A new quantitative air-lift sampler for collecting macroinvertebrates on stony bottoms in deep rivers

SUMMARY. 1. As three previous comparative studies of deep-water samplers for benthic macroinvertebrates in rivers highlighted the need for a quantitative sampler for use on stony substrata, a new air-lift sampler was developed. It can be operated from a small boat by two people, weighs 13.5–20.0 kg, depending on the length of riser used, and extends the maximum range of substrata that may be sampled quantitatively from 16–32 mm to 128—256 mm. The sampling area is isolated by forcing a collecting cylinder into the substratum, and rapid evacuation of the contents is assisted by a vibrator.
2. All the major specifications of the sampler were determined experimentally in a large tank using three sizes of substrata and plastic pellets to represent invertebrates. The sampler performed accurately to a depth of at least 8 cm on substrata ranging from gravel (2–4 mm) to large stones (32–36 mm long).
3. The performance of the sampler was compared with that of a Ponar grab and Pearson el at. air-lift sampler at two sites on a large river and also with a Naturalist's dredge and a diver-operated Hess-Waters sampler at one of the sites where there were large stones up to 280 mm long. In terms of both mean taxa per sample and mean numbers m⁻², samples taken using the new air-lift sampler provided estimates comparable to or belter than those obtained with the other samplers.     

A comparative study of seven grabs used for sampling benthic macroinvertebrates in rivers

SUMMARY. After considering the large number of grabs described in the literature, seven grabs of weight < 25 kg were chosen for manual operation from a small boat: Van-Veen grab, weighted and unweighted Ponar grabs, Friedinger version of the Petersen grab, Dietz-La Fond mud-snapper, pole-operated Birge-Ekman grab and pole-operated Allan grab. Random samples (number of sampling units n= 10) were taken in a large tank with a known number of 2-mm cylindrical plastic pellets amongst stones of uniform size. Separate experiments were performed with four sizes of stones (model ranges: 2–4 mm, 8–16 mm, 16–32 mm, 32–64 mm). Stratified random samples (n= 10) were taken in rivers and the modal particle sizes at four sites were 0.004–0.06 mm, 0.5–2 mm, 16–64 mm and 64–128 mm. All grabs usually took a representative sample of the substratum at each site with no strong bias towards a particular particle size. The general performance of the Friedinger, Dietz-La Fond and Allan grabs was poor, except on a muddy bottom, with frequent failure to operate, small samples of substratum and a mean depth of penetration < 3 cm in all substrata except mud for the Dietz-La Fond and Allan grabs. The Van-Veen and Birge-Ekman grabs sampled to a mean depth < 3 cm in mud and fine gravel (2–4 mm), but the Birge-Ekman jammed frequently in fine gravel. Both Ponar grabs operated well and sampled to a mean depth ≥ 5 cm in mud and fine gravel, > 3 cm when small stones (8–16 mm) were present and 2 cm (weighted Ponar only) when larger stones (> 16 mm) were present in a gravel bottom. The mean depth was <0.8 cm for all grabs when larger stones (>16 mm) were predominant on the bottom. In the tank experiments with pellets, the efficiencies for the total catches of the Friedinger, Dietz-La Fond and Allan grabs were low with values <45% for fine gravel (2–4 mm), < 22% for small stones (8–16 mm) and <5% for a substratum of larger stones (>16 mm). If 50% is the minimum acceptable efficiency, then the Ponar, Van-Veen and Birge-Ekman grabs were adequate for fine gravel, only the two Ponar grabs were adequate for small stones and no grabs were adequate for sampling a substratum of larger stones (>16 mm). In field trials, the relative abundances of major taxa were similar for most grabs at each site; Friedinger and Dietz-La Fond grabs were the major exceptions. In terms of both mean number of taxa and mean number of invertebrates m^?2 the Ponar, Birge-Ekman and Allan grabs performed well on the predominantly muddy substratum at site 1, but only the weighted Ponar grab performed adequately on the predominantly gravel bottom with some large stones (>16 mm) at site 2. All grabs performed badly when larger stones (>16 mm) were predominant on the bottom (sites 3, 4). The relationship between the variances and means of the samples taken with each grab followed a power law for the catches of pellets in tank experiments, and for major taxa and total numbers at each site in field trials. Values of exponents in the power law lay within the range 1.14–2.34. The coefficient of variation was also frequently related to the sample mean and was an unreliable statistic for comparing the precision of grabs.     

