Spring Diatom Bloom Research Articles

A Comparison of 1988-1990 Flavor Profile Analysis Results with Water Conditions in Two Northern California Reservoirs

Flavor Profile Analysis (FPA) results were compared with water quality data for two storage reservoirs of the East Bay Municipal Utility District in Oakland, California to determine what conditions exist at the time of an earthy or musty taste and odor episode. Strong musty and earthy aromas coincided most frequently with fall Anabaena sp. blooms and summer Anacystis sp. blooms. Occasional Aphanizomenon sp. blooms were concurrent with Anabaena sp. blooms, so odor problems associated with Aphanizomenon sp. could not be distinguished. Geosmin concentrations of 30-140 ng/L were found in water containing 100,000-300,000 Anabaena sp. cells/100 mL, but 2-methylisoborneol concentrations never exceeded 25 ng/L. Both reservoirs experienced relatively odorless large spring diatom blooms resulting in high chlorophyll a concentrations, so chlorophyll a alone did not serve as a helpful indicator of imminent odor problems. Fall cyanobacteria blooms closely followed the onset of reservoir destratification, so weekly temperature and dissolved oxygen depth profiles successfully predicted the start of a cyanobacteria bloom. Musty and earthy odors in the filter plant effluent were lower than those in the influent, but effluent FPA numbers reached 4 during two large taste and odor episodes, suggesting that granular activated carbon installed 1-2 years earlier may not remove all odor-causing compounds of a large taste and odor episode.

A daily study of the diatom spring bloom at Roscoff (France) in 1985. III. Free amino acids composition studied by HPLC analysis

The growth of a natural phytoplankton population was studied during a monospecific spring bloom of the diatom Rhizosolenia delicatula at Roscoff (western English Channel). Direct examination of the intracellular pool of 19 free amino acids (FAA) was used as an index of the physiological status of the cells. Total FAA in the particulate matter shows a general decrease during the bloom, and FAA cell content varies from 200 mM 1 cell volume−1 to 10 mM at the time of maximum biomass. FAA-N/particulate N is <3% during the study, slightly decreasing at the time of maximum biomass. Individual free amino acids appear reliable for the development of the diatom biomass and good indicators of the growing population. At maximum biomass, major compounds are glutamic acid (30.8 mol%), glutamine (11.7%), alanine (9.9%), isoleucine (6.6%) and lysine (6.4%). Serine, glycine, arginine and aspartic acid appear also as major components during other periods of the study. We suggest that the observed changes are an indication of the physiological state of the cells during the bloom. In particular glutamine (GLN), glutamic acid (GLU) and the GLN/GLU ratio allow the metabolic evolution of the natural population to be characterized. GLN is strictly linked to the living biomass (Chla) while GLU is present at high percentage throughout the study. The ecological significance of β-alanine (BALA) is also revealed during this study, being strongly correlated to degraded matter represented by phaeopigments. These results demonstrate the validity of using individual free amino acids as an aid in understanding the physiological status of algae in natural bloom conditions.

Limiting Factors for Phytoplankton in the North Sea

Underwater light intensity and nutrients are important for the abundance and species composition of phytoplankton. In winter the development of phytoplankton in the North Sea is limited by light. In the central parts of the North Sea the spring bloom starts earlier than in coastal areas. This difference is caused by the higher light attenuation coefficients in the coastal zone. In summer the surface mixed layer (SML) of the stratified areas shows light saturation of phytoplankton photosynthesis. During the growing season the continental coastal waters of the North Sea are potentially phosphorus or silicon limited when tested with a bioassay of the diatom Skeletonemacostatum. The offshore waters are potentially nitrogen limited. There are indications that the spring diatom bloom in the coastal waters ends because of silicon depletion and that the nitrogen and phosphorus concentrations are still large enough to allow the development of a large bloom of Phaeocvstiscf. pouchetii. In summer diatoms disappear from the SML of the stratified areas, but they survive under the thermocline. Possible effects of a reduction of the nutrient loads to the North Sea are discussed in the context of experience in the Delta region (SW-Netherlands).

