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View the pdf version of this report. ECOHAB-PNW VI CRUISE REPORT B.M. Hickey, W.P. Cochlan, E. Lessard, V.L. Trainer, M.L. Wells,
N. Kachel, A. MacFadyen and T. Connolly Area of Operations
1. Regional Surveys (ECOHAB-PNW team) 2. Drift Studies (Amy MacFadyen, Tom Connolly, Barbara Hickey, drifters; whole ECOHAB PNW team for water/nutrient) 3. Drifter Deployments (Amy MacFadyen, Tom Connolly, Barbara Hickey) 4. Satellite Imagery (Rick Stumpf, Jack Weckell) 5. Laboratory Analyses a) Lessard Group (Evelyn Lessard, Julie Wright, Mike Foy, and Megan Bernhardt) Acknowledgements List of Tables and Figures
ECOHAB-PNW 6
Arrive Seattle, WA, October 4, 2006
Romburg Tiburon Center, San Francisco State University University of Maine University of Washington
Chief Scientist
Principle Investigators
Dr. Evelyn Lessard, University of Washington Dr. Vera Trainer, NOAA/Northwest Fisheries Science Center Dr. Mark Wells, University of Maine Visiting Investigator
Staff
Keri Baugh, NOAA/Northwest Fisheries Science Center Megan Bernhardt, School of Oceanography, University of Washington Julia Betts, RTC/San Francisco State University Sheryl Day, NOAA/Northwest Fisheries Science Center Denis Costello, North High School, Torrance CA (Teacher-At-Sea) Tony Elias, Evil Bunny Films Mike Foy, School of Oceanography, University of Washington Kathy Hardy, University of Maine Julian Herndon, RTC/San Francisco State University Margaret Hughes, University of California, Santa Cruz Dr. Nancy Kachel, University of Washington Jennifer Maas, Evil Bunny Films Anne Mataia, NOAA/Northwest Fisheries Science Center Christine Muir, Woodside Priory School, Woodside, CA (Teacher-At-Sea) Dr. Stephanie Moore, University of Washington Shelly Nance, NOAA/Northwest Fisheries Science Center Anthony Odell, University of Washington Olympic Natural Resource Center Shuk Tsui, NOAA/Northwest Fisheries Science Center Students
Brian Bill, NOAA/Northwest Fisheries Science Center/ RTC/San Francisco St. U. Tom Connolly, University of Washington Lauren Kuehne, Evergreen State College Amy MacFadyen, University of Washington Elizabeth Moore, RTC/San Francisco State University Lisa Pickell, University of Maine Regina Radan, RTC/San Francisco State University Sally Warner, University of Washington Julie Wright, School of Oceanography, University of Washington Cruise Objectives and Sampling Scheme The purpose of this cruise was to determine the physical, chemical and physiological conditions under which diatoms of the genus Pseudo-nitzschia (PN) produce the neurotoxin domoic acid (DA), and the ecophysiological conditions which promote cellular release of toxin to the surrounding environment. We attempted to observe the conditions under which toxic cells advect towards the coast of Washington where they are consumed by shellfish. Such occurrences lead to closure of beaches to razor clam collection to avoid outbreaks of amnesic shellfish poisoning. Sampling was organized around a comprehensive grid of stations, sampled repeatedly as environmental conditions changed. Continuous surface water measurements included: temperature, salinity and in vivo fluorescence, discrete surface samples for planktonic community analysis and species identification were collected with net tows. Property profiles were obtained with an instrumented rosette including a CTD (conductivity, temperature, depth) and additional sensors that measured in vivo fluorescence, photosynthetically active radiation (PAR), beam attenuation (light transmission), and oxygen concentration. During CTD casts discrete samples were collected with Niskin water samplers for chlorophyll, inorganic and organic nutrients, plankton species and community identification (via FlowCAM and flow cytometer analyses), and particulate and dissolved DA. A trace metal clean, underway sampling system was employed to collect subsurface samples that could be measured on board (e.g. iron), and to collect samples for multi-element determination (including copper) ashore. On-deck incubations of phytoplankton assemblages were conducted for growth, nitrogenous nutrition and grazing experiments, and shipboard analyses of the plankton were routinely conducted using both traditional (microscopic) and advanced (FlowCAM image and flow cytometric analyses) methods. Satellite-tracked drifters were released in and near the Juan de Fuca eddy and off the coast of Washington. The cruise was diverted to Neah Bay on September 22 and 24 to exchange personnel. The overall ship track and CTD stations are shown in Figure 1. ADCP lines: ~3000 km Size-fractionated chlorophyll a samples: > all ECOHAB grid stations, Juan de Fuca and Puget Sound stations, anchovy study, dilution experiments and deck-board manipulation experiments (>4500 samples) The ECOHAB PNW VI cruise was unique in several ways: first-surface nutrients were extremely high farther offshore and also farther northwestward than we have