Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health

This paper is not subject to U.S. copyright. The definitive version was published in Harmful Algae 14 (2012): 271-300, doi:10.1016/j.hal.2011.10.025.Over the last decade, our understanding of the environmental controls on Pseudo-nitzschia blooms and domoic acid (DA) production has matured. Pseudo-nitzschia have been found along most of the world's coastlines, while the impacts of its toxin, DA, are most persistent and detrimental in upwelling systems. However, Pseudo-nitzschia and DA have recently been detected in the open ocean's high-nitrate, low-chlorophyll regions, in addition to fjords, gulfs and bays, showing their presence in diverse environments. The toxin has been measured in zooplankton, shellfish, crustaceans, echinoderms, worms, marine mammals and birds, as well as in sediments, demonstrating its stable transfer through the marine food web and abiotically to the benthos. The linkage of DA production to nitrogenous nutrient physiology, trace metal acquisition, and even salinity, suggests that the control of toxin production is complex and likely influenced by a suite of environmental factors that may be unique to a particular region. Advances in our knowledge of Pseudo-nitzschia sexual reproduction, also in field populations, illustrate its importance in bloom dynamics and toxicity. The combination of careful taxonomy and powerful new molecular methods now allow for the complete characterization of Pseudo-nitzschia populations and how they respond to environmental changes. Here we summarize research that represents our increased knowledge over the last decade of Pseudo-nitzschia and its production of DA, including changes in worldwide range, phylogeny, physiology, ecology, monitoring and public health impacts

Virus and Virus-like Particles Affecting Cephalopods

3 pages, 1 figure, 1 table.-- This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International LicenseThis chapter compiles the information available to date regarding virus affecting different species of cephalopods. A clear evidence of a virus-related disease on cephalopods was not stablished yet. However, the first description of a virus-like in Octopus vulgaris was observed in nodular tumors that finally caused the death of the animal. It is noteworthy that not too much effort has been focused on this area to date. However, the incidence of viruses in cephalopods might be further investigated since the attention on these species as an alternative to the aquaculture sector is increasing rapidly over last years and huge efforts are being made to stablish new culturesPeer reviewe

Histological and microbiological investigations in farmed mussels (Mytilus galloprovincialis) of La Spezia Gulf, Italy to evaluate the health status

Introduction: Mass mortality episodes in cultured mussels (Mytilus galloprovincialis) occurred in early February 2015 in the Gulf of La Spezia (Ligurian Sea, Italy). The mortality was suspected to be the consequence to dredging and excavation works of the fund to increase the depth of the seabed in La Spezia harbor, an important military, commercial and touristic port. Methodology: Histological and microbiological analysis were carried out in M. galloprovincialis of 4 different sites in the Gulf of La Spezia over a l-year period monthly from October 2015 to September 2016 excluding August. The histopathological examinations were performed on a total of 440 samples processed by standard histological techniques. The populations were \u201chealthy\u201d at the time of sampling. Histological aspects of mussels were evaluated considering 28 health parameters: pathogens, inflammatory and non-specific pathology. Bacteriological analysis were conducted for the isolation of Vibrio splendidus- related and V. aestuarianus strains from pieces of gills and/or mantle according to a method previously published by IFREMER. Colonies morphologically corresponding to Vibrio were selected and tested for DNA presence by a Real time PCR. To identify the pathogenicity of the isolated V. splendidus-related strains, PCR analysis was used to detect the DNA of virulence factors vsm and ompU. Results: Parasites observed were Steinhausia mytilovum 3.9%, Proctoeces maculatus 3.4%, Mytilicola intestinalis 0.9%, ciliated protozoa 2%, Eugymnanthea inquilina and Urastoma cyprinae 31%. Of significance, a previously undescribed haplosporidian was detected in a single mussel sample (0.2%) and was confirmed by in situ hybridization. Biomolecular investigation are currently in progress to confirm the genus of observed a protozoan looking like Perkinsus parasite (0.7%). Different pathological aspects regressive changes, host defense responses and progressive changes were detected in gills, digestive gland, gonads and mantle. It has been observed a single case of haemocytic neoplasia (0.2%). V. splendidus clade was detected in 72.7% (32/ 44) of shellfish samples while all samples were negative for V. aestuarianus. Among the positive samples 46.8% (15/ 32) contained virulence factors: in particular, 14 strains tested positive for vsm and only 1 to ompU, no samples showed positive for both

Marteilia refringens and Marteilia pararefringens sp. nov. are distinct parasites of bivalves and have different European distributions

Marteilia refringens causes marteiliosis in oysters, mussels and other bivalve molluscs. This parasite previously comprised two species, M. refringens and Marteilia maurini, which were synonymized in 2007 and subsequently referred to as M. refringens ‘O-type’ and ‘M-type’. O-type has caused mass mortalities of the flat oyster Ostrea edulis. We used high throughput sequencing and histology to intensively screen flat oysters and mussels (Mytilus edulis) from the UK, Sweden and Norway for infection by both types and to generate multi-gene datasets to clarify their genetic distinctiveness. Mussels from the UK, Norway and Sweden were more frequently polymerase chain reaction (PCR)-positive for M-type (75/849) than oysters (11/542). We did not detect O-type in any northern European samples, and no histology-confirmed Marteilia-infected oysters were found in the UK, Norway and Sweden, even where co-habiting mussels were infected by the M-type. The two genetic lineages within ‘M. refringens’ are robustly distinguishable at species level. We therefore formally define them as separate species: M. refringens (previously O-type) and Marteilia pararefringens sp. nov. (M-type). We designed and tested new Marteilia-specific PCR primers amplifying from the 3’ end of the 18S rRNA gene through to the 5.8S gene, which specifically amplified the target region from both tissue and environmental samples