Laboratory based feeding behaviour of the Chinese mitten crab, <i>Eriocheir sinensis</i>, (Crustacea: Decapoda: Brachyura: Varunidae):fish egg consumption

Dispersal of Eriocheir sinensis from its native habitat is a worldwide concern. As one of the most invasive species known, this crab causes significant disruption to foreign ecosystems. In particular, populations in the United Kingdom (UK) are increasing in number and E. sinensis has been reported from many river catchments. The ecological implications of this invasion are not fully understood. One aspect of concern lies in the potential for mitten crabs to predate fish eggs which, if realistic, could contribute to the decline of riverine populations. In this study, 100 mitten crabs from the River Thames were used in experimental feeding trials to 1) investigate foraging ability on a variety of fish eggs and 2) establish whether crab size affected foraging potential. Eggs ranged from 1–6 millimetres (mm) in diameter from one of four species of marine and freshwater fish; zebrafish, lumpfish, Pacific salmon and trout. Predation by crabs varied with egg type; crabs were capable of foraging 1mm zebrafish eggs, but the majority consumed eggs 2–6mm in diameter. The most attractive eggs were apparently lumpfish, where the median proportion consumed was 100%. Crab size did not appear to govern foraging potential, though variation was observed in the size range of juvenile crabs consuming the different eggs with the largest, salmon, being consumed by crabs of the broadest size range. E. sinensis does have the potential to predate on a range of fish eggs, and the results are used to infer the risk presented to specific groups of UK fish stocks.© 2015 The Author(s). Journal compilation © 2015 REABIC. Aquatic Invasions is an Open Access journal which means that all content is freely available without charge to the user or his/her institution. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles in this journal without asking prior permission from the publisher or the author. This is in accordance with the BOAI definition of Open Access

Trace metal bioavailabilities in the Thames estuary:continuing decline in the 21st century

Levels of pollution, including contamination by toxic metals, in the Thames estuaryreduced over the last four decades of the 20th century. This 2014 study investigateswhether the declines in the bioavailabilities of trace metals (Ag, Cd, Co, Cr, Cu, Fe,Mn, Ni, Pb, V, Zn) have continued in the 21st century, using a suite of littoralbiomonitors also employed in 2001- the brown seaweed Fucus vesiculosus, thestrandline, talitrid amphipod Orchestia gammarellus and the estuarine barnacleAmphibalanus improvisus. Bioaccumulated concentrations represent relativemeasures of the total bioavailabilities of each metal to the biomonitor over a previoustime period, and can be compared over space and over time. Trace metalbioavailabilities varied along the estuary, and, in general, fell between 2001 and2014, a reflection of the continuing remediation of the Thames estuary from itsseverely polluted state in the middle of the 20th century

The effects of wet wipe pollution on the Asian clam, Corbicula fluminea (Mollusca: Bivalvia) in the River Thames, London

The aim of the present study was to evaluate “flushable” and “non-flushable” wet wipes as a source of plastic pollution in the River Thames at Hammersmith, London and the impacts they have on the invasive Asian clam, Corbicula fluminea, in this watercourse. Surveys were conducted to assess whether the density of wet wipes along the foreshore upstream of Hammersmith Bridge affected the distribution of C. fluminea. High densities of wet wipes were associated with low numbers of clams and vice versa. The maximum wet wipe density recorded was 143 wipes m-2 and maximum clam density 151 individuals m-2. Clams adjacent to the wet wipe reefs were found to contain synthetic polymers including polypropylene (57%), 21 polyethylene (9%), polyallomer (8%), nylon (8%) and polyester (3%). Some of these 22 polymers may have originated from the wet wipe reefs

Long-term variation of trochid populations in an Irish sea lough

Snapshot assessments of species which live for a number of years are often misleading if they are conducted at an inappropriately short temporal scale. Densities of the trochid gastropods Steromphala umbilicalis (da Costa, 1778) and S. cineraria (Linnaeus, 1758) fluctuated widely between 1996 and 2014 at 10 rocky-shore sites within Lough Hyne, SW Ireland. Between 2014 and 2018, abundance of S. cineraria decreased to levels not seen in the previous two decades. This significant reduction was possibly in response to extreme dissolved oxygen fluctuations related to eutrophication of the semi-enclosed lough. The congener S. umbilicalis showed low density in 2018, but this was within the limits of inter-annual fluctuations. The Lusitanian trochid Phorcus lineatus (da Costa, 1778) was first recorded by us in the lough in the early 2000s, establishing a flourishing population with densities of ca. 6 snails per 0.25 m2. Although this native trochid survived the cold winters of 2009-2012, the population suffered high adult mortality and little recruitment. Between 2013 and 2018, the population increased and population density stabilised. The increase in P. lineatus reflects its position high on the shore where air temperatures have risen over the last two decades. It may therefore be a sentinel species to detect the effects of climate change. By contrast, the decrease in S. cineraria was related to its shallow subtidal habitat where hypoxia and superoxia have recently become marked in the lough. This trochid, therefore, offers potential as an indicator of eutrophication-associated stress. These temporal variations in trochid species emphasise the need for longer-term assessments when estimating the importance of any one species to the ecosystem

Pathogens co-transported with invasive non-native aquatic species: implications for risk analysis and legislation

Invasive Non-Native Species (INNS) can co-transport externally and internally other organisms including viruses, bacteria and other eukaryotes (including metazoan parasites), collectively referred to as the symbiome. These symbiotic organisms include pathogens, a small minority of which are subject to surveillance and regulatory control, but most of which are currently unscrutinized and/or unknown. These putatively pathogenetic symbionts can potentially pose diverse risks to other species, with implications for increased epidemiological risk to agriculture and aquaculture, wildlife/ecosystems, and human health (zoonotic diseases). The risks and impacts arising from co-transported known pathogens and other symbionts of unknown pathogenic virulence, remain largely unexplored, unlegislated, and difficult to identify and quantify. Here, we propose a workflow using PubMed and Google Scholar to systematically search existing literature to determine any known and potential pathogens of aquatic INNS. This workflow acts as a prerequisite for assessing the nature and risk posed by co-transported pathogens of INNS; of which a better understanding is necessary to inform policy and INNS risk assessments. Addressing this evidence gap will be instrumental to devise an appropriate set of statutory responsibilities with respect to these symbionts, and to underpin new and more effective legislative processes relating to the disease screening and risk assessment of INNS

Big brands impact small islands:Sources of plastic pollution in a remote and protected archipelago

Remote islands are disproportionately affected by plastic pollution, often originating from elsewhere, so it is important to understand its origins, to stop debris entering the ocean at their source. We investigated the origins of beached plastic drink bottles in the Chagos Archipelago, a large remote Marine Protected Area (MPA) in the Indian Ocean. We recorded the brands, countries of manufacture, types of drink, and ages of plastic bottles and their lids. The prevalent type of drink was water, with items mostly manufactured in Indonesia, China, and the Maldives. The main brands were Danone and the Coca-Cola Company. We deduced that 10 % of the items originated from ships passing the archipelago, including all the items manufactured in China. The identification of the brands creating plastic pollution in remote MPAs with high biodiversity supports extended producer responsibility, one of the proposed policy development areas of the Global Plastics Treaty