Shipboard Culture Research Articles

The Ship as Laboratory: Making Space for Field Science at Sea

Expanding upon the model of vessels of exploration as scientific instruments first proposed by Richard Sorrenson, this essay examines the changing nature of the ship as scientific space on expedition vessels during the late nineteenth century. Particular attention is paid to the expedition of H.M.S. Challenger (1872-1876) as a turning point in the design of shipboard spaces that established a place for scientists at sea and gave scientific legitimacy to the new science of oceanography. There was a progressive development in research vessel design from "ship as instrument" to "ship as laboratory" and changing spatial practices aboard these vessels were paralleled by changes in shipboard culture. I suggest that the "ship as laboratory" has now in turn been supplanted by a new model, the "ship as invisible technician", as oceanographic research vessels deploy remote-sensing equipment and gather data that are no longer analyzed on board.

The Social history of English seamen, 1485-1649

Traditionally, the history of English maritime adventures has focused on the great sea captains and swashbucklers. However, over the past few decades, social historians have begun to examine the less well-known seafarers who were on the dangerous voyages of commerce, exploration, privateering and piracy, as well as naval campaigns. This book brings together some of their findings. There is no comparable work that provides such an overview of our knowledge of English seamen during the sixteenth and seventeenth centuries and the tumultuous world in which they lived. Subjects covered include trade, piracy, wives, widows and the wider maritime community, health and medicine at sea, religion and shipboard culture, how Tudor and Stuart ships were manned and provisioned, and what has been learned from the important wreck the Mary Rose. CHERYL A. FURY is an associate professor of history at the University of New Brunswick, and on the editorial board of Northern Mariner (the Canadian journal of maritime history). Contributors: J.D. ALSOP, JOHN APPLEBY, CHERYL A. FURY, GEOFFREY HUDSON, DAVID LOADES, VINCENT PATARINO JR, ANN STIRLAND.

Nutrient and diatom dynamics during late winter and spring in the Oyashio region of the western subarctic Pacific Ocean

We investigated the nutrient and diatom dynamics during late winter and spring (9-March to 1-May 2007) in the Oyashio region as part of the OECOS-WEST research cruises. Macronutrients, iron, chlorophyll a (Chl- a) and biogenic silica (BSi) concentrations in the upper mixed layer varied remarkably ranges were 1.88–18.8 μmol L −1 for NO 3+NO 2, 0.64–1.85 μmol L −1 for PO 4, 3.14–35.7 μmol L −1 for Si(OH) 4, 0.14–0.54 nmol L −1 for D-Fe, 0.64–24.6 nmol L −1 for T-Fe, 0.30–17.4 μg L −1 for Chl- a, and 0.34–14.1 μmol L −1 for BSi. Mixed-layer depth (MLD) varied from 8–190 m during the cruises. The growth rate of in situ phytoplankton communities, dominated by centric diatoms, varied in shipboard culture experiments from 0.55 d −1 for iron-replete to 0.14 d −1 for iron-limited conditions. A relationship between BSi and Chl- a concentrations indicates that the in situ diatom community in the warmer water system (>4 °C) was heavily silicified, probably due to iron-limitation. The in situ macronutrient and dissolved iron concentrations below the MLD and estimated macronutrient concentrations during winter were negatively correlated to temperature (1–6 °C), that is to the relative proportion of warm modified Kuroshio Water mixed into the colder Oyashio water system. The rate of decrease in Si(OH) 4 per °C increase was greater than the rates for NO 3+NO 2 and PO 4 for both in situ and estimated winter values. These results suggest that the spring bloom in the cold-water system with high macronutrients and iron concentrations would progress rapidly and intensely, and then be terminated by nitrogenous nutrient depletion. However, the diatom bloom in warmer waters with lower macronutrients and iron concentrations would be terminated by Si- and/or iron-limitation of heavily-silicified diatoms. In the OECOS study, variation of macronutrients and iron due to the surface intrusions of several water masses and modification from different chemical conditions during winter were the most important factors regulating the progression, magnitude and probably fate of the spring phytoplankton bloom in the Oyashio region.