previously observed. In addition: diatoms of the Pseudo-nitzschia (PN) genus were the least abundant in the eddy region of all four fall ECOHAB PNW cruises. Finally, domoic acid concentrations were the lowest we have observed in the eddy region. Cell numbers, domoic acid concentrations and chlorophyll were all higher near the Washington (WA) coast than in the eddy, as in September 2005. However, values were much lower this fall than in fall 2005. This cruise took place during a year with record level upwelling-favorable winds-and these strong winds continued through the early part of our cruise. In contrast, the 2005 fall cruise took place during a summer with anomalously late onset of upwelling-favorable winds (mid July). Community variability from year to year, independent of summertime upwelling, may play a role in the character of the planktonic ecosystem we observe in any given year. Also a major fall storm occurred during the first week of our cruise-winds in this storm were much stronger than in other fall ECOHAB PNW cruises. This storm increased northwestward currents and likely contributed to the along coast lengthening of the area of very high (> 15 µm) nitrate. The observed distributions may represent the beginning of the breakdown of the summertime eddy. We note that this cruise took place later in the year than the other cruises, thus under lower light levels. The lack of plankton accumulation in the presence of large amounts of nitrate intrigued the PIs and an experiment was conducted on the importance of light to PN growth. The study obtained multi disciplinary data from a large scale grid (Section 1), sampling water properties and plankton while following a drifter (Section 2), deployment of surface drifters (Section 3), satellite imagery (Section 4), and on-board laboratory studies using water/plankton collected at selected sites (Section 5). The setting of cruise sampling events with respect to wind direction (upwelling or downwelling-favorable) is shown in Figure 2. Winds during the cruise were strong and upwelling-favorable for roughly a week, strong and downwelling-favorable for the next several days, then primarily upwelling-favorable for the remainder of the cruise. The complete grid survey took several more days than usual because the iron sampler could only be towed at a speed of 5 knots. Thus the primary grid sampling occurred during several wind environments. All data sections and maps on the website are grouped into three periods independent of winds: survey 0 includes data prior to the major grid sampling; survey 1 includes data collected on the complete grid survey, including lines LD and LE; survey 2 includes data following the grid survey. Personnel transfers occurred on September 22 and 24. Over 230 water column profiles were obtained. Satellite imagery [sea surface temperature (SST) and chlorophyll] was limited in the first two weeks of the cruise. However a number of very good surface SST and fluorescence (Chl a) were obtained in the upwelling period beginning September 21. Cruise activities were recorded in a sequential "Event" log (Table 1). Our cruises to date provide sufficient information to allow a comparative analysis of various environmental factors and their effects on PN, growth, grazing, nutrient pathways and DA production in the eddy and WA coast regions. In particular, with the new information obtained during this cruise we have shown that:
1. Regional Surveys (ECOHAB-PNW team) Our large scale survey grid was designed to include areas influenced by the Strait of Juan de Fuca, the Juan de Fuca eddy region and the coastal upwelling region off the Washington coast (Fig. 3). Data collected on surveys included conductivity (C), temperature (T), light transmission, PAR, oxygen and fluorescence (Fl) profiles, and bottle samples for size-fractionated phytoplankton biomass (chlorophyll a), whole cell fluorescent molecular probe assays, particulate DA, dissolved DA, FlowCAM and Flow cytometry samples, samples for scanning electron microscopy of PN species, plankton (including PN cell counts) and macronutrients, all at selected depths in the water column. Surface net tows for qualitative community assessment were taken at all survey stations. Water samples containing PN were placed in medium for isolation and culturing in the laboratory. Underway data included T, C and Fl pumped from a depth of about 4 m as well as ADCP current profiles from 75 khz broad and narrow band RDI ADCPs. CTD/nutrient/net transects were made along Puget Sound and along the Strait of Juan de Fuca on September 12 during the transit from Seattle (Fig. 4a). Bucket and net samples were obtained on the return journey. Lines were sampled in whichever direction made best use of ship time. CTD profiles were taken to 500 m where possible. For modeling purposes and to investigate interannual changes, one station was taken to 1000 m (CTD 197). For the third time in our ECOHAB PNW studies, the