The feeding response of copepods from the Peru upwelling system: Food size selection

Two cruises to the Peru upwelling in 1976 and 1977 provided the opportunity to examine the feeding response of Centropages brachiatus, Calanus chilensis, and Eucalanus inermis. The shipboard experiments with naturally occurring particulate matter were designed to test two hypotheses: 1) that food size selectivity by a copepod is a function of overall food concentration, and 2) that a copepod varies the range of food sizes ingested as a function of food concentration and available food size...

Copepods from warm-core ring 82-H

See Supplementary information.txt for information regarding how access and use the files in WHOI-89-24-data.zipNet tows were collected with a Multiple Opening/Closing Net Environmental Sampling System (MOCNESS) carrying twenty 1-m2 nets in October 1982 in and near warm-core ring 82-H in the North Atlantic (RV/Knorr cruise 98). This report includes the species list and abundance tables of the copepods found in five of the tows. There are four types of abundance tables: raw data, standardized to #/1000 m3 , integrated #/m2 to 1000 m depth, and cumulative percents over the depth of the tows.Funding was provided by the National Science Foundation through grant Number OCE 80-12748, OCE 85-08350, OCE 87-09962, OCE 80-19055, and OCE 80-17271

A High-Speed, Wireless Network for Ship-to-Ship and Ship-to-Shore Data Exchange

Wireless networking equipment was installed on three research vessels and at three shore stations during the 1998 Thin Layers Experiment in East Sound, Washington. This wireless network provided high-speed data communication between scientists on separate vessels and permitted rapid transfer of data from vessels and from moored instruments to a common file server at one of the shore stations. This server was connected, via wireless link, to a local Internet service provider, thus permitting continuous Internet access from each vessel and each shore station. The wireless network used 900-MHz and 2.4-GHz spread spectrum systems and provided throughput comparable to T1 lines. Omnidirectional antennas were used between vessels and shore stations, providing communications at ranges up to 12 km. Such systems provide the capability for rapid data exchange during coordinated field operations and give investigators on separate vessels the opportunity to adapt sampling protocols to rapidly evolving conditions observed a few kilometers away

Spectral backscattering properties of marine phytoplankton cultures

The backscattering properties of marine phytoplankton, which are assumed to vary widely with differences in size, shape, morphology and internal structure, have been directly measured in the laboratory on a very limited basis. This work presents results from laboratory analysis of the backscattering properties of thirteen phytoplankton species from five major taxa. Optical measurements include portions of the volume scattering function (VSF) and the absorption and attenuation coefficients at nine wavelengths. The VSF was used to obtain the backscattering coefficient for each species, and we focus on intra- and interspecific variability in spectral backscattering in this work. Ancillary measurements included chlorophyll-a concentration, cell concentration, and cell size, shape and morphology via microscopy for each culture. We found that the spectral backscattering properties of phytoplankton deviate from theory at wavelengths where pigment absorption is significant. We were unable to detect an effect of cell size on the spectral shape of backscattering, but we did find a relationship between cell size and both the backscattering ratio and backscattering crosssection. While particulate backscattering at 555 nm was well correlated to chlorophyll-a concentration for any given species, the relationship was highly variable between species. Results from this work indicate that phytoplankton cells may backscatter light at significantly higher efficiencies than what is predicted by Mie theory, which has important implications for closing the underwater and remotely sensed light budget

Edge gradients provide evidence of ecological interactions in planktonic thin layers

Physical, optical, and acoustical data from Monterey Bay, California, USA, describing the distributions of phytoplankton, zooplankton, and small fish as well as gradients in the physical habitat were used to examine the interactions between vertically compressed plankton structures (thin layers), their consumers, and the local physical forces they experience. The relationship between upper and lower edge gradients of a layer were used to define layer ‘shape’. The steepness of the vertical gradient on the top vs. the bottom of the plankton layer was correlated to the difference in the relative abundance of consumers above and below the layer. Phytoplankton layer gradients were steeper when more zooplankton were present on one side of the layer vs. the other while zooplankton layers were more diffuse when a greater number of fish were adjacent to one side of the layer than the other. Both layer types showed nearly symmetrical gradients when predators were in low abundance or absent. Predator-associated differences in phytoplankton and zooplankton layer shape were not correlated with vertical gradients in shear or mixing potential surrounding layers. In the absence of strong physical gradients, grazers can play an important role in structuring plankton thin layers. These observations likely represent one end of a continuum of biological and physical forcing responsible for formation and maintenance of thin plankton layers

Acoustic doppler current profiler observations during the JGOFS AESOPS Antarctic polar front process studies I and II : R/V Revelle cruises from 30-Nov-97 to 3-Jan-98 and 13-Feb-98 to 19-Mar-98

We present velocity observations from a shipboard acoustic Doppler current profiler (ADCP) on RIV Revelle during cruises R9711 (30 November 1997 to 3 January 1998) and R9802 (13 February 1998 to 19 March 1998). The cruises were conducted as part of the Southern Ocean JGOFS (Joint Global Ocean Flux) Antarctic Polar Frontal Zone program. The ADCP was an RD Instruments hull-mounted 153-kHz narrowband unit. Data were collected nearly continuously during these Spring and Summer Process cruises, using an ensemble averaging interval of 2.5 min and a vertical bin length of 8 m. To reference the velocities to earth coordinates, we used GPS navigation in combination with the ship's gyrocompass and a GPS attitude system. An online version of this report is available at http://diana.coas.oregonstate.edu/sojgofs. In addition, the complete data sets and all processing details are available from the NODC Joint Archive for Shipboard ADCP: http://ilikai.soest.hawaii.edu/sadcp. This work was funded by National Science Foundation grant OPP-9530758