Changes in iron concentrations and bio-availability during an open-ocean mesoscale iron enrichment in the western subarctic Pacific, SEEDS II

Abstract A patch of water in the western subarctic gyre (low iron concentration, After the iron fertilization, we observed a significant increase in dissolved iron (1.38 nM at 5 m depth) at the center of the patch (D1). Dissolved iron concentrations subsequently decreased to an ambient level (~0.08 nM) on D16–D17, despite the second iron fertilization made on D6. During the 4-day incubations of the shipboard culture experiments, excess DFB-inoculated treatment inhibited the phytoplankton growth compared to the controls for D2, D7 and D11 patch water. This indicated that available iron existed in the iron-fertilized patch at least until D11. Moreover, iron-inoculated treatments induced growth of large-sized phytoplankton with an accompanying silicate decrease for D7, D11 and D17 patch water, but not for D23 patch water. These results indicated that large diatoms, which can respond to additional iron inoculation, existed in the iron-fertilized patch in evolution and early termination phase of the iron-induced bloom (at least until D17); however, there was no significant amount of large diatoms, which could rapidly respond to iron, in late termination phase (D23) of the iron-induced phytoplankton bloom.

Manipulating iron availability in nearshore waters

The consideration of iron effects on marine ecosystems has focused mainly on high‐nitrate low‐chlorophyll regions, but iron likely has an equally important regulatory role in coastal waters. Iron requirements of neritic phytoplankton not only are comparatively high but also differ substantially among species, so that iron fluctuations within metal‐replete systems should strongly influence the composition and distribution of phytoplankton assemblages. But unlike the simplicity of testing iron effects in iron‐depleted waters, ascertaining iron effects in apparently replete waters has been forestalled by a lack of experimental tools that can regulate iron availability independent of other bioactive metals in seawater. I present here the results of size‐fractionated shipboard culture experiments using the fungal siderophore desferriferrioxime B (DFB) to regulate iron availability in coastal upwelling waters. Addition of excess DFB essentially eliminated 59Fe uptake by both phytoplankton and heterotrophic bacteria over a 6‐h period and allowed only marginal iron uptake over 5 d of incubation. Carbon uptake by small (0.2–5.0‐ µm) phytoplankton was immediately curtailed upon addition of DFB, signifying a rapid onset of iron stress. In contrast, short‐term (0–6 h) carbon uptake by larger (&5.0‐ µm) phytoplankton was not affected, indicating that larger cells contained significant iron reserves. Nonetheless, carbon assimilation was substantially lower in DFB treatments relative to the controls after 5 d of incubation. Uptake of 54Mn, 65Zn, and 57Co was not immediately affected by DFB but then slowed after 4 h and was significantly lower after 5 d, presumably because iron limitation lowered the cellular requirements for these bioactive metals. These findings demonstrate that DFB can be used to manipulate biologically accessible iron to determine how iron affects algal community structure and carbon cycling in iron‐replete waters.

The influence of copepod and krill grazing on the species composition of phytoplankton communities from the Scotia Weddell sea

The influence of copepods (mainly Oithona sim-ilis) and krill (Euphausia superba) grazing on the species composition of plankton communities in ship board con tainers was investigated during the spring and post spring period in the Scotia Weddell Sea in the Antarctic ocean. Numbers of grazers were experimentally manipulated in containers with natural phytoplankton assemblages. With ratural levels of copepods but no krill a high (700–950 μg C·l1, ca 30 μg chl a·.l1) phytoplankton biomass developed. In these cultures large diatoms, e.g. Corethron criophilum and chains of Thalassiosira sp., made up 80% of total phytoplankton cell carbon at the end of the experiment. In cultures with elevated numbers of copepods (5X or 10X the natural level) phytoplankton biomass was somewhat reduced (ca 23 μg chl a · l1) compared to cultures with natural copepod abundance, but still high. Phytoplankton species composition was on the other hand greatly influenced. Instead of large diatoms these cultures were dominated by Phaeocystis pouchetii (70%) together with small Nitszchia sp. and Chaetoceros neogracile (20%). In containers with krill (both juveniles and adults), but without elevated numbers of copepods, phytoplankton biomass rapidly approached zero. With 10X the in situ level of copepods, krill first preyed on these before Corethron criophilum and Thalassiosira sp. were grazed. When krill were removed a plankton community dominated by flagellates (60–90%), e.g. Pyramimonas sp. and a Cryptophycean species, grazed by an unidentified droplet-shaped heterothrophic flagellate, developed. These flagellates were the same as those which dominated the plankton community in the Weddell Sea after the ‘spring bloom’. A similar succession was observed in situ when a krill swarm grazed down a phytoplankton ‘bloom’ in a few hours. Our experiments show that copepods cannot control phytoplankton biomass in shipboard cultures even at artificially elevated numbers. Krill at concentrations similar to those in natural swarms have a great impact on both phytoplankton biomass and species composition in shipboard cultures. Both copepods and krill may have an impact on phytoplankton species composition and biomass in situ since the rates of phytoplankton cell division were probably artificially increased in shipboard cultures compared to natural conditions, where lower growth rates make phytoplankton more vulnerable to grazing. A similarity between phytoplankton successions in containers and in situ, especially with respect to krill grazing, supports the conclusion that grazing may structure phytoplankton communities in the Scotia-Weddell Sea.