northern line LD was sampled. A new line (LE) farther northwest was sampled because of the northwestward spread of the surface eddy water. Note that LE begins at the location of the Institute of Ocean Sciences (IOS) LE line, but is oriented differently than that line and thus stations are not identical to the IOS stations. Another new line (WB, offshore of Willapa Bay) was sampled because an increase in PN cell numbers was observed on the beach by ORHAB, our partner program, at Twin Harbors and Long Beach. Two or three calibration CTDs were taken at each of the four mooring sites. Chlorophyll a (size-fractionated samples: >5 µm and GF/F filters), particulate and dissolved DA and plankton samples (for both microscope and occasional molecular probe analysis) were taken near the surface (~0 m), 5 m and 10 m and chlorophyll max. Preserved samples for flow cytometric analysis of nanoplankton, cyanobacteria, and bacterial abundance were taken from 5 m at all grid (survey 2) stations. DA samples were also taken at 15, 30 and 50 m at other stations, for example, at the drift A stations. Macronutrients (nitrate + nitrite, phosphate, silicate) were taken generally at the surface, 5 m, 10 m, 15 m, 30 m, 50 m, 100 m, 200 m, 500 m and ~5-10 m above bottom if the bottom was less than 500 m deep. In the Juan de Fuca Strait survey, samples were taken also at 150 m. Whole water samples (4 L) from these deep stations were concentrated through a 20 micron mesh and plankton and were visualized through the FlowCAM. On transects, macro-nutrients were taken in most cases at the two stations closest to shore on a line and then every other station on each line. On LE only surface nitrate samples were taken, but they were taken at every station. During survey period 2, macronutrients were not generally taken, because the ISUS (see below) was working well. Stations were taken when the ISUS briefly failed, on the LAB line (second pass) where we wanted phosphate for Amy MacFadyen's water mass analysis, for drifter endpoint CTDs and for mooring sensor calibration. Most of the macro nutrient samples were processed onboard ship by Julian Herndon (Cochlan group) to enable future onboard sampling decisions. Data will be quality controlled and remaining samples will be processed by mid January 2007. The ISUS nitrate sensor data, mounted on the instrumented CTD rosette, can be used for vertical profiling, with appropriate calibration. For the first time, the ISUS worked very well, thanks to the efforts of Nick Adams. Regressions between measured nitrate and ISUS nitrate were obtained with a correlation of 0.99 By Sally Warner and Tom Connolly (Bottle = 0.4075 + 1.0987 *ISUS). The slope and intercept remained constant throughout the cruise. Sections were compared between ISUS and bottle data-in some cases the ISUS provided significantly better structure below 100 m. Upper water column iron samples were taken at selected stations (Table 1). Samples were obtained by flying the trace-metal sampler "FISH" below the surface (~4 m). Samples were taken as the ship approached station (within 10-min). Water was pumped for roughly 10 minutes (20 min prior to station location) to flush the lines thoroughly before samples were taken. In addition to FISH sampling for trace metals, all physiological measures and growth rates (phytoplankton and bacteria) were obtained from the FISH, as well as samples for deckboard incubation experiments. Physiological studies were made on several stations per grid line during the main survey. On some grid lines (GH, LB and LC), a GoFlo bottle at ~10 m was used instead of the towed package. When using these data with the ~4 m data care should be taken to ensure that a mixed layer was present. CTD profiles are available in pdf format on the cd of ship's data (note: disregard PAR profiles, which are quite wrong, see below). These were prepared by the ship's marine technician and are unedited, although a good reference. The CTD data were partially edited onboard ship by Nancy Kachel. Shipboard editing included replacing downcast data with upcast data when necessary. The shipboard data were used to construct the preliminary maps and sections appended to the report. Following the cruise, salinity calibration will be performed and more detailed editing completed (Hickey group). Although water property spatial patterns are likely robust, actual values may change slightly following the final editing which we hope to complete this fall. ADCP data were processed onboard ship by Tom Connolly. Preliminary water property maps and sections obtained from CTD data are given on the ECOHAB PNW website (T, S, O2, Chl, Fl maps at selected depths; T, S, density, Fl, O2 transects versus depth for all transects, 0-100 m and 0-500 m scales). Maps of relative abundance of PN at the surface are also included. The CTD data are organized into three groups: Survey 0 (September 12-September 14), Survey 1 (September 14- September 