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Susan E. Hartman, Richard S. Lampitt, Kate E. Larkin, Maureen Pagnani, Jon Campbell, Thanos Gkritzalis, Zong-Pei Jiang, Corinne A. Pebody, Henry A. Ruhl, Andrew J. Gooday, Brian J. Bett, David S. M. Billett, Paul Provost, Rob McLachlan, Jon D. Turton, Steven Lankester, The Porcupine Abyssal Plain fixed-point sustained observatory (PAP-SO): variations and trends from the Northeast Atlantic fixed-point time-series, ICES Journal of Marine Science, Volume 69, Issue 5, July 2012, Pages 776–783, https://doi.org/10.1093/icesjms/fss077
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Abstract
The Porcupine Abyssal Plain sustained observatory (PAP-SO) in the Northeast Atlantic (49°N 16.5°W; 4800 m) is the longest running open-ocean multidisciplinary observatory in the oceans around Europe. The site has produced high-resolution datasets integrating environmental and ecologically relevant variables from the surface to the seabed for >20 years. Since 2002, a full-depth mooring has been in place with autonomous sensors measuring temperature, salinity, chlorophyll-a fluorescence, nitrate, and pCO2. These complement ongoing mesopelagic and seabed observations on downward particle flux and benthic ecosystem structure and function. With national and European funding, the observatory infrastructure has been advanced steadily, with the latest development in 2010 involving collaboration between the UK's Meteorological Office and Natural Environment Research Council. This resulted in the first simultaneous atmospheric and ocean datasets at the site. All PAP-SO datasets are open access in near real time through websites and as quality-controlled datasets for a range of remote users using ftp sites and uploaded daily to MyOcean and the global telecommunications system for use in modelling activities. The combined datasets capture short-term variation (daily–seasonal), longer term trends (climate-driven), and episodic events (e.g. spring-bloom events), and the data contribute to the Europe-wide move towards good environmental status of our seas, driven by the EU's Marine Strategy Framework Directive (http://ec.europa.eu/environment/water/marine).Hartman, S. E., Lampitt, R. S., Larkin, K. E., Pagnani, M., Campbell, J., Gkritzalis, T., Jiang, Z.-P., Pebody, C. A., Ruhl, H. A., Gooday, A. J., Bett, B. J., Billett, D. S. M., Provost, P., McLachlan, R., Turton, J. D., and Lankester, S. 2012. The Porcupine Abyssal Plain fixed-point sustained observatory (PAP-SO): variations and trends from the Northeast Atlantic fixed-point time-series. – ICES Journal of Marine Science, 69: 776–783.
The Porcupine Abyssal Plain sustained observatory
The Porcupine Abyssal Plain sustained observatory (PAP-SO) is situated in the subpolar Northeast Atlantic (49°N 16.5°W) at a water depth of 4800 m (Figure 1). This location is considered remote from the complexities of the continental slope and the Mid-Atlantic Ridge. It is the longest running multidisciplinary open-ocean time-series observatory in Europe and one of the longest in the world. Since 1989, it has produced high-resolution in situ time-series data of climatically and environmentally relevant variables from the entire water column and the seabed beneath. Historically, the measurements have been sampled from a research vessel. However, a fixed-point mooring has been in place since 2002, with a surface buoy being added in 2007. In 2010, collaboration between the UK's Natural Environment Research Council (NERC) and the Meteorological Office led to a redesigned infrastructure, deployed on 1 June 2010, and the first simultaneous monitoring of in situ meteorological and ocean variables at the PAP-SO (Table 1).
