Seaglider observations of blooms and subsurface chlorophyll maxima off the Washington coast
TL;DR: In this paper, an autonomous, underwater Seaglider continuously ran a V-shaped transect off Washington State from about 200m water depth to offshore waters with depths >2700 m.
Abstract: From September 2003 to December 2007, autonomous, underwater Seaglider continuously ran a V-shaped transect off Washington State from about 200-m water depth (i.e., at the break between the shelf and slope) to offshore waters with depths >2700 m. Seaglider visited the offshore vertex at 47°N, 128°W, where our observations concentrated, approximately monthly. Seaglider measured temperature, conductivity, and dissolved oxygen to 1000 m and also recorded chlorophyll a (Chl a) fluorescence and particulate optical backscatter to 150 m. Distinct interannual variation was documented in timing and depths of winter mixing, transition to a shallow summer pycnocline, and onset of mixed-layer erosion in autumn. Chl a concentrations estimated from fluorescence were directly comparable among the seven laboratory-calibrated sensors used, but their estimates exceeded concurrent, satellite-derived concentrations by a factor of three. Seaglider optical profiles enabled interpretation of satellite imagery by revealing that the apparent autumn bloom after destratification was instead a vertical redistribution of phytoplankton from the subsurface maximum to a depth where they could be observed by satellites. Results of 4 yr of sampling within 25 km of the vertex demonstrate the value of gliders in ocean observing and their capability to carry out multiyear, fully autonomous operations under any sea state. The true power of glider programs will be realized in combination with other measurement platforms, including larger spatial coverage by satellites and more comprehensive biogeochemical measurements from moorings and occasional ship-based sampling.
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TL;DR: In this review, research topics are grouped by time and length scales and large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability.
Abstract: Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.
216 citations
Cites background from "Seaglider observations of blooms an..."
...Perry et al. (2008) noted the relationship between density stratification, chlorophyll fluorescence, and optical backscatter in the annual cycle and in interannual variations off the Washington coast....
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...…glider operators have better performance, as must be the case for the glider programs that have been gathering data continuously for several years (Davis et al. 2008, Perry et al. 2008, Todd et al. 2011a, Pierce et al. 2012, Pelland et al. 2013, Mazzini et al. 2014, Johnston & Rudnick 2015)....
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TL;DR: In this article, the main mode of expected future changes (ecological shifts in timing and spatial distribution to accommodate fixed environmental niches vs. evolutionary adaptation of timing controls to maintain fixed biogeography and seasonality) is examined.
Abstract: Increasing availability and extent of biological ocean time series (from both in situ and satellite data) have helped reveal significant phenological variability of marine plankton. The extent to which the range of this variability is modified as a result of climate change is of obvious importance. Here we summarize recent research results on phenology of both phytoplankton and zooplankton. We suggest directions to better quantify and monitor future plankton phenology shifts, including (i) examining the main mode of expected future changes (ecological shifts in timing and spatial distribution to accommodate fixed environmental niches vs. evolutionary adaptation of timing controls to maintain fixed biogeography and seasonality), (ii) broader understanding of phenology at the species and community level (e.g. for zooplankton beyond Calanus and for phytoplankton beyond chlorophyll), (iii) improving and diversifying statistical metrics for indexing timing and trophic synchrony and (iv) improved consideration of spatio-temporal scales and the Lagrangian nature of plankton assemblages to separate time from space changes.
211 citations
Cites background from "Seaglider observations of blooms an..."
...Quantitative analysis of the life histories of several species of euphausiids is advancing (Tanasichuk, 1998a, b; Hofmann and Lascara, 2000; Cuzin-Roudy et al., 2004; Fach et al., 2008; Pinchuka et al., 2008; Wiedenmann et al., 2008; 2009; Feinberg et al., 2009)....
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TL;DR: In this paper, the authors review the scientific motivation and the prospects for a global observing system for ocean biogeochemistry, which might operate on a scale comparable to the current Argo array.
Abstract: Chemical and biological sensor technologies have advanced rapidly in the past five years. Sensors that require low power and operate for multiple years are now available for oxygen, nitrate, and a variety of bio-optical properties that serve as proxies for important components of the carbon cycle (e.g., particulate organic carbon). These sensors have all been deployed successfully for long periods, in some cases more than three years, on platforms such as profiling floats or gliders. Technologies for pH, pCO2, and particulate inorganic carbon are maturing rapidly as well. These sensors could serve as the enabling technology for a global biogeochemical observing system that might operate on a scale comparable to the current Argo array. Here, we review the scientific motivation and the prospects for a global observing system for ocean biogeochemistry.
