Differential Gene Expression Supports a Resource‐Intensive, Defensive Role for Colony Production in the Bloom‐Forming Haptophyte, Phaeocystis globosa

Phaeocystis globosa forms dense, monospecific blooms in temperate, northern waters. Blooms are usually dominated by the colonial morphotype—nonflagellated cells embedded in a secreted mucilaginous mass. Colonial Phaeocystis blooms significantly affect food‐web structure and function and negatively impact fisheries and aquaculture, but factors regulating colony formation remain enigmatic. Destructive P. globosa blooms have been reported in tropical and subtropical regions more recently and warm‐water blooms could become more common with continued climate change and coastal eutrophication. We therefore assessed genetic pathways associated with colony formation by investigating differential gene expression between colonial and solitary cells of a warm‐water P. globosa strain. Our results illustrate a transcriptional shift in colonial cells with most of the differentially expressed genes downregulated, supporting a reallocation of resources associated with forming and maintaining colonies. Dimethylsulfide and acrylate production and pathogen interaction pathways were upregulated in colonial cells, suggesting a defensive role for producing colonies. We identify several protein kinase signaling pathways that may influence the transition between morphotypes, providing targets for future research into factors affecting colony formation. This study provides novel insights into genetic mechanisms involved in Phaeocystis colony formation and provides new evidence supporting a defensive role for Phaeocystis colonies

Continuous monitoring of near-bottom mesoplankton communities in the East China Sea during a series of typhoons

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Oceanography 71 (2015): 115-124, doi:10.1007/s10872-014-0268-y.Typhoons are a common feature of summer and autumn months in the East China Sea. These events often promote phytoplankton growth in surface waters as a result of upwelling and transport of nutrients, but their effects on sub-surface waters and ecosystems are little known. Furthermore, biological studies tend to focus on phytoplankton (using chlorophyll a assays), rather than on heterotrophic zooplankton. Indeed, measurements of biological and physicochemical changes induced by the storms are difficult to perform and risky, using standard shipboard sampling techniques. Using a camera mounted on an underwater, cabled observatory system in shallow coastal waters of Okinawa, Japan, we collected the first continuous, in-situ observations of the near-bottom, mesoplankton community during a series of typhoons. An increase in diatoms and radiolarians was found during all typhoons, whereas the response of larger zooplankton groups was variable between typhoons. A bloom of Trichodesmium cyanobacteria and diatoms was seen after a series of typhoons, while the total chlorophyll a concentration remained nearly unchanged at the sampling location. These findings shed new light on short-term responses of sub-surface ecosystems during typhoons.This work was funded by the Special Framework budget, Okinawa Promotion for Education and Research Project awarded to OIST for the 2012 fiscal year.2015-12-3

IS-20 Atmospheric Science within a One Health Perspective

In the atmosphere, particulate matters exist as aerosols which may have essential functions for the earth system to health quality of the individuals. A field of atmospheric sciences associated with aerosols has been focusing mainly on their chemical and physical properties to characterize their role and effect for the climate system, ocean-atmosphere interaction, health-related issue, and more.It is well recognized that biological aerosols defined as “bioaerosols” to be present ubiquitously in the atmosphere, yet the scientific knowledge of their roles and functions are somewhat limited [1].Since the bioaerosols may have a significant effect on climate, health quality of human and livestock animals, and ecological system, it is of great importance to acquire further knowledge in many aspects. The bioaerosols such as bacteria, virus fungi, and their fragments are not well in-cooperated with the atmospheric science researches mainly due to the difficulty associated with detection of bioaerosols. Often the concentration of bioaerosols in the air is very low, which requires sampling of a large air mass. Furthermore, the current scientific communities still lack the multidisciplinary approaches to tackle airborne infection, allergen dispersion, the stability of the biological material and more in the atmosphere.Traditionally in both human and veterinary medical sciences, the bioaerosol investigations focused on understanding the infectivity of potential airborne infectious materials. For example, influenza, tuberculosis, mycoplasma, and other pathogenic ones to be examined. For example, the main focus points are finding strains which are more easily spread and the probability of infection to occur. Also, for the prevention of infectious diseases, understanding host susceptibility and immune response are also important focal points. However, in the real atmospheric condition, there are many substances in the air both gas and particulate phases. Thus understanding the mechanism of airborne infection requires not only the pathogen by itself, but it also needs to include some other co-existing airborne materials such as dust and air pollutants. Therefore, investigating the viability of bacteria with the effects of the particulate matters commonly found in the atmosphere as the co-existing material is important. Our research activities primarily focus on interactions between the bioaerosols and some other particulate matters such as dust and air pollutant in the atmosphere. This approach tries to evaluate the factors attributing the prolongation or reduction of the viability of bioaerosols. More specifically, understanding the critical factors to determine the viability of airborne pathogen, it may be easier to find solutions to control the airborne infection. Our work also focuses on emerging diseases such as Non-tuberculosis mycobacterium (NTM) clinical case in Japan [2].  In order to achieve global health, the one health approach can bridge the medical and environmental sciences as the multidisciplinary effort to safeguard human, animal, and environmental health.  

