taxonomic expertise and investigation, the necessity to avoid the unfounded sense of confidence given by names in closed nomenclature when the NIS belong to taxa that have not enjoyed ample taxonomic work, and the necessity to continue collecting samples-rather than relying on visual censuses and bio-blitzes-to enable accurate detection of non-indigenous species.

Using the Fossil Record to Understand Extinction Risk and Inform Marine Conservation in a Changing World

Understanding the long-term effects of ongoing global environmental change on marine ecosystems requires a cross-disciplinary approach. Deep-time and recent fossil records can contribute by identifying traits and environmental conditions associated with elevated extinction risk during analogous events in the geologic past and by providing baseline data that can be used to assess historical change and set management and restoration targets and benchmarks. Here, we review the ecological and environmental information available in the marine fossil record and discuss how these archives can be used to inform current extinction risk assessments as well as marine conservation strategies and decision-making at global to local scales. As we consider future research directions in deep-time and conservationpaleobiology, we emphasize the need for coproduced research that unites researchers, conservation practitioners, and policymakers with the communities for whom the impacts of climate and global change are most imminent.

Community recovery of benthic macroinvertebrates in a stream influenced by mining activity: Importance of microhabitat monitoring

The decrease in freshwater biodiversity owing to anthropogenic disturbances such as mining activity is a global challenge; hence, there is an urgent need for systematic approaches to continuously monitor such disturbances and/or the recovery of biodiversity in freshwater habitats. The Hwangjicheon Stream is the source of South Korea's longest river and has been subjected to runoff from coal mining. We investigated changes in the diversity of the benthic macroinvertebrate community in various microhabitats, including riffle, run, and pool, to monitor the recovery of biodiversity in the stream following the improvement of a mining water treatment plant in 2019. The dataset comprised 111 samples obtained from four types of microhabitats (riffle, run, pool, and riparian) over a four-year period from 2018 to 2021. The mining-affected sites had lower macroinvertebrate community complexities according to a network analysis, and grouped into the same cluster based on self-organizing map (SOM) analysis. Moreover, 51 taxa selected as indicator species represented each cluster obtained through the SOM analysis. Among them, only Limnodrilus gotoi and Radix auricularia were included as indicator species at the mining-affected sites. However, after 2020, the benthic macroinvertebrate community complexity increased, and some of the microhabitats at the mining-affected sites were included in the same cluster as the reference sites in the SOM analysis, indicating that the recovery of benthic macroinvertebrate communities had initiated in certain microhabitats (e.g., riparian). Further analysis confirmed that the macroinvertebrate community clearly differed according to the survey year, even in different microhabitats at the same sites. This suggests that more acute microhabitat monitoring may be necessary to quickly confirm biodiversity restoration when assessing the degree of the recovery in river biodiversity from anthropogenic disturbances.

Diversity of protist genera in periphyton of tufa-depositing karstic river

Purpose

In aquatic ecosystems, protists play a crucial role and cover numerous ecological functions. The karstic Krka River (Croatia) is a unique hotspot for high diversity of aquatic organisms, especially protists. The main objective of the present study was to obtain a detailed overview of the protist community structure in the periphyton of the Krka River and to determine the differences in protist diversity along the river.

Methods

Protist diversity was detected by amplicon sequencing of the hypervariable region V9 of the 18S rRNA gene, using the universal eukaryotic primer pair.

Results

The three main groups of protists were as follows: Ciliophora, Cercozoa, and Bacillariophyta. In terms of abundance of protist OTUs, the shade plot revealed an evident difference from the upstream to downstream river section, which increased between locations from Krka spring to Skradinski buk. Diversity was explored using measures of alpha and beta diversity. Alpha diversity showed an increasing trend in the downstream direction of the river. The location effect, or clustering/grouping of samples by location, was confirmed by the PERMANOVA permutation test of beta diversity.

