Jan Newton

Primary productivity and its regulation in the equatorial Pacific during and following the 1991–1992 El Niño

The cycling of carbon in the equatorial Pacific Ocean was investigated by the Equatorial Pacific (EqPac) Study in 1992. As part of that study in situ primary productivity was measured on survey and time-series cruises along 140°W from 12°N to 12°S with methods determined to be trace-metal clean. Primary productivity, chlorophyll and chlorophyll-specific productivity rates varied coherently in relation to two large-scale features: temporally, primary productivity was reduced during the El Nino dominated period (February–April 1992) and increased during the cool period (August–October 1992); and spatially enhanced primary productivity persisted close to the equator relative to the oligotrophic regions poleward of 10°N and 10°S. On the equator in October 1992 during the period of relatively cool water, primary productivity was about twice (125 mmol C m−2 day−1) the value during the peak warm period (60 mmol C m−2 day−1). The climatological mean equatorial productivity in the cold tongue has been recalculated to be about 75 mmol C m−2 day−1 (Chavez et al., 1996). The mean 1992 productivity on the equator (1°S–1°N) was about 25% higher than climatology (95 vs 75 mmol Cm−2 day−1) and about 3 times the value in oligotrophic waters poleward of 10°N and 10°S (95 vs 30 mmol C m−2 day−1). Higher chlorophyll-specific productivity during the cool period relative to the warm period (3.9 vs 2.4 mmol C mg chl−1 day−1) indicates that the increase in absolute productivity did not result solely from a biomass increase, but from a change in the nutrient-regulated specific productivity rate. The regulating nutrient was not a macronutrient, such as nitrate or silicic acid, because macronutrients (and light) were present in uptake-saturating concentrations during both the warm and cool periods of the 1992 EqPac study. Physiological constraint by a micronutrient, such as iron, is implicated as the factor regulating these productivity variations. The change in iron supply resulted from a change in equatorial circulation processes. During the warm period, El Nino-Southern Oscillation (ENSO)-driven changes in pycnocline topography depressed the Equatorial Undercurrent (EUC), thereby decreasing the amount of iron-rich EUC water entrained into equatorial upwelling and vice versa during the cool period. During the August–October cool period of generally increased productivity, two further episodic increases in specific productivity, biomass and diatom abundance occurred during intense and remotely forced upwelling events associated with a front or the passage of a frontal wave. In both mesoscale episodes, temperature and salinity show that the intensified upwelling reached more deeply into the already relatively shallow EUC. Productivity and biomass increases during both of these events were quantitatively similar to those in an in situ iron addition experiment (IronEx) carried out in equatorial Pacific waters in 1993. Variations in the supply of upwelled iron provided by the iron-rich EUC best account for the warm-cool period difference in phytoplankton productivity as well as the episodic increases in specific productivity, biomass and diatom abundance during intense mesoscale upwelling events seen in the dynamic equatorial region in the EqPac study.

Export flux of particulate organic carbon from the central equatorial Pacific determined using a combined drifting trap-234Th approach