Reef influence quantification in light of the 1771 Meiwa tsunami

While interactions between regular wave driven flooding and reefs have been widely studied due to climate change pressure, the effects of reefs on tsunami flooding have less been investigated. From studies of historical events, reefs can behave as buffers or as amplifiers of inundation, depending upon the location. Interactions between reefs and tsunamis have generally been analyzed with idealized models, and there have been only few studies of specific reefs and their characteristics. Using numerical NonLinear Shallow Water models, this study characterizes the influence of the Southeast Ishigaki Island reef during the 1771 tsunami that hit the Yaeyama Islands. In this work, we modified reef topography in silico and then, measured the impact of these changes using a new parameter, the Reef Impact Factor (RIF). First, a reference model was built, simulating the real event with an accurate reef representation and using run-up data to calibrate bottom friction. This calibration highlights the difficulty of representing reef friction with a homogeneous coefficient. Second, a model without a reef was compared to the reference model. The impact of reef removal varies considerably along the coastline and maximum wave heights at the shore were strongly affected, with a increase on average. Overall, this suggests a protective role of the reef along most of the coast. However, at local scale, channels that break the continuity of the front reef, increased wave heights by up to on the proximate coast, revealing their strong focusing influence. Finally, changes in tide level, which regulates reef depth, were investigated, showing a global positive correlation between sea level and maximum wave height at the coast. However, the impact of the reef depth appeared weak compared to the impact of incident wave parameters. This study contributes to a global effort to understand tsunami-reef interactions in a non-idealized framework, suggesting a Reef Impact Factor for inter-reef/study comparisons. Moreover, vulnerable and exposed coasts were identified at Ishigaki Island, which may help to improve inundation forecasting, resulting in more appropriate management of these vulnerable sections of the coast

Genetic changes involving the coral gastrovascular system support the transition between colonies and bailed-out polyps: evidence from a Pocillopora acuta transcriptome

BackgroundA coral colony is composed of physiologically integrated polyps. In stony corals, coloniality adopts a wide diversity of forms and involves complex ontogenetic dynamics. However, molecular mechanisms underlying coloniality have been little studied. To understand the genetic basis of coloniality and its contribution to coral ecology, we induced polyp bail-out in a colonial coral, Pocillopora acuta, and compared transcription profiles of bailed-out polyps and polyps in normal colonies, and their responses to heat shock and hyposalinity.ResultsConsistent with morphological formation of a gastrovascular system and its neural transmission and molecular transport functions, we found genetic activation of neurogenesis and development of tube-like structures in normal colonies that is absent in bailed-out polyps. Moreover, relative to bailed-out polyps, colonies showed significant overexpression of genes for angiotensin-converting enzymes and endothelin-converting enzymes. In response to hyperthermal and hyposaline treatments, a high proportion of genetic regulation proved specific to either bailed-out polyps or colonies. Elevated temperatures even activated NF-κB signaling in colonies. On the other hand, colonies showed no discernible advantage over bailed-out polyps in regard to hyposalinity.ConclusionsThe present study provides a first look at the genetic basis of coloniality and documents different responses to environmental stimuli in P. acuta colonies versus those in bailed-out polyps. Overexpression of angiotensin-converting enzymes and endothelin-converting enzymes in colonies suggests possible involvement of these genes in development of the gastrovascular system in P. acuta. Functional characterization of these coral genes and further investigation of other forms of the transition to coloniality in stony corals should be fruitful areas for future research

