Showing papers in "Limnology and Oceanography in 1969"

Spectrophotometric determination of hydrogen sulfide in natural waters1

Abstract: Winkler method for dissolved oxygen analysis. Limnol. Oceanog., 10: 135-140. CARRITT, D. E., AND J. H. CARPENTER. 1966. Comparison and evaluation of currently employed modifications of the Winkler method for determining dissolved oxygen in seawater; a NASCO report. J. Marine Res., 24: 286318. CLINE, J. D. 1968. Kinetics of the sulfide-oxygen reaction in seawater; An investigation at constant temperature and salinity. M.S. Thesis, Univ. Washington, Seattle. 68 p. CUSTER, J. J., AND S. NATELSO?\T. 1949. Spectrophotometric determination of microquantities of iodine. Anal. Chem., 21: 1005-1009. THOMPSON, T. G., AND R. J. ROBINSON. 1939. Notes on the determination of dissolved oxygen in sea water. J. Marine Res., 2: 1-8. WHEATLAND, A. B., AND L. J. SMITH. 1955. Gasometric determination of dissolved oxygen in pure and saline water as a check of titrimetric methods. J. Appl. Chem. (London), 5: 144-148. WINKLER, L. W. 1888. Die Bestimmung des im Wasser gelosten Sauerstoffes. Chem. Ber., 21: 2843-2855.

Half‐saturation constants for uptake of nitrate and ammonium by marine phytoplankton1

Abstract: Uptake rate of nitrate and ammonium was studied as a function of nitrate or ammonium concentration with cultures of 16 species of marine phytoplankton. Half-saturation constants (the concentration supporting an uptake rate one-half the maximum rate) were computed as a measure of the ability of a species to use low levels of nitrate and ammonium. The half-saturation constant (Ks) varied approximately in proportion to cell size and inversely with specific growth rate. Small-celled oceanic species, such as Coccolithus huxleyi, showed the lowest K8 values (⩽0.5μm) and Gonyaulax polyedra the highest (Ks > 5 µm). The Ks values are considered to be important characteristics of organisms living in nitrogen-limited environments. Some apparent success was achieved in predicting the competitive advantage of one species over another by calculating specific growth rates as functions of nitrate and ammonium concentration for species with known growth response to irradiance, temperature, and daylength. For example, at about 20C and 16 hr daylength C. huxleyi should be able to compete successfully with Skeletonema costatum when nitrate, ammonium, and irradiance are low. Skeletonema costatum should grow faster than C. huxleyi only when irradiance and nitrate or ammonium are fairly high. Rock pool forms appear to be relatively unsuccessful in the ocean because of a sluggish response to irradiance and not because of an inability to use low levels of nitrate and ammonium. The success of G. polyedra, often the dominant dinoflagellate in local red water blooms, appears to be due to its vertical migration from the sea surface in daylight to nitrate-rich water at 10-15-m depth at night, rather than to any special ability to grow rapidly or use low levels of nitrate and ammonium.

The effects of grazing by sea urchins, strongylocentrotus spp., on benthic algal populations1

Abstract: A series of shallow intertidal pools at Mukkaw Bay, Washington, ranging in height from −0.3 to +0.6 m had the urchin Strongylocentrotus purpuratus removed from them. Subtidal rocks at Friday Harbor, −7.3 to −8.2 m, were either caged or had Strongylocentrotus fransiscanus removed at monthly intervals. Observations of the rate and pattern of algal succession for periods of up to three years showed that following an initial establishment of new species, brown algae began to dominate. The rate of domination is related to the area’s tidal height, with succession most rapid in the lower intertidal areas or subtidally. After a variable period, the majority of the algal biomass was vested in a single perennial brown algal species, Hedophyllum sessile in the inter tidal and Laminaria complanata or Laminaria groenlandica subtidally. These plants existed neither in the control areas throughout the study, nor in the experimental pools and rocks before urchin removal. Intermittent urchin browsing could make a major contribution to the variety of algae coexisting within limited areas on these rocky shores.

