Congruence between fine-scale genetic breaks and dispersal potential in an estuarine seaweed across multiple transition zones

Genetic structure in biogeographical transition zones can be shaped by several factors including limited dispersal across barriers, admixture following secondary contact, differential selection, and mating incompatibility. A striking example is found in Northwest France and Northwest Spain, where the estuarine seaweed Fucus ceranoides L. exhibits sharp, regional genetic clustering. This pattern has been related to historical population fragmentation and divergence into distinct glacial refugia, followed by post-glacial expansion and secondary contact. The contemporary persistence of sharp ancient genetic breaks between nearby estuaries has been attributed to prior colonization effects (density barriers) but the effect of oceanographic barriers has not been tested. Here, through a combination of mesoscale sampling (15 consecutive populations) and population genetic data (mtIGS) in NW France, we define regional genetic disjunctions similar to those described in NW Iberia. Most importantly, using high resolution dispersal simulations for Brittany and Iberian populations, we provide evidence for a central role of contemporary hydrodynamics in maintaining genetic breaks across these two major biogeographic transition zones. Our findings further show the importance of a comprehensive understanding of oceanographic regimes in hydrodynamically complex coastal regions to explain the maintenance of sharp genetic breaks along continuously populated coastlines.Foundation for Science and Technology (FCT-MEC, Portugal) [DL57/2016/CP1361/CT0035]National Research Foundation of South AfricaNational Research Foundation - South Africa [64801]FCTPortuguese Foundation for Science and TechnologyEuropean Commission [SFRH/BPD/88935/2012, SFRH/BPD/111003/2015]Pew Marine Fellowship (USA) [SFRH/BPD/111003/2015][BIODIVERSA/004/2015][IF/01413/2014/CP1217/CT0004][UID/Multi/04326/2019]info:eu-repo/semantics/publishedVersio

Heme b distributions through the Atlantic Ocean: evidence for "anemic" phytoplankton populations

Heme b is an iron-containing cofactor in hemoproteins that participates in the fundamental processes of photosynthesis and respiration in phytoplankton. Heme b concentrations typically decline in waters with low iron concentrations but due to lack of field data, the distribution of heme b in particulate material in the ocean is poorly constrained. Here we report particulate heme b distributions across the Atlantic Ocean (59.9°N to 34.6°S). Heme b concentrations in surface waters ranged from 0.10 to 33.7 pmol L−1 (median = 1.47 pmol L−1, n = 974) and were highest in regions with a high biomass. The ratio of heme b to particulate organic carbon (POC) exhibited a mean value of 0.44 μmol heme b mol−1 POC. We identified the ratio of 0.10 µmol heme b mol−1 POC as the cut-off between heme b replete and heme b deficient (anemic) phytoplankton. By this definition, we observed anemic phytoplankton populations in the Subtropical South Atlantic and Irminger Basin. Comparison of observed and modelled heme b suggested that heme b could account for between 0.17–9.1% of biogenic iron. Our large scale observations of heme b relative to organic matter provide further evidence of the impact of changes in iron supply on phytoplankton iron status across the Atlantic Ocean

The Role of Mean Sea Level Annual Cycle on Extreme Water Levels Along European Coastline

The knowledge of extreme total water levels (ETWLs) and the derived impact, coastal flooding and erosion, is crucial to face the present and future challenges exacerbated in European densely populated coastal areas. Based on 24 years (1993-2016) of multimission radar altimetry, this paper investigates the contribution of each water level component: tide, surge and annual cycle of monthly mean sea level (MMSL) to the ETWLs. It focuses on the contribution of the annual variation of MMSL in the coastal flooding extreme events registered in a European database. In microtidal areas (Black, Baltic and Mediterranean Sea), the MMSL contribution is mostly larger than tide, and it can be at the same order of magnitude of the surge. In meso and macrotidal areas, the MMSL contribution is 30%) in the North Sea. No correlation was observed between the average annual cycle of monthly mean sea level (AMMSL) and coastal flooding extreme events (CFEEs) along the European coastal line. Positive correlations of the component variance of MMSL with the relative frequency of CFEEs extend to the Central Mediterranean (r = 0.59), North Sea (r = 0.60) and Baltic Sea (r = 0.75). In the case of positive MMSL anomalies, the correlation expands to the Bay of Biscay and northern North Atlantic (at >90% of statistical significance). The understanding of the spatial and temporal patterns of a combination of all the components of the ETWLs shall improve the preparedness and coastal adaptation measures to reduce the impact of coastal flooding

