53 research outputs found

    Data from: Form–function relationships in a marine foundation species depend on scale: a shoot to global perspective from a distributed ecological experiment

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    Abstract Form-function relationships in plants underlie their ecosystem roles in supporting higher trophic levels through primary production, detrital pathways, and habitat provision. For widespread, phenotypically-variable plants, productivity may differ not only across abiotic conditions, but also from distinct morphological or demographic traits. A single foundation species, eelgrass (Zostera marina), typically dominates north temperate seagrass meadows, which we studied across 14 sites spanning 32-61° N latitude and two ocean basins. Body size varied by nearly two orders of magnitude through this range, and was largest at mid-latitudes and in the Pacific Ocean. At the global scale, neither latitude, site-level environmental conditions, nor body size helped predict productivity (relative growth rate 1-2% d-1 at most sites), suggesting a remarkable capacity of Z. marina to achieve similar productivity in summer. Furthermore, among a suite of stressors applied within sites, only ambient leaf damage reduced productivity; grazer reduction and nutrient addition had no effect on eelgrass size or growth. Scale-dependence was evident in different allometric relationships within and across sites for productivity and for modules (leaf count) relative to size. Z. marina provides a range of ecosystem functions related to both body size (habitat provision, water flow) and growth rates (food, carbon dynamics). Our observed decoupling of body size and maximum production suggests that geographic variation in these ecosystem functions may be independent, with a future need to resolve how local adaptation or plasticity of body size might actually enable more consistent peak productivity across disparate environmental conditions

    Radio-loud ROSAT sources near the North Ecliptic Pole

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    A deep and large-area survey of the North Ecliptic Pole region was made with the ROSAT All-Sky Survey and the VLA to elucidate the population of radio-loud extragalactic objects. A region of 29.3 square degrees was surveyed with sensitivities around 5 x 10"-"1"4 erg s"-"1 cm"-"2 in the soft X-ray band and 1 mJy at 1.5 GHz. Optical counterparts were sought on digitized Schmidt plates from POSS-I and II. Seventy-four reliable RASS-VLA sources were found. The sample is a heterogeneous mixture of Seyfert galaxies, quasars, BL Lac objects, galaxy clusters and groups containing a radio galaxy. Optical magnitudes range from B#approx =#14 to B>22. Three results are noteworthy: (1) the bimodality in the ratio of radio to optical emission seen in optically- and X-ray-selected AGN samples is also evident in the ROSAT-VLA objects; (2) X-ray and radio selection is an effective method for locating poor galaxy clusters and groups; and (3) a considerable population of optically faint but X-ray/ratio-bright objects is present. This last group may be either distant clusters with radio galaxies or 'red quasars'. (orig.)Available from TIB Hannover: RN 9303(446) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

    Surface Ocean CO2 Atlas (SOCAT) V6

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    The Surface Ocean CO2 Atlas (SOCAT) is a synthesis activity by the international marine carbon research community (>100 contributors). SOCAT version 6 has 23.4 million quality-controlled, surface ocean fCO2 (fugacity of carbon dioxide) observations from 1957 to 2017 for the global oceans and coastal seas. Calibrated sensor data are also available. Automation allows annual, public releases. SOCAT data is discoverable, accessible and citable. SOCAT enables quantification of the ocean carbon sink and ocean acidification and evaluation of ocean biogeochemical models. SOCAT represents a milestone in biogeochemical and climate research and in informing policy. 424 datasets Version 5: https://doi.pangaea.de/10.1594/PANGAEA.877863 Version 4: https://doi.pangaea.de/10.1594/PANGAEA.866856 Version 3: https://doi.pangaea.de/10.1594/PANGAEA.849770 Version 2: https://doi.org/10.1594/PANGAEA.81515

    The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans

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    AbstractWhile considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30Âş of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions, and traits can help us predict how communities may respond to environmental change
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