Microbial activity in sediments of a shallow, highly eutrophic lake following the sedimentation of a spring diatom bloom

Microbial activity in sediments of a shallow, highly eutrophic lake following the sedimentation of a spring diatom bloom

Plankton distribution and the impact of copepod grazing on primary production in Fram Strait, Greenland Sea

Two hydrobiological transects across the East Greenland Shelf and the open waters of Fram Strait in summer were chosen to illustrate the distribution and production of phyto- and zooplankton in relation to water masses and ice cover. The parameters used were temperature and salinity, inorganic nutrients, chlorophyll a, primary production, phytoplankton species composition, abundance of the dominant herbivorous copepods Calanus finmarchicus, C. glacialis, C. hyperboreus, Metridia longa and egg production of C. finmarchicus and C. glacialis. Grazing impact of copepodites and adults of these four species was modelled for each station by using egg production rates as an index of growth. Seasonal development of plankton communities was closely associated with the extent of the ice cover, hydrographic conditions and the water masses typical of the different hydrographic domains. Four regions were identified from their biological activities and physical environment: The Northeast Water polynya on the East Greenland Shelf, with a springbloom of diatoms and active reproduction of herbivorous copepods. The pack ice region, dominated by small flagellates and negligible grazing activities. The marginal ice zone, with high variability and strong gradients of autotroph production related to eddies and ice tongues, an active microbial loop and low egg production. The open water, with high station-to-station variability of most of the parameters, probably related to hydrographic mesoscale activities. Here, Phaeocystis pouchetii was a prominent species in the phytoplankton communities. Its presence may at least partly be responsible for the generally low egg production in the open waters. Grazing impact on primary production was always small, due to low zooplankton biomass in the polynya and due to low ingestion in the remaining regions.

Mosaicism of microplankton communities in the northern Strait of Georgia, British Columbia

The northern Strait of Georgia, British Columbia, Canada, was sampled five times between March and September 1986, employing a grid of stations spanning the strait. The spring diatom bloom was not observed and may have been suppressed by a combination of wind exposure and grazing by microzooplankton, notably non-loricate oligotrichs and the dinoflagellateGyrodinium spirale. Macrozooplankton were not studied. By June, the ecosystem was dominated by flagellates, and ciliate biomass was three times greater than that of the nanoflagellates. The photosynthetic dominantHeterosigma akashiwo was possibly inhibiting diatom growth, as environmental conditions were conducive to the latter's growth. During late summer (August–September), surface waters became nutrient-depleted and a mosaic of organismal types was formed. The pattern included diatoms on the more turbulent west side, nanoflagellates on the more stable east side, and dinoflagellates in the north associated with frontal boundaries. The driving force behind the mosaic appeared to be tidal turbulence and was most effective at times of advanced water-column stratification. Other points of interest were subsurface concentrations ofChaetoceros species, which were perhaps maintained at the pycnocline by entrainment in areas of high tidal turbulence, and a large ratio of heterotrophic to photoautotrophic biomass, possibly due to mixotrophy in ciliates.

Size Structure of Particulate Biogenic Silica in Lake Michigan

Recent data suggest that chemical estimates of biogenic silica in the Laurentian Great Lakes include large fractions of non-living fragmented diatoms. Therefore, measurements of particu-late biogenic silica (BSi) in different size classes (0.2–0.4 μm, 0.4–10 μm, 10–20 μm, and >20 μm) were made from April through July 1987 in southeastern Lake Michigan to assess the importance of diatom fragments to chemical estimates of BSi. During the spring diatom bloom, the period of maximum BSi concentrations, the greatest percentage of BSi (86%) was found in the microplankton size fraction (> 10 μm) associated with living diatoms. By contrast, following thermal stratification, when dissolved silica was depleted from epilimnetic waters, particles <10 μm in size dominated and averaged 52% of total BSi. This fraction contained mostly fragmented diatom frustules. Our estimate of non-living diatoms is consistent with previous studies showing that, following the spring diatom bloom, 40% to 60% of total diatom abundance is non-living. Seasonal decreases in epilimnetic BSi, declining from 11.3 μmol L −1 in late April to an average of 1.96 μmol L −1 during the stratified period, were due primarily to loss of the largest size fraction (>20 pm) which decreased from 76% of total BSi in April to 36% in July. BSi < 10 μm varied by less than a factor of two throughout the study period, averaging 3.23 ± 2.79 fumol L −1. Particles 0.2-0.4 μm averaged 0.277 ± 0.178 μmol L −1. These particles are probably produced through frustule dissolution, settle slo wly, and may lead to enhanced BSi recycling rates.

