Unexpected biotic resilience on the Japanese seafloor caused by the 2011 Tōhoku-Oki tsunami

On March 11th, 2011 the Mw 9.0 2011 Tōhoku-Oki earthquake resulted in a tsunami which caused major devastation in coastal areas. Along the Japanese NE coast, tsunami waves reached maximum run-ups of 40 m, and travelled kilometers inland. Whereas devastation was clearly visible on land, underwater impact is much more difficult to assess. Here, we report unexpected results obtained during a research cruise targeting the seafloor off Shimokita (NE Japan), shortly (five months) after the disaster. The geography of the studied area is characterized by smooth coastline and a gradually descending shelf slope. Although high-energy tsunami waves caused major sediment reworking in shallow-water environments, investigated shelf ecosystems were characterized by surprisingly high benthic diversity and showed no evidence of mass mortality. Conversely, just beyond the shelf break, the benthic ecosystem was dominated by a low-diversity, opportunistic fauna indicating ongoing colonization of massive sand-bed deposits.Peer reviewe

Genetic diversity and ecology of the planktonic foraminifers Globigerina bulloides , Turborotalita quinqueloba and Neogloboquadrina pachyderma off the Oman margin during the late SW Monsoon

The molecular work was funded by an Advanced Fellowship award to K. Darling (UK Natural Environment Research Council (NERC); NER/J/S/2000/00860 and NE/D009707/1). SA received support from a DAAD fellowship (A0998101) and HS was supported by a DFG grant (SCHU 1605/2-1).The tropical waters of the Arabian Sea are among the richest biological areas of the world. The highly complex monsoonal system is particularly challenging for palaeoenvironmental study, which relies heavily upon understanding the modern-day ecology of planktonic foraminiferal assemblages and their geochemical signatures throughout the monsoonal cycle. Major upwelling responders such as G. bulloides, T. quinqueloba and N. pachyderma, typically associated with cooler mid to higher latitude ecosystems, are also found in number in the tropical Arabian Sea. Due to the more usual cooler water affinity of these morphospecies, the oceanographically isolated tropical upwelling ecosystem of the Arabian Sea potentially harbours new ecologically distinct genotypes (ecotypes). Samples were collected off the Oman margin at 15 stations towards the end of the summer monsoon to determine the genetic profiles of these morphospecies in both upwelling and open ocean regimes. Phylogenetic analysis of their small subunit (SSU) rDNA sequences revealed several new genetically distinct ecotypes. Two genetically divergent ecotypes of G. bulloides (Types Ia and IIf) were identified along the cruise track. Type Ia, a member of the G. bulloides warm water lineage, was found in both the upwelling and open ocean regions. The second genotype (IIf), a member of the G. bulloides cool water lineage, was found only in more marginal late upwelling cooler waters. Initial visual assessment of G. bulloides images suggests that it may be morphologically cryptic. Two highly divergent genotypes of T. quinqueloba (Types Ib and IIe) were also identified, which were largely confined to the eastern and northern Arabian Sea. Type IIe is a new member of the T. quinqueloba cool water lineage which points to its potential cool water affinity, but genotyping numbers are too low to confirm a specific association with upwelling. A new highly divergent genotype of N. pachyderma (Type VIII) was also identified at the western and southern stations. Comparison of global upwelling system genotype assemblages currently indicate little regional commonality. This complicates regional palaeoproxy understanding, since geochemical calibrations are known to be species and genotype specific. Detailed studies of the ecology and diversity of genotypes within each system should therefore be carried out to ensure the accuracy of palaeorecord interpretation.Publisher PDFPeer reviewe

Surveys of full–coverage restorations made of titanium at Matsumoto Dental University Hospital