Mesoscale physical and bio-optical structure of the Antarctic Polar Front near 170°W during austral spring

As part of the U.S. Joint Global Ocean Flux Study Southern Ocean program, high-resolution surveys of the Antarctic Polar Front near 170øW were conducted during October-November 1997 with a towed undulating system equipped with conductivity-temperature-depth and bio-optical sensors. Transects along 170°W and two successive mapping surveys revealed zonal bands with sharp meridional gradients in east-west velocity. The Polar Front (PF) was characterized by a sea surface temperature drop from 1.6° to -1.6°C between 60.35° and 61.10°S, with eastward velocities of 0.4-0.5m s¯1 in the core of the PF jet. Deep mixed layers (> 200 m) were found within and north of the PF, but mixed layers shoaled to 100-125m south of the PF to the edge of loose ice at 62.3°S. Highest mixed layer chlorophyll concentration (0.35 mg m¯3) in late October along 170°W were to the south of the PF and associated with cold, fresh water. A large meander of the PF was observed with an alongfront wavelength of 175 km, a cross-front peak-to-peak amplitude of 100 km, and an eastward phase propagation of 0.05-0.08m s¯1, all of which are consistent with its formation via hydrodynamic instability of the PF jet. Highest-phytoplankton biomass was located just poleward of the center of the PF jet. A high-chlorophyll (up to 1.1 mg m¯3) 50 by 50 km region was found downstream of the cyclonic bend associated with the meander. A survey 7.5 days later revealed growth of this high biomass regions to that chlorophyll as in excess of 0.8mg m¯3 over an 80 km cross front by (at least) 80 km along front region. High biomass was observed to grow in place with respect to the meander rather than being displaced far downstream as would be expected from advection. This pattern is consistent with meander-driven upwelling of nutrients and/or trace metals, which in turn stimulates phytoplankton growth. Detailed cross sections of the PF reveal narrow 10-20 km wide bands or filaments of phytoplankton biomass that have temperature/salinity properties distinct from surrounding water and are coherent for at least 120 km alongfront.Copyrighted by American Geophysical Union

Interdisciplinary study of warm core ring physics, chemistry, and biology

We are conducting an interdisciplinary study of the structure and dynamics of Gulf Stream \Warm Core Rings by a time series investigation of selected rings. This program consists of highly integrated components which include physical, chemical, and biological investigation and modeling studies. These components are designed to provide information on the structure of rings and exchange mechanisms at ring boundaries, on their marine chemistry, and on the environmental controls of biological activity of selected constituents associated with Warm Core Rings. This research is being conducted by approximately two dozen investigators from thirteen marine institutions. An interdisciplinary program of the scope proposed is required in order to understand the interdependence among biological, chemical, and physical processes in the ocean. This study of the structure and evolution of Warm Core Rings will enhance the understanding of fundamental oceanic processes and the role of rings in the region where they occur

In situ monitoring of ocean chlorophyll via laser-induced fluorescence backscattering through an optical fiber

The first seagoing test of a prototype laser/fiber-optic system for in situ detection of ocean chlorophyll fluorescence is described. Radiation at 488 nm originating from a shipboard argon laser was transmitted through 20 of 200-µm core optical fiber to the distal tip mounted on the microstructure profiler, the Rapid Sampling Vertical Profiler. The backscattered fluorescence emission signal was collected through the same fiber and processed on board ship. A series of measurements indicated that (1) successful isolation of shipinduced vibrations could be achieved using our optical bench framework to maintain optical alignments; (2) ambient chlorophyll concentrations could be detected in situ; (3) a Raman scattering signal from water could also be detected and should provide an internal standard against which chlorophyll fluorescence may be calibrated.This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ao/home.cfm. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law

Distribution and variability of iron input to Oregon coastal waters during the upwelling season

We measured iron concentrations off the Oregon coast in spring (May–June) and summer (August) of 2001 as part of the Coastal Ocean Advances in Shelf Transport (COAST) program. Dissolvable and total dissolvable iron levels in surface waters were generally higher in spring (mean of 2.1 and 33.9 nmol L¯¹, respectively) than in summer (means of 1.4 and 15.4 nmol L¯¹). In spring and summer, high iron concentrations in surface waters were associated with both cold and saline, recently upwelled waters, and with fresh, relatively warm water influenced by the Columbia River. Comparison of total dissolvable iron in 0.45 μm filtered and in unfiltered samples indicated a substantial contribution from particulate iron. Iron concentrations in summer were generally lower than in spring throughout the water column, with the exception of the near-bottom, where concentrations were generally higher in summer than spring. Optical backscatter data from moored sensors were used to infer the vertical and cross-shelf transport of iron-bearing particles during the upwelling season over a steep shelf. Cross-correlation analysis showed downslope movement of particles from the deep inner shelf to the deep midshelf. There was also evidence for sinking of biogenic particles at the midshelf and inner shelf, but we found no evidence of upslope transport of benthic particles. Sufficient iron is available in this system to meet the demands of the phytoplankton, which are able to make full use of available nitrate.Keywords: iron, particle, Oregon, upwelling, backscatter, Columbia Rive