Jellyfish Stings Trigger Gill Disorders and Increased Mortality in Farmed Sparus aurata (Linnaeus, 1758) in the Mediterranean Sea

none8siJellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.Bosch-Belmar, Mar; M'Rabet, Charaf; Dhaouadi, Raouf; Chalghaf, Mohamed; Daly Yahia, Mohamed Néjib; Fuentes, Verónica; Piraino, Stefano; Kéfi-Daly Yahia, OnsBosch Belmar, Mar; M'Rabet, Charaf; Dhaouadi, Raouf; Chalghaf, Mohamed; Daly Yahia, Mohamed Néjib; Fuentes, Verónica; Piraino, Stefano; Kéfi Daly Yahia, On

Population dynamics and predatory impact of the alien jellyfish Aurelia solida (Cnidaria, Scyphozoa) in the Bizerte Lagoon (southwestern Mediterranean Sea)

Understanding the life cycle strategies and predatory impact of alien jellyfish species is critical to mitigate the impact these organisms may have on local populations, biodiversity, and ultimately on the functioning of food webs. In the Mediterranean Sea, little is known about the dynamics of alien jellyfish, although this area is a biodiversity hotspot and one of the most threatened by an increasing number of alien jellyfish. Here, we investigated the population dynamics and predatory impact of a non-indigenous scyphomedusa, Aurelia solida Browne 1905, in the Bizerte Lagoon, Tunisia. The study was based on a bimonthly survey performed over two consecutive years, from November 2012 to August 2014. Field observations showed that the planktonic phase of A. solida occurs from winter to early summer. Prey composition was investigated by means of gut content and field zooplankton analyses. Calanoid copepods, mollusc larvae and larvaceans represented the main food items of A. solida. To determine the jellyfish feeding rate and their predatory impact on zooplankton populations, the digestion time for zooplankton prey was assessed at three different temperatures: 13, 18 and 23 °C in laboratory conditions, corresponding to the average range of temperatures encountered by A. solida in the Bizerte Lagoon. We found that A. solida consumed 0.5–22.5% and 0.02–37.3% of the daily zooplankton standing stock in 2013 and 2014, respectively. These results indicate a non-negligible but restricted seasonal grazing impact on some mesozooplankton groups, explained by the relatively short lifespan of the medusa stage (5–6 months)

The invasive tropical scyphozoan Rhopilema nomadica Galil, 1990 reaches the Tunisian coast of the Mediterranean Sea

The alien Erythraean jellyfish Rhopilema nomadica was first recorded in Tunisia waters (Gulf of Gabes) in 2008. Subsequently it was sighted in the Bizerte Channel and Gulf of Tunis where it has been regularly observed since 2010 during summer and autumn months.peer-reviewe

Further spread of the venomous jellyfish Rhopilema nomadica Galil, Spannier & Ferguson, 1990 (Rhizostomeae, Rhizostomatidae) in the western Mediterranean

The present paper documents the further spread of the venomous scyphomedusa Rhopilema nomadica Galil, Spannier & Ferguson, 1990, which first appeared in the Mediterranean off the Israeli coast in the mid-1970s. This report provides the northernmost and westernmost record of the species in the Mediterranean—from the eastern coast of the Italian island of Sardinia—based on a new record of the species within the Sicily Channel (Aegadian Islands) and provides evidence of its further establishment within Tunisian coastal waters.peer-reviewe

Unfolding jellyfish bloom dynamics along the Mediterranean basin by transnational citizen science initiatives