Importance of a winter dinoflagellate-microflagellate bloom in the Patuxent River estuary

A dense bloom of Katodinium rotundatum was observed in the Patuxent River estuary from December to February 1989. The dinoflagellate dominated phytoplankton densities reaching 10 8 cells l −1 and contributed up to 1900 μgC l −1 in near-surface depths. The bloom maintained a distinct patch extending over 10–25 km of the estuary or approximately one-third to one-half of the total estuary (salinities from 5–13 ppt) and was restricted to regions immediately upriver of the transition between the shallow upriver (3–4 m) and deeper lower estuary (10 m). Daily measurements collected in the primary bloom area at the same time each day in the study area indicated 80- and 120-fold variations in chlorophyll and cell densities from day to day. Densities of potential grazers in the region were high with rotifers, primarily Synchaeta baltica, reaching densities of 1000 l −1 in early winter, and the copepod Eurytemora affinis reaching levels exceeding 1·15 × 10 5 m −3 in February. Estimates of grazing pressure by these planktonic herbivores indicated substantial grazing losses for the bloom, with up to 67% of bloom biomass consumed day −1 in February. Nutrient concentrations and ratios of N P during the bloom suggested potentially N-limited conditions; bloom demise was coincident with a shift to high N P ratios and high river flows. These data as well as other historical data suggest that dinoflagellate blooms in the lower Patuxent River estuary could be the primary source of carbon to the system during the winter and supply a large reservoir of labile organic matter to planktonic secondary producers prior to annual spring diatom blooms in the region.

Annual cycle of particle size fractions and phytoplankton biomass in the northern Baltic proper

A larqe data set of particle concentrations in the ranqe 1 to 1000 rrm, chloro~hvll a, and . . associated measur&nents from the surface waters of the northern ~iitic Drooer durino 1985 to 1989 was . . a ~~~ ~ ~~~~ ~~ anilly7~!d to roncrruct spdlially and temporally averaged annual rlnle curvrs of pdrrlrlr size fractions and phytoplanklorl Im,rnasi. Chlorophyll a concenrratlon wdz wrll t.c,rr~.l,atrrl wlrh the 28-73 -m s.ze lractron and had 2 seasonal peaks: in A~I-M~~, corresponding to the diatom spring bloom, and in August, corresponding to the late-summer bloom of blue-green algae. The 2 maxima were separated by the early summer minimum when the 1-10 p particle fractions corresponding to a mixed assemblage of small phytoplankton and microheterotrophs reached their maxima. The largest particles (163-1000 p), corresponding to smaller mesozooplankton, reached their maximum in July-August before the blue- green maximum. Automated particle counting is well suited for routine monitoring of pelagic systems as it reveals all major shifts in the planktonic community.

Viruses as Partners in Spring Bloom Microbial Trophodynamics

Population sizes of algae, bacteria, heterotrophic flagellates, and viruses were observed through the 1989 spring diatom bloom in Raunefjorden in western Norway. The culmination of the diatom bloom was followed by a peak in the concentration of bacteria and an increase in the concentration of heterotrophic flagellates, a pattern consistent with the concept of a food chain from photosynthetically produced organic material, through bacteria, to bacterivorous flagellates. The concentration of viruses varied through the spring bloom from 5 x 10 in the prebloom situation to a maximum of 1.3 x 10 viruses ml 1 week after the peak of the diatom bloom. Coinciding with the collapse in the diatom bloom, a succession of bacteria and viruses was observed in the mucous layer surrounding dead or senescent diatoms, with an estimated maximum of 23% of the total virus population attached to the diatoms. The dynamic behavior observed for the virus population rules out the possibility that it is dominated by inactive species, and the viruses are suggested to be active members of the microbial food web as agents causing lysis in parts of the bacterial population, diverting part of the bacterial production from the predatory food chain.