Chemical and physical effects on the shape and growth of the diatomBiddulphia sinensis Greville in batch cultures: A contribution to bioindication in plankton ecology

Different influences, like changes in salinity and temperature, the effects of heavy metals like copper and mercury, and the influences of nitrate and silicate deficiencies on the shape, generation time, and yield of the marine plankton diatomBiddulphia sinensis were tested in batch cultures. Those cells which show multiple or missing setae are classified as seta-aberrant, teratological forms. Sudden changes in salinity and temperature (30–15%. S; 12–20°C) lead to no more than 5% of aberrant cells (control cultures below 1%). Heavy metals (copper and mercury) cause a significant increase of the generation time, a distinct decrease of the cell yield, and (in the case of copper) up to 50% of seta-aberrant cells. The cells die at concentrations of copper above 10−5M.l−1, though EDTA was added as chelant. At concentrations below 10−5M.l−1 of copper, addition of EDTA as well as an increase of temperature from 12 to 20°C cause a reduction of toxicity. During batch growth the cells adapt to mercury but not to copper. At mercury concentrations above 10−8M.l−1 the cells die, even if EDTA is added. Unlike in copper-treated medium, EDTA does not reduce the toxicity of mercury. However, a detoxicating effect (20 instead of 12°C) can be observed due to higher temperature. Silicate deficiency, like the influence of copper and mercury leads to an elongation of the pervalvar axes. Particularly at a temperature of 20°C bended pervalvar axes and sometimes lateral evaginations of the frustule will be formed; this does not happen under the influence of copper and mercury. Multiple setae never appear under silicate deficiency. Under nitrate deficiency more than 10% of the cells are seta-aberrant. The suitability ofBiddulphia sinensis for test experiments in shipboard cultures is shown. Water samples were tested on the lack of nitrate, silicate, and phosphate. The percentage of seta-aberrant cells, the generation times, and the yields were determined. Simultaneous lack of phosphate and nitrate causes up to 30% of teratological cells. The seta-aberrant cells always appear during the exponential growth phase.

The toxic effect of copper on Oscillatoria (Trichodesmium) theibautii1

[14C]CO2 fixation in Oscillatoria theibautii decreased in response to copper at low cupric ion activities (10−10 M) in test media containing Tris as a copper chelator and to low concentrations (10−8 M) of total added copper in filtered seawater. This sensitivity could be important to natural systems as well as laboratory and shipboard cultures.

13C and 15N Uptake by Phytoplankton in the Antarctic Upwelling Area: Results from the Antiprod I Cruise in the Indian Ocean Sector

13C and 15N uptake measurements were carried out in the Indian sector of the Antarctic Ocean along a 66�30'E. transect. Integrated values ranged from 0.41 to 1.00 and from 0.03 to 0.12 mg-atom m-2 h-1 for inorganic carbon and nitrogen respectively. These low values were in contrast to the high nutrient concentrations and the total irradiation available. Nitrate-nitrogen concentrations for example were mostly above 20�g-atom l-1 and on-deck total irradiation integrated over the entire incubation period was on average 10 MJ m-2. Integrated values for particulate matter varied between 337.5 and 694.4 mg-atom m-2 for carbon and between 48.2 and 92.2 mg-atom m-2 for nitrogen. Carbon to nitrogen composition ratios of the particulate matter have been compared with the uptake ratios of the same elements. While euphotic zone profiles of the former ratio exhibited only small changes (6.0-8.1, all stations included), corresponding uptake ratios varied over a wide range (0.1-25.1). Generally, the latter ratio decreased with decreasing available radiation. Response curves of specific uptake rate for carbon and nitrogen to increasing available radiation were found to be hyperbolic in shape and yielded half-saturation constants ranging between 0.9 and 3.9% of surface quantum irradiance, or between 4.9 and 16.2 × 1021 quanta m-2 h-1, if expressed in absolute units. Specific uptake rate for nitrate was directly related to ambient water temperature along a north-south cross section, but this relationship may have been an indirect one as other factors were possibly involved (ammonium concentration for example). Maximum growth rates as doublings per day expected from water temperature were about an order of magnitude higher than the measured actual specific uptake rates for inorganic carbon and nitrogen. This was also observed in a culture of natural phytoplankton. However, measured growth rates obtained from cell counts in the same culture agreed very well with the calculated maximum expected growth rates. Phytoplankton cells from the shipboard culture continued to divide while decreasing the nutrient cell content and without a corresponding increase in specific nutrient uptake rate. The lack of intensive nutrient utilization reflected the field situation and the limiting factor could not be identified in the culture or in the field.