26) and Survey 2 (September 27-October 3). Stations sampled in each period are shown in Figures 4a,b,c. Survey 0 includes the Puget Sound and Strait data. Survey 1, which took place during variable winds, following a period of upwelling winds, was the only complete grid survey (Fig. 4b). Lines sampled in Survey 2 are useful for characterizing changes over the cruise period. In particular, the KB, CB, GH and WB lines include information on a freshwater plume from the Columbia River-this plume developed along the WA coast during the September 16-19 storm. Underway data should be treated with caution. Water is pumped from about 5 m depth near the bow. As is customary, two temperatures are available. The exterior temperature had a slight offset from 5 m CTD bottle data (5 m bottle = -0.01363+ 1.0033*ext Temp, r2 = 0.98, data through September 21). The salinometer data from September 12 through September 18 should not be used. After careful analysis we determined that the conductivity cell was biofouled. Numerous regressions between CTD bottle and salinometer salinity and also conductivity were performed (by Sally Warner). Although the conductivity regression was very tight (r2 = 0.93), the salinity regression was quite poor and offsets were nonlinear. We did not perform new regressions after the cell was cleaned-this should be done before using the later data. The PAR sensors on the CTD had a variety of problems, and the converted data (in uE) are not usable. This includes profiles plotted in the shipboard pdf files. The PAR sensor on the CTD was a 2pi, which is not appropriate for underwater PAR measurements, and had an unusually narrow voltage range response (0-2 volts). The appropriate 4pi sensor was put on the CTD on September 23, but it also had an unusually low voltage range. An inspection of the connection revealed water entry and corrosion of one of the pins, which most likely accounted for the reduced voltage. The connection was remade, and the voltage range appeared normal. However, the calculated uE values in the CTD data files are not correct; it will be necessary to work with the voltage data to determine extinction coefficients and use the PAR data from deckboard sensors. A comparison of the 2pi data to the 4pi data will hopefully allow a correction to the 2pi sensor data. One drift study was performed on the cruise-this was a brief drift in the shelf edge jet region during a period of upwelling (September 9-12) in an area with moderate nitrate and low concentrations of PN (drifter # 3918, deployed on the front between stations LC 8 and 9). After 1.5 days, 3918 was removed and replaced with drifter #66684. Since it was moving well offshore (and southward) it was not sampled again during the cruise and it was not recovered. Some Preliminary Results: This cruise was unique in several ways: surface nutrient concentrations were extremely high farther offshore and also farther northwestward than we have previously observed, and chlorophyll was much lower than usual, in spite of the more than adequate nutrient supply. This was the case in both early and late survey periods. Surface nitrate >15 µM was observed from the mouth of the strait northwest well past Barkley Sound and south along the WA coast past Grays Harbor. Diatoms of the PN genus were less abundant in the eddy region than in any of the other three fall ECOHAB PNW cruises. High numbers of PN were only observed near the southern WA coast. After 2 weeks working in the eddy region and completing the survey grid, we moved back to the southern coastal region where satellite imagery showed high biomass and the early cruise data showed more PN cells present as well as low but measurable toxin levels. The WA coastal region did have more PN than the eddy, but much fewer than the preceding year's fall cruise. Chlorophyll was also much higher on the WA coast than in the eddy. Nevertheless only very low levels of toxin were detected. Domoic acid concentrations were the lowest observed in the eddy region in all six survey cruises. All values were below detection limits of the receptor binding assay. However low levels (picomolar) were detected using the ELISA method. In spite of the macronutrient, DA and plankton differences from other years, the eddy was well defined in temperature, salinity and velocity patterns at the surface and at deeper depths. However it was more elongated along the coast, extending well past Barkley Sound. Both 2006 and 2005 September cruises had low chlorophyll in the eddy region, although not along the WA coast. The 2006 cruise took place during a year with record level upwelling-favorable winds-and these strong winds continued through the early part of our cruise. In contrast, the 2005 fall cruise took place during a summer with anomalously late onset of upwelling-favorable winds (mid August). The reason for the higher concentrations of PN and chlorophyll near the WA coast than in the eddy on these cruises are