TIMING OF SPAWNING OF THYSANOESSA RASCHII (EUPHAUSIACEA) AND OCCURRENCE OF THEIR FEEDING-STAGE LARVAE IN AN ALASKAN BAY

ABSTRACT The timing of spawning and onset of feeding for euphausiid larvae in Auke Bay, Alaska, was monitored for 3 years. Thysanoessa raschii was the most abundant euphausiid species in the study area. In all years the eggs were most abundant in the plankton soon after the major spring phytoplankton bloom was completed. During all 3 years of observation, the major cohort of stage I calyptopis, which is the first feeding stage, appeared in the plankton after the primary diatom bloom was finished. When the calyptopes initiated feeding, the water column was physically stratified and low nutrient availability limited primary production in the photic zone. The results suggest that euphausiid larvae in Auke Bay are dependent on secondary phytoplankton blooms for food, rather than the major spring diatom bloom. The concentrations of nauplii were about 70,000·m―2 in 1986, 40,000·m―2 in 1987, and 140,000·m―2 in 1988. Concentrations of calyptopes peaked at about 40,000·m―2 in 1986, 10,000·m―2 in 1987, and 70,000·m―2 in 1988. Maximum concentrations of furciliae were 730 to 1,660·m―2 in 1988, 1,037·m―2 in 1986, and 10 to 19·m―2 in 1987.

GROWTH OF STAGE I KING CRAB LARVAE OF PARALITHODES CAMTSCHATICA (TILESIUS) (DECAPODA: LITHODIDAE) IN NATURAL COMMUNITIES

ABSTRACT Growth assays were done with first stage zoeae of Paralithodes camtschatica (Tilesius), which are grazers, to determine what types of phytoplankton communities could support larval growth. First stage zoeae were initially reared in water collected from depths with the highest chlorophyll concentration in Auke Bay, Alaska. In those 1987 experiments the highest growth rate was 8% dry body weight per day (b.w.d-1) and occurred when Thalassiosira spp. dominated the phytoplankton community. Later in the bloom, when Skeletonema costatum was the dominant diatom, growth rates averaged 2-3% dry b.w.d '. Additional growth assays during 1988 in Auke Bay used water from depths of 5, 10, and 20 m as the growth medium. In all 1988 experiments, Thalassiosira spp. dominated the phytoplankton community. The other two common diatom genera, Chaetoceros spp. and Skeletonema, were not abundant enough during the 1988 growth assays to be primary energy sources. Average growth rates varied from 1.4―10% dry b.w.d-1. Zoeae reared in water from all 3 depths during the spring diatom bloom grew. In 1987 and 1988 the best growth rates were observed during the peak of the spring bloom of Thalassiosira spp. Zoeal growth correlated well with abundance of Thalassiosira spp. in the growth assays. When concentrations of Thalassiosira spp. were less than 1,000 cells·ml-1, the equation relating growth to abundance of this genus was: growth (% dry b.w.d-1) = 0.013 (Thalassiosira spp. cells·ml-1) ― 1.07; r2 = 0.94. When Thalassiosira spp. were between 1,000 and 4,000 cells·ml-1 mean growth rates were similar to each other at 9―10% dry b.w.d-1. We suggest that diatom species composition and relative abundance are important factors modifying feeding success and growth of stage I larval king crab.

Effects of Food Removal on Nutrient Release Rates and Lipid Content of Lake Michigan Pontoporeia hoyi

