The description of diversity is a key imperative in current biological studies and has been revolutionised by the molecular era that allows easy access to microbial diversity not visible to the naked eye. Broadly targeted SSU rRNA gene amplicon studies of diverse environmental habitats continue to reveal new microbial eukaryotic diversity. However, some eukaryotic lineages, particularly parasites, have divergent SSU sequences, and are therefore undersampled or excluded by the methodologies used for SSU studies. One such group is the Microsporidia, which have particularly divergent SSU sequences and are rarely detected in even large-scale amplicon studies. This is a serious omission as microsporidia are diverse and important parasites of humans and other animals of socio-economic importance. Whilst estimates of other microbial diversity are expanding, our knowledge of true microsporidian diversity has remained largely static. In this work, we have combined high throughput sequencing, broad environmental sampling and microsporidian-specific primers to broaden our understanding of the evolutionary diversity of the Microsporidia. Mapping our new sequences onto a tree of known microsporidian diversity we uncover new diversity across all areas of the microsporidian tree and uncover clades dominated by novel sequences, with no close described relatives.

Hamilton, K. M., Shaw, P. W., and Morritt, D. 2009. Prevalence and seasonality of Hematodinium (Alveolata: Syndinea) in a Scottish crustacean community. – ICES Journal of Marine Science, 66: 1837–1845. Protist parasites of the genus Hematodinium were detected in seven crustacean species (Cancer pagurus, Carcinus maenas, Liocarcinus depurator, Munida rugosa, Necora puber, Pagurus bernhardus, and Pagurus prideaux) from the Clyde Sea in Scotland. Seasonal screening of different tissues with sensitive molecular probes showed average infection of 3–23%, with prevalence reaching almost 60% in hermit crabs (P. bernhardus) and brachyuran hosts in spring and >30% in C. pagurus and N. puber in autumn. During summer, Hematodinium infections were rare. Hematodinium seemed to be present in all host sizes sampled. The infection was equally distributed between males and females in most host species, except C. maenas, where males seemed to be more susceptible to infection. PCR amplification of the Hematodinium ribosomal RNA gene in crustacean tissue detected the parasite most frequently in muscle, gills, and heart throughout the 2-year sampling period.

Marine reserves (or No-Take Zones) are implemented to protect species and habitats, with the aim of restoring a balanced ecosystem. Although the benefits of marine reserves are commonly monitored, there is a lack of insight into the potential detriments of such highly protected waters. High population densities attained within reserves may induce negative impacts such as unfavourable trophic cascades and disease outbreaks. Hence, we investigated the health of lobster populations in the UK’s Marine Conservation Zone (MCZ) at Lundy Island. Comparisons were made between the fished, Refuge Zone (RZ) and the un-fished, No-Take Zone (NTZ; marine reserve). We show ostensibly positive effects such as increased lobster abundance and size within the NTZ; however, we also demonstrate apparent negative effects such as increased injury and shell disease. Our findings suggest that robust cost-benefit analyses of marine reserves could improve marine reserve efficacy and subsequent management strategies.

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