Conclusion

The combination of alpha and beta diversity can help provide deeper insight into the study of diversity patterns, but also point out to decline in species diversity and allow for effective ways to protect aquatic karst habitats in future management.

Exotic asphyxiation: interactions between invasive species and hypoxia

Non-indigenous species (NIS) and hypoxia (<2 mg O₂ l^-1 ) can disturb and restructure aquatic communities. Both are heavily influenced by human activities and are intensifying with global change. As these disturbances increase, understanding how they interact to affect native species and systems is essential. To expose patterns, outcomes, and generalizations, we thoroughly reviewed the biological invasion literature and compiled 100 studies that examine the interaction of hypoxia and NIS. We found that 64% of studies showed that NIS are tolerant of hypoxia, and 62% showed that NIS perform better than native species under hypoxia. Only one-quarter of studies examined NIS as creators of hypoxia; thus, NIS are more often considered passengers associated with hypoxia, rather than drivers of it. Paradoxically, the NIS that most commonly create hypoxia are primary producers. Taxa like molluscs are typically more hypoxia tolerant than mobile taxa like fish and crustaceans. Most studies examine individual-level or localized responses to hypoxia; however, the most extensive impacts occur when hypoxia associated with NIS affects communities and ecosystems. We discuss how these influences of hypoxia at higher levels of organization better inform net outcomes of the biological invasion process, i.e. establishment, spread, and impact, and are thus most useful to management. Our review identifies wide variation in the way in which the interaction between hypoxia and NIS is studied in the literature, and suggests ways to address the number of variables that affect their interaction and refine insight gleaned from future studies. We also identify a clear need for resource management to consider the interactive effects of these two global stressors which are almost exclusively managed independently.

Trace metals accumulation on modern sediments from Po river prodelta, North Adriatic Sea

Trace Metals (TMs: Pb, Zn, Cu, Cr, Cd, and Ni), major elements (Al and Fe) and radionuclides (²¹⁰Pb/¹³⁷Cs) investigations on EL-C01 sediment core provides new information on sedimentary regime and anthropogenic impacts during the last 175 years in the Po river prodelta area. The results allow to identify some TMs/Al peak in the upper part of the core, likely related to the major flood events of the Po river during the XXth century. Sediments deposited after the year 1900 exhibit a gradual increase of some TMs concentrations compared to pre-industrial era values. In particular, Pb, Zn, and Cu high contents are detected after the World War II and during the "Italian Economic Miracle" period. The decrease of heavy metal (Zn and Pb) contents from the second half of the 1980s is probably the effect of the Italian Law 319/76 and anti-pollution environmental policies concerning industrial and urban emitters.

Benthic macroinvertebrate community response to environmental changes over seven decades in an urbanized estuary in the northeastern United States

Narragansett Bay is representative of New England, USA urbanized estuaries, with colonization in the early 17th century, and development into industrial and transportation centers in the late 18th and early 20th century. Increasing nationwide population and lack of infrastructure maintenance led to environmental degradation, and then eventual improvement after implementation of contaminant control and sewage treatment starting in the 1970s. Benthic macroinvertebrate community structure was expected to respond to these environmental changes. This study assembled data sets from the 1950s through 2010s to examine whether quantitative aggregate patterns in the benthic community corresponded qualitatively to stressors and management actions in the watershed. In Greenwich Bay and Providence River, patterns of benthic response corresponded to the decline and then improvement in sewage treatment at the Fields Point wastewater treatment plant. In Mount Hope Bay, the benthos corresponded to changes in bay fish populations due to thermal discharge from the Brayton Point power plant. The benthos of the Upper West Passage corresponded to climatic changes that caused regime shifts in the plankton and fish communities. Future work will examine the effects of further environmental improvements in the face of continued climatic changes and population growth.