176 citations
Cites background or methods from "Seaglider observations of blooms an..."
...Recent studies of the seasonal buildup of oxygen in the sub-mixed-layer euphotic zone using Argo float data (Riser and Johnson, 2008) and Seaglider measurements (Nicholson et al., 2008; Perry et al., 2008) demonstrate the potential to quantify net community production (NCP) using sensors....
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...Oxygen sensors have been deployed on gliders, also with excellent results (Figure 2; Nicholson et al., 2008; Perry et al., 2008)....
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...Many of these time series have been sustained for years (Nicholson et al., 2008; Niewiadomska et al., 2008; Perry et al., 2008)....
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TL;DR: In this paper, the authors demonstrate the ability by pairing satellite ocean color data with records from a profile float that obtained continuous, high-quality optical data for 3 years in the North Atlantic Ocean.
Abstract: Profiling floats with optical sensors can provide important complementary data to satellite ocean color
determinations by providing information about the vertical structure of ocean waters, as well as surface waters
obscured by clouds. Here we demonstrate this ability by pairing satellite ocean color data with records from a
profiling float that obtained continuous, high-quality optical data for 3 yr in the North Atlantic Ocean. Good
agreement was found between satellite and float data, and the relationship between satellite chlorophyll and floatderived
particulate backscattering was consistent with previously published data. Upper ocean biogeochemical
dynamics were evidenced in float measurements, which displayed strong seasonal patterns associated with
phytoplankton blooms, and depth and seasonal patterns associated with an increase in pigmentation per particle
at low light. Surface optical variables had shorter decorrelation timescales than did physical variables (unlike at
low latitudes), suggesting that biogeochemical rather than physical processes controlled much of the observed
variability. After 2.25 yr in the subpolar North Atlantic between Newfoundland and Greenland, the float crossed
the North Atlantic Current to warmer waters, where it sampled an unusual eddy for 3 months. This anticyclonic
feature contained elevated particulate material from surface to 1000-m depth and was the only such event in the
float’s record. This eddy was associated with weakly elevated surface pigment and backscattering, but depthintegrated
backscattering was similar to that previously observed during spring blooms. Such seldom-observed
eddies, if frequent, are likely to make an important contribution to the delivery of particles to depth.
110 citations
Pierre-and-Marie-Curie University1, Memorial University of Newfoundland2, University of Cyprus3, IFREMER4, Institut de recherche pour le développement5, École Normale Supérieure6, Centre national de la recherche scientifique7, Leibniz Institute of Marine Sciences8, Centre for Maritime Research and Experimentation9, National Institute of Oceanography, India10, Bjerknes Centre for Climate Research11, National Oceanography Centre, Southampton12, Scottish Association for Marine Science13, Atlantic Oceanographic and Meteorological Laboratory14, Oregon State University15, Rutgers University16, University of Maine17, University of Washington18, Scripps Institution of Oceanography19, Woods Hole Oceanographic Institution20
TL;DR: In this paper, Testor, Meyers, and Meybodi discuss the role of race and gender in the development of Testor's Testor Testor and Meyers Testor this paper.
Abstract: Pierre Testor(1), Gary Meyers(2), Chari Pattiaratchi(3) , Ralf Bachmayer(4), Dan Hayes(5), Sylvie Pouliquen(6), Loic Petit de la Villeon(6), Thierry Carval(6), Alexandre Ganachaud(7), Lionel Gourdeau(7), Laurent Mortier(8), Herve Claustre(9), Vincent Taillandier(9), Pascale Lherminier(10), Thierry Terre(10), Martin Visbeck(11), Johannes Karstensen(11), Gerd Krahmann(11), Alberto Alvarez(12), Michel Rixen(12), Pierre-Marie Poulain(13), Svein Osterhus(14), Joaquin Tintore(15), Simon Ruiz(15), Bartolomeo Garau(15), David Smeed(16), Gwyn Griffiths(16), Lucas Merckelbach(16), Toby Sherwin(17), Claudia Schmid(18), John A. Barth(19), Oscar Schofield(20), Scott Glenn(20), Josh Kohut(20), Mary Jane Perry(21), Charlie Eriksen(22), Uwe Send(23), Russ Davis(23), Daniel Rudnick(23), Jeff Sherman(23), Clayton Jones(24), Douglas Webb(24), Craig Lee(25), Breck Owens(26)
97 citations
Cites background or methods from "Seaglider observations of blooms an..."
...Other experiments have demonstrated that relatively small fleets (5-15 gliders) can be deployed for extended periods in the same area (at coastal and regional scales) in the Atlantic, in the Pacific, and in the Mediterranean [13], [23], [24] and [25]....