Science is addressing global societal challenges, and due to limitations in research financing, scientists are turning to the public at large to jointly tackle specific environmental issues. Citizens are therefore increasingly involved in monitoring programs, appointed as citizen scientists with potential to delivering key data at near to no cost to address environmental challenges, therein fostering scientific knowledge and advising policy- and decision-makers. One of the first and most successful examples of marine citizen science in the Mediterranean is represented by the integrative and collaborative implementation of several jellyfish-spotting campaigns in Italy, Spain, Malta, and Tunisia starting in 2009. Altogether, in terms of time coverage, geographic extent, and number of citizen records, these represent the most effective marine citizen science campaigns thus far implemented in the Mediterranean Sea. Here, we analyzed a collective database merging records over the above four countries, featuring more than 100,000 records containing almost 25,000 observations of jellyfish specimens collected over a period of 3 to 7 years (from 2009 to 2015) by citizen scientists participating in any of the national citizen science programs included in this analysis. Such a wide citizen science exercise demonstrates a valuable and cost-effective tool to understanding ecological drivers of jellyfish proliferation over the Western and Central Mediterranean basins, as well as a powerful contribution to developing tailored adaptation and management strategies; mitigating jellyfish impacts on human activities in coastal zones; and supporting implementation of marine spatial planning, Blue Growth, and conservation strategies.peer-reviewe

Photodegradation and Its Effect on Plant Litter Decomposition in Terrestrial Ecosystems: A Systematic Review

Photodegradation is an important mechanism that affects carbon and nutrient cycling; a significant amount of data has been reported previously. The present review includes the effect of a wider spectrum of solar radiation (sun light, UV, and visible light) on plant litter decay in terrestrial ecosystems. Although the positive effect of photodegradation on decomposition is most common, a substantial number of studies reports contrasting results. Litter from 148 plant species, from 41 families, have been used in photodegradation studies, representing functional groups of trees (33%), graminoids (30%), shrubs (23%), forbs (11%), and peat (1%). Although the majority of studies focused on mass loss, a growing number focuses on nutrient release. Positive effects on mass loss are most common across different climate regions and laboratory studies, whereas “positive” influence and “no effect” on nitrogen and lignin release are equally common in temperate and sub-tropical environments. This may potentially be due to other decomposition processes which increase in relevance with increasing moisture and can facilitate microbial activity, leaching, and fractioning by soil fauna. In addition to climate region, initial litter quality influences photodegradation. Field-based and laboratory experiments frequently obtain contrasting results, suggesting that the mechanisms controlling the responses are unclear and might be dependent on several interactions, and/or the differences in experimental approaches (such as UV filters), or coverage by particles. Future research should focus on interactions between different factors, and on conducting experiments that test specific relationships such as the potential interaction between photodegradation, soil moisture, microbial communities, soil fauna, and their effects on litter decomposition (both mass loss and nutrient release). Furthermore, the topic would benefit from international studies applying the same experimental approach, as has successfully been conducted in other fields.This research was funded by [Qatar Petroleum] grant number [QUEX-CAS-QP-RD-18/19]

Are anti-jellyfish nets a useful mitigation tool for coastal tourism? Hindsight from the MED-JELLYRISK experience

The mitigation of coastal hazards, notably jellyfish blooms, has assumed great significance in recent years in view of the potential detrimental impact of such hazards on the welfare of coastal communities. This is especially true in a basin such as the Mediterranean with a very high degree of coastal settlement and dependence on coastal economic activities. Within the MED-JELLYRISK project and over the course of two summers (2014 and 2015), a total of 15 anti-jellyfish nets within several Mediterranean tourist hotposts were installed in Italy (islands of Lipari, Salina, Ustica, Lampedusa and Favignana), Spain (two beaches on the island of Ibiza), Tunisia (beaches at Monastir and Hammamet) and Malta. Manufactured in 25m-long modules, the nets were specifically designed to exclude individuals of jellyfish species from the enclosed bathing areas, and were installed on shallow sandy and rocky bottoms from the coastal fringe down to a water depth of 2.5m. The performance of the same nets was monitored through scientific surveys inside and outside the net-enclosed areas. In parallel, the colonization of fouling organisms on the submerged sections of the nets was investigated, and the public perception of the installed nets was assessed through ad hoc questionnaires deployed on the beaches. Useful hindsight for coastal managers, concerning best sites and conditions for deployment, net design and materials, has been gained from this experimental anti-jellyfish net deployment effort within the MED-JELLYRISK project.peer-reviewe