The export flux of particulate organic carbon from the euphotic zone in the central equatorial Pacific was measured using an approach that utilizes 234Th and organic carbon analyses on water column and drifting sediment trap samples. This study was conducted as part of the U.S. Joint Global Ocean Flux Study (U.S. JGOFS) EqPac process study from 12°N to 12°S at 140°W. Samples were collected during the Survey I (February–March 1992) and Survey II (August–September 1992) cruises. The accuracy of drifting sediment traps was evaluated by comparing the measured flux of 234Th with the flux calculated from the deficiency of 234Th relative to 238U in the water column. Calculated 234Th fluxes were corrected for the effects of horizontal and vertical advection. The uncertainties on these 234Th fluxes averaged 39% for Survey I and 20% for Survey II. Comparison of measured and calculated 234Th fluxes revealed evidence for overtrapping, especially in the shallow traps (≤ 100 m). Measured and calculated 234Th fluxes agreed to within 50% for traps at 150–250 m. Good correlation was obtained between measured fluxes of organic carbon and 234Th except for some shallow samples high in organic carbon, suggesting that 234Th was a good tracer for organic carbon. The flux of particulate organic carbon (POC) was calculated as the product of the calculated flux of 234Th times the organic carbon/234Th ratio in trap samples. Assuming that the organic carbon/234Th ratio in trap samples was representative of sinking particles, we used an average value for the organic carbon/234Th ratio for each station. The variability in the station-averaged POC/234Th ratio ranged from 10% to 30%. The POC fluxes calculated using our combined 234Th-trap approach ranged from 1 to 6 mmol C m−2 day−1 during Survey I, and from 2 to 30 mmol C m−2 day−1 during Survey II. The average uncertainty for the POC fluxes was ±60%. Primary and new production integrated to the depth of the 0.1 % light level varied by factors of 2–3 for Survey I and Survey II, respectively. The export of particulate organic carbon from the euphotic zone also increased by a factor of 3. The corresponding e-ratios (POC export/primary production) ranged from 0.03 to 0.11 for Survey I, and 0.04 to 0.23 for Survey II. Annual average regional rates (10°N–10°S; 90°W–180°E) of new (0.47 Gt C year−1) and particulate export (0.42 Gt C year−1) production were in good agreement, suggesting that, on an annual basis, significant export of DOC need not be invoked to balance new and export production in this region.

Dynamics of Willapa Bay, Washington: A Highly Unsteady, Partially Mixed Estuary

Results from 3 yr of hydrographic time series are shown for Willapa Bay, Washington, a macrotidal, partially mixed estuary whose river and ocean end members are both highly variable. Fluctuating ocean conditions— alternations between wind-driven upwelling and downwelling, and intrusions of the buoyant Columbia River plume—are shown to force order-of-magnitude changes in salinity gradients on the event (2‐10 day) scale. An effective horizontal diffusivity parameterizing all up-estuary salt flux is calculated as a function of riverflow: results show that Willapa’s volume-integrated salt balance is almost always far from equilibrium. At very high riverflows (the top 15% of observations) the estuary loses salt, on average, while at all other riverflow levels it gains salt. Under summer, low-riverflow conditions, in fact, the effective diffusivity K is large enough to drive a net increase in salinity that is 3‐6 times the seaward, river-driven salt flux. This diffusion process is amplified, not damped, by increased tidal forcing, contrary to the expectation for baroclinic exchange. Furthermore, K varies along the length of the estuary as ;5% of the rms tidal velocity times channel width, a scaling consistent with density-independent stirring by tidal residuals. To summarize Willapa’s event- and seasonal-scale variability, a simple diagnostic parameter space for unsteady estuarine salt balances is presented, a generalization from the Hansen and Rattray steady-state scheme.

A meeting place of great ocean currents: shipboard observations of a convergent front at 2°N in the Pacific

Abstract We present a synthesis of physical, chemical and biological shipboard observations of a convergent front at 2°N, 140°W and its surrounding environment. The front was a component of a tropical instability wave generated by shear between westward-flowing equatorial waters to the south and warmer equatorial counter current water to the north. Surface waters on the cold side were undersaturated with oxygen, which suggests that the water had only been exposed at the sea surface for a period of a few weeks. Although the atmospheric exposure time was short, the effects of biological activity could be detected in enhanced concentrations of total (dissolved plus suspended particulate) organic carbon concentration, proving that TOC can be produced in the top centimeters of the changing environmental conditions. The front itself was dominated by the accumulation of a “patch” of buoyant diatoms Rhizosolenia castracanei concentrated in the top centimeters of the warm surface water north of the front, and elevated chlorophyll concentrations were observed from the air over a spatial scale of order 10–20 km northward from the front. The nitrogen budget and thorium data suggest that a significant fraction of the elevated POC, and virtually all of the PON, arrived in the patch waters as imported particles rather than in situ photosynthesis. Photosynthetic uptake of carbon appears to have occurred in patch waters, but without corresponding uptake of fixed nitrogen (an uncoupling of the usual Redfield stoichiometry). Solute chemistry of the patch appears to be controlled by turbulent mixing, which flushes out patch waters on a time scale of days

Seasonal Carbonate Chemistry Covariation with Temperature, Oxygen, and Salinity in a Fjord Estuary: Implications for the Design of Ocean Acidification Experiments

Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall). pCO2 exceeded the 2008–2011 mean atmospheric level (392 µatm) at all depths and seasons sampled except for the near-surface waters (< 10 m) in the summer. Further, undersaturated conditions with respect to the biogenic carbonate mineral aragonite were widespread (Ωar<1). We show that pCO2 values were relatively uniform throughout the water column and across regions in winter, enriched in subsurface waters in summer, and in the fall some values exceeded 2500 µatm in near-surface waters. Carbonate chemistry covaried to differing levels with temperature and oxygen depending primarily on season and secondarily on region. Salinity, which varied little (27 to 31), was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight the wide range of carbonate chemistry conditions organisms may currently experience in this and similar coastal ecosystems.

Experiments with Seasonal Forecasts of ocean conditions for the Northern region of the California Current upwelling system

Resource managers at the state, federal, and tribal levels make decisions on a weekly to quarterly basis, and fishers operate on a similar timeframe. To determine the potential of a support tool for these efforts, a seasonal forecast system is experimented with here. JISAO’s Seasonal Coastal Ocean Prediction of the Ecosystem (J-SCOPE) features dynamical downscaling of regional ocean conditions in Washington and Oregon waters using a combination of a high-resolution regional model with biogeochemistry and forecasts from NOAA’s Climate Forecast System (CFS). Model performance and predictability were examined for sea surface temperature (SST), bottom temperature, bottom oxygen, pH, and aragonite saturation state through model hindcasts, reforecast, and forecast comparisons with observations. Results indicate J-SCOPE forecasts have measurable skill on seasonal timescales. Experiments suggest that seasonal forecasting of ocean conditions important for fisheries is possible with the right combination of components. Those components include regional predictability on seasonal timescales of the physical environment from a large-scale model, a high-resolution regional model with biogeochemistry that simulates seasonal conditions in hindcasts, a relationship with local stakeholders, and a real-time observational network. Multiple efforts and approaches in different regions would advance knowledge to provide additional tools to fishers and other stakeholders.

In situ and remote monitoring of water quality in Puget Sound: The ORCA time-series

High frequency hydrological and meteorological measurements have been made in Puget Sound from 2001 to the present using remote profiling moorings. The moorings consists of a toroidal float upon which is mounted an electric winch that is powered by solar panels. Meteorological variables include, wind velocity and direction, air temperature, barometric pressure, and incident solar radiation while hydrographic variables include water temperature, salinity, dissolved oxygen, chlorophyll fluorescence and nitrate. Currently three moorings are operating in Puget Sound. All hydrographic variables displayed high frequency variability at all locations in Puget Sound, likely due to tidally advecting, patchy distributions. In the main basin of Puget Sound, the water column was well mixed during the winter months and water temperature was warmer than air temperature. With the onset of spring conditions plankton (fluorescence) bloomed and oxygen became supersaturated. However, there were numerous and frequent periods of destratification that could be correlated with wind events which mixed chlorophyll-containing surface waters downwards and nutrient-rich, oxygen-undersaturated water upwards. This process enhanced export production and injected oxygen into the deep waters. The chlorophyll maximum was found in the surface waters during the spring and fall bloom periods, but was located in the pycnocline during the summer months. By pooling all the oxygen data by hour of the day a diurnal oxygen curve was determined. The diurnal oxygen cycle was approximately sinusoidal with the minimum slightly before dawn and the maximum about at about 1800h and the amplitude was 17m moles of oxygen per liter. Primary production estimates derived from the oxygen cycle agreed with those determined from classical 14-C incubation methods. Statistical analysis of the data revealed that, at a minimum, daily sampling is necessary to assess the true values of the many measured variables. Without this sampling frequency resolving interannual differences or climate related changes would be difficult. However, given daily or greater sampling it should be possible to determine these types of changes as well as overall trends and cycles.

