Mark Huntley - Academia.edu (original) (raw)

Papers by Mark Huntley

Polar Biology, Sep 30, 1989

Public reporting burden lor this collection of information is estimated to average one hour per r... more Public reporting burden lor this collection of information is estimated to average one hour per response, including the time for reviewing instructions, searching existing dels s gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of collection of information, including suggestions for reducing the burden to Washington Headquarters Services. Directorate for Informtion Operatins and Reports, 1216 Jeffers Davis Highway, Suite 1204, Arlington, VA 22202-4302. and to the Office of Management and Budget. Paperwork Reduction Project I0704-0188). Washington, DC 20503 2. REPORT DATE |3. REPORT TYPE AND DATES COVERED REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 1. AGENCY USE ONLY (Leave Wank) None NSN 7B40-01-280-5600 Standard Form 298 (Rev. 2-89)

Marine Biology, 1995

Elemental composition and excretion rates of ammonium-nitrogen of zooplankton, ranging over more ... more Elemental composition and excretion rates of ammonium-nitrogen of zooplankton, ranging over more than five orders of magnitude in body size, were measured in mid-winter in coastal waters west of the Antarctic Peninsula. Excretion rates were constant for the initial 12 h of incubation in the four species tested, and experimental stocking densities of up to t26 mg dry wt 1-1 did not cause variability in the rate of ammonium production. Weightspecific excretion rates of freshly caught Euchaeta antarctica, Conchoecia sp., Thysanoessa macrura, Euphausia superba, and early stage copepodites ofMetridia gerlachei were not significantly different from those reported in summer. However, adult copepods of M. gerlachei and Calanoides acutus appear to have reduced their nitrogen metabolism during winter. Turnover rates of body nitrogen increased with diminishing size, ranging from < 0.5% body N d -1 for large E. superba to >7% body N d -1 for CII and CIII copepodites of M. gerlachei. Only the nitrogen turnover rates of C. acutus were sufficiently low as to suggest that it could survive the entire austral winter without feeding. Phytoplankton and bacterioplankton were virtually absent in both the water column and the sea-ice. We conclude that carnivory is the dominant trophic mode of the pelagic zooplankton community in Antarctica during winter. Production of ammonium-nitrogen by the zooplankton community probably accounts for < 10% of the total ammonium regenerated prior to the annual spring bloom.

Page 1. OTC 20074 Enabling Ultra-Deepwater Mooring With Aramid Fiber Rope Technology CH Chi and E... more Page 1. OTC 20074 Enabling Ultra-Deepwater Mooring With Aramid Fiber Rope Technology CH Chi and EM Lundhild, SPE, DuPont; T. Veselis, InterMoor Inc.; and MB Huntley, Whitehill Manufacturing Corporation Copyright ...

Polar Biol, 1995

Diel vertical migration and feeding cycles of adult female Metridia gerlachei in the upper 290 m ... more Diel vertical migration and feeding cycles of adult female Metridia gerlachei in the upper 290 m of a 335-m water column were measured during a total of 65 h in two periods of early summer ( Dec 20-21 and Dec 25-26, 1991). Samples collected in eight depth strata by 35 MOCNESS tows (333%tm mesh) were analyzed for abundance and mean individual gut pigment content. Most of the copepod population was concentrated in a 50-m depth interval at all times. Feeding began simultaneously with nocturnal ascent from a depth of 200-250 m at ,,~ 18:00 h (local time), when the relative change in ambient light intensity was greatest. Ingestion rate increased exponentially (ki = 0.988 h -1) at double the gut evacuation rate (ke = 0.488 h-1) as the population moved upward at 22.3 26.5m h-1 through increasing concentrations of particulate chlorophyll-a. Although the bulk of the population did not move to depths shallower than 50 m, and began its downward migration at a rate of 20.8-31.7mh -1 in complete darkness, individual females continued to make brief excursions into chlorophyll-rich surface waters (4-8 gg1-1) during the first few hours of population descent. Ingestion rate diminished abruptly by one order of magnitude (ki = 0.068 h-1) at dawn ( ,,~ 03:30 h). Within four more hours, the population had reached its daytime depth and gut pigment content remained constant at a minimum value until the next migration cycle. No feeding appeared to take place at depth during the day. Ingestion by M. gerlachei females removed < 4% of daily primary production, with only ~ 20% of this amount being removed from surface waters by active vertical transport.