not immediately apparent. A major fall storm occurred during the end of the first week of our cruise-winds in this storm were much stronger than in other fall cruises. This storm increased northwestward currents and likely contributed to the along coast lengthening of the area of very high (> 15 µM) nitrate. The storm also created a northward plume from the Columbia, as mentioned above, and that plume moved offshore in the upwelling-favorable winds of the survey 2 period. Thus in survey 2 transects we observed high nitrate near the coast in the upwelling zone, lower nitrate farther offshore in the plume, and higher nitrate offshore of the plume in the waters that had originated farther north near the eddy. High nitrate continued throughout the cruise in mid to outer shelf waters in spite of the variable wind conditions-strong upwelling, a strong downwelling-favorable wind period and then weaker but persistent upwelling winds. It is possible that the observed distributions may represent the beginning of the breakdown of the summertime eddy. We note that this cruise took place later in the year than the other fall cruises. 2. Drift Studies (Amy MacFadyen, Tom Connolly, Barbara Hickey, drifters; whole ECOHAB PNW team for water/nutrient) One brief (1.5 days) drift study was performed, following a water patch with an ARGOS-tracked Brightwaters drifter (# 3918). Nutrients and CTD profiles were taken in the upper 50 m only at the three stations taken. The drifter moved southward along the major front. When it became evident that the drifter was not going to be entrained by the eddy, the non expendable, lighted drifter was replaced with expendable drifter # 66684. Drifter deployment and recovery times and deployment location are listed in Table 2. A number of drifters deployed on September 13 (see below) with accompanying bucket samples (#60054 and #60056) were sampled with CTDs on recovery from September 30 to October 3. The goal was to determine whether toxicity or chlorophyll had increased over the initial very low levels and whether species composition had changed over the 3 week interval between deployment and recovery. 3. Drifter Deployments (Amy MacFadyen, Tom Connolly, Barbara Hickey) Several Brightwaters model drifters (Davis or deep-drogue configurations) were deployed to delineate patterns and speeds of surface flows in the eddy area, as well as to determine the ultimate fate of eddy water. Data were stored at the University of Washington and were also available online on the ship as the ship had web access. Drifter location and water temperatures are available at 30 minute intervals during deployment periods. Eight drifters were deployed at the beginning of the cruise in a small area over the spur canyon (Table 2). The objective was to characterize vorticity over the canyon and in the central part of the eddy. Three were surface drifters (Fig. 6a); five were drogued at 25 m (Fig. 6b). A fourth surface drifter was deployed just east of the primary array (# 60056) to help characterize the larger eddy circulation (Fig. 6a). Drifters were deployed during strong upwelling-favorable winds (Fig. 2). During the strong downwelling winds of September 16-19 the surface drifters moved rapidly northwestward, passing well north of Barkley Sound (Fig. 6a). When upwelling-favorable winds returned these drifters all moved offshore and turned southeast along the isobaths. The drogued drifters that remained near the eddy center moved at speeds of a few cm/sec, much slower than the surface drifters (Fig. 6b). Two of the drogued drifters appeared to escape the eddy core region. On recovery it was discovered that these drifters had lost their drogues. The other drogued drifters eventually began to turn counterclockwise following the density contours at 30 m. The surface drifters moved southeastward and returned to the eddy region, following water that still contained high nitrate. Most of the surface drifters eventually moved onshore and then southward along the coastal front. Most had nitrate ~10 µM upon recovery on the central WA coast. Additional drifters were deployed to help describe the circulation. One drifter (#60058) was deployed south of the eddy on September 13. This drifter moved south along the WA midshelf, subsequently moving past Grays Harbor. This drifter was sampled with a CTD on October 1, but was left in the water so that it could interact with the Columbia plume. Two drifters were deployed on September 24: one at LB 13 (#66685); another on the south side of the eddy (#66684). Both of these drifters turned shoreward and then moved southward along the WA shelf. They were subsequently recovered, following a CTD to delineate final conditions. 