Invasiveness is linked to greater commercial success in the global pet trade

The pet trade has become a multibillion-dollar global business, with tens of millions of animals traded annually. Pets are sometimes released by their owners or escape, and can become introduced outside of their native range, threatening biodiversity, agriculture, and health. So far, a comprehensive analysis of invasive species traded as pets is lacking. Here, using a unique dataset of 7,522 traded vertebrate species, we show that invasive species are strongly overrepresented in trade across mammals, birds, reptiles, amphibians, and fish. However, it is unclear whether this occurs because, over time, pet species had more opportunities to become invasive, or because invasive species have a greater commercial success. To test this, we focused on the emergent pet trade in ants, which is too recent to be responsible for any invasions so far. Nevertheless, invasive ants were similarly overrepresented, demonstrating that the pet trade specifically favors invasive species. We show that ant species with the greatest commercial success tend to have larger spatial distributions and more generalist habitat requirements, both of which are also associated with invasiveness. Our findings call for an increased risk awareness regarding the international trade of wildlife species as pets.

Parasitism and host behavior in the context of a changing environment: The Holocene record of the commercially important bivalve Chamelea gallina, northern Italy

Rapid warming and sea-level rise are predicted to be major driving forces in shaping coastal ecosystems and their services in the next century. Though forecasts of the multiple and complex effects of temperature and sea-level rise on ecological interactions suggest negative impacts on parasite diversity, the effect of long term climate change on parasite dynamics is complex and unresolved. Digenean trematodes are complex life cycle parasites that can induce characteristic traces on their bivalve hosts and hold potential to infer parasite host-dynamics through time and space. Previous work has demonstrated a consistent association between sea level rise and increasing prevalence of trematode traces, but a number of fundamental questions remain unanswered about this paleoecological proxy. Here we examine the relationships of host size, shape, and functional morphology with parasite prevalence and abundance, how parasites are distributed across hosts, and how all of these relationships vary through time, using the bivalve Chamelea gallina from a Holocene shallow marine succession in the Po coastal plain. Trematode prevalence increased and decreased in association with the transition from a wave-influenced estuarine system to a wave-dominated deltaic setting. Prevalence and abundance of trematode pits are associated with large host body size, reflecting ontogenetic accumulation of parasites, but temporal trends in median host size do not explain prevalence trends. Ongoing work will test the roles of temperature, salinity, and nutrient availability on trematode parasitism. Parasitized bivalves in one sample were shallower burrowers than their non-parasitized counterparts, suggesting that hosts of trematodes can be more susceptible to their predators, though the effect is ephemeral. Like in living parasite-host systems, trematode-induced malformations are strongly aggregated among hosts, wherein most host individuals harbor very few parasites while a few hosts have many. We interpret trace aggregation to support the assumption that traces are a reliable proxy for trematode parasitism in the fossil record.

Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification

New data on 52 non-indigenous mollusks in the Eastern Mediterranean Sea is reported. Fossarus sp. (aff.aptus sensu Blatterer 2019), Coriophoralessepsiana Albano, Bakker & Sabelli, sp. nov., Cerithiopsissp. aff.pulvis, Joculatorproblematicus Albano & Steger, sp. nov., Cerithiopsis sp., Elachisina sp., Iravadiaaff.elongata, Vitrinella aff. Vitrinella sp. 1 (sensu Blatterer 2019), Melanellaorientalis, Parviorisaff.dilecta, Odostomiacf.dalli, Oscillavirginiae, Partheninacossmanni, Partheninatypica, Pyrgulinacraticulata, Turbonillafuniculata, Cylichnacollyra, Musculuscoenobitus, Musculusaff.viridulus, Chavaniaerythraea, Scintillacf.violescens, Iacraseychellarum and Corbulaerythraeensis are new records for the Mediterranean. An unidentified gastropod, Skeneidae indet., Triphora sp., Hypermastus sp., Sticteulima sp., Vitreolinacf.philippi, Odostomia (s.l.) sp. 1, Henrya (?) sp., and Semelidae sp. are further potential new non-indigenous species although their status should be confirmed upon final taxonomic assessment. Additionally, the status of Dikolepsmicalii, Hemiliostracaclandestinacomb. nov. and H.athenamariaecomb. nov. is changed to non-indigenous, range extensions for nine species and the occurrence of living individuals for species previously recorded from empty shells only are reported. Opimaphorablattereri Albano, Bakker & Sabelli, sp. nov. is described from the Red Sea for comparison with the morphologically similar C.lessepsiana Albano, Bakker & Sabelli, sp. nov. The taxonomic part is followed by a discussion on how intensive fieldwork and cooperation among institutions and individuals enabled such a massive report, and how the poor taxonomic knowledge of the Indo-Pacific fauna hampers non-indigenous species detection and identification. Finally, the hypothesis that the simultaneous analysis of quantitative benthic death assemblages can support the assignment of non-indigenous status to taxonomically undetermined species is discussed.