Depth . | Parameters/variables . | Sensor . | Frequency . |
---|---|---|---|
Atmospheric (UK Meteorological Office buoy) | |||
3.5 m above surface | Windspeed and direction | Gill acoustic sensor and revolution magnetic compass | Hourly (10 min mean) |
2 m above surface | Relative humidity | Rotronic Hygroclip R/S sensor | Hourly (instantaneous reading) |
2 m above surface | Air temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1 m (subsurface) | Sea temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1.75 m above surface | Atmospheric pressure | Druck RPT350 pressure sensor | Hourly (20 s mean) |
Surface | Significant wave height and period | Datawell heave sensor; 17.5 min average | Hourly (over 17.5 min sample) |
Surface ocean (fixed frame) | |||
30 m | CTD | Seabird MicroCAT | 10 min |
30 m | CTD + dissolved oxygen | Seabird MicroCAT IDO | 30 min |
30 m | Nitrate and nitrite (chemistry) | NAS | 4 h |
30 m | Nitrate and nitrite (UV absorption) | Satlantic ISUS | 1 h |
30 m | Chlorophyll | WETlabs (FLNTUSB) and Cyclops | 6 h, 1 h |
30 m | Dissolved oxygen | Aanderaa optode on Seaguard | 1 h |
30 m | Currents | DCS | 1 h |
30 m | CO2 (IR absorbance after equilibration) | PRO-OCEANUS | 12 h |
30 m | Dissolved gases (gas tension device) | PRO-OCEANUS gas tension device | 12 h |
30 m | Radiance Lu upwelling radiance | Radiometer (Satlantic OCR, 7-channel with standard wavelengths) | 1 h |
30 m | Irradiance Ed, Eu downwelling irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Irradiance Es total irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Zooplankton sampler | McLane zooplankton sampler | Every 2 d |
Deep ocean (subsurface mooring) | |||
25–1 000 m | CTD | Seabird MicroCAT | 10 min |
3 000 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
3 000 m | Currents | Aanderaa RCM9 | 4 h |
3 050 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Currents | Aanderaa RCM9 | 4 h |
Seabed (lander) | |||
Seabed (4 800 m) | Time-lapse photos | Imenco AS (SDS 12100) stills camera | 8 h |
Depth . | Parameters/variables . | Sensor . | Frequency . |
---|---|---|---|
Atmospheric (UK Meteorological Office buoy) | |||
3.5 m above surface | Windspeed and direction | Gill acoustic sensor and revolution magnetic compass | Hourly (10 min mean) |
2 m above surface | Relative humidity | Rotronic Hygroclip R/S sensor | Hourly (instantaneous reading) |
2 m above surface | Air temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1 m (subsurface) | Sea temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1.75 m above surface | Atmospheric pressure | Druck RPT350 pressure sensor | Hourly (20 s mean) |
Surface | Significant wave height and period | Datawell heave sensor; 17.5 min average | Hourly (over 17.5 min sample) |
Surface ocean (fixed frame) | |||
30 m | CTD | Seabird MicroCAT | 10 min |
30 m | CTD + dissolved oxygen | Seabird MicroCAT IDO | 30 min |
30 m | Nitrate and nitrite (chemistry) | NAS | 4 h |
30 m | Nitrate and nitrite (UV absorption) | Satlantic ISUS | 1 h |
30 m | Chlorophyll | WETlabs (FLNTUSB) and Cyclops | 6 h, 1 h |
30 m | Dissolved oxygen | Aanderaa optode on Seaguard | 1 h |
30 m | Currents | DCS | 1 h |
30 m | CO2 (IR absorbance after equilibration) | PRO-OCEANUS | 12 h |
30 m | Dissolved gases (gas tension device) | PRO-OCEANUS gas tension device | 12 h |
30 m | Radiance Lu upwelling radiance | Radiometer (Satlantic OCR, 7-channel with standard wavelengths) | 1 h |
30 m | Irradiance Ed, Eu downwelling irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Irradiance Es total irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Zooplankton sampler | McLane zooplankton sampler | Every 2 d |
Deep ocean (subsurface mooring) | |||
25–1 000 m | CTD | Seabird MicroCAT | 10 min |
3 000 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
3 000 m | Currents | Aanderaa RCM9 | 4 h |
3 050 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Currents | Aanderaa RCM9 | 4 h |
Seabed (lander) | |||
Seabed (4 800 m) | Time-lapse photos | Imenco AS (SDS 12100) stills camera | 8 h |
Depth . | Parameters/variables . | Sensor . | Frequency . |
---|---|---|---|
Atmospheric (UK Meteorological Office buoy) | |||
3.5 m above surface | Windspeed and direction | Gill acoustic sensor and revolution magnetic compass | Hourly (10 min mean) |
2 m above surface | Relative humidity | Rotronic Hygroclip R/S sensor | Hourly (instantaneous reading) |