4. Satellite Imagery (Rick Stumpf, Jack Weckell) Satellite imagery during the cruise was provided by two groups who sent data to the ECOHAB PNW ftp site-Jack Weckell from the Trainer NOAA group provided SST imagery. Chlorophyll imagery was provided by Rick Stumpf at NOAA. The available imagery and an assessment of its quality are listed in Table 3. Because of delay in imagery sent from R. Stumpf's group, additional imagery was kindly provided by Raphael Kudela at UC Santa Cruz and by Jim Gower at the Institute of Ocean Sciences. Few good images were obtained in the first part of the cruise, particularly during the downwelling wind period. However, clear imagery was obtained after September 21 when upwelling-favorable winds returned. Lessard Group (Evelyn Lessard, Julie Wright, Mike Foy, and Megan Bernhardt) The main goal of this component of ECOHAB PNW is to determine the role of grazers in PN population dynamics and DA production. We used the dilution technique to experimentally alter grazing rate and nutrient recycling to determine the effects of grazers on the net growth rate of the whole and size fractionated phytoplankton community, specific species and groups of phytoplankton, and the production of dissolved and particulate DA. These experiments also provide estimates of the in situ growth rates of PN compared to other phytoplankton. We also took FlowCAM (an imaging flow cytometer) and fixed samples to follow the in situ spatial and temporal changes in the microphytoplankton and protist grazing community in relation to PN and hydrography. On this cruise, we performed the following:
b) RTC/SFSU Research Group (William Cochlan, Maureen Auro, Julia Betts, Julian Herndon, Regina Radan, Elizabeth Moore, and two Teachers-at-Sea: Denis Costello and Christine Muir) The primary objective of this component of ECOHAB PNW is to examine the relationship between elevated concentrations of the pennate diatom PN and its toxin DA, and ambient concentrations of macro-nutrients and phytoplankton biomass. In addition a number of bioassays (grow-out experiments) were conducted in association with the Wells research group to determine the relationship between copper, iron and DA production. At each station of the survey sampling grid, size-fractionated phytoplankton biomass levels were estimated from chlorophyll a (Chl a) concentrations determined using in vitro fluorometry (aboard ship) after extraction for 24 h with 90% acetone. Chl a samples generally were collected at three depths (0, 5, 10 m) and, at an additional depth corresponding to the chlorophyll maximum layer, when present. Size-fractionated biomass estimates were conducted as follows: total planktonic community was collected on Whatman GF/F filters (nominal pore-size of 0.7 µm), and cells >5 µm in size were collected on Poretics polycarbonate membrane filters. At every second station, dissolved inorganic nutrients were collected at 0, 5, 10, 15, 30, 50, 100, 200 m and near bottom) and analyzed using appropriate colorimetric methods for determination of nitrate plus nitrite, phosphate, and silicate with a Lachat Instruments QuickChem 8000 Series Flow Injection Automated Ion Analyzer. Both Chl a and nutrients were determined at the two most shoreward stations of each sampling line. Vertical profiles of dissolved inorganic nutrients were also determined at the drifter stations, at six vertical stations in the Strait of Juan de Fuca and six stations in Puget Sound. Samples from the Juan de Fuca and Puget Sound transits and grow-out experiments were also collected for ammonium (analyzed onboard using a sensitive fluorometric method) and urea (90% analyzed onboard using a spectrophotometric method), in addition to the standard inorganic nutrients. Dissolved nutrients were determined at the beginning (time-zero) and end (time-final) of all of the dilution experiments performed by Lessard's research group, daily for the anchovy experiments (Lefebvre group) and, when requested, for graduate student research. A series of shipboard incubation experiments (conducted in association with the Wells group) were designed to assess the role of trace metal (Cu and Fe) and light availability on the growth of PN and DA production. These multi-day experiments were conducted with water collected from the surface mixed layer (~ 4-5 m) using the trace-metal clean sampling system (FISH; Wells Group) at stations throughout the sampling grid, with particular emphasis in regions previously found to harbor elevated concentrations of PN and DA. During all grow-out experiments, samples were preserved for onshore bacterial and picoplankton abundance determination by the University of Western Ontario team using flow cytometry (Becton Dickinson, FACSCalibur), and will be used to generate specific rates of bacterial productivity from the bacterial protein synthesis estimates (3H-leucine method). Photosynthetic-irradiance (P-E) curves were generated from short-term (1-1.5 h) 14C uptake experiments using photosynthetrons at the initiation of all grow-out experiments, at selected times during the drifter experiments and throughout the large volume grow-out experiments, and at the termination of continuous culture experiments (in