Roles of Dispersal Limit and Environmental Filtering in Shaping the Spatiotemporal Patterns of Invasive Alien Plant Diversity in China

Biological invasion pose a severe threat to global biodiversity, and studies of bioinvasion patterns and the underlying mechanisms provide critical tests to ecological theories. China is a global hotspot of biodiversity and also biological invasions. The understanding of mechanisms for bioinvasion patterns has been limited by inadequacy of data spatial resolution, and lack of a historical perspective. This study compiled the first nation-scale distribution data with a sub-provincial spatial unit (prefecture) for 463 invasive alien plants species (IAPS) recorded in China, as well as their introduction times. The spatiotemporal patterns of species richness of invasive alien plants, including three life forms (annual-biennial, perennial, and woody) were explored, then related the species richness patterns with environmental, social-economic and historical factors. Statistical analyses included quantile regression, generalized linear model (GLM), and hierarchical variation partitioning. The results indicated that: (1) herbaceous species comprised 84% of the 463 IAPS in China; (2) plant introductions into China accelerated since 1800, reaching the maximum rate during 1900–1940. IAPS richness had a closer correlation with the time of newest introduction (R2 = 0.155) than with that of the oldest introduction (R2 = 0.472); (3) IAPS richness decreases with increasing latitude (r = −0.32, P &lt; 0.001) and decreases from the coastal and southern terrestrial borders to inland regions, but doesn’t increase with prefecture size. The three life forms of IAPS showed similar latitudinal patterns of species richness and divergent latitudinal patterns of species percentage. (4) IAPS richness showed significantly positive correlations with thermal climate and a negative relationship with climate seasonality. GLM explained up to 65% of the variation in spatial patterns of IAPS and three life forms; with much less variation explained in the species percentage patterns. The year of the most recent IAPS introduction and the low temperature limit jointly dominated spatial patterns of IAPS richness in China, whereas road density showed little effect. Therefore, global warming and economic globalization play a prominent role in promoting biological invasion in the last few decades, and will continue to drive the trend of plant invasion in China and probably elsewhere.

Conservation Paleobiology as a Tool to Define Reference Conditions in Naturally Stressed Transitional Settings: Micropaleontological Insights from the Holocene of the Po Coastal Plain (Italy)

The key role of paralic environments as providers of ecosystem services, associated with their increasingly threatened state, led to the definition of international water management policies aimed to improve ecological quality status (EcoQs). Restoration actions rely on the definition of reference conditions, which is a particularly challenging task in naturally stressed transitional environments. In the present work, we apply the diversity index Exp(H’bc) on benthic foraminifer assemblages from two anthropogenically unimpacted transitional to coastal Holocene sediment successions of the Po coastal plain, in order to assess past EcoQs (PaleoEcoQs). Ostracod ecological groups provided detailed insights on naturally stressful paleoenvironmental conditions. We show that “poor” to “moderate” PaleoEcoQs are recorded by biological indicators at reference conditions under fluctuations of chemical-physical parameters and organic matter enrichment. We emphasize the importance of a site-specific paleobiological approach, as significant differences in diversity occur even on a short spatial scale. This study illustrates that early to mid-Holocene sediment successions resulted to be appropriate for conservation paleobiological purposes, providing a high-resolution paleoecological record under the influence of the Holocene sea-level rise in analogy with the present-day global change.