Considering the presence of metal allergies and the sharp rise in the prices of precious metals, full–coverage restorations made of titanium have been covered by Japanese insurance since June 1, 2020. The clinical application of these restorations is expected to increase in the future. However, due to its high melting point and high affinity to oxygen at high temperatures, titanium has not been widely used in prosthetic clinical practice. This study aimed to survey the actual use of full–coverage metal restorations at Matsumoto Dental University Hospital. Patients who had full–coverage metal restorations placed on their molars from June 1 to December 28, 2020, were consecutively enrolled, and data on the type of metal, placement site, and time were recorded. Besides, the dentists who used titanium restorations (Ti–Rs) were given a questionnaire. We asked them to rate their impressions of Ti–Rs in comparison with full–coverage restorations made of Ag–Pd–Cu–Au alloy (Pd–R) in six categories, including occlusal adjustment, polishing, and luting operations. In all, 338 molars received full–coverage metal restorations. Ti–R was used in 33 cases and Pd–R in 305 cases; 14 upper and 19 lower, 12 first molars, 18 second molars, and 3 third molars received Ti–Rs, while 137 upper and 168 lower, 174 first molars, 174 second molars, and 3 third molars received Pd–Rs. Seven dentists responded to the questionnaire survey. Many dentists stated that Ti–R was more challenging to use than Pd–R for occlusal adjustment, polishing, and adjustment time. On the other hand, most of them stated that the luting process was similar for both. Besides, Ti–R was favorably evaluated in terms of metal allergy. The number of patients who received Ti–Rs increased during the study period, suggesting that Ti–Rs will be a commonly used metal allergy–friendly prosthetic in the future. We plan to continue the survey and study the prognosis

Genetic and morphometric evidence for parallel evolution of the Globigerinella calida morphotype

Molecular genetic investigations of the highly abundant extant planktonic foraminifera plexus Globigerinella siphonifera/Globigerinella calida have recently shown this group to be the genetically most diverse one within planktonic foraminifera, separating it into 12 distinct genetic types belonging to three main genetic lineages. Independently, several morphological or physiological variants have been described within the group, but the correlation between the high genetic diversity and the phenotypic variability remains unclear. In this study, we combine genetic data with morphometric analyses of shell shape and porosity of genotyped individuals of the different genetic lineages. Our morphometric measurements suggest a differentiation of three morphotypes within the plexus, two of which possess the elongated chambers described as a typical trait of G. calida. These two morphotypes with elongated chambers are associated with two distinct genetic lineages. The G. calida morphology therefore appears to have evolved twice in parallel. Unexpectedly, we show that the two morphotypes with elongated chambers can be separated from each other by characters seen in the lateral view of their shells. This implies that the taxonomy of the extant members of the genus Globigerinella should be revised. A comparison with the original descriptions and type specimens of members of the genus shows that two genetic types of one major lineage correspond to G. calida. The second group with elongated chambers is associated with a recently diverged genetic type and we propose to reinstate the name Globigerinella radians for this distinct form. The remaining nine of the 12 genetic types correspond to the G. siphonifera morphology, and in the absence of evidence for morphological differentiation, they form a paraphyletic morpho-taxon. Our results highlight the prevalence of parallelism in the evolution of shell morphology in planktonic foraminifera even at the lowest level of relatedness represented by genetic types

Phylogeography of the tropical planktonic foraminifera lineage Globigerinella reveals isolation inconsistent with passive dispersal by ocean currents

Morphologically defined species of marine plankton often harbor a considerable level of cryptic diversity. Since many morphospecies show cosmopolitan distribution, an understanding of biogeographic and evolutionary processes at the level of genetic diversity requires global sampling. We use a database of 387 single-specimen sequences of the SSU rDNA of the planktonic foraminifera Globigerinella as a model to assess the biogeographic and phylogenetic distributions of cryptic diversity in marine microplankton on a global scale. Our data confirm the existence of multiple, well isolated genetic lineages. An analysis of their abundance and distribution indicates that our sampling is likely to approximate the actual total diversity. Unexpectedly, we observe an uneven allocation of cryptic diversity among the phylogenetic lineages. We show that this pattern is neither an artifact of sampling intensity nor a function of lineage age. Instead, we argue that it reflects an ongoing speciation process in one of the three major lineages. Surprisingly, four of the six genetic types in the hyperdiverse lineage are biogeographically restricted to the Indopacific. Their mutual co-occurrence and their hierarchical phylogenetic structure provide no evidence for an origin through sudden habitat fragmentation and their limitation to the Indopacific challenges the view of a global gene flow within the warm-water provinces. This phenomenon shows that passive dispersal is not sufficient to describe the distribution of plankton diversity. Rather, these organisms show differentiated distribution patterns shaped by species interactions and reflecting phylogenetic contingency with unique histories of diversification rates