association with Lisa Pickell, Univ. Maine); these results will be used to describe the efficiency and capacity of phytoplankton photosynthesis with respect to light intensity. Phytoplankton biomass estimates (as previously described) were determined for all metal and macronutrient treatments at the initiation, throughout and termination of each incubation experiment. These measures, together with draw-down rates of macronutrients, will be used to estimate the growth response (including DA production) of the phytoplankton community to copper and iron bioavailability. Other biological measurements conducted during the grow-out experiments included: microscopic taxonomy (Trick Group), total and dissolved DA (Trainer Group), trace metals (Wells Group), and cellular fluorescence capacity (CFC; as measured using the inhibitor DCMU). Two, large volume (10-L) multi-day grow-out experiments involving sixteen carboys (and one parallel experiment employing 24, 2-L PC bottles) were conducted to elucidate the role of nitrogen source (nitrate, ammonium and urea) in the growth of PN species and their production of domoic acid as a function of iron and copper bioavailability. These experiments will discern if anthropogenic nitrate sources, associated with agricultural and human activities, promote either the growth or toxicity of PN in the study region and the role of trace metals as a determinant factor in any preferential utilization of nitrogen sources and/or production of DA. Expected Results:
c) University of Western Ontario Research Group (Charlie Trick) Our contribution to the ECOHAB project is two-fold: 1) to provide flow cytometric analysis (FCM) to characterize the community assemblage; and 2) to provide experimental evidence of factors that either increase the competitive ability of PN or increase the level of DA per cell. Samples for FCM were collected for our lab at all Puget Sound, Juan de Fuca and grid survey stations at 5 m depth. This will allow for quantitative analysis of bacteria, cyanobacteria, and nanoplankton communities. In our second major contribution to the cruise mandate, the personnel from the Cochlan and Wells labs carried out deckboard incubation growth experiments (see Wells description below). All labs offered their expertise to the common goal of all growth experiments (biomass formation, nutrient drawdown measurements, DA analysis (particulate and dissolved), community structure changes, bacterial and phytoplankton productivity and photosynthetic efficiency and capacity). The overall foundation of these grow-out experiments was aimed at elucidating the factors that influence the initiation, formation and/or maintenance of PN blooms or DA levels (either cellular or extracellular). The working hypothesis for this set of experiments was that PN benefits from producing DA because DA serves as an iron and/or copper chelator. Thus in the presence of macronutrients (either in upwelling sites or in the areas of high nutrients associated with the Juan de Fuca eddy) DA would act as an iron chelator, ensuring that the cells would have a supply of iron as iron concentrations diminish, either through colloid formation or utilization. Alternatively DA could serve as a copper chelator, reducing the levels of cupric ion to less inhibitory levels, allowing PN to fully utilize the macro-nutrients and grow effectively. d) Trainer Group (Vera Trainer, Keri Baugh, Shelly Nance, Sheryl Day, Brian Bill, Nicolaus Adams, Stephanie Moore, Anthony Odell, Anne Mataia, Shuk Tsui, Lauren Kuehne) Bucket and net tow (20 µm mesh) samples were taken to rapidly assess the presence of cells and DA at a number of stations. At each survey and drift station, samples were routinely taken from CTD rosette bottles at 0, 5, 10 m for measurement of particulate and dissolved levels of DA, whole cell counts of PN, enumeration of PN size classes, and scanning electron microscopy for species determination in selected samples. A net tow was taken at every station to rapidly determine the presence or absence of PN and their relative abundance. At selected coastal stations, depth profiles of cells and toxins were done at some of the following depths: 0, 5, 10, 20, 30, 50 m to determine the role of the Columbia River plume in HAB advection to the coast. Particulate DA was analyzed by filtering 1 L seawater through a Nucleopore HA filter (0.45 micron pore size). Filters were minced in 5 ml distilled water with a thin metal spatula and sonicated for 2 h in a bath sonicator to lyse cells. An aliquot of each sample was analyzed using a receptor binding assay in 96-well plate format using a multiwell harvester and Top Count scintillation counter. The receptor binding assay tests the displacement of [3H]kainate by DA in a sample from a cloned glutamate receptor. Each plate of was compared to known DA standards analyzed on the same plate. Endogenous glutamate was digested prior to sample analysis using glutamate dehydrogenase.
