Utermohl Technique Research Articles

Phytoplankton in transitional waters: Sedimentation and Counting methods

1 - The methodological issues in the analysis of phytoplankton guilds in transitional waters, using inverted microscopy (Utermohl technique), will showing and discuss, in reference to UNI EN 15204, particularly regarding sedimentation and counting steps. 2 - The statistical processes for the validation of the two steps will showing and discuss

Methodological aspects of phytoplankton analysis in transitional waters

1 - The methodological issues in the analysis of phytoplankton guilds in transitional waters, using inverted microscopy (Utermohl technique), will showing and discuss the four steps (sampling, conservation, sedimentation and counting). 2 - The importance of inter- and intra-laboratory comparison tests to avoid or minimize discrepancies in identification and counting among analysts was also emphasized.

Quality control of Utermöhl-based phytoplankton counting and biovolume estimates—an easy task or a Gordian knot?

The most suitable way for standardizing biovolume based assemblage analysis using the Utermohl technique for counting combined with biomass conversion has not yet been found even though this method has been successfully used in plankton studies for many years. Due to the complexity of the approach easily applicable steps to initially meet primary standard end point or target counts for intra-laboratory standardization tested here seem promising. Examples from count validation and biometric data from the large datasets of three laboratories are given. The first two examples initially intended to quantify the taxon specific scatter of counts by (A) using identical replica of field samples combined with a half-chamber count (scan of every second transect) and the 30 random field approach, respectively, and (B) the replication of transect counts in one sample. Both examples identified relatively low minimum count thresholds to delimit counting errors for single cell counts. The third example identifies shape variability and allometric relationships of the main axes and shows a way to improve taxon specific biomass estimates with special reference to cell thickness. However improved precision of quantitative phytoplankton analysis requires optimization of combined counting strategy and biovolume assessment methods.

Proliferaciones de Pseudo-nitzschia spp. (Bacillariophyceae) y otras especies del microplancton en la Bahía de Mazatlán, México

Observations on microplankton in the autumn of 1996 revealed the existence of high densities of Pseudo-nitzschia spp. A similar phenomenon was found in November 1998 and November 1999 and a month later it shifted to the southern Mazatlan Bay while in California, USA, incidents of the poisoning of sea mam- mals were being recorded; this also happened on the Mexican Pacific coasts from January to March. Water sam- ples collected at surface (<0.5 m deep) and subsurface (10 m deep) monthly, from November 1998 to January 1999 and every week from February 1999 to May 2000, were analyzed by the Utermohl technique at 400 enlargements. Phytoplankton quantification showed winter and summer pulses; the 1998-1999 period was high- er than the 1999-2000 period. Five species of Pseudo-nitzschia were identified by electron microscopy (TEM and SEM); a new study has revealed other species. High values of Pseudo-nitzschia were observed: 730 P-n/ml (Dec. 1999), 610 P-n/ml (Dec. 1998), 335 P-n/ml (Jul. 1999), 198 P-n/ml (Feb. 1999), 170 P-n/ml (Nov. 1998), 123 P-n/ml (Mar. 1999), 108 P-n/ml (Aug. 1999). The blooms of other species of diatoms (Thalassiosira spp., Asterionellopsis glacialis, Chaetoceros spp., Skeletonema costatum), dinoflagellates (Prorocentrum spp., Scripsiella trochoidea) and ciliates (Myrionecta rubra) were also observed.

Enumerating phytoplankton with an upright compound microscope using a modified settling chamber

A modified settling chamber is described which permits the use of an upright compound microscope for phytoplankton enumerations. The chamber is composed of a 75 × 51 mm rectangular or 70 mm round-glass microslide base with a 130 μm thick piece of sheet styrene attached to the upper surface. A circular cell is cut into the styrene material making a 26 mm diameter chamber which is approximately 130–150 μm deep. Settling procedures follow Utermohl's technique, with the use of a 0.13–0.15 mm thick coverslip (50 × 45 mm) to cover the chamber. The overall thickness of the settling slide is 1.13 mm which does not impact on the optical requirements for most objectives, including oil immersion objectives. The chamber encloses a total volume of 69–80 mm3. No statistical differences are observed in cell, filament or colony counts between the new and traditional chambers. Furthermore, count comparisons at different cell concentrations using the new chambers give consistent results. Thus, the resolution and availability of an upright microscope makes the use of the new settling chamber an attractive method for phytoplankton counting, especially in teaching situations.