2 m above surface | Air temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1 m (subsurface) | Sea temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1.75 m above surface | Atmospheric pressure | Druck RPT350 pressure sensor | Hourly (20 s mean) |
Surface | Significant wave height and period | Datawell heave sensor; 17.5 min average | Hourly (over 17.5 min sample) |
Surface ocean (fixed frame) | |||
30 m | CTD | Seabird MicroCAT | 10 min |
30 m | CTD + dissolved oxygen | Seabird MicroCAT IDO | 30 min |
30 m | Nitrate and nitrite (chemistry) | NAS | 4 h |
30 m | Nitrate and nitrite (UV absorption) | Satlantic ISUS | 1 h |
30 m | Chlorophyll | WETlabs (FLNTUSB) and Cyclops | 6 h, 1 h |
30 m | Dissolved oxygen | Aanderaa optode on Seaguard | 1 h |
30 m | Currents | DCS | 1 h |
30 m | CO2 (IR absorbance after equilibration) | PRO-OCEANUS | 12 h |
30 m | Dissolved gases (gas tension device) | PRO-OCEANUS gas tension device | 12 h |
30 m | Radiance Lu upwelling radiance | Radiometer (Satlantic OCR, 7-channel with standard wavelengths) | 1 h |
30 m | Irradiance Ed, Eu downwelling irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Irradiance Es total irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Zooplankton sampler | McLane zooplankton sampler | Every 2 d |
Deep ocean (subsurface mooring) | |||
25–1 000 m | CTD | Seabird MicroCAT | 10 min |
3 000 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
3 000 m | Currents | Aanderaa RCM9 | 4 h |
3 050 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Currents | Aanderaa RCM9 | 4 h |
Seabed (lander) | |||
Seabed (4 800 m) | Time-lapse photos | Imenco AS (SDS 12100) stills camera | 8 h |
Depth . | Parameters/variables . | Sensor . | Frequency . |
---|---|---|---|
Atmospheric (UK Meteorological Office buoy) | |||
3.5 m above surface | Windspeed and direction | Gill acoustic sensor and revolution magnetic compass | Hourly (10 min mean) |
2 m above surface | Relative humidity | Rotronic Hygroclip R/S sensor | Hourly (instantaneous reading) |
2 m above surface | Air temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1 m (subsurface) | Sea temperature | Electrical resistance thermometer (ERT) | Hourly (10 s mean) |
1.75 m above surface | Atmospheric pressure | Druck RPT350 pressure sensor | Hourly (20 s mean) |
Surface | Significant wave height and period | Datawell heave sensor; 17.5 min average | Hourly (over 17.5 min sample) |
Surface ocean (fixed frame) | |||
30 m | CTD | Seabird MicroCAT | 10 min |
30 m | CTD + dissolved oxygen | Seabird MicroCAT IDO | 30 min |
30 m | Nitrate and nitrite (chemistry) | NAS | 4 h |
30 m | Nitrate and nitrite (UV absorption) | Satlantic ISUS | 1 h |
30 m | Chlorophyll | WETlabs (FLNTUSB) and Cyclops | 6 h, 1 h |
30 m | Dissolved oxygen | Aanderaa optode on Seaguard | 1 h |
30 m | Currents | DCS | 1 h |
30 m | CO2 (IR absorbance after equilibration) | PRO-OCEANUS | 12 h |
30 m | Dissolved gases (gas tension device) | PRO-OCEANUS gas tension device | 12 h |
30 m | Radiance Lu upwelling radiance | Radiometer (Satlantic OCR, 7-channel with standard wavelengths) | 1 h |
30 m | Irradiance Ed, Eu downwelling irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Irradiance Es total irradiance | Radiometer (Satlantic OCR as above) | 1 h |
30 m | Zooplankton sampler | McLane zooplankton sampler | Every 2 d |
Deep ocean (subsurface mooring) | |||
25–1 000 m | CTD | Seabird MicroCAT | 10 min |
3 000 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
3 000 m | Currents | Aanderaa RCM9 | 4 h |
3 050 m | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Particle flux (sediment traps) | McLane sediment trap | Variable (d) |
100 m above seabed | Currents | Aanderaa RCM9 | 4 h |
Seabed (lander) | |||
Seabed (4 800 m) | Time-lapse photos | Imenco AS (SDS 12100) stills camera | 8 h |
The multidisciplinary set of sensors on the mooring (Figure 2) have produced high-resolution in situ time-series datasets, including subsurface (∼30 m depth) measurements of temperature, salinity, chlorophyll-a fluorescence, nitrate, and pCO2. Recent enhancements to the mixed layer variables include oxygen and irradiance, and a water sampler has been added to the sensor frame. A full list of the variables is provided in Table 1. Data are sent in near real time from the upper 1000 m through Iridium telemetry to the UK National Oceanography Centre (NOC). This full-depth observatory has allowed the analysis of trends in seasonal and interannual processes, and forms an integrated system from the euphotic zone to the benthic boundary layer and seabed.
