Ecological restoration of European flat oysters in the German Bight

Several marine ecosystems currently face severe degradation, in the form of habitat loss. As a consequence, humans are undertaking initiatives to restore species and habitats to restore and preserve ecosystem services and functions. Although there have been many initiatives to restock commercial marine species for fisheries and aquaculture, the restoration of marine habitats is a relatively new discipline. To recover ecosystem conditions that maintain their structure and function, ecological restoration was conducted and implemented by the Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung (AWI) and the Bundesamt für Naturschutz (BfN) for re-establishing lost and ecologically relevant biogenic oyster reefs in the frame of marine conservation measures in the German North Sea. From 2016 to 2019, the AWI-led and BfN-funded RESTORE project actively investigated the technical and biological feasibility of restoration, from which this thesis originates. In this context, three key topics (and their associated subtopics), relevant for the development of a successful restoration programme, are addressed in this thesis: I) Oyster supply - How can we provide ecological restoration efforts with substantial amounts of appropriate Ostrea edulis seeds (i.e. gametes, larvae and spat)? Which production techniques and knowledge exist? Which are appropriate for restoration? II) Supply of essential settlement substrate for the oyster life cycle - Which types of substrate to use in accordance with biological traits of O. edulis? Which types of substrate to use in accordance with legislative restrictions? III) Biosecurity aspects of oyster restoration - How to avoid the transfer of pathogens or invasive species during ecological restoration projects (focusing on seed production and substrate transfer)

Ecological restoration of European flat oysters in the German Bight

Several marine ecosystems currently face severe degradation, in the form of habitat loss. As a consequence, humans are undertaking initiatives to restore species and habitats to restore and preserve ecosystem services and functions. Although there have been many initiatives to restock commercial marine species for fisheries and aquaculture, the restoration of marine habitats is a relatively new discipline. To recover ecosystem conditions that maintain their structure and function, ecological restoration was conducted and implemented by the Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung (AWI) and the Bundesamt für Naturschutz (BfN) for re-establishing lost and ecologically relevant biogenic oyster reefs in the frame of marine conservation measures in the German North Sea. From 2016 to 2019, the AWI-led and BfN-funded RESTORE project actively investigated the technical and biological feasibility of restoration, from which this thesis originates. In this context, three key topics (and their associated subtopics), relevant for the development of a successful restoration programme, are addressed in this thesis: I) Oyster supply - How can we provide ecological restoration efforts with substantial amounts of appropriate Ostrea edulis seeds (i.e. gametes, larvae and spat)? Which production techniques and knowledge exist? Which are appropriate for restoration? II) Supply of essential settlement substrate for the oyster life cycle - Which types of substrate to use in accordance with biological traits of O. edulis? Which types of substrate to use in accordance with legislative restrictions? III) Biosecurity aspects of oyster restoration - How to avoid the transfer of pathogens or invasive species during ecological restoration projects (focusing on seed production and substrate transfer)? A review paper on the reproductive biology of O. edulis and on existing seed production techniques relevant for aquaculture and restoration (Chapter I) provides the knowledge basis for successful production, tailored to the demands of ecological restoration. It reviews four majour seed production processes of O. edulis, discusses them in the context of different aquaculture and ecological restoration scenarios (e.g. techniques to minimise disease transmission, or to manage genetic variability), and identifies critical knowledge gaps that need to be closed to facilitate stable and substantial O. edulis seed production. Twenty substrate types are evaluated in the context of seed supply in natural environments (to enhance recruitment in the field) as well as in hatchery seed production (Chapter II). The approach is complementary (in situ and in vitro tests) and shows clear differences in settlement preferences of O. edulis larvae in relation to substrate type and environment. The results indicate that substrate selection (for practicioners) is essential to optimise O. edulis restoration practices. Biosecurity measures are investigated for the substrate supply chain (Chapter III) as well as for hatchery production (Chapter IV). The lack of established and recognised practical measures regarding the potential risks of translocations of non-native species, diseases and/or pests highlights the early stage of ecological restoration in Europe. A new method for sorting and processing shell substrate from France for restoration projects in Germany is presented here. Based on different treatments, first conclusions are drawn and future research directions suggested for the practice of importing shells for re-establishment at sea

Isolation and Pathogenic Characterization of Vibrio bivalvicida Associated With a Massive Larval Mortality Event in a Commercial Hatchery of Scallop Argopecten purpuratus in Chile