Marine Ecology Progress Series, 2000

Zooplankton in the central jet of the California Current and an adjacent mesoscale cyclonic eddy ... more Zooplankton in the central jet of the California Current and an adjacent mesoscale cyclonic eddy centered at 125.1°W, 38.4°N were studied in early July, 1993, using a SeaSoarmounted Optical Plankton Counter. Within 3 d after the 2 d survey of these mesoscale features we completed a MOCNESS transect across the study area. Zooplankton in the rapidly moving (> 40 cm s -1 near surface) jet were negatively correlated with the vertical distribution of phytoplankton biomass, which displayed strong fluorescence maxima in the upper 200 m. Zooplankton in the recirculating eddy, however, were positively correlated with fluorescence maxima at the pycnocline (ca 50 m) and at 150 m. Euphausiids, dominated by Euphausia pacifica, and the copepod Calanus pacificus accounted for most of the zooplankton in the upper 50 m of the eddy, while the copepod Metridia pacifica dominated the abundance maximum of medium size zooplankton at 150 m. These species were also present in the jet, but male:female ratios of the 2 copepod species differed greatly, suggesting that populations within the jet and the eddy were distinct from one another. Earlier observations of the cyclonic eddy indicate that it departed California coastal waters in April; resident zooplankton populations may have gone through several generations before they reached the position at which we found it in July. Waters of the jet, by contrast, probably departed from the California coastal region in mid-June, so that its populations of zooplankton may have been essentially the same as those advected to our sampling location.

Deep Sea Research Part A. Oceanographic Research Papers, 1991

The Research on Antarctic Coastal Ecosystem Rates (RACER) program of 1986-87 was designed to exam... more The Research on Antarctic Coastal Ecosystem Rates (RACER) program of 1986-87 was designed to examine physical and biological processes that give rise to high biological productivity in the vicinity of the Antarctic Peninsula, In a 25,0tXI km 2 sampling area at the western end of Bransfield Strait and during the period from mid-December 1986 to late March 1987, four 2v.eek cruises were made over a 69-station grid encompassing the coastal shelf, the continental shelf break, numerous island shelves, the BelIingshausen Sea-Weddell Sea confluence, and a portion of Drake Passage. Studies were focused on the upper ocean (0-200 m) and included detailed measurements of hydrography, ocean optics, vertical flux. and the distribution, abundance and productivity of bacteria, phytoplankton, zooplankton and krill. This paper describes the program logistics and presents the results of a carbon flux model, based on empirical observations, for the ncarshorc pelagic marine ecosystem.

Proceedings of Offshore Technology Conference, 2009

Primary Productivity in the Sea, 1980

The American Naturalist, 1992

The American Naturalist, 1984

ABSTRACT

Polar Biology, 1995

Marine Ecology Progress Series, 1997

Here we construct a fundamental mathematical theory of population dynamics in the context of the ... more Here we construct a fundamental mathematical theory of population dynamics in the context of the normalized spectra of abundance and biomass of plankton. The theory begins with the distribution function of abundance as a function of individual body weight and growth rate, and the law of the conservation of mass. The basic governing equations for population growth and biomass production are then deduced without empirical assumptions. The governing equations represent the fundamental mass balance between the biomass flux from small to large sizes due to individual growth and the sum of sources and sinks such as birth, natural death and predation. The slope of the normalized biomass spectrum at steady state is proved to be approximately equal to the ratio of the intrinsic rate of increase in abundance to individual weight-specific growth rate. We demonstrate that measurements of biomass spectra in nature can be used to estimate population-dynamics parameters of individual growth rate and the intrinsic rate of increase. We further apply this population dynamics theory to data collected by an Optical Plankton Counter in the California Current region during June and July, 1993. These data cover a range in the marine biomass spectrum from 1 0 ' to 104 pg C individual body weight.

Marine Ecology Progress Series, 1994

Euphausia superba Dana was collected at stations encompassing 3" of latitude in icecovered waters... more Euphausia superba Dana was collected at stations encompassing 3" of latitude in icecovered waters west of the Antarctic Peninsula in winter of 1992 (July-August), and in the same region the previous summer (December-January). There was no significant change in any biometric index (dry weight vs length, carbon vs dry weight, nitrogen vs dry weight, or body C:N). Rates of ammonium excretion in winter were not significantly different from those previously reported for E. superba in summer. It was clear that E. superba fed as a carnivore in winter. Copepod body parts consistently occurred in M 1 guts. During winter shipboard experiments, freshly caught krill ingested copepods and produced faeces at rates comparable to those measured in summer. The low ratio of N:P excretion (2.02) also suggests carnivorous feeding. A physiological model of carbon and nitrogen metabolism indicates that E. superba must feed during winter to maintain its observed C : N ratio and rate of ammonium excretion. On a diet of less than 1 Metridia gerlachei female copepod per day, a 20 mm knll can grow with a growth efficiency comparable to that achieved in summer. We suggest that starvation, body shrinkage and reduced metabohsm are unusual behaviors for knll in winter, and that carnivory sustains growth until ice algae become available as food in late winter and early spring.