Respiration Corrections for Bacterial Uptake of Dissolved Organic Compounds in Natural WATERS1

Abstract: The uptake of 14C-labeled organic compounds has been used by many workers to study heterotrophic microorganisms in natural waters. However, if flux rates of organic compounds are to be measured, the loss of 14CO2 during incubation becomes an important source of error. A method is proposed in which the experiment is run in a closed system and the 14CO2 collected after killing and acidification. Phenethylamine on chromatographic paper is the absorbing agent and the paper is counted by liquid scintillation. Studies of 19 compounds from pond water showed that 60% (aspartic acid) to 8% (arginine) of the labeled material entering the microorganisms was respired.

On estimating annual production

Abstract: The method of IIynes and Coleman is modified to make it more adaptable and more consistent with their underlying assumptions. If most organisms comprising a community are univoltine and have approximately the same maximum size, the average standing crop can bc used to obtain a realistic estimate of annual production. The size frequency distdbution can be regarded as a first estimate of an “average cohort” when the number of “average cohorts” equals the number of size classes through which the organisms grow. If growth, in terms of the size units used, is assumed to bc linear, then numerical differences in adjacent size classes can be attributed to mortality. When all size classes are considered togcthcr, the effect of nonlinear growth on the cstimatc of annual production is not large. In contrast, a serious error is introduced if the organisms are not univoltine. When the growth pattern and generation time are known, it is relatively simple to modify the average size frequency distribution to improve the cstimatc of the “average cohort” and hence improve the estimate of annual production. A reply to the criticisms of Fagcr is included.

Studies of nitrate reductase in marine phytoplankton1

Abstract: Certain marine phytoplankton contain the enzyme nitrate reductase when growing on nitrate, but only low levels of enzyme were found during growth with ammonium or when the nitrogen source was depleted. Netted samples of oceanic phytoplankton contained the enzyme when taken from waters with nitrate concentrations 2–10 µm. Ammonium was assimilated in preference to nitrate in phytoplankton cultures supplied with both forms of nitrogen at 5–15 µm. Enzyme synthesis and nitrate use began when ammonium was depleted to 0.5–1.0 µm. Nitrate reductase assay of phytoplankton samples is a useful tool in that a positive result indicates utilization of nitrate and a negative one implies growth on ammonium, nitrogen depletion, or, improbably, growth with other N-sources such as nitrite, urea, or amino acids. The enzyme assay seems especially useful for studying the timecourse of phytoplankton blooms because it provides a sensitive measure of the initiation and cessation of nitrate assimilation.

A short core sampler for subaqueous deposits

Abstract: The instrument described has been designed to obtain a core 1 m long and 5 cm diam, and to include a few centimeters of water above the sediment surface so that the position of the sediment-water interface can be determined with accuracy. The meter long core provides sufficient overlap with the longer cores to allow measurements to be continued without interruption to the present sediment surface. The ability to obtain undisturbed cores of the upper meter of sediment also has considerable value in the examination of changes in sedimentary composition resulting from relatively recent alteration in the trophic status of lakes.

Release of dissolved organic matter by marine seaweeds and distribution of their total organic production to inshore communities1

Abstract: Under controlled experimental conditions, release rates of organic matter were estimated for five species of Barents Sea macrophytes and for thirteen species of Black Sea macrophytes. The release rates of different species from the Barents Sea were between 0.9 and 2.9 mg of organic matter per gram (dry wt) of plants per hour (mg g−1 hr−1) in March and between 1.7 and 9.8 mg g−1 hr−1 in June. The release rates of different species from the Black Sea were between 1.25 and 6.1 mg g−1 hr−1 in fast growing plants and between 0.5 and 1.6 mg g−1 hr−1 in slowly growing plants. Approximate quantities of total dissolved organic matter released per year have been calculated to be about 39% of gross production in brown algae, about 38% in red algae, and about 23% in green algae. The rest of the organic matter was released during decomposition of that part of standing stock not consumed by herbivorous animals. About 30% of gross production may be released in this way. Thus, the total flow of dissolved organic matter from seaweeds during growth and after death may be as much as 70% of their gross production. The ecological significance of external organic metabolites released in the surrounding water is discussed.

Subsurface chlorophyll maximum in the northeast pacific ocean1

Abstract: A well-developed subsurface chlorophyll maximum is present during summer in oceanic waters off the Oregon coast. It appears to be formed at depth by a photosynthetically active phytoplankton community that is adapted to low light intensity. It may be present and may affect the distributions and concentrations of primary production, oxygen, and nutrients over large areas of the North Pacific Ocean.