Research to date at the PAP-SO site has focused on understanding surface processes (e.g. Hartman et al., 2010) and the link between upper ocean physical and biogeochemical processes, the supply of particulate organic carbon (POC) to the deep ocean (e.g. Lampitt et al., 2010a), and the response (in terms of biodiversity and ecosystem functioning) of the benthic fauna below (e.g. Billett et al., 2001, 2010; Wigham et al., 2003; Gooday et al., 2010; Kalogeropoulou et al., 2010; Soto et al., 2010). In some cases, community changes have been attributed to longer-term climate-driven changes (Ruhl et al., 2008). More details on the benthic biological observations and time-series from the PAP-SO site can be found in Glover et al. (2010), Lampitt et al. (2010b), and Larkin et al. (2010).
Upper ocean biogeochemistry
A three-year time-series (2003–2005) of physical and biogeochemical data was analysed for both seasonal and interannual variation (Hartman et al., 2010). Results from that analysis showed evidence of increased temperature and salinity signals in surface waters from 2003 to 2005, with increased stratification, decreased nitrate concentration (Figure 3) and consequent decline in productivity, and delay in the spring bloom (Hartman et al., 2010). In addition, indications of changes in surface circulation and mode waters supplying the region suggested that eddy activity and lateral advection cannot be ignored at the site (Hartman et al., 2010).
The variation in open ocean in situ data, of increasing temperature and salinity over a three-year period, confirms other observations including UK coastal in situ observations, e.g. the L4 buoy in the western English Channel (Smyth et al., 2010). Results from the PAP-SO also align with the trend documented from remote (satellite) observations of chlorophyll-a fluorescence across the North Atlantic, showing a progressive decline in primary production in the open ocean from 1999 to 2004 (Gregg et al., 2003; Behrenfeld et al., 2006). Progressive warming at the PAP-SO site from winter 2003 to winter 2005 was observed in both the National Centre for Environmental Prediction (NCEP) sea surface temperature (SST) and subsurface (30 m) temperature records from the PAP-SO mooring. Associated decreases in nitrate concentrations and productivity (Behrenfeld et al., 2006) may be attributable to a combination of shallower convective mixing, changes in surface circulation, and mode waters supplying the region (Hartman et al., 2010). These variations in the physical and biogeochemical processes in the Northeast Atlantic will have a notable impact on the pelagic (and benthic) ecosystems. This will cause a variability in zooplankton distribution and population size that ultimately relates to fish stock dynamics.
A persistent feature of the North Atlantic is undersaturation of CO2 in surface waters throughout the year, which gives rise to a perennial CO2 sink (Körtzinger et al., 2008). This makes this a region of great importance in the global carbon cycle. The continuous undersaturation is characteristic of the entire Subpolar North Atlantic, resulting from the general cooling of surface waters during their passage from low to high latitudes. However, there is evidence for a trend of less CO2 being absorbed into the oceans for the period 2003/2004 (Körtzinger et al., 2008). This demonstrates the need to monitor temporal changes in the ocean in a sustained way on oceanographic and ecologically relevant time-scales. Changes in the amount of CO2 absorbed into the ocean may have implications for the global carbon cycle and importance of the oceans as a carbon sink in the future. To assist in making these estimates, pCO2 data are available from the site in near real time (Figure 4).
Deep ocean and benthic studies
The PAP-SO is the only long-term time-series site in the Atlantic to combine sustained water column and benthic biological sampling effort. This dataset is vital for understanding environmental change. For example, carbon sequestration from the upper ocean is monitored through an understanding of the changes in the downward flux of particulate material in the deep-sea environment. At the PAP-SO site, mesopelagic particle flux samples have been collected from the mooring for more than 20 years using sediment traps at depths between 3000 and 4700 m (Figure 5). Results show that the site is characterized by a relatively high level of flux of organic carbon with high seasonal and interannual variability (Lampitt et al., 2001, 2010a). The causes and trends for this long-term variability of downward particle flux in the region are discussed in Lampitt et al. (2010a). These include indications that substantial variation in the date of the spring change in mixing (shoaling) may have a large effect on the biogeochemistry of the remainder of the productive season and the resulting carbon sequestration.