The VPAP30 strain was isolated as the highly predominant bacteria from an episode of massive larval mortality occurring in a commercial culture of the Chilean scallop Argopecten purpuratus. The main aims of this study were, to characterize and identify the pathogenic strain using biochemical and molecular methods, to demonstrate its pathogenic activity on scallop larvae, to characterize its pathogenic properties and to describe the chronology of the pathology. The pathogenic strain was identified as Vibrio bivalvicida based on its phenotypic properties, the multilocus sequence analysis (MLSA) of eight housekeeping genes (ftsZ, gapA, gyrB, mreB, pyrH, recA, rpoA, and topA) and different in silico genome-to-genome comparisons. When triplicate cultures of healthy 10 days old scallop larvae were challenged with 1 × 105 colony forming units (CFU) mL-1 of the VPAP30 strain, percentages of larval survival of 78.9 ± 3.3%, 34.3 ± 4.9%, and 0% were observed at 12, 2,4 and 36 h, respectively, whereas uninfected larval cultures showed survival rates of 97.4 ± 1.2% after of 48 h. Clinical symptoms exhibited by the scallop larvae infected with the VPAP30 strain include the accumulation of bacteria around the scallop larvae, velum disruption and necrosis of digestive gland. The 50% lethal dose (LD50) of VPAP30 strain at 24 and 48 h was 1.3 × 104 and 1.2 × 103 CFU mL-1, respectively. The invasive pathogenic activity of the VPAP30 strain was investigated with staining of the bacterial pathogen with 5-DTAF and analyzing bacterial invasion using epifluorescence, and a complete bacterial dissemination inside the larvae at 24 h post-infection was observed. When scallop larvae were inoculated with cell-free extracellular products (ECPs) of VPAP30, the larval survival rate was 59.5 ± 1.7%, significantly (P < 0.001) lower than the control group (97.4 ± 1.2%) whereas larvae treated with heat-treated ECPs exhibited a survival rate of 61.6 ± 1.8% after 48 h of exposure. V. bivalvicida VPAP30 exhibits high pathogenic activity on scallop larvae, mediated both by bacterial invasion and the production of toxigenic heat-stable compounds. This report constitutes the first isolation of V. bivalvicida out of Europe and extends the host range of this species, having demonstrated its pathogenic activity on the Chilean scallop larvae (A. purpuratus). These results supporting the pathogenic potential of V. bivalvicida to kill the larvae of a broad range of bivalve species reared in hatcheries located in the Atlantic and the Pacific coasts.This study was financially supported by the Science and Technology National Council (CONICYT) of Chile by the Postdoctoral Project Grant No. 3150395 and FONDECYT grant No. 1140734 and FONDEF ID16I10291S

Adult spawning and early larval development of the endangered bivalve Pinna nobilis

[EN] The development of aquaculture activities has posed an alternative solution for the preservation of some overexploited shell¿sh ¿sheries worldwide. In the same way, endemic Mediterranean bivalves such as Pinna nobilis, highly threatened by habitat loss and coastal pollution, could found in aquaculture a solution for preserving the continuity of the species. Given the endangered status of the species, the biological and ecological processes regulating natural populations have been well studied, but there are still important knowledge gaps preventing the development of viable arti¿cial cultures. This study describes for the ¿rst time the larval development of P. nobilis (from fertilization until pediveliger larval stages) in captivity conditions. Moreover, di¿erent rearing tanks of 5, 16 and 80 L, larvae density from 1 to 600 larvae mL¿1, light conditions, food doses, were tested in order to establish the bases for the optimal rearing of the species and provide a source of individuals for restoring ¿eld populations. Results showed that 16 L tanks with a concentration of 2 larvae mL¿1, constant temperature of 21 °C, 12/12 h photoperiod and fed with an ¿optimal¿ mixture of 25 cells per ¿L of Chaetoceros calcitrans + 33.3 cells per¿L ofPavlova lutheri + 100 cells per¿L ofIsochrysis galbana¿ appear to be the best conditions to rearlarvae ofP. nobilis.Di¿erentcaptivity conditions such as loweror highertank volume, larvae density, or food doses; light privation did not report better results for larval development.The present study was financed by the Caisse d'Epargne Cote d'Azur. We are also grateful to the research crew of the Institut Oceanographique Paul Ricard and the Catholic University of Valencia for their technical support and help collecting and maintaining fan mussels. Special thanks to the reviewers for their constructive and necessary suggestions.Trigos, S.; Vicente, N.; Prado, P.; Espinos Gutierrez, FJ. (2018). Adult spawning and early larval development of the endangered bivalve Pinna nobilis. Aquaculture. 483:102-110. doi:10.1016/j.aquaculture.2017.10.015S10211048

