Ocean time-series provide vital information needed for assessing ecosystem change. This paper summarizes the historical context, major program objectives, and future research priorities for three contemporary ocean time-series programs: The Hawaii Ocean Time-series (HOT), the Bermuda Atlantic Time-series Study (BATS), and the CARIACO Ocean Time-Series. These three programs operate in physically and biogeochemically distinct regions of the world’s oceans, with HOT and BATS located in the open-ocean waters of the subtropical North Pacific and North Atlantic, respectively, and CARIACO situated in the anoxic Cariaco Basin of the tropical Atlantic. All three programs sustain near-monthly shipboard occupations of their field sampling sites, with HOT and BATS beginning in 1988, and CARIACO initiated in 1996. The resulting data provide some of the only multi-disciplinary, decadal-scale determinations of time-varying ecosystem change in the global ocean. Facilitated by a scoping workshop (September 2010) sponsored by the Ocean Carbon Biogeochemistry (OCB) program, leaders of these time-series programs sought community input on existing program strengths and for future research directions. Themes that emerged from these discussions included:
1. Shipboard time-series programs are key to informing our understanding of the connectivity between changes in ocean-climate and biogeochemistry.
2. The scientific and logistical support provided by shipboard time-series programs forms the backbone for numerous research and education programs. Future studies should be encouraged that seek mechanistic understanding of ecological interactions underlying the biogeochemical dynamics at these sites.
3. Detecting time-varying trends in ocean properties and processes requires consistent, high-quality measurements. Time-series must carefully document analytical procedures and, where possible, trace the accuracy of analyses to certified standards and internal reference materials.
4. Leveraged implementation, testing, and validation of autonomous and remote observing technologies at time-series sites provide new insights into spatiotemporal variability underlying ecosystem changes.
5. The value of existing time-series data for formulating and validating ecosystem models should be promoted.
In summary, the scientific underpinnings of ocean time-series programs remain as strong and important today as when these programs were initiated. The emerging data inform our knowledge of the ocean’s biogeochemistry and ecology, and improve our predictive capacity about planetary change.
Continue reading ‘Sea change: charting the course for biogeochemical ocean time-series research in a new millennium’
The Palaeocene–Eocene Thermal Maximum was marked by global warming and ocean acidification. Fossil and experimental analyses show that different species of marine calcifying algae responded very differently to the environmental upheavals.
Continue reading ‘Palaeontology: plankton in a greenhouse world’
Phytoplankton support most marine food webs, but little is known about their intraspecific diversity. Research shows the strains that are most responsive to changes in CO2 concentration may outcompete less flexible types in an acidifying ocean.
Continue reading ‘Biological oceanography: plastic plankton prosper’
Published 28 February 2013
Tags: algae, community composition, field, laboratory, mesocosms, morphology, multiple factors, North Atlantic, reproduction, survival, temperature
Climate-driven and biodiversity effects on the structure and functioning of ecosystems are increasingly studied as multiple stressors, which subsequently may influence species invasions. We used a mesocosm experiment to test how increases in temperature and CO2 partial pressure (pCO2) interact with functional diversity of resident macroalgal assemblages and affect the invasion success of the non-indigenous macroalga Sargassum muticum. Early settlement of S. muticum germlings was assessed in the laboratory under common environmental conditions across three monocultures and a polyculture of functional groups of native macroalgae, which had previously grown for 3 weeks under crossed treatments of temperature and pCO2. Functional diversity was a key driver shaping early settlement of the invader, with significant identity and richness effects: higher settlement occurred in low-diversity and low-stature assemblages, even after accounting for treatment biomass. Overall, early survivorship of settled germlings responded to an interaction of temperature and pCO2 treatments, with survivorship enhanced in one treatment (high pCO2 at ambient Temperature) after 3 days, and reduced in another (ambient pCO2 at high Temperature) after 10 days, although size was enhanced in this same treatment. After 6 months in the field, legacy effects of laboratory treatments remained, with S. muticum reaching higher cover in most assemblages previously subjected to ambient pCO2, but ephemeral green algae appearing disproportionately after elevated-pCO2 treatment. These results caution that invasion outcomes may change at multiple points in the life cycle under higher-CO2, higher-temperature conditions, in addition to supporting a role for intact, functionally diverse assemblages in limiting invader colonization.
Continue reading ‘Functional diversity and climate change: effects on the invasibility of macroalgal assemblages’
Published 28 February 2013
Meetings , Science
Dates: 4 July (all day)
Organised by: Rod Wilson (University of Exeter), Fredrik Jutfelt (University of Gothenburg)
Confirmed Speakers: Phil Munday (James Cook University, Australia), Goran Nilsson (University of Oslo), Hans Otto Poertner (Alfred Wegener Institute), Frank Melzner (GEOMAR Helmholtz Centre for Ocean Research Kiel)
Continue reading ‘Aquatic life in a warmer and higher CO2 world – session at SEB Valencia 2013′
Published 28 February 2013
Projects , Science
Submission deadline: 31 July 2013
The problem Over the last 150 years, atmospheric carbon dioxide has increased from 290 ppm to 395 ppm, primarily due to the burning of fossil fuels. Ocean acidification is occurring because the world’s oceans, as a primary sink for atmospheric carbon dioxide, are absorbing increasing amounts of CO2, resulting in a lower pH. Ocean acidification, together with changes in ocean temperature, salinity, and stratification, is altering the fundamental chemical balance of ocean and coastal waters, impacting the global ocean ecosystem, and potentially threatening marine food supplies.
The challenge The Paul G. Allen Family Foundation, as part of a larger ocean health initiative, and in collaboration with The Oceanography Society, is offering a $10,000 prize for the most promising new science-based concept for mitigating environmental and/or societal impacts of ocean acidification.
Continue reading ‘The Paul G. Allen Ocean Challenge: mitigating acidification impacts’
Ocean ecosystems are increasingly stressed by human-induced changes of their physical, chemical and biological environment. Among these changes, warming, acidification, deoxygenation and changes in primary productivity by marine phytoplankton can be considered as four of the major stressors of open ocean ecosystems. Due to rising atmospheric CO2 in the coming decades, these changes will be amplified. Here, we use the most recent simulations performed in the framework of the Coupled Model Intercomparison Project 5 to assess how these stressors may evolve over the course of the 21st century. The 10 Earth System Models used here project similar trends in ocean warming, acidification, deoxygenation and reduced primary productivity for each of the IPCC’s representative concentration parthways (RCP) over the 21st century. For the “business-as-usual” scenario RCP8.5, the model-mean changes in 2090s (compared to 1990s) for sea surface temperature, sea surface pH, global O2 content and integrated primary productivity amount to +2.73 °C, −0.33 pH unit, −3.45% and −8.6%, respectively. For the high mitigation scenario RCP2.6, corresponding changes are +0.71 °C, −0.07 pH unit, −1.81% and −2.0% respectively, illustrating the effectiveness of extreme mitigation strategies. Although these stressors operate globally, they display distinct regional patterns. Large decreases in O2 and in pH are simulated in global ocean intermediate and mode waters, whereas large reductions in primary production are simulated in the tropics and in the North Atlantic. Although temperature and pH projections are robust across models, the same does not hold for projections of sub-surface O2 concentrations in the tropics and global and regional changes in net primary productivity.
Continue reading ‘Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models’