The PAP-SO site is an important long-term reference site across the global ocean for benthic biological community studies. The benthic studies carried out at the site are reviewed in Glover et al. (2010) and Lampitt et al. (2010b), and summarized together with other key benthic biological time-series in Larkin et al. (2010). More than 20 years of sampling the abyssal seabed (4800 m) at the PAP-SO site has permitted studies of benthic biodiversity, rate processes, and ecosystem change in the deep seabed. Results have revealed that benthic ecosystems and geochemistry are intimately linked with ocean-surface processes through variations in POC flux quantity and/or quality arriving on the seabed. The responsiveness of benthic biological communities to climatic drivers and shifts makes them powerful indicators of biogeochemical and other environmental change in the oceans. Results suggest that biodiversity and ecosystem functioning are likely to be closely coupled, and in some cases driven, by global changes in the atmosphere and surface ocean. For example, biodiversity at depth may be linked to seasonal variability in productivity and the resultant flux of organic material at the surface (Wigham et al., 2003; Billett et al., 2010).
All components and size classes constituting the benthic ecosystem communities have shown a response to bentho-pelagic coupling. Since the 1980s, an autonomous time-lapse camera system, Bathysnap, has been used to take 4-hourly still benthic images. Benthic research at the site has revealed significant variations in faunal densities and community composition over seasonal and interannual time-scales, from small meiofauna to larger macro- and megafaunal size classes. Often, this impact can be related to food quality and quantity (Wigham et al., 2003; Billett et al., 2010). In particular, the quality and quantity of the organic matter were shown to influence benthic ecosystem functioning and resulted in radical changes in the density and species diversity of benthic fauna, in particular of large invertebrates (megafauna), as documented in a population explosion of holothurians dominated by the species Amperima rosea in 1997 and 2002, in the latter case, following a notable peak in particle flux (Figure 6). Community shifts and population changes were also seen in other size classes, e.g. the macrofauna. Significant differences were observed in some trophic groups (predators, surface deposit-feeders, and burrowers) and in the dominant families (Cirratulidae, Spionidae, and Opheliidae). Studies of benthic foraminifera have shown a significant increase in total densities from 1996 to 2002 compared to 1989–1994, together with changes in assemblage composition at the species and higher taxon levels (Gooday et al., 2010).
Community changes at the PAP-SO site have been attributed to climate-driven changes in POC flux quantity and quality. The North Atlantic Oscillation (NAO), for example, was linked to POC fluxes to the seabed with a time-lag of several months, as well as to megafauna community composition (Billett et al., 2010). Notably, the observed ecosystem changes at the PAP-SO were linked to qualitative variations in the biochemistry of particulate organic matter (Wigham et al., 2003) that are believed to be critical to the reproductive and recruitment success of key species such as A. rosea (FitzGeorge-Balfour et al., 2010).
European and global context
The PAP-SO is funded by the UK National Environment Research Council (NERC) with dedicated webpages (www.noc.soton.ac.uk/pap). In addition, the site has been supported by a number of earlier European projects, including BENGAL, ANIMATE, MERSEA, and MarBEF. Most recently, the PAP-SO has become a key open-ocean time-series site contributing to the EuroSITES network (www.eurosites.info). Within the EuroSITES FP7 Collaborative Project (2008–2011), the PAP-SO was maintained and enhanced with additional sensors, including measurements of carbon dioxide and meteorological variables, thereby increasing its capacity to monitor environmentally and climatically relevant variables (Table 1). Further maintenance will be supported largely by national funding (NERC) together with support for benthic research by the European project HERMIONE.