Phased cell division in natural populations of marine dinoflagellates from shipboard cultures

In June 1975 samples were preserved every 2 h for 26 h from water collected from Santa Monica Bay, California and which was incubated on shipboard. The percentage of dividing dinoflagellate cells in the samples was determined by microscopic examination after applying a nuclear stain. The maximum proportion of dividing cells was at 03.30 h, 05.30 h, and 09.30 h for Ceratium dens Ostf. & Schmidt, C. furca (Ehrenb.) Claparède & Lachmann, and Dinophysis fortii Pavillard, respectively. Mean doubling times for these species, calculated from the percentage of dividing cells, were 3.3,4.6, and 1.4 days. Temporal stratification in the timing of cell division may reflect a selective process for minimizing interspecific competition.

Significance of cellular nitrate content in natural populations of marine phytoplankton growing in shipboard cultures

Phytoplankton intracellular nitrate concentrations have been monitored in a 56-h experiment on a shipboard culture of surface sea water from an upwelling region. These measurements were related to parameters of biomass (particulate nitrogen) and nitrate assimilation using the 15N isotope technique and the nitrate reducase (NR) assay. The procedure for measuring cellular nitrate concentrations is described. This parameter exhibited diurnal variations, ranging from 3.1 to 20.6 ng-at nitrate per μg-at particulate nitrogen, and could be correlated positively with NR activity. Nitrogen budgets show that NR activity represents only 12% of nitrate incorporation in organic phytoplankton material when nitrate is available in the sea water. However, upon depletion of the environmental nitrate (zero uptake), NR activity can fully account for the decrease of internal nitrate. From the results, it seems that internal nitrate content is a better index of nitrate consumption by marine phytoplankton than the external concentration of nitrate-nitrogen.

An automated assay for the determination of nitrate reductase in marine phytoplankton

Nitrate reductase activity in marine phytoplankton has been assayed on a Technicon AutoAnalyzer®. A description of the automation is given with details of the apparatus and procedure. Twenty samples an hour can be processed. The automated method has been compared with the manual method. The results are in good agreement; a correlation coefficient of 0.96 has been calculated from the data. The results of a study on the diurnal variation of nitrate reductase activity in a phytoplankton shipboard culture are presented.

A COMPARISON OF CHEMICAL, ISOTOPIC, AND ENZYMATIC METHODS FOR MEASURING NITROGEN ASSIMILATION OF MARINE PHYTOPLANKTON1

Shipboard cultures of natural seawater enriched with nitrate, ammonium, or urea were used to compare different techniques for measuring nitrogen assimilation by phytoplankton and to measure the rates of uptake of these nutrients when more than one was present. Increases in particulate nitrogen, decreases of nitrogenous nutrients, and the uptake by phytoplankton (using the 15N‐isotope technique) balanced rather well and for the nitrate‐enriched culture were in good agreement with the estimate of nitrogen assimilation from nitrite reductase activity. Glutamic dehydrogenase activity was present with both NADH and NADPH in all three cultures; either singly or as a sum it agreed poorly with ammonium uptake estimated by the 15N‐isotope technique. The presence of ammonium almost totally suppressed the uptake of nitrate and urea over a wide range of concentrations. The suppression of nitrate uptake in the presence of urea was nearly the same as the suppression of urea uptake in the presence of nitrate.Comparisons between the isotopic and enzymatic techniques were also made in seawater samples. Nitrite reductase activity was usually much greater than the rate of nitrate uptake estimated by the 15N‐isotope technique. Comparisons with chlorophyll a and ATP analysis indicate that chlorophyll‐containing cells were primarily responsible for the nitrite reductase activity. The rate of pyridine nucleotide oxidation with both NADII and NADPII was more consistent with the ATP than with the chlorophyll a content of seawater samples, suggesting that this enzymatic activity was not restricted to the phytoplankton.