Evidence for rangewide panmixia despite multiple barriers to dispersal in a marine mussel

Oceanographic features shape the distributional and genetic patterns of marine species by interrupting or promoting connections among populations. Although general patterns commonly arise, distributional ranges and genetic structure are species-specific and do not always comply with the expected trends. By applying a multimarker genetic approach combined with Lagrangian particle simulations (LPS) we tested the hypothesis that oceanographic features along northeastern Atlantic and Mediterranean shores influence dispersal potential and genetic structure of the intertidal mussel Perna perna. Additionally, by performing environmental niche modelling we assessed the potential and realized niche of P. perna along its entire native distributional range and the environmental factors that best explain its realized distribution. Perna perna showed evidence of panmixia across > 4,000 km despite several oceanographic breaking points detected by LPS. This is probably the result of a combination of life history traits, continuous habitat availability and stepping-stone dynamics. Moreover, the niche modelling framework depicted minimum sea surface temperatures (SST) as the major factor shaping P. perna distributional range limits along its native areas. Forthcoming warming SST is expected to further change these limits and allow the species to expand its range polewards though this may be accompanied by retreat from warmer areas.Fundacao para a Ciencia e Tecnologia (FCT-MEC, Portugal) [UID/Multi/04326/2013, IF/01413/2014/CP1217/CT0004]; South African Research Chairs Initiative (SARChI) of the Department of Science and Technology; National Research Foundation; South African National Research Foundation (NRF); Portuguese Fundacao para a Ciencia e Tecnologia (FCT) [SFRH/BPD/85040/2012, SFRH/BPD/111003/2015]info:eu-repo/semantics/publishedVersio

The Effect of Multiple Formats on Understanding Complex Visual Displays

Provides pedagogical insight concerning the skill of contours The resource being annotated is: http://www.dlese.org/dds/catalog_DLESE-000-000-004-595.htm

The Effect of Multiple Formats on Understanding Complex Visual Displays

Students in introductory science courses frequently have difficulty comprehending complex graphics such as contour maps. Computer-assisted instruction (CAI), because of its ability to convey the same information in different formats, may help students gain necessary graphic interpretation skills. This article describes a research project in which students practiced reading two temperature maps in either a standard black and white contour or a color-enhanced contour format. They were then divided into groups and tested using only standard contour maps. The tests examined comprehension of the distribution of sea surface temperature, oceanographic phosphate concentration, and brain activation. Results suggest that having students practice with differently formatted maps of the same information improves later comprehension of standard contour maps. Educational levels: Graduate or professional

The Effects of Chlorophyll Assimilation on Carbon Fluxes in a Global Biogeochemical Model

In this paper, we investigated whether the assimilation of remotely-sensed chlorophyll data can improve the estimates of air-sea carbon dioxide fluxes (FCO2). Using a global, established biogeochemical model (NASA Ocean Biogeochemical Model, NOBM) for the period 2003-2010, we found that the global FCO2 values produced in the free-run and after assimilation were within -0.6 mol C m(sup -2) y(sup -1) of the observations. The effect of satellite chlorophyll assimilation was assessed in 12 major oceanographic regions. The region with the highest bias was the North Atlantic. Here the model underestimated the fluxes by 1.4 mol C m(sup -2) y(sup -1) whereas all the other regions were within 1 mol C m(sup -2) y(sup -1) of the data. The FCO2 values were not strongly impacted by the assimilation, and the uncertainty in FCO2 was not decreased, despite the decrease in the uncertainty in chlorophyll concentration. Chlorophyll concentrations were within approximately 25% of the database in 7 out of the 12 regions, and the assimilation improved the chlorophyll concentration in the regions with the highest bias by 10-20%. These results suggest that the assimilation of chlorophyll data does not considerably improve FCO2 estimates and that other components of the carbon cycle play a role that could further improve our FCO2 estimates