As a European platform, PAP-SO has been used for science missions and the development and testing of novel sensors. These include the IODA6000 for in situ oxygen consumption (developed by CNRS: University of Marseille) and the research and development for enhancing long-term capabilities of a mesozooplankton sampler. Strong links exist between EuroSITES and other European initiatives, e.g. ESONET (European Sea Observatory Network). For example, ESONET funded a collaboration design study to enhance the seabed observation infrastructure at the PAP-SO site. This utilized the existing water-column mooring to send multidisciplinary data in near real time via an acoustic link from a lander at 4800 m to the surface and to shore. The PAP-SO is also a key site in the European Multidisciplinary Seabed Observatory (EMSO) planning that aims to establish a long-term governance entity for operating observatories in Europe.
PAP-SO ocean and atmospheric data are sent in near real time from the upper 1000 m through Iridium telemetry to NOC (Southampton), acting as the PAP-SO and EuroSITES Data Assembly Centre. Data are available through the EuroSITES website (www.eurosites.info). Internationally, the site contributes to the OceanSITES global array (www.oceansites.org), complementing other in situ observing systems (e.g. Argo, CPR, Ships of Opportunity) that monitor the region. In line with other time-series sites within this network, there is an open access policy to data that are available through the CORIOLIS ftp site (ftp://ftp.ifremer.fr/ifremer/oceansites). Physical datasets (temperature and salinity) are also sent to the global telecommunication system.
As a component of EuroSITES and OceanSITES, the PAP-SO is a key data provider to MyOcean (European Marine Core Services). In future, it is envisaged that more near real-time data will be utilized by modelling and reanalysis activities to produce services and products for society. The PAP-SO is located in international waters, but in proximity to four member-state European economic zones. It is also an associated site in the Western Shelf Observatory (http://www.westernshelfobservatory.org/). The PAP-SO time-series datasets from the open ocean North Atlantic are invaluable as an early warning system for the European shelf and coastal waters at a regional level. Research at the PAP-SO site contributes to the subsea component of GMES (Global Monitoring for Environment and Security) and to the Global Earth Observation System of Systems (GEOSS) through the OceanSITES deep-water reference stations and the Global Ocean Observing System (GOOS).
Many science themes benefit from data supplied by ocean observatories (Ruhl et al., 2011), and PAP-SO scientists regularly inform government policy on strategic issues, e.g. marine processes and climate, marine habitats and species (biodiversity in the deep sea), open ocean productivity, ocean governance, geo-engineering, and ocean fertilization. Regular advice is provided to the Royal Society, the Department of Environment, Food and Rural Affairs (Defra), the UN International Seabed Authority, and the European Commission (EC). The PAP-SO is also detailed as an existing in situ infrastructure for ocean observation contributing to the Group on Earth Observation (GEO) in Lampitt et al. (2010c) and related outputs from the OceanObs'09 conference. The combined datasets obtained enable short-term (daily–seasonal) and longer-term (climate-driven) trends to be captured, contributing to the Europe-wide initiative for good environmental status of our seas by the EU Marine Strategy Framework Directive (http://ec.europa.eu/environment/water/marine/).
Summary and conclusions
The PAP-SO in the Northeast Atlantic at 49°N 16.5°W is the longest running multidisciplinary open ocean time-series observatory in Europe and has produced a high-resolution in situ multidisciplinary time-series dataset of climatically and environmentally relevant variables from the euphotic zone to the seabed beneath (4800 m) for >20 years. More than 225 peer-reviewed papers have been published on the PAP-SO since 1975, including a recent special issue in Deep Sea Research (Volume 57, Issue 15) that details recent water column and seabed studies at the PAP-SO.
Results from the time-series have proven vital for understanding a range of ocean processes at different temporal scales, including an integrated understanding of seasonal and interannual surface processes and how these affect the deep ocean and seabed communities. Results have also highlighted the potential role of deep-sea benthic communities as indicators of climate change. As technology allows the measurement of more variables to be available in near real time from the open and deep ocean, the potential for societal benefit from these datasets, in terms of products and services, is set to increase exponentially. There is therefore a growing need for developing and maintaining long-term time-series sites to provide important in situ ocean datasets. However, sustaining these time-series through long-term funding commitments is an ongoing challenge.
Acknowledgements
The research leading to these results received support from the European Community's 7th Framework Programme FP7/2007-2013 under EuroSITES, grant agreement 202955, and under the HERMIONE project, grant agreement 226354 (see Article II.30. of the grant agreement), as well as from the European Community's 7th Framework Programme (FP7/2007-2013).
References
Author notes
Handling editor: Dr Bill Turrell