Determination of microbial biomass in ocean profiles1

Abstract: Total particulate carbon, nitrogen, adenosine triphosphate (ATP), deoxyribonucleic acid (DNA), and chlorophyll have been measured in detailed profiles to 600 and 1,000 m off the coast of southern California. Biomass estimations based on chlorophyll and ATP measurements were in excellent agreement with those estimated by direct examination. Because of the large amounts of DNA in the detrital fraction, it cannot be used as a biomass indicator. Below 200 m, the concentrations of total particulate carbon and nitrogen were fairly uniform, averaging about 7 µg C/liter and 0.6 µg N/liter.

Fayetteville green lake, new york. ii. precipitation and sedimentation of calcite in a meromictic lake with laminated sediments1

Abstract: The activities of calcium and carbonate in Fayetteville Green Lake were estimated from detailed seasonal measurements of pH, calcium, and titration alkalinity. By comparison of observed ion activity products (IAP) for Ca2+ and CO32− with the calcite equilibrium activity product (Kcq), the water column was found to be supersaturated throughout the year. In the surface waters of the mixolimnion, the ratio IAP: Keq increased from 2 to 4 in winter to 6 to 8 during late May through October. Precipitation of calcite was confirmed by collection of crystals in the water column by filtration, identification by X-ray diffraction, and quantitative measurement by a gas chromatographic technique. Maximal crystal loads of 35 g CaCO3 m−2 in the water column occurred in June and July (1965–1967), while calcite loads in fall, winter, and early spring were reduced by an order of magnitude. From isopleths of suspended calcite, settling rates of 2–4 in day−1 were estimated for spring, which was close to values predicted from Stokes’ Law. About 90% of the total sedimentation occurred from June through October, and 80% of this mass was calcite. The laminae occurring in monimolimnetic sediments were regarded as annual couplets resulting from seasonal sedimentation of calcite, with deposition of organic matter throughout the year. The sedimentation rate derived from sediment trap data was 300 g dry matter m−2 yr−1. From the chemical composition of these samples, sedimentation rates were derived for CaCO3, acid insoluble organic carbon, acid insoluble nitrogen, and total nitrogen, sulfur, phosphorus, silicon, and iron.

Oceanic CO2 system: An evaluation of ten methods of investigation

Abstract: ABsTRAcr By combining two or more of the parameters pH, carbonate alkalinity, total carbon dioxide, and partial pressure of carbon dioxide, six equations can be obtained to express the concentration of carbonic acid that include molecular carbon dioxide, ten equations for bicarbonate ion, and eleven equations for carbonate ion concentrations. When the presentday analytical precision and the normal oceanic variances of the above four parameters are considered, the pH-partial pressure of carbon dioxide combination is the most promising to study the oceanic COz system.

The use of a deep tank in plankton ecology. i. studies of the growth and composition of phytoplankton crops at low nutrient levels1

Abstract: A deep tank (3-m diam, 10 m deep), in which phytoplankton crops can be grown under simulated natural conditions of nutrient concentration and cell density, is described. Three growth experiments have been performed in the tank with DityZum brightwe& (8 centric diatom), Cachoninu niei ( an armored dinoflngellatc), and with a mixed crop of the dinoflagellate Cony&ax polyedra and Phaeocystis sp. (a colonial member of the Haptophyceae). Each experiment lasted about two weeks. In each case ammonia was assimilated first, then nitrate as the plants grew. Successful nitrogen budgets were achieved in the experiments with D. brightwellii and C. niei. The chemical composition of the tank-grown cultures of D. brightwellii, C. niei, and G. polyedra is reported for cell carbon, nitrogen, phosphorus, lipid, carbohydrate, DNA, ATP, chlorophyll a, and carotenoids. The composition of these cultures was very similar to that obtained in laboratory cultures grown with relatively high nutrient levels.