Marine farming and enhancement: Proceedings of the Fifteenth U.S.-Japan Meeting on Aquaculture, Kyoto, Japan October 22-23, 1986

The United States and Japanese counterpart panels on aquaculture were formed in 1969 under the United States-Japan Cooperative Program in Natural Resources (UJNR). The panels currently include specialists drawn from the federal departments most concerned with aquaculture. Charged with exploring and developing bilateral cooperation, the panels have focused their efforts on exchanging information related to aquaculture which could be of benefit to both countries. The UJNR was begun during the Third Cabinet-Level Meeting of the Joint United States-Japan Committee on Trade and Economic Affairs in January 1964. In addition to aquaculture, current subjects in the program include desalination of seawater, toxic microorganisms, air pollution, energy, forage crops, national park management, mycoplasmosis, wind and seismic effects, protein resources, forestry, and several joint panels and committees in marine resources research, development, and utilization. Accomplishments include: Increased communication and cooperation among technical specialists; exchanges of information, data, and research findings; annual meetings of the panels, a policy-coordinative body; administrative staff meetings; exchanges of equipment, materials, and samples; several major technical conferences; and beneficial effects on international relations. (PDF file contains 134 pages.

Responses of Mytilus galloprovincialis to challenge with the emerging marine pathogen Vibrio coralliilyticus

Vibrio coralliilyticus has emerged as a coral pathogen of concern throughout the Indo-Pacific reef. The interest towards understanding its ecology and pathogenic potential has increased since V. coralliilyticus was shown to be strongly virulent also for other species; in particular, it represents a serious threat for bivalve aquaculture, being one of the most important emerging pathogen responsible for oyster larval mortalities worldwide. V. coralliilyticus has a tightly regulated temperature-dependent virulence and it has been related to mass mortalities events of benthic invertebrates also in the temperate northwestern Mediterranean Sea. However, no data are available on the effects of V. coralliilyticus in the mussel Mytilus galloprovincialis, the most abundant aquacultured species in this area. In this work, responses of M. galloprovincialis to challenge with V. coralliilyticus (ATCC BAA-450) were investigated. In vitro, short term responses of mussel hemocytes were evaluated in terms of lysosomal membrane stability, bactericidal activity, lysozyme release, ROS and NO production, and ultrastructural changes, evaluated by TEM. In vivo, hemolymph parameters were measured in mussels challenged with V. coralliilyticus at 24h p.i. Moreover, the effects of V. coralliilyticus on mussel early embryo development (at 48 hpf) were evaluated. The results show that both in vitro and in vivo, mussels were unable to activate immune response towards V. coralliilyticus, and that challenge mainly induced lysosomal stress in the hemocytes. Moreover, V. coralliilyticus showed a strong and concentration-dependent embryotoxicity. Overall, the results indicate that, although M. galloprovincialis is considered a resistant species to vibrio infections, the emerging pathogen V. coralliilyticus can represent a potential threat to mussel aquaculture

Disease Diagnostics and Potential Coinfections by Vibrio coralliilyticus During an Ongoing Coral Disease Outbreak in Florida

A deadly coral disease outbreak has been devastating the Florida Reef Tract since 2014. This disease, stony coral tissue loss disease (SCTLD), affects at least 22 coral species causing the progressive destruction of tissue. The etiological agents responsible for SCTLD are unidentified, but pathogenic bacteria are suspected. Virulence screens of 400 isolates identified four potentially pathogenic strains of Vibrio spp. subsequently identified as V. coralliilyticus. Strains of this species are known coral pathogens; however, cultures were unable to consistently elicit tissue loss, suggesting an opportunistic role. Using an improved immunoassay, the VcpA RapidTest, a toxic zinc-metalloprotease produced by V. coralliilyticus was detected on 22.3% of diseased Montastraea cavernosa (n = 67) and 23.5% of diseased Orbicella faveolata (n = 24). VcpA+ corals had significantly higher mortality rates and faster disease progression. For VcpA– fragments, 21.6% and 33.3% of M. cavernosa and O. faveolata, respectively, died within 21 d of observation, while 100% of similarly sized VcpA+ fragments of both species died during the same period. Further physiological and genomic analysis found no apparent differences between the Atlantic V. coralliilyticus strains cultured here and pathogens from the Indo-Pacific but highlighted the diversity among strains and their immense genetic potential. In all, V. coralliilyticus may be causing coinfections that exacerbate existing SCTLD lesions, which could contribute to the intraspecific differences observed between colonies. This study describes potential coinfections contributing to SCTLD virulence as well as diagnostic tools capable of tracking the pathogen involved, which are important contributions to the management and understanding of SCTLD