Pontoporeia hoyi, the dominant benthic invertebrate in the upper Great Lakes, appears to be well adapted to environments with seasonal inputs of high-quality food such as those supplied by the spring diatom bloom. Ammonium and phosphate excretion rates and lipid content were examined in P. hoyi under the following conditions: (1) field animals sampled seasonally, (2) food-deprived animals in filtered lake water, and (3) control animals held in native sediments without new food inputs. Nutrient excretion rates for P. hoyi (0.5 to 2 nmole NH4 (milligrams dry weight)−1∙h−1 and 0 to 0.15 nmole PO4 (milligrams dry weight)−1∙h−1) were low relative to rates previously reported for other benthic and pelagic invertebrates and varied little among the three treatment groups. In contrast to the animals held in the laboratory without new food inputs, field-collected P. hoyi accumulated increased levels of lipids following the spring diatom bloom. However, after lipid levels in field animals peaked in May, they decreased during the rest of the season at rates similar to those of starved and control animals. P. hoyi's low nutrient-excretion rates, and its ability to accumulate and store energy as lipids, for periods when food is not abundant, appear to be important factors allowing this animal to thrive in temperate lakes with spring diatom blooms.

Seasonal phosphate uptake by size-fractionated plankton in the Skagerrak

Uptake of dissolved inorganic phosphate by different size fractions of natural populations of marine plankton was studied during four periods in 1988, March, May, July, and September, in the Kosterfjorden, northeastern Skagerrak. The major part (70–90%) of the total phosphate uptake was due to the 0.2–3-μm fraction, except during the Chl a peak of the diatom spring bloom, dominated by Chaetoceros spp. (Ehrenberg). The size fraction > 10 μm was not important for phosphate uptake, even during a dense bloom of Gyrodinium aureolum (Hulburt) in the September survey. Uptake rates ranged between 2 and 20 nmol · 1 −1 · h −1, except in the winter when they were undetectable. Particulate P was mainly in the > 10-μm fraction, indicating the efficiency of the smallest organisms in assimilating phosphate. The importance of the 0.2–3-μm fraction for phosphate uptake is emphasized. The inability to measure low phosphate concentrations with the methods available at present is a major obstacle when measuring phosphate-uptake rates.

Production and release of dimethyl sulfide from the Great Lakes

Dimethyl sulfide has been detected in all the water samples from Lakes Superior, Erie and Ontario. The average concentrations in the surface waters were 5.2 ng l-1 for Lake Superior, 16 ng l-1 (June) and 7.3 ng l-1 (August) for Lake Erie and 27 ng l-1 (June) and 13 ng l-1 (August) for Lake Ontario. The profiles in the water column and the seasonal variations (with highest concentrations following after the crash of spring diatom bloom) suggest that DMS production in these lakes stems primarily from the microbial decomposition of dead algal cells. Only a small fraction (>5%) of the sulfur used in planktonic protein synthesis is converted to DMS, however. The emissions of DMS to the atmosphere were calculated to 49-107-be and 69 tonnes year-1 respectively in Lakes Superior, Erie and Ontario. The biogenic sulfur emissions from the lakes are thus insignificant compared to the contributions from anthropogenic sources in the Great Lakes basin.

Biomass Regulation of Microbenthic Algae in Danish Lowland Streams

In this paper the seasonal abundance of microbenthic algae in two small eutrophic Danish Iowland streams is described and predicted. No plants were present during high winter discharge. Increasing surface irradiance and falling discharge, turbidity and water depth induced an extensive spring bloom of benthic diatoms followed one month later by growth of submerged macrophytes and decline of microbenthic biomass

Filter feeding by Oikopleura vanhoeffeni: grazing impact on suspended particles in cold ocean waters

Because of the abundance and size of Oikopleura vanhoeffeni its quantitative role as a suspension feeder in cold ocean waters needs to be defined. To minimize the effect of manipulation and containment, and to assess the effect of naturally occurring factors on clearance rate, I used an in situ latex microbead technique in Logy Bay, Newfoundland, from February 1985 to June 1986. Individual clearance rates ranged from 8–944 ml h-1, increasing exponentially with increasing trunk length. Partial correlation and principal components analysis indicated that trunk length and the concentration of ingestible chlorophyll a accounted for a majority of the variation in clearance rate. At densities of 4–110 m-3, O. vanhoeffeni populations removed from >1 to 13% of the standing stock of ingestible food particles each day. Grazing by near-surface populations was lowest during the spring diatom bloom (>1.4% of daily particle production removed per day), and was highest in June during the post-bloom crash (4 to 10% of daily production removed). Some populations in mid-depth waters had much higher population clearance rates (ca. 50% of daily production removed) because of a greater proportion of large animals. The median percentage daily ration (μg Cxμg C-1xd-1x100%) of 64% accounted for observed house production rates (1 to 2 d-1, with each house=23% of body carbon).