Effect of phosphorus on the toxicity of zinc to the microalga Raphidocelis subcapitata

The aim of this study was to evaluate the effect of phosphorus (P) on the toxicity of zinc (Zn) for the alga Raphidocelis subcapitata. P was provided in three concentrations: 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1. Algal cells were acclimated to the specific P concentrations before the start of the experiment. The chemical equilibrium software MINEQL+ 4.61 was employed to calculate the Zn2+ concentration. After acclimated, the algal cells were inoculated into media containing different Zn concentrations (0.09 x 10-6 mol L-1 to 9.08 x 10-6 mol L-1). The study showed that besides the reduction in algal growth rates, phosphorus had an important influence on the toxicity of zinc for microalga. The inhibitory Zn2+ concentration values for R. subcapitata were 2.74 x 10-6 mol L-1, 0.58 x 10-6 mol L-1 and 0.24 x 10-6 mol L-1 for the microalgae acclimated at P concentrations of 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1, respectively. Ecotoxicological studies should consider the interaction between metal concentrations and varying P values to provide realistic data of what occurs in phytoplankton communities in environments.

Ecological regime shift preserved in the Anthropocene stratigraphic record

Palaeoecological data are unique historical archives that extend back far beyond the last several decades of ecological observations. However, the fossil record of continental shelves has been perceived as too coarse (with centennial-millennial resolution) and incomplete to detect processes occurring at yearly or decadal scales relevant to ecology and conservation. Here, we show that the youngest (Anthropocene) fossil record on the northern Adriatic continental shelf provides decadal-scale resolution that accurately documents an abrupt ecological change affecting benthic communities during the twentieth century. The magnitude and the duration of the twentieth century shift in body size of the bivalve Corbula gibba is unprecedented given that regional populations of this species were dominated by small-size classes throughout the Holocene. The shift coincided with compositional changes in benthic assemblages, driven by an increase from approximately 25% to approximately 70% in median per-assemblage abundance of C. gibba. This regime shift increase occurred preferentially at sites that experienced at least one hypoxic event per decade in the twentieth century. Larger size and higher abundance of C. gibba probably reflect ecological release as it coincides with an increase in the frequency of seasonal hypoxia that triggered mass mortality of competitors and predators. Higher frequency of hypoxic events is coupled with a decline in the depth of intense sediment mixing by burrowing benthic organisms from several decimetres to less than 20 cm, significantly improving the stratigraphic resolution of the Anthropocene fossil record and making it possible to detect sub-centennial ecological changes on continental shelves.

Ecological regime shift preserved in the Anthropocene stratigraphic record

Palaeoecological data are unique historical archives that extend back far beyond the last several decades of ecological observations. However, the fossil record of continental shelves has been perceived as too coarse (with centennial-millennial resolution) and incomplete to detect processes occurring at yearly or decadal scales relevant to ecology and conservation. Here, we show that the youngest (Anthropocene) fossil record on the northern Adriatic continental shelf provides decadal-scale resolution that accurately documents an abrupt ecological change affecting benthic communities during the twentieth century. The magnitude and the duration of the twentieth century shift in body size of the bivalve Corbula gibba is unprecedented given that regional populations of this species were dominated by small-size classes throughout the Holocene. The shift coincided with compositional changes in benthic assemblages, driven by an increase from approximately 25% to approximately 70% in median per-assemblage abundance of C. gibba. This regime shift increase occurred preferentially at sites that experienced at least one hypoxic event per decade in the twentieth century. Larger size and higher abundance of C. gibba probably reflect ecological release as it coincides with an increase in the frequency of seasonal hypoxia that triggered mass mortality of competitors and predators. Higher frequency of hypoxic events is coupled with a decline in the depth of intense sediment mixing by burrowing benthic organisms from several decimetres to less than 20 cm, significantly improving the stratigraphic resolution of the Anthropocene fossil record and making it possible to detect sub-centennial ecological changes on continental shelves.

