Changes in abundances of Alexandrium tamarense resting cysts after the tsunami caused by the Great East Japan Earthquake in Funka Bay,Hokkaido, Japan

The 2011 Great East Japan Earthquake and the subsequent huge tsunami greatly affected both human activity and the coastal marine ecosystem along the Pacific coast of Japan. The tsunami also reached Funka Bay in northern Japan and caused serious damage to the scallop cultures there, and this tsunami was believed to have affected the coastal environments in the bay. Therefore, we investigated the changes in the spatial abundance and distribution of the toxic dinoflagellates Alexandrium tamarense cysts before the tsunami (August 2010) and after the tsunami (May 2011, August 2011, May 2012 and August 2012) in the bay. Further, monthly sampling was conducted after the tsunami to identify seasonal changes of Alexandrium catenella/tamarense cysts and vegetative cells. Significant increases were observed in the populations of A. catenella/tamarense cysts, comparing the abundances before the tsunami (in August 2010; 70 ± 61 cysts g⁻¹ wet sediment) to those just after it (in May 2011; 108 ± 84 cysts g⁻¹ wet sediment), and both A. tamarense bloom (a maximum density was 1.3 × 10³ cells L⁻¹) and PSP (Paralytic Shellfish Poisoning) toxin contamination of scallops (9.4 mouse unit g⁻¹ was recorded) occurred in the bay. Seasonal sampling also revealed that the encystment of A. tamarense and the supply of the cysts to bottom sediments did not occur in the bay from September to April. These results strongly suggested that the mixing of the bottom sediments by the tsunami caused the accumulation of the toxic A. tamarense cysts in the surface of bottom sediment through the process of redeposition in Funka Bay. Moreover, this cyst deposition may have contributed to the toxic bloom formation as a seed population in the spring of 2011.     

Detection of Clostridium perfringens in tsunami deposits after the Great East Japan Earthquake

The Great East Japan Earthquake struck off the Tohoku and caused a tsunami in 2011. Most of the microbial characteristics of tsunami‐affected soil remain unknown and no published study has shown how a tsunami affects the risk of infection by Clostridium perfringens living in soil. In 2011 and 2015, C. perfringens was assessed in deposits in soil from tsunami‐damaged areas and undamaged areas of Miyagi. It was found that the number of C. perfringens was overwhelmingly greater in 2011 than in 2015 in the tsunami‐damaged areas. According to real‐time PCR, the prevalence C. perfringens organisms (%) was 10³ fold greater in the damaged than in the undamaged areas.     

Complex and interactive effects of ocean acidification and warming on the life span of a marine trematode parasite

Human activities have caused an increase in atmospheric CO₂ over the last 250 years, leading to unprecedented rates of change in seawater pH and temperature. These global scale processes are now commonly referred to as ocean acidification and warming, and have the potential to substantially alter the physiological performance of many marine organisms. It is vital that the effects of ocean acidification and warming on marine organisms are explored so that we can predict how marine communities may change in future. In particular, the effect of ocean acidification and warming on host-parasite dynamics is poorly understood, despite the ecological importance of these relationships. Here, we explore the response of one himasthlid trematode, Himasthla sp., an abundant and broadly distributed species of marine parasite, to combinations of elevated temperature and pCO₂ that represent physiological extremes, pre-industrial conditions, and end of century predictions. Specifically, we quantified the life span of the free-living cercarial stage under elevated temperature and pCO₂, focussing our research on functional life span (the time cercariae spend actively swimming) and absolute life span (the period before death). We found that the effects of temperature and pCO₂ were complex and interactive. Overall, increased temperature negatively affected functional and absolute life span, e.g. across all pCO₂ treatments the average time to 50% cessation of active swimming was approximately 8 h at 5 °C, 6 h at 15 °C, 4 h at 25 °C, and 2 h at 40 °C. The effect of pCO₂, which significantly affected absolute life span, was highly variable across temperature treatments. These results strongly suggest that ocean acidification and warming may alter the transmission success of trematode cercariae, and potentially reduce the input of cercariae to marine zooplankton. Either outcome could substantially alter the community structure of coastal marine systems.     