e) Wells Group (Peggy Hughes, Lisa Pickell, Kathleen Hardy) The University of Maine component of the ECOHAB PNW cruise had two primary goals: to collect seawater samples from the study area for trace metal analysis and to optimize, and to conduct deckboard incubation studies (in conjunction with Cochlan/Trick group) testing the effects of trace metals on phytoplankton production, community structure (i.e., PN abundance) and cell toxicity. Approximately 150 surface samples from the survey station grid were collected for trace metal analyses while underway through a trace-metal clean sampling towfish. On some grid lines (GH, LB and LC), a GoFlo bottle at ~10 m was used instead of the towed package. When using these data with the ~4 m data care should be taken to ensure that a mixed layer was present. Vertical profiles also were collected with GoFlo bottles from three sites (offshore, in the eddy core, and a comparatively shallow shelf station in the southern part of the study area. Preliminary analyses of Fe concentrations on a subset of samples were conducted on-board by flow injection chemiluminescence detection. The collected samples will be later analyzed at the University of Maine by high resolution Inductively Coupled Plasma Mass Spectrometry to observe spatial and temporal variability of trace metals, and to serve as means for comparison with the shipboard iron method. The shipboard method for iron provided preliminary iron concentrations to guide various grow-out experiments conducted by the Wells and Cochlan research teams. The veracity of towfish and shallow GoFlo bottle sampling was tested by collection of surface waters from a small boat away from, and upwind of the vessel. These reference samples will help to demonstrate that sample collections were not affected by metal contamination in either the system (Towfish) or by close proximity to the vessel (GoFlo bottles). In addition to the large growout studies described above, the Wells group also were logistically responsible for conducting 8 independent batch culture incubation experiments, involving > 350 sample bottles, testing the synergistic effects of trace metals, macronutrients, metal complexing ligands, and light intensity. Two separate continuous culture experiments, each consisting of 14 simultaneous culture vessels, were performed to study how community composition evolves over time as a function of different metal and macronutrient stresses. f) Jen Boehme (visiting scientist, Smithsonian Environmental Research Center) Approximately 100 samples were collected from CTD casts along the station grid. Optical properties of chromophoric dissolved organic matter were examined for filtered samples (0.2 µm) using absorbance spectroscopy and excitation emission matrix spectroscopy (EEMS). Samples collected on this cruise will be added to a global database of CDOM fluorescence, with the intention of examining fluorescence variability within different marine biogeochemical provinces. Additional absorbance and EEMS analyses were performed in collaboration with grazer incubations from the Lessard growth and grazing experiments, as well as from selected treatments of the Wells continuous culture and batch culture experiments. Samples were also collected from the ship's underway system for a SERC project relating chemical tracer concentration (CDOM and trace elements) with distance from shore. In collaboration with Cochlan (RTC/SFSU), Wells (U. Maine) and Trainer (NOAA NWFSC) two, highly experienced, in-service high school teachers from California were invited to join the final ECOHAB PNW cruise to serve as Teachers-At-Sea (TAS). Christine Muir (Woodside Priory School, Portola Valley, CA) and Denis Costello (North High School, Torrance, CA), both previous participants of San Francisco Bay Educator's 'Coastal Oceanography' Workshops held at the Romberg Tiburon Center, posted daily logs of the ECOHAB PNW research being conducted throughout the three-week cruise. Their detailed journals outline the primary research objectives of ECOHAB PNW, the theory behind the science, how the research is actually conducted, and finally the people and equipment necessary for ECOHAB PNW's scientific objectives to be met. Both TAS also were heavily involved in around-the clock biological sampling and analyses and their scientific contribution to success of ECOHAB PNW VI was significant and very much appreciated by the scientists onboard. With funding from NOAA's Northwest Fisheries Science Center (NWFSC), Jennifer Maas and Tony Elias (Evil Bunny Films, Seattle, WA) came aboard the vessel for 3 days to film ECOHAB PNW scientists in action as an example of collaborative oceanographic research. Their goal, in collaboration with the two TAS was to create a 3-minute film on ECOHAB PNW science and a 20-minute film for senior high school and freshman college students and the general public on the nature of oceanographic research at sea. The teachers' journals and short videos are linked to the outreach page on the ECOHAB PNW website, and outline the experimental design and analyses conducted at sea, the lives of scientists onboard the ship and numerous aspects of the science of harmful algal blooms, and how ECOHAB collaborative research is conducted and funded. We would like to thank the captain and crew of the R/V T.G. Thompson for their support during the September 2006 cruise. We also thank our shoreside support team: Jack Wekell, Bich-Thuy Eberhart, and Susan Geier. Nancy Kachel deserves our special thanks for handling cruise leader responsibilities before and after the cruise, and Julian Herndon for handling the chemical issues for all research groups before the cruise. This research was supported through the Ecology and Oceanography of Harmful Algal Blooms program by National Oceanographic and Atmospheric Administration/Coastal Ocean Program Award No. NA17OP2789 and National Science Foundation Award No. 0234587. Table 1 Event log Fig. 1 Cruise track with sampling stations.
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