Toxicity assessment of cadmium chloride on planktonic copepods Centropages ponticus using biochemical markers

Pollution of the aquatic environment by heavy metals has become a worldwide problem. Most heavy metals exhibit toxic waste on aquatic organisms. Cadmium (Cd) is a highly toxic metal which affects aquatic organisms acutely and chronically. Planktonic calanoid copepods are the secondary dominant producers of pelagic ecosystems and play a considerable role in the transfer of energy and organic matter from primary producers to higher trophic levels. We investigated the effect of cadmium chloride on biochemical responses of the planktonic calanoid copepods Centropages ponticus which is a key species in the Mediterranean Sea. The response of copepods to cadmium chloride was examined under laboratory-controlled conditions during a 72-h exposure. Catalase (CAT), Glutathion Reductase (GR), Glutathione Peroxidase (GPx), Glutathione-S-Transferase (GST) and Acetylcholinesterase (AChE) were analyzed for cadmium chloride treatments (0, 0.2 and 0.4 μg/L) after 24, 48 and 72 h. Additionally, the thiobarbituric reactive species assay was used to evaluate lipid peroxidation (LPO) level of the copepod. In this study, it is observed that contents of protein increased gradually with an increase in concentrations of metals and exposure time. Our findings showed that cadmium chloride directly influenced malondialdehyde (MDA) levels in the treated copepods hinting that the copepods had suffered from oxidative damage. During exposure, the Cd treatments significantly influenced the biochemical markers (CAT, GR, GPx, GST and AChE). Thus, Centropages ponticus could be used as a suitable bioindicator of exposure to Cd using biochemicals markers. Keywords: Biomarker, Planktonic copepod, Cadmium, Centropages ponticu

A novel index based on planktonic copepod reproductive traits as a tool for marine ecotoxicology studies

Copepods are excellent bioindicators of climate change and ecosystem pollution in anthropized coastal waters. This work reviewed the results of previous studies examining changes in egg production rate (EPR), hatching success (HS), and nauplius survival rate (NSR) in natural conditions and in the presence of pollutants, including heavy metals and organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs). At high concentrations, cadmium and silver induce an increase in EPR in the copepods Acartia tonsa and Acartia hudsonica, while exposure to mercury decreases EPR in adults by 50%. All three metals affect HS, with mercury inducing a stronger effect than cadmium and silver. Cadmium affects reproductive traits in Centropages ponticus, decreasing EPR and particularly HS. Furthermore, copper and chromium at high concentrations induce significant decreases in eggs per female in Notodiaptomus conifer. In terms of organic contaminant and Polycyclic Aromatic Hydrocarbons (PAHs), Eurytemora affinis is reported to be affected by naphthalene, 2-methylnaphthalene, 2,6-dimethylnaphthalene, and 2,3,5-trimethylnaphthalene and can thus be used in ecotoxicity studies, but only if the exposure time is high. Acartia tonsa shows significant reductions in EPR and HS at high concentrations of fluoranthene, phenanthrene, and pyrene. However, the response to Persistent Organic Pollutants (POPs) such as pentachlorophenol (PCP) and 1,2-dichlorobenzene (DCB) differs. In E. affinis, EPR increases with DCB, but HS falls to <1%. EPR increases when the species is exposed overnight, but HS remains low in the presence of DCB. Based on these results, we developed a novel copepod reproductive trait index (CRT-Index) for use in marine ecotoxicology surveys and tested in some simple cases. We show that copepods are good candidates as models for ecotoxicology studies, in particular using reproductive traits (EPR, HS and NSR) because of their sensitivity to a wide range or pollutants

MED-JELLYRISK 2013-2015 (Integrated monitoring of jellyfish outbreaks under anthropogenic and climatic impacts in the Mediterranean Sea (coastal zones): trophic and socio-economic risks

Fourth International Jellyfish Bloom Symposium, 5-7 June 2013, Hiroshima, JapanPeer reviewe