Taxonomic and geographic bias in the genetic study of helminth parasites

The use of genetic information is now fundamental in parasite taxonomy and systematics, for resolving parasite phylogenies, discovering cryptic species, and elucidating patterns of gene flow among parasite populations. The accumulation of available gene sequences per geographical area or per parasite taxonomic group is likely proportional to species richness, but not without some biases. Certain areas and certain taxonomic groups receive more research effort than others, possibly causing a deficit in the relative number of parasite species being characterized genetically in some areas or taxonomic groups. Here, we use data on the number of parasite records per country or helminth family from the London Natural History Museum host-parasite database, and matching data on the number of gene sequences available from the National Center for Biotechnology Information (NCBI) GenBank database, to determine how available gene sequences scale with species richness across countries or parasitic helminth families. Our quantitative analysis identified countries/regions of the world and helminth families that have received the most effort in genetic research. More importantly, it allowed us to generate lists (based on residuals from the statistical model) of the 20 countries/regions and the 20 helminth families with the largest deficit in available gene sequences relative to their helminth species richness. We propose these lists as useful guides toward future allocation of effort to maximise advances in parasite biodiscovery, systematics and population structure.     

Estimating the maximum sustainable yield of snow crab (Chionoecetes opilio) off Tohoku,Japan via a state-space stock assessment model with time-varying natural mortality

A maximum sustainable yield (MSY) obtained by maintaining or restoring fish stock levels is a tangible benefit of ecosystem services. Snow crab (Chionoecetes opilio) off Tohoku, Japan has been managed by a total allowable catch since 1996, although the abundance has not increased. Surprisingly, there was no increase after 2011, when fishing pressure was greatly reduced because of the Great East Japan earthquake. This implies that some of the crab's biological characteristics, such as recruits, natural mortality coefficient (M) and terminal molting probabilities (p), might have changed. We developed “just another state-space stock assessment model” to estimate the MSY of the snow crab off Tohoku considering interannual variations in M and p. The multimodel inference revealed that M increased from 0.2 in 1997 to 0.59 in 2018, although it did not vary according to instars, sex or terminal molt. The parameter p also increased by 1.34–2.46 times depending on the instar growth stages from 1997 to 2018. We estimated the MSYs in three scenarios, which changed drastically if M and p were set as they were in the past or at the current values estimated from this study. This result indicated that the MSY of snow crab would also vary with time based on their time-varying biological characteristics.     

Melanoderma boninense,a new species of Melanoderma (Polyporales,Agaricomycota) from the Bonin Islands in Japan

Melanoderma boninense is described and illustrated as a new species from the Bonin Islands, Japan, on the basis of morphological and phylogenetic investigations. This species is characterized by sessile basidiocarps with an ungulate pileus, a black crust on the pileus surface, pores 4–6/mm, a dimitic hyphal system comprising clamped generative hyphae and cyanophilous skeletal binding hyphae with or without a dextrinoid reaction, cylindrical basidiospores measuring 5.5–7.5 × 2–3 μm, and cystidioles on the sides of tubes and near the pore surface. Morphological examination of authentic specimens of other Melanoderma species revealed that the genus is variable in terms of the shape and size of cystidioles. A black crust on the pileus surface composed of palisade and highly agglutinated hyphae is a distinctive diagnostic morphological feature of Melanoderma that differentiates it from allied genera. Melanoderma boninense, which is currently known from a restricted area of the Bonin Islands, is potentially threatened by environmental reduction of the type locality due to the invasive tree Bischofia javanica.     

Notes on the species of Naarda Walker, 1866 (Lepidoptera: Erebidae,Hypeninae) from mainland China,with the description of a new species and establishment of a new synonymy

The species Naarda postpallida de Joannis, 1929 is reported for the first time from mainland China. Naarda pectinata Sugi, 1982 is synonymised with N. postpallida on the basis of material from Vietnam. This species can immediately be recognised by its dark grey forewing, white hindwing and several genital characters. The female genitalia of N. postpallida, together with those of N. lingualis Tóth and Ronkay, 2015 are presented for the first time. Naarda macrostigma sp. n. is described. The hitherto known nine Chinese Naarda species are listed. With nineteen figures.www.zoobank.org/urn:lsid:zoobank.org:pub:092AE905-08AA-4818-BDA8-2B9EF150793A     

On the identities of Rhinoleucophenga pallida Hendel and Rhinoleucophenga obesa (Loew) (Diptera,Drosophilidae), with description of a new sibling species from Brazil