Signaling pathways in the coral polyp bail-out response

Polyp bail-out is a stress response exhibited by some pocilloporid corals, with mechanisms and consequences distinct from those of bleaching. Although induction of polyp bail-out has been demonstrated in the laboratory, molecular mechanisms underlying this response have rarely been discussed. We conducted genetic analyses of Pocillopora acuta during initiation of hyperosmosisinduced polyp bail-out, using both transcriptomic and qPCR techniques. Beyond upregulation of apoptosis and proteolysis, corals showed significant activation of tumor necrosis factor and fibroblast growth factor (FGF) signaling pathways during induction of polyp bail-out. In our qPCR analysis, a common upregulation profile, peaking at 43.0% salinity, was found in the FAS and CASP8 genes, whereas a different profile, showing significant upregulation up to 45.0%, was displayed by matrix metalloproteinases and genes in the FGF signaling pathway. These results suggest parallel involvement of an extrinsic apoptotic signaling pathway and FGF-mediated extracellular matrix degradation in polyp bail-out. Furthermore, in the XIAP, JNK, and NFKB1 genes, we detected a third expression profile showing linear upregulation that becomes maximal at the endpoint salinity level of the experiment (46.0%), indicating activation of anti-apoptotic and cell survival signals during polyp bail-out. Our results provide new insights into signaling pathways responsible for polyp bail-out and suggest the feasibility of inducing bail-out by specifically triggering these pathways without exerting lethal stresses on the corals, which in turn will facilitate acquisition of viable polyps for possible use in coral reef restoration

Eddy-induced transport of the Kuroshio warm water around the Ryukyu Islands in the East China Sea

In this study, an oceanic downscaling model in a double-nested configuration was used to investigate the role played by the Kuroshio warm current in preserving and maintaining biological diversity in the coral coasts around the Ryukyu Islands (Japan). A comparison of the modeled data demonstrated that the innermost submesoscale eddy-resolving model successfully reproduced the synoptic and mesoscale oceanic structures even without data assimilation. The Kuroshio flows on the shelf break of the East China Sea approximately 150–200 km from the islands; therefore, eddy-induced transient processes are essential to the lateral transport of material within the strip between the Kuroshio and the islands. The model indicated an evident predominance of submesoscale anticyclonic eddies over cyclonic eddies near the surface of this strip. An energy conversion analysis relevant to the eddy-generation mechanisms revealed that a combination of both the shear instability due to the Kuroshio and the topography and baroclinic instability around the Kuroshio front jointly provoke these near-surface anticyclonic eddies, as well as the subsurface cyclonic eddies that are shed around the shelf break. Both surface and subsurface eddies fit within the submesoscale, and they are energized more as the grid resolution of the model is increased. An eddy heat flux (EHF) analysis was performed with decomposition into the divergent (dEHF) and rotational (rEHF) components. The rEHF vectors appeared along the temperature variance contours by following the Kuroshio, whereas the dEHF properly measured the transverse transport normal to the Kuroshio\u27s path. The diagnostic EHF analysis demonstrated that an asymmetric dEHF occurs within the surface mixed layer, which promotes eastward transport toward the islands. Conversely, below the mixed layer, a negative dEHF tongue is formed that promotes the subsurface westward warm water transport

Turbulent dispersal promotes species coexistence

Several recent advances in coexistence theory emphasize the importance of space and dispersal, but focus on average dispersal rates and require spatial heterogeneity, spatio-temporal variability or dispersal-competition tradeoffs to allow coexistence. We analyse a model with stochastic juvenile dispersal (driven by turbulent flow in the coastal ocean) and show that a low-productivity species can coexist with a high-productivity species by having dispersal patterns sufficiently uncorrelated from those of its competitor, even though, on average, dispersal statistics are identical and subsequent demography and competition is spatially homogeneous. This produces a spatial storage effect, with an ephemeral partitioning of a ‘spatial niche’, and is the first demonstration of a physical mechanism for a pure spatiotemporal environmental response. ‘Turbulent coexistence’ is widely applicable to marine species with pelagic larval dispersal and relatively sessile adult life stages (and perhaps some wind-dispersed species) and complements other spatial and temporal storage effects previously documented for such species