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. Here, expert knowledge was elicited to prioritize 11 management actions for controlling 12 model species, distinguished by differences in dispersion capacity, distribution in the area to be managed, and taxonomic identity. Each action was assessed using five criteria (effectiveness, feasibility, acceptability, impacts on native communities, and cost), which were combined in an 'applicability' metric. Raising public awareness and encouraging the commercial use of invasive species were highly prioritized, whereas biological control actions were considered the least applicable. Our findings can guide rapid decision-making on prioritizing management options for the control of invasive species especially at early stages of invasion, when reducing managers' response time is critical.

The potential of large rafting objects to spread Lessepsian invaders: the case of a detached buoy

A diverse and abundant fouling community dominated by Lessepsian non-indigenous species was identified on a 13.5-m-long steel buoy stranded on the Israeli coast but originating from Port Said, at the Mediterranean entrance of the Suez Canal, Egypt. The molluscan community was sampled quantitatively by scraping. Three quarters of the individuals and more than half of the species were non-indigenous. Among the latter, a mytilid bivalve, Gregariella cf. ehrenbergi, was first recorded in the Mediterranean Sea on the basis of these samples, suggesting that the full consideration of all potential vectors can contribute to non-indigenous species detection. Large floating objects in coastal waters, such as buoys, are particularly suitable for colonization by Lessepsian species because hard substrates, and artificial ones in particular, are highly susceptible to the establishment of non-indigenous species. Moreover, their size and persistence enable the development of abundant and mature fouling communities that can disseminate propagules as eggs and larvae over long distances and for extended periods if detached. This report highlights the potential for large rafting debris as a vector of the spread of non-indigenous biota within the Mediterranean Sea.

20th century increase in body size of a hypoxia-tolerant bivalve documented by sediment cores from the northern Adriatic Sea (Gulf of Trieste)

An increase in the frequency of hypoxia, mucilages, and sediment pollution occurred in the 20th century in the Adriatic Sea. To assess the effects of these impacts on bivalves, we evaluate temporal changes in size structure of the opportunistic bivalve Corbula gibba in four sediment cores that cover the past ~500 years in the northern, eutrophic part and ~10,000 years in the southern, mesotrophic part of the Gulf of Trieste. Assemblages exhibit a stable size structure during the highstand phase but shift to bimodal distributions and show a significant increase in the 95th percentile size during the 20th century. This increase in size by 2-3 mm is larger than the northward size increase associated with the transition from mesotrophic to eutrophic habitats. It coincides with increasing concentrations of total organic carbon and nitrogen, and can be related to enhanced food supply and by the tolerance of C. gibba to hypoxia.

New records of non-indigenous molluscs from the eastern Mediterranean Sea

We report new findings of non-indigenous Indo-Pacific molluscs from shallow water habitats off Israel, Greece and Egypt, eastern Mediterranean Sea. The bivalves Pillucina vietnamica Zorina, 1978 and Alveinus miliaceus (Issel, 1869) were collected from sandy bottoms off Israel, whereas Gregariella cf. ehrenbergi (Issel, 1869) was recovered from a buoy originating from Port Said, Egypt, and stranded on the Israeli coast. The three species are first records for the Mediterranean Sea. Additionally, we report range extensions for several gastropods: Varicopeza pauxilla (A. Adams, 1855) is recorded from Israel, Phidiana militaris (Alder and Hancock, 1864) from southern Israel (Ashqelon), and Viriola cf. bayani Jousseaume, 1884 from Israel and Crete. Shells and valves of an unidentified lucinid bivalve morphologically distinct from any known Mediterranean species were found along the Israeli Mediterranean shore.