The Carbonate Chemistry of the “Fattening Line,” Willapa Bay, 2011–2014

Willapa Bay has received a great deal of attention in the context of rising atmospheric CO2 and the concomitant effects of changes in bay carbonate chemistry, referred to as ocean acidification, and the potential effects on the bay’s naturalized Pacific oyster (Crassostrea gigas) population and iconic oyster farming industry. Competing environmental stressors, historical variability in the oyster settlement record, and the absence of adequate historical observations of bay-water carbonate chemistry all conspire to cast confusion regarding ocean acidification as the culprit for recent failures in oyster larval settlement. We present the first measurements of the aqueous CO2 partial pressure (PCO2) and the total dissolved carbonic acid (TCO2) at the “fattening line,” a location in the bay that has been previously identified as optimal for both larval oyster retention and growth, and collocated with a long historical time series of larval settlement. Samples were collected from early 2011 through late 2014. These measurements allow the first rigorous characterization of Willapa Bay aragonite mineral saturation state (Ωar), which has been shown to be of leading importance in determining the initial shell formation and growth of larval Crassostrea gigas. Observations show that the bay is usually below Ωar levels that have been associated with poor oyster hatchery production and with chronic effects noted in experimental work. Bay water only briefly rises to favorable Ωar levels and does so out of phase with optimal thermal conditions for spawning. Thermal and carbonate conditions are thus coincidentally favorable for early larval development for only a few weeks at a time each year. The limited concurrent exceedance of thermal and Ωar thresholds suggests the likelihood of high variability in settlement success, as seen in the historical record; however, estimates of the impact of elevated atmospheric CO2 suggest that pre-industrial Ωar conditions were more persistently favorable for larval development and more broadly coincident with thermal optima.

Using web-based and social networking technologies to disseminate coastal hazard mitigation information within the Pacific Northwest component of the Integrated Ocean Observing System (IOOS)

At 9:46:23 pm Pacific Time on March 10, 2011 (05:46:23 UTC on March 11), a magnitude 9.0 earthquake occurred 129 km (80 miles) off the coast of Sendai, a city in Honshu, Japan. The Tōhoku earthquake triggered a catastrophic tsunami that produced an inundation wave height as high as 30 m that propagated throughout the entire Pacific Ocean basin. Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys positioned around the Pacific Ocean provided real-time data of the impending tsunami as it travelled across the ocean towards the U.S. West Coast. Because of this warning, coastal communities in Washington and Oregon were on guard by the time the tsunami hit the West Coast almost 9 hours after the earthquake occurred. Harbors along the Oregon coast, including Depoe Bay, Coos Bay, and Brookings, and in Crescent City, California reported damage to docks and boats in the harbor. In the Pacific Northwest, the Northwest Association of Networked Ocean Observing Systems (NANOOS), the regional association that manages and operates the Regional Coastal Ocean Observing System (RCOOS) for this area of the country as part of the U.S. Integrated Ocean Observing System (IOOS®) enterprise, provided extensive information to the public about the timing, severity, and government agency recommended actions to take as a result of this event. These included Tsunami Evacuation Zones for the Oregon Coast, providing users of the NANOOS Visualization System with easy access to near real-time current, water height, and other information for a wide variety of U.S. IOOS assets, and posting NANOOS Facebook updates regarding the tsunami passage. We discuss the implications of the use of standard (web-based) means of disseminating coastal hazard mitigation information and discuss possible opportunities that social networking technologies present for providing such information as our society increasingly depends on mobile-technologies and applications.

Challenges for global ocean observation: the need for increased human capacity

ABSTRACT Sustained global ocean observations are needed to recognise, understand, and manage changes in marine biodiversity, resources and habitats, and to implement wise conservation and sustainable development strategies. To meet this need, the Global Ocean Observing System (GOOS), a network of observing systems distributed around the world and coordinated by the Intergovernmental Oceanographic Commission (IOC) has proposed Essential Ocean Variables (EOVs) that are relevant to both the scientific and the broader community, including resource managers. Building a network that is truly global requires expanding participation beyond scientists from well-resourced countries to a far broader representation of the global community. New approaches are required to provide appropriate training, and resources and technology should follow to enable the application of this training to engage meaningfully in global observing networks and in the use of the data. Investments in technical capacity fulfil international reporting obligations under the UN Sustainable Development Goal 14A. Important opportunities are emerging now for countries to develop research partnerships with the IOC and GOOS to address these obligations. Implementing these partnerships requires new funding models and initiatives that support a sustained research capacity and marine technology transfer.