Global Diversity of the Stylasteridae (Cnidaria: Hydrozoa: Athecatae)

The history and rate of discovery of the 247 valid Recent stylasterid species are discussed and graphed, with emphasis on five historical pulses of species descriptions. A table listing all genera, their species numbers, and their bathymetric ranges are presented. The number of species in 19 oceanographic regions is mapped, the southwestern temperate Pacific (region including New Zealand) having the most species; species are cosmopolitan from the Arctic Circle to the Antarctic at depths from 0 to 2789 m. The current phylogenetic classification of the genera is briefly discussed. An illustrated glossary of 53 morphological characters is presented. Biological and ecological information pertaining to reproduction, development, commensals, and distribution is discussed. Aspects of stylasterid mineralogy and taxa of commercial value are discussed, concluding with suggestions for future work

Cruise Report C-200 : Scientific data collected aboard SSV Corwith Cramer, Woods Hole, MA – Sable Island, Canada – Halifax, Nova Scotia – Woods Hole, MA, 6 July, 2005 – 2 August, 2005

Woods Hole, MA – Sable Island, Canada – Halifax, Nova Scotia – Woods Hole, MA, 6 July, 2005 – 2 August, 2005This cruise report provides a record of data collected during C200 aboard the SSV Corwith Cramer from Woods Hole, MA, USA to Sable Island, Canada, continuing on to Halifax, Nova Scotia, Canada and returning to Woods Hole (Figure 1). We collected samples or data with 98 individual deployments from 37 discrete stations (Table 2) along our cruise track. In addition we continuously sampled water depth, sub-bottom profiles and Acoustic Doppler Current Profiles (ADCP) along with flow-through sea surface temperature, salinity and in vivo fluorescence. This report summarizes physical, chemical and biological characteristics at the sea surface (Table 3, Figure 2) and at depth (Tables 4 and 5, Figure 3a) along our cruise track. A complete oceanographic survey of two submarine canyons (Hydrographer’s canyon south of Georges bank and The Gully, east of Sable Island) were completed. Bathymetry and surface currents for each seamount are available on request. Temperature, salinity and fluorescence profiles are presented (Figures 3b and 3c). Large scale hydrography is summarized by contour plots of temperature, salinity and fluorescence (Figure 4); whereas large scale current patterns are summarized by contour plots of current direction, magnitude and echo amplitude (Figure 5). In addition, the distribution and density of zooplankton at the sea surface (Table 6) and at depth (Figures 7 and 8) are presented. Sediment samples were sieved and grain size percentage of each fraction was determined (Figure 9). Additional CTD, bathymetry (CHIRP), current (ADCP) and biological data are not reported here but are available on request through Sea Education Association (SEA) and the Chief Scientist. The information in this report is not intended to represent final interpretation of the data and should not be excerpted or cited without written permission from SEA. Unpublished data can be made available by arrangement with the SEA archivist by contacting: Erik R. Zettler, Science Coordinator Sea Education Association, P.O. Box 6, Woods Hole, MA 02543, U.S.A. 508-540-3954 x29 fax 508-457-4673 email: [email protected] website: www.sea.edu As part of SEA’s educational program, undergraduates conducted student-designed oceanographic research during the cruise. Project topics included physical, chemical, biological and geological oceanography (Table 10). Student research efforts culminated in a written report and public presentation to the ship’s company. These papers are available on request from SEA.NS

Turbulence as a driver for vertical plankton distribution in the subsurface upper ocean

Vertical distributions of turbulent energy dissipation rates and fluorescence were measured simultaneously with a high-resolution micro-profiler in four different oceanographic regions, from temperate to polar and from coastal to open waters settings. High fluorescence values, forming a deep chlorophyll maximum (DCM), were often located in weakly stratified portions of the upper water column, just below layers with maximum levels of turbulent energy dissipation rate. In the vicinity of the DCM, a significant negative relationship between fluorescence and turbulent energy dissipation rate was found. We discuss the mechanisms that may explain the observed patterns of planktonic biomass distribution within the ocean mixed layer, including a vertically variable diffusion coefficient and the alteration of the cells’ sinking velocity by turbulent motion. These findings provide further insight into the processes controlling the vertical distribution of the pelagic community and position of the DCM