Quantifying connectivity between mesophotic and shallow coral larvae in Okinawa Island, Japan: a quadruple nested high-resolution modeling study

Coral bleaching has recently been occurring extensively across the world’s oceans, primarily because of high water temperatures. Mesophotic corals that inhabit depths of approximately 30–150 m are expected to survive bleaching events and reseed shallow water corals afterward. In Okinawa, Japan, mesophotic coral ecosystems have been reported to serve as a refuge for preserving the genotypic diversity of bleaching-sensitive corals. The connectivity of larval populations among different habitats is a key element that determines the area to be conserved in desirable coral ecosystems. Because coral larvae are largely transported passively by ambient oceanic currents, particularly in the horizontal direction, numerical ocean circulation models greatly help to quantify connectivity with detailed spatiotemporal network structures. The present study aimed to quantify the short-distance connectivity of shallow and mesophotic coral larvae in reef areas on the northwest coast of Okinawa Island. To this end, a quadruple nested high-resolution synoptic ocean model at a lateral spatial grid resolution of 50 m was developed, which was capable of realizing detailed coastal currents influenced by complex nearshore topography, and coupled with an offline 3-D Lagrangian particle-tracking model. After validating the developed model, short-distance horizontal coral connectivity across reef areas on the northwest coast was successfully evaluated. The alongshore lateral connectivity had apparent asymmetry caused by depth-dependent horizontal currents, whereas the larvae spawned at shallow and mesophotic depths were reachable to each other. Such across-depth larval dispersal was attributable to the mixed-layer depth in the spawning period, viz., the boreal spring, which approximately coincides with the boundary between shallow and mesophotic coral, leading to the intensive vertical exchange of virtual larvae

Extremely Stochastic Connectivity of Island Mangroves

Studies of mangrove population connectivity have focused primarily on global to regional scales and have suggested potential for long-distance connectivity, with archipelagos serving as stepping stones for trans-oceanic dispersal. However, the contribution of propagule dispersal to connectivity is still largely unknown, especially at local-scale. Identifying fine-scale propagule dispersal patterns unique to individual island systems is important to understand their contribution to global species distributions, and to select appropriate sizes and locations for mangrove conservation in archipelagos. Using population genetic methods and a release-recapture method employing GPS drifting buoys, we investigated the spatiotemporal scale of propagule dispersal of Rhizophora stylosa, one of the widely distributed mangrove species in the Indo-West Pacific. This study sought to quantify intra- and inter-island connectivity and to assess their contributions to oceanic scale dispersal of R. stylosa from the Ryukyu Archipelago, which spans over 545 km in southwestern Japan. Using 7 microsatellite markers, we tested 354 samples collected from 16 fringing populations on 4 islands. We identified 3 genetic populations, indicating distinct genetic structures comprising 3 distinguishable bioregions (genetic clusters). The western end of the archipelago receives relatively frequent migration (m > 0.1), but is genetically isolated from other sites. Based on genetic migration rates, we found that the central area of the archipelago serves as a stepping stone for southwestward, but not northeastward dispersal. On the other hand, with in-situ drifting buoys, we did not confirm prevailing dispersal directionality within the archipelago, instead confirming local eddies. Some buoys trapped in those eddies demonstrated potential for successful beaching from another island. A large portion of buoys were carried predominantly northeastward by the Kuroshio Current and drifted away from the coastal areas into the Pacific, contrary to local migrations. We found that the spatiotemporal scale of propagule dispersal is limited by the distance between islands (< 200km), propagule viability duration, and fecundity. Over all, recruitment does not occur frequently enough to unify the genetic structure in the archipelago, and the Ryukyu Archipelago is isolated in the center of the global mangrove distribution