Eutrophication and macroalgal blooms in temperate and tropical coastal waters: Nutrient enrichment experiments with Ulva spp.

Receiving coastal waters and estuaries are among the most nutrient-enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast-growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth-limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low- to high-nutrient supplies. We carried out N and P enrichment field experiments on Ulva spp. in seven coastal systems, with one of these systems represented by three different subestuaries, for a total of nine sites. We showed that rate of growth of Ulva spp. was directly correlated to annual dissolved inorganic nitrogen (DIN) concentrations, where growth increased with increasing DIN concentration. Internal N pools of macroalgal fronds were also linked to increased DIN supply, and algal growth rates were tightly coupled to these internal N pools. The increases in DIN appeared to be related to greater inputs of wastewater to these coastal waters as indicated by high δ15N signatures of the algae as DIN increased. N and P enrichment experiments showed that rate of macroalgal growth was controlled by supply of DIN where ambient DIN concentrations were low, and by P where DIN concentrations were higher, regardless of latitude or geographic setting. These results suggest that understanding the basis for macroalgal blooms, and management of these harmful phenomena, will require information as to nutrient sources, and actions to reduce supply of N and P in coastal waters concerned.Fil: Teichberg, Mirta. Leibniz Center For Tropical Marine Research; AlemaniaFil: Fox, Sophia E.. Marine Biological Laboratory; Estados UnidosFil: Olsen, Ylva S.. Bangor University; Reino UnidoFil: Valiela, Ivan. Marine Biological Laboratory; Estados UnidosFil: Martinetto, Paulina Maria del Rosario. Universidad Nacional de Mar del Plata; ArgentinaFil: Iribarne, Oscar Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Muto, Elizabeti Yuriko. Universidade de Sao Paulo; BrasilFil: Petti, Monica A.V.. Universidade de Sao Paulo; BrasilFil: Corbisier, Thaïs N.. Universidade de Sao Paulo; BrasilFil: Soto-Jiménez, Martín. Universidad Nacional Autónoma de México; MéxicoFil: Páez-Osuna, Federico. Universidad Nacional Autónoma de México; MéxicoFil: Castro, Paula. University Of Coimbra; BrasilFil: Freitas, Helena. University Of Coimbra; BrasilFil: Zitelli, Andreina. Università Iuav Di Venezia; ItaliaFil: Cardinaletti, Massimo. Gruppo Veritas; ItaliaFil: Tagliapietra, Davide. Consiglio Nazionale delle Ricerche; Itali

Food supply confers calcifiers resistance to ocean acidification

Invasion of ocean surface waters by anthropogenic CO emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.This work was funded by grants from the Danish Environmental Protection Agency within the Danish 486 Cooperation for Environment in the Arctic (DANCEA), ASSEMBLE grant agreement no. 227799 from European Community and from the Spanish Ministry of Economy and Competitiveness (ESTRESX, number CTM2012-32603). N.A.L. acknowledges support from grants Fondecyt 1140938 and NC 1200286 (Millennium Nucleus Project MUSELS) and L.R. was supported by BECAS CHILE fellowship program from Comisión Nacional de Investigación Científica y Tecnológica de Chile (CONICYT)Peer Reviewe

A Systematic Review of How Multiple Stressors from an Extreme Event Drove Ecosystem-Wide Loss of Resilience in an Iconic Seagrass Community