Phytoplankton and nutrients in the Helgoland region

During recent decades, phytoplankton stock on the one hand and inorganic nutrients (P and bound N) on the other have increased considerably in the southern North Sea, as demonstrated at a permanent station (since 1962) near the island Helgoland. This correlation between phytoplankton and inorganic P and N need not have anything to do with causality; exceptional algal blooms have been observed and reported in the literature since in the 19th century. Furthermore, these increases (four-fold for phytoplankton and two-fold for nutrients) are in the same range as the fluctuations from year to year under different hydrographical conditions. A detailed investigation carried out in 1981 demonstrated the presence of a slowly growing phytoplankton population. Starting with a considerable stock of flagellates in spring, it reached a peak in cell numbers over a long reproduction period which contrasted with the normal duration of a spring bloom of diatoms. These processes were not related to a limited production by P or N. A considerable concentration of these nutrients was permanently available in the form of inorganic compounds. The total amount of nutrients surpassed by far the portion incorporated in the phytoplankton. This is a consequence of the fact that small organisms have a high metabolic rate. Therefore, the relation between stock and production (daily production ≈stock) is completely different from that known e.g. in agriculture. The nutrients exist during the vegetation period mainly in the form of dissolved organic matter that is accessible to plankton. The great dynamics of this system, including a phase shifting during the year between inorganic P, N, Si, and production, indicates the significance of permanent and fast remineralization. Calculations demonstrate that the natural nutrient content of seawater normally satisfies the demands of phytoplankton present in the North Sea area under study. Only in the more productive coastal region (salinity<30 associated with fresh water run-offs of low nutrient content — an unrealistic assumption in the German Bight) might some limitation be observed. For diatoms, silicate may represent a critical component, but a high dynamic force exists in the presence of small Si concentrations. Therefore, a lack of silicon must not represent any limitation; however, knowledge on the silicon system is insufficient up to now.

Grazing of the spring diatom bloom in the New York Bight by the calanoid copepods Calanus finmarchicus, Metridia lucens and Centropages typicus

Spring in shelf waters of the New York Bight was characterized by a relatively rapid increase in the numbers and biomass of the large herbivorous copepod Calanus finmarchicus, which seemed to be growing at an in situ rate of approximately 8% body weight per day. The functional feeding response of females of all three taxa never showed saturation. The proportion of daily primary production which was ingested by these three taxa increased from 13 to 46% in the March–April interval at one shelf location and was >100% in both March and April at another shelf location. In contrast, the proportion of daily production which was ingested in slope water in April was only 4%. The implication is that most of the spring diatom bloom over the shelf is ingested over the shelf by the population of rapidly growing C. finmarchicus juveniles. The fecal carbon calculated to be generated by the grazing activities of the observed populations of C. finmarchicus, Metridia lucens, and Centropages typicus resulted in a daily vertical carbon flux very similar to that observed over the shelf with sediment traps and pellet collectors.

Changes in photosynthetic carbon assimilation in Antarctic sea-ice diatoms during spring bloom: variation in synthesis of lipid classes

Carbon assimilation into three lipid classes (neutral lipids, glycolipids, and phospholipids) as well as into protein, low-molecular weight metabolites, polysaccharides, and total lipids was determined during a spring bloom of sea-ice diatoms in McMurdo Sound, Antarctica. The most dramatic changes in incorporation of NaH 14CO 3 were found in the neutral-lipid fraction. During late November, when chl a · m −2 showed an overall increase, 7–11% of the total carbon assimilated was incorporated into neutral lipids. Incorporation dropped to 0.1 % in early December as chl a · m −2 leveled off, then recovered to 13 % in late December, as a secondary sea-ice diatom bloom became established. The dynamic changes in photosynthetic carbon assimilation into neutral lipids suggested that profound changes in physiological state occurred in sea-ice diatom communities during the spring bloom.