Heterotrophic dinoflagellates in the ecosystem of the Gulf of Gdansk

Quantitative studies on heterotrophic dinoflagellates were carried out in 1987 at 3 stations located in the Gulf of Gdansk (southern Baltic) and differing in environmental conditions. Heterotrophic dinoflagellates were identified under an epifluorescence microscope and counted, using Utermohl's technique, in Lugol-solution-treated samples. Two biomass peaks were recorded over the year: one in the spring, co-occurring with the spring phytoplankton bloom, and the other in autumn. Heterotrophic dinoflagellates were the dominant component of the protozooplankton, particularly in the eutrophic, highly productive Gulf waters where they made up almost half of the total zooplankton and dominated over the metazooplankton.

Phytoplankton observations in offshore Norwegian coastal waters between 62° N and 69° N. 2. Diatom societies from Möre to Vesterålen, March–April 1968–1971

Abstract Phytoplankton data obtained by the Utermohl technique were analysed for a description of diatom, societies. Near-coastal, intermediate coastal, semiatlantic, and atlantic waters were considered separately. Regional variation was most evident in the near-coastal and intermediate coastal categories, especially a definite change from a Skeletonema society in the south to a 'Mixed spring diatom society' in the north. Changes from year to year were most notable in the atlantic and semiatlantic water-masses, 1970 being outstanding by the predominance of a Chaetoceros-Tha- lassiosira nordenskioeldii society with a very subordinate Skeletonema component, from Trondelag to the northernmost part of the area. The introduction in 1927 of an allochthonous Asterionella glacialis society in the whole More area, recorded by Gran, and the occurence of the 1970 vegetation in atlantic waters during the present survey, are taken as illustrations of long-distance transport from the northern North Sea area to More, Tr...

Electronic and utermöhl comparative techniques in quantitative analysis of freshwater particulates

The Coulter Counter Model B and the Millipore Particle Measurement Computer System were compared with the Utermohl technique in counting and sizing test objects and suspended freshwater particulate matter. Replicate samples of lake water and pulp mill effluent were analyzed with the electronic instruments for an estimate of counting error % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaada% WcaaqaaiGacofaciGGfbGaaiOlaiaacshacaGGUaGaaiymaiaaccda% caGGWaaabaGabiiEayaaraaaaaGaayjkaiaawMcaaaaa!3EB7!\[\left( {\frac{{\operatorname{S} \operatorname{E} .t.100}}{{\bar x}}} \right)\] Coulter Counter error for determinations of number, volume, and diameter of homogeneous particles was less than io%, and for natural populations of freshwater particles, less than 2o%. Millipore errors of number, area, and horizontal chord were roughly twice these values. Precision was least at low concentration of particles. In practical applications, pulp mill effluent analyses were characterized by close correlation between electronic methods of counting, but lake water particle determinations failed to relate. Microscope counts and sizes of freshwater particles were generally unrelated to electronic measurements. A definite electronic instrument specificity for homogeneous particles was apparent. Wide variations in determinations of characteristics by electronic and manual methods existed. The greatest problem in the. estimation of freshwater biomass is the determination of the unknown detrital fraction.

A simplified method of phytoplankton counting

The problems connected with the study of phytoplankton for species composition and volumetric determination of the biomass are discussed. A simplified method of the Utermohl technique is reported, where a limited number of species is counted, covering about 90% or more of the total volume of phytoplankton. If the number of individuals of each species is restricted, for example to 60, the estimated error will be ±26%. The volumes of individual species are calculated and the mean sizes and mathematical formulae used in the calculations are given. The median volume is preferred to the arithmetical mean. A statistical evaluation was performed on material from Lake Malaren, central Sweden, in May and August 1972 to estimate the error of phytoplankton counting where a limited number of species and at least 60 individuals of each species were counted. The results show that the smallest variations between the samples were found in Asterionella formosa and Chrysococcus minutus in May and in Aphanizomenon flos-aqua...

A device for safe sedimentation using the Utermohl technique

A device for safe sedimentation using the Utermohl technique