A central question in contemporary ecology is how climate change will alter ecosystem structure and function across scales of space and time. Climate change has been shown to alter ecological patterns from individuals to ecosystems, often with negative implications for ecosystem functions and services. Furthermore, as climate change fuels more frequent and severe extreme climate events (ECEs) like marine heatwaves (MHWs), such acute events become increasingly important drivers of rapid ecosystem change. However, our understanding of ECE impacts is hampered by limited collection of broad scale in situ data where such events occur. In 2011, a MHW known as the Ningaloo Niño bathed the west coast of Australia in waters up to 4°C warmer than normal summer temperatures for almost 2 months over 1000s of kilometres of coastline. We revisit published and unpublished data on the effects of the Ningaloo Niño in the seagrass ecosystem of Shark Bay, Western Australia (24.6 – 26.6o S), at the transition zone between temperate and tropical seagrasses. Therein we focus on resilience, including resistance to and recovery from disturbance across local, regional and ecosystem-wide spatial scales and over the past 8 yearsThermal effects on temperate seagrass health were severe and exacerbated by simultaneous reduced light conditions associated with sediment inputs from record floods in the south-eastern embayment and from increased detrital loads and sediment destabilisation. Initial extensive defoliation of Amphibolis antarctica, the dominant seagrass, was followed by rhizome death that occurred in 60-80% of the bay’s meadows, equating to decline of over 1000 km2 of meadows. This loss, driven by direct abiotic forcing, has persisted, while indirect biotic effects (e.g. dominant seagrass loss) have allowed colonisation of some areas by small fast-growing tropical species (e.g. Halodule uninervis). Those biotic effects also impacted multiple consumer populations including turtles and dugongs, with implications for species dynamics, food web structure, and ecosystem recovery. We show multiple stressors can combine to evoke extreme ecological responses by pushing ecosystems beyond their tolerance. Finally, both direct abiotic and indirect biotic effects need to be explicitly considered when attempting to understand and predict how ECEs will alter marine ecosystem dynamics

Integrating isotopes and documentary evidence : dietary patterns in a late medieval and early modern mining community, Sweden

We would like to thank the Archaeological Research Laboratory, Stockholm University, Sweden and the Tandem Laboratory (Ångström Laboratory), Uppsala University, Sweden, for undertaking the analyses of stable nitrogen and carbon isotopes in both human and animal collagen samples. Also, thanks to Elin Ahlin Sundman for providing the δ13C and δ15N values for animal references from Västerås. This research (Bäckström’s PhD employment at Lund University, Sweden) was supported by the Berit Wallenberg Foundation (BWS 2010.0176) and Jakob and Johan Söderberg’s foundation. The ‘Sala project’ (excavations and analyses) has been funded by Riksens Clenodium, Jernkontoret, Birgit and Gad Rausing’s Foundation, SAU’s Research Foundation, the Royal Physiographic Society of Lund, Berit Wallenbergs Foundation, Åke Wibergs Foundation, Lars Hiertas Memory, Helge Ax:son Johnson’s Foundation and The Royal Swedish Academy of Sciences.Peer reviewedPublisher PD

Effect of field exposure to 38-year-old residual petroleum hydrocarbons on growth, condition index, and filtration rate of the ribbed mussel, Geukensia demissa

Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Environmental Pollution 154 (2008): 312-319, doi:10.1016/j.envpol.2007.10.008.In September 1969, the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor, MA. Today a substantial amount, approximately 100 kg, of moderately degraded petroleum remains within the sediment and along eroding creek banks. The ribbed mussels, Geukensia demissa, which inhabit the salt marsh creek bank, are exposed to the spilled oil. Examination of short-term exposure was done with transplantation of G. demissa from a control site, Great Sippewissett marsh, into Wild Harbor. We examined the effects of long-term exposure with transplantation of mussels from Wild Harbor into Great Sippewissett. Both the short- and long-term exposure transplants exhibited slower growth rates, shorter mean shell lengths, lower condition indices, and decreased filtration rates. Our results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas.This work is the result of research sponsored by NOAA National Sea Grant College Program Office, Department of Commerce, under Grant No. NA16RG2273, Woods Hole Oceanographic Institution Sea Grant Project No. R/P-73. Additional support was provided by funding from the NSF-funded Research Experience for Undergraduates program, award 0453292, an Office of Naval Research Young Investigator Award (N00014-04-01-0029) to C. Reddy

Combined effect of warming and infection by Labyrinthula sp. on the Mediterranean seagrass Cymodocea nodosa