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...There are some plans in Europe to make gliders 'swarm' experiments in the Alboran Sea (Mediterranean) and in the Tropical Atlantic in 2010....
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...Optical observations of large diatoms and sinking particles during the North Atlantic Spring Bloom made from seagliders, floats and a ship....
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...Similar long sections exist along the coasts of the USA in the Pacific, and in the Atlantic [13], [17 and [21] and demonstrated the capacity of gliders to carry out, over many years, measurements of the local vertical structure of the ocean over 0-200m or 0-1000m from the near-shore environment (10-100m depth) to the open sea (hundreds of km offshore)....
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...At the moment, the assimilation of glider data is already operational for T-S, in regional (Mediterranean/MFS (Mediterranean Forecasting System; Pacific/NCOM (NRL (Naval Research Laboratory) Coastal Ocean Model) or even global (North Atlantic/MERCATOR) models....
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References
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TL;DR: Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along a sawtooth trajectory through the water as mentioned in this paper.
Abstract: Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along a sawtooth trajectory through the water. Their low hydrodynamic drag and wide pitch control range allow glide slopes in the range 0.2 to 3. They are designed for missions in a range of several thousand kilometers and durations of many months. Seagliders are commanded remotely and report their measurements in near real time via wireless telemetry. The development and operation of Seagliders and the results of field trials in Puget Sound are reported.
978 citations
TL;DR: Most vertical distributions of chlorophyll can be explained by the interaction between hydrography and growth, behavior, or physiological adaptation of phytoplankton with no special consideration of grazing by herbivores, even though vertical distribution of epizooplankon are not uniform.
Abstract: The relationship between chlorophyll a and phytoplankton biomass (organic carbon content) is highly variable as is the yield of in vivo fluorescence per unit chlorophyll. Thus, vertical profiles of...
824 citations
"Seaglider observations of blooms an..." refers background in this paper
...Subsurface chlorophyll a (Chl a) maxima are ubiquitous in the global ocean (Cullen 1982)....
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...Enhanced cellular Chl a concentration at depth, however, is not the only explanation for subsurface Chl a maxima (Cullen 1982)....
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TL;DR: In this article, the authors review the roles played by various seawater constituents in light backscattering and address a question of missing backscatter in the open ocean and show that due to substantial variability in water composition, different types of constituents can explain the missing back-scatter.
394 citations
"Seaglider observations of blooms an..." refers background in this paper
...(2) Particulate backscatter in offshore waters is typically correlated with Chl a, although there is a nonzero backscatter intercept (Stramski et al. 2004; Boss et al. 2008)....
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342 citations
TL;DR: A quantitative criterion for the observed coexistence of vertically distinct phytoplankton assemblages in oligotrophic systems is suggested: the vertical position at which a species occurs in highest abundance in the water column is determined by the ‘‘general compensation depth’’— that is, the depth at which specific growth and all loss rates, including the divergence of sinking/swimming and vertical mixing, balance.
Abstract: In oligotrophic lakes and oceans, the deep chlorophyll maximum may form independently of a maximum of phytoplankton biomass, because the ratio of chlorophyll to phytoplankton biomass (in units of carbon) increases with acclimation to reduced light and increased nutrient supply at depth. Optical data (beam attenuation as proxy for phytoplankton biomass and chlorophyll fluorescence and absorption as proxies for chlorophyll concentration) and conventional measurements of biovolume, particulate organic carbon, and chlorophyll from two oligotrophic systems (Crater Lake, Oregon, and Sta. ALOHA in the subtropical North Pacific Ocean) are presented and show a vertical separation of the maxima of biomass and chlorophyll by 50‐80 m during stratified conditions. We use a simple mathematical framework to describe the vertical structure of phytoplankton biomass, nutrients, and chlorophyll and to explore what processes contribute to the generation of vertical maxima. Consistent with the observations, the model suggests that biomass and chlorophyll maxima in stable environments are generated by fundamentally different mechanisms. Maxima in phytoplankton biomass occur where the growth rate is balanced by losses (respiration and grazing) and the divergence in sinking velocity, whereas the vertical distribution of chlorophyll is strongly determined by photoacclimation. A deep chlorophyll maximum is predicted well below the particle maximum by the model. As an interpretation of these results, we suggest a quantitative criterion for the observed coexistence of vertically distinct phytoplankton assemblages in oligotrophic systems: the vertical position at which a species occurs in highest abundance in the water column is determined by the ‘‘general compensation depth’’— that is, the depth at which specific growth and all loss rates, including the divergence of sinking/swimming and vertical mixing, balance. This prediction can be tested in the environment when the divergence of sinking and swimming is negligible.
243 citations