Rhinoleucophenga pallida Hendel, 1917 (type species of the genus) is redescribed based on its female holotype and a male from a nearby locality, and Rhinoleucophenga obesa (Loew, 1872) on its two syntypes, which are designated as the male lectotype and a female paralectotype. Both are valid species. A proposal is made to establish the genus Pseudophortica Sturtevant, 1918 (type species R. obesa), a junior synonym of Rhinoleucophenga, to subgenus rank and include all species of Rhinoleucophenga described or redescribed from males except R. pallida, which is unique in having a remarkable pedunculate surstylus, among other differences. The North American R. obesa is compared to its closest sibling, the South American species Rhinoleucophenga gigantea (Thomson, 1869). The occurrence of R. obesa in Brazil is also questioned, as suggested long ago by Marshall R. Wheeler. The specimens from Brazil previously identified as such most probably belong to the new species described in the present paper as Rhinoleucophenga (Pseudophortica) cantareira sp. nov. (type locality: Parque Estadual da Cantareira, City of São Paulo, State of São Paulo, Brazil). Numerous photomicrographs of their habitus and male terminalia taken with a Smartphone's rear camera and digitally stacked to create images with greater depth of focus are provided.     

Chytrid infecting the bloom-forming marine diatom Skeletonema sp.: Morphology,phylogeny and distribution of a novel species within the Rhizophydiales

Chytrids have long been recognised as important parasites of microalgae in freshwater systems, able to shape the dynamics of blooms, the gene pool of their host and phytoplankton succession. In the sea however, where the presence of these organisms is erratic and ephemeral, studies concerning chytrids are sparse and confined to metabarcoding surveys or microscopy observations. Despite the scarcity of data, chytrid epidemics are supposed to play an important role in marine biogeochemical cycles, being one of the drivers of phytoplankton dynamics. Here we combine microscopy observations and in silico mining of a single-cell whole genome to molecularly and morphologically characterise a novel chytrid parasite of the dominant diatom genus Skeletonema. Morphological observations highlight features of the thallus and ascertain the parasitic nature of the interaction whilst the genetic markers obtained allows for a phylogenetic reconstruction, placing the new species in the order Rhizophydiales. Thanks to the molecular data obtained we are also able to provide a first investigation of the global distribution of this organism by screening the Ocean Sampling Day (OSD) dataset, highlighting a northern transatlantic dissemination.     

No barrier breakdown between human and cattle schistosome species in the Senegal River Basin in the face of hybridisation

Schistosomiasis is widely distributed along the Senegal River Basin (SRB), affecting both the human population and their livestock. Damming of the Senegal River for irrigation purposes in the 1980s induced ecological changes that resulted in a large outbreak of Schistosoma mansoni, followed a few years later by an increase and spread of Schistosoma haematobium infections. The presence of hybrid crosses between the human and cattle schistosomes, S. haematobium and Schistosoma bovis, respectively, is adding complexity to the disease epidemiology in this area, and questions the strength of the species boundary between these two species. This study aimed to investigate the epidemiology of S. haematobium, S. bovis and their hybrids along the Senegal River basin using both microsatellite genetic markers and analysis of mitochondrial and nuclear DNA markers. Human schistosome populations with a S. haematobium cox1 mtDNA profile and those with a S. bovis cox1 mtDNA profile (the so-called hybrids) appear to belong to a single randomly mating population, strongly differentiated from the pure S. bovis found in cattle. These results suggest that, in northern Senegal, a strong species boundary persists between human and cattle schistosome species and there is no prolific admixing of the populations. In addition, we found that in the SRB S. haematobium was spatially more differentiated in comparison to S. mansoni. This may be related either to the presence and susceptibility of the intermediate snail hosts, or to the colonisation history of the parasite.     

A new species of Stegodon (Mammalia,Proboscidea) from the Kazusa Group (lower Pleistocene), Hachioji City,Tokyo, Japan and its evolutionary morphodynamics

Abstract: Stegodon protoaurorae sp. nov. (Proboscidea) from the lower Pleistocene Terada Formation of the Kazusa Group in Japan is proposed as a new species based on characteristic features of plate formula, molar size, tooth enamel and plate frequency, and is described herein. The specimen of the new species was transported by autumn storms and buried. The new species fills an evolutionary gap between S. miensis and S. aurorae. Speciation in the lineage from S. miensis through S. protoaurorae to S. aurorae is inferred to have been caused by reduction of terrestrial space during marine transgression. The biostratigraphic distribution of S. protoaurorae suggests intercalation of a new S. protoaurorae Zone between the S. miensis Zone and the S. aurorae Zone. The S. protoaurorae Zone can be defined in the Nakatsu Group and the Terada Formation of the Kazusa Group, and can be assigned an age of 2.9–2.1 Ma.