© 2015 Inter-Research. Global warming is predicted to alter host-pathogen relationships and increase disease outbreaks in terrestrial and marine environments. We evaluated the effect of warming on the susceptibility of Cymodocea nodosa to infection by Labyrinthula sp. (the causative agent of seagrass wasting disease) by monitoring disease symptoms and seagrass photobiology. Seagrass shoots were incubated at temperatures between 24 and 32°C, encompassing maximum summer seawater temperatures projected for the Mediterranean during the 21st century, and exposed to Labyrinthula sp. for 2 wk. The effect of temperature on pathogen growth was also tested by growing Labyrinthula sp. in liquid medium for 24 h. Disease severity, measured as lesion size, decreased with warming, but the presence of lesions had a negative effect on quantum yield, quantum efficiency, optimum irradiance and the maximum electron transport rate (ETRmax) in adjacent tissue across the full range of temperatures. The direct effect of increased temperature on photochemical efficiency was positive in terms of quantum yield, whereas compensation and optimum irradiances and ETRmax decreased slightly with warming. Warming stimulated Labyrinthula sp. growth up to a threshold of around 26 to 28°C, beyond which cell division and elongation of the ectoplasmic network decreased. At 32°C almost no growth was observed. Our results indicate that warming does not make C. nodosa more susceptible to infection by Labyrinthula sp. and that the disease is unlikely to pose a serious threat to C. nodosa, but that the pathogen is able to persist during forecasted warm periods.Peer Reviewe

Ecophysiological responses of three Mediterranean invasive seaweeds (Acrothamnion preissii, Lophocladia lallemandii and Caulerpa cylindracea) to experimental warming

© 2015 Elsevier Ltd. The Mediterranean Sea is a hotspot for invasive species and projected Mediterranean warming might affect their future spreading. We experimentally examined ecophysiological responses to the temperature range 23-31. °C in three invasive seaweeds commonly found in the Mediterranean: Acrothamnion preissii, Caulerpa cylindracea and Lophocladia lallemandii. The warming range tested encompassed current and projected (for the end of 21st Century) maximum temperatures for the Mediterranean Sea. Optimal ecophysiological temperatures for A. preissii, C. cylindracea and L. lallemandii were 25. °C, 27. °C and 29. °C, respectively. Warming below the optimal temperatures enhanced RGR of all studied invasive seaweeds. Although sensitive, seaweed photosynthetic yield was less temperature-dependent than growth. Our results demonstrate that temperature is a key environmental parameter in regulating the ecophysiological performance of these invasive seaweeds and that Mediterranean warming conditions may affect their invasion trajectory.This work was funded by Spanish (MEDEICG: CTM2009-07013, and EstresX: CTM2012-32603) and AXA Foundation projectsPeer Reviewe

Photosynthetic activity buffers ocean acidification in seagrass meadows

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Warming Reduces Pathogen Pressure on a Climate-Vulnerable Seagrass Species

© 2014, Coastal and Estuarine Research Federation. Climate change is predicted to alter pathogen–host relationships and there is evidence of an increase in disease in both terrestrial and marine environments. Infection rates do not always increase linearly with temperature since thermal tolerance ranges of host and pathogens do not necessarily overlap and the host may benefit from thermal refugia of low or no disease pressure. Here, we demonstrate that climate warming may alleviate pathogen pressure in a climate-vulnerable Mediterranean seagrass, Posidonia oceanica. We tested the impact of warming on infection by Labyrinthula sp.—the causative pathogen of wasting disease—and the combined effect of elevated temperature and disease on photobiology. Infected and control shoots of P. oceanica were incubated at temperatures between 24 and 32 °C, encompassing maximum summer seawater temperatures projected for the Mediterranean Sea during the twenty-first century. Warming reduced the occurrence and severity of the disease and temperatures >28 °C inhibited cell division and growth of Labyrinthula. Photochemical efficiency was not significantly affected by short-term warming or by Labyrinthula infection. These results suggest that, unlike what has been predicted for the majority of pathogen–host relationships, warming may lead to a reduced risk of wasting disease in P. oceanica and relieve pathogen pressure from this species.This research was supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (TEMSPATH, 254297: FP7-PEOPLE-2009-IEF) awarded to YS Olsen and the ESTRESX project funded by the Spanish Ministry of Economy and Competitivity (CTM2012-32603). M. Potouroglou was funded by a Short-Term Scientific Mission of the COST action ES0906 “Seagrass productivity: from genes to ecosystem management”Peer Reviewe