The feeding of calanus helgolandicus on synchronously growing populations of the marine diatom ditylum brightwellii1

Abstract: The filtering rates of Calanus helgolandicus were measured on synchronously growing populations of the diatom Ditylum brightwellii, by following changes in cell numbers and also by measuring the ingestion of 14C labeled cells at selected intervals during 2-day periods. The growth of the diatoms was adjusted to be one cell division per day by selecting appropriate photoperiods and light intensities. When the alga was synchronized, cell division took place in the dark. Filtering rates were calculated separately for animals grazing on single cells and on “paired” daughter cells (before separation after division). The volume of paired cells was 1.5 times that of the singles. There was no significant difference in the filtering of single cells in the light or dark part of the cycle. Filtering on paired cells was significantly higher in the dark or at those times when high percentages of pairs were present. Between 0 and 20% pairs, the animals filtered at a constant rate of 50 ml copepod−1 day−1. Above 40% pairs, there was a maximum filtering rate of approximately 170 ml copepod−1 day−1. Between 20–40% pairs, the filtering rate increased proportionally to the percentage of pairs, and ingestion of paired cells increased exponentially in relation to their concentration. It is suggested that C. helgolandicus actively hunted and selected the paired cells and passively filtered the singles. In addition, the data support the idea that there is no innate diurnal feeding rhythm in these copepods.

Some effects of lake renewal on phytoplankton productivity and species composition1

Abstract: Primary production in Marion Lake is inversely related to the rate at which water enters the lake when light intensity is corrected to a standard level. Increased flushing rates reduce the phytoplankton standing crop thereby lowering the total primary productivity in the lake. Thus seasonal variations in rainfall in southwestern British Columbia exert an appreciable influence on the annual productivity pattern of the lake’s phytoplankton. Lake water artificially enclosed within small areas of the lake produced algal blooms while phytoplankton standing crop in the rest of the lake remained low. Nannoplankton appear to have a selective advantage over larger, more slowly reproducing forms in Marion Lake. The production: biomass ratio for lake phytoplankton was used as an indication of the general type of limiting factor affecting the instantaneous rate of productivity in the lake.

On the mechanism of langmuir circulations and their role in epilimnion mixing1

Abstract: Six mechanisms have so far been proposed to explain Langmuir circulations and their associated wind streaks. One mechanism involving shearing instability and two requiring the action of a surface film are supported by the greatest amount of evidence. Studies at Lake George, New York, suggest that more than one mechanism may operate at one location. A particular mechanism may operate at a specific site because of typical conditions at that site, but a different mechanism may be more important at another site. Plots of thermal structure in the near-surface layer of Lake George and measurements of vertical current velocities suggest that Langmuir circulations are the most important mixing process in the epilimnia of lakes.

OXYGEN CONSUMPTION BY THE SEABED. II. IN SITU MEASUREMENTS TO A DEPTH OF 180 m1

Abstract: Oxygen consumption by the seabed in Puget Sound was measured in situ in bell jars pushed into the bottom while monitored by television. Eleven stations were visited irregularly between January and August 1967. Depths ranged from 11 to 180 m, and sediment varied from coarse sand to mud. Observed short-term rates were between 4 and 40 ml O2 m−2 hr−1 and were unrelated to depth (pressure), mean grain size, fine fraction of the sediment, organic matter or organic nitrogen in the upper 0.5 cm, or the biomass of macrofauna. Temperature accounted for only about 30% of the total variation in rates. We suggest that the seasonal changes of rates, and possibly the differences between stations, are caused primarily by changes of activity of small organisms as governed by the rate of supply of organic matter from the plankton. Estimates of annual rates of oxidation of organic matter on the seabed correspond to 17 and 25% of the phytoplankton production (14C uptake) near the stations in northern and southern Puget Sound, respectively.

Body nitrogen and nitrogenous excretion in neomysis rayii murdoch and euphausia pacifica hansen1

Abstract: The rates of nitrogenous excretion in the form of ammonia, amino acids, urea, and total nitrogen are determined for Neomysis rayii and Euphausia pacifica at two temperatures, 10 and 4C. Temperature has a marked effect on the excretory rates. Ammonia-N is the dominant form of excretion in both species (72–87% of nitrogen excreted), and the amounts of amino nitrogen excreted by both organisms are much lower than reported by earlier authors for other zooplankton. There is evidence that amino-N is excreted below 6C. Small quantities of urea are excreted by Euphausia pacifica only. Neomysis rayii excretes 25 µg N/mg body nitrogen per day at 10C and 15 µg N/mg body nitrogen per day at 4C. Euphausia pacifica excretes 21 µg N/mg body nitrogen per day at 10C and 12 µg at 4C. While starved, these species catabolize proteins almost exclusively and lose about 2% of body protein per day.