A comparative study of four dredges used for sampling benthic macroinvertebrates in rivers

SUMMARY. After considering the large number of dredges described in the literature, four light-weight dredges were chosen for manual operation from a small boat or the bank: Irish triangular dredge, small Fast dredge, medium-sized and large Naturalist's dredges. The dredges were tested in a series of trials at three sites in two rivers. A stratified random sample (number of sampling units, n = 5) was taken at each site and the modal particle sizes at sites 1–3 were 1–2 mm (fine gravel), 64–128 mm (larger stones) and 128–256 mm, respectively. The dredges usually took a similar range of stone sizes at each site but the design of the Fast dredge excluded larger stones (>16 mm). The Irish dredge sometimes failed to operate correctly. Variations in the volume of substrata taken with each dredge were large, both between sampling units in the same sample and between samples. The latter differences were partially due to the increase in the modal size of the stones, especially between sites 1 and 2, the different sampling areas of the dredges and the depth of penetration into the substratum. Penetration depth was probably greatest for the two Naturalist's dredges, smaller for the Fast dredge and smallest for the Irish dredge. In field trials, the relative abundances of major taxa were similar for most dredges at each site; major exceptions were the Fast dredge at site 2 and the Irish dredge at site 3. There was a high variability between sampling units in the same sample and therefore a lack of precision in the estimates of the mean number of invertebrates per sample. Therefore, the dredges cannot be used as quantitative samplers for the estimation of population density. Their adequacy as qualitative samplers for the estimation of total number of taxa per sample varied considerably and maximum estimates of their efficiencies for a small sample (n= 5) were <40% for the Irish and Fast dredges, >57% for the medium-sized Naturalist's dredge and >76% for the large Naturalist's dredge. There was a clear relationship between the number of taxa and the number of invertebrates taken at each site and this relationship was well described by a power law with an exponent within the range 0.18–0.53. The number of sampling units in the sample had no significant effect on the power-law equations for each site. The power-law equation was very similar for most of the dredges at each site, the only major exception being the Fast dredge at site 1. The implications of this relationship are discussed.     

On the reliability of Ponar grab samples for the quantitative study of benthic invertebrates in ponds

We present observations on the variability of sediment penetration depth by the Ponar grab sampler, which lead us to question the reliability of grab samples in the quantitative study of freshwater benthos. Penetration depth of the Petite Ponar grab depends on substrate type, and correlates with the amount of organic carbon, the water content and the granulometry of the sediment. Since these factors can also influence faunal composition and vertical distribution in the sediment, it is important to study the performance of the sampler before a biological explanation for the observed pattern is given. At the site studied, a case study was performed, in which variable grab penetration did not influence biological interpretation because the penetration depth of the grab followed that of the organisms under study.Research Assistant of the Belgian National Fund for Scientific Research (N.F.W.O.)Research Assistant of the Belgian National Fund for Scientific Research (N.F.W.O.)     

An evaluation of artificial substrates for sampling macrobenthos in reservoirs

Artificial substrates were compared with a Ponar grab for sampling benthic macroinvertebrates in Lake Anna, Louisa Co., Virginia. The objective was t0 find which technique was best for assessment 0f thermal effluent effects using the following criteria: 1) provide reliable data on density and composition 0f the macrobenthos with a reasonable number 0f replicates; 2) collect the most taxa; and, 3) require the least amount 0f time. Leaves, 3M Corporation's #200 conservation web, and limestone rocks were compared. Each material was tested separately in chicken wire baskets placed 0n the bottom at several depths. Three replicates of each type were retrieved monthly from each depth using SCUBA and cloth flour sacks and compared with grab samples taken from the same depths. Lesser amounts of these materials were tested separately in smaller plastic containers. All large artificial substrate samplers collected significantly more individuals (P = 0.05) and taxa than the Ponar grab. Small web and leaf samplers best met all three 0f the established criteria. The SCUBA system developed in the study is a fast and reliable sampling method.     

Use of personal sporetraps to complement continuous aerobiological monitoring

We analysed pollen and spore data obtained from one continuous and two personal Burkard sporetraps during the spring months of three years (2007–2009). For the statistical analysis, the data was normalised with a log transformation, and then subjected to an ANOVA and a Pearson correlation analysis. The best time to use the personal samplers was determined from 15 years of continuous aerobiological monitoring pollen data to be between 11:00–16:00, when highest concentration was found and in a steady way. Height of sampling was compared at floor level and at 1.1 m with personal samplers; both of them were on a terrace at 6 m above the ground, but no statistically significant differences were found. The results revealed that there were apparently no differences between continuous and personal Burkard samplers for total pollen and spores. Nevertheless, distinguishing the main pollen types (i.e., Poaceae, Quercus, Olea, Cupressaceae, Plantago, and Platanus) revealed that there are some differences for Poaceae pollen only. In conclusion, personal samplers could be used to anticipate continuous monitoring data because their sampling is shorter and the results may be obtained quicker than with a continuous sampler, although they must never be considered as a replacement.     

Distribution and habitat of Nitellopsis obtusa (Characeae) in the Laurentian Great Lakes

Nitellopsis obtusa, a macroalga (Characeae) native to Europe and Asia, was found in U.S. waters of the St. Clair-Detroit River system in 1983, thus extending the range of this taxon into the Laurentian Great Lakes about 850 km from the St. Lawrence River where it was first discovered in North America in 1978. Its occurrence only in water frequented by commercial shipping vessels suggests that it is distributed via this mechanism. In the St. Clair-Detroit River system, N. obtusa was collected with a Ponar grab at four locations, and with a grapnel at one additional location. It was the ninth most frequently found macrophyte and it was most abundant at Belle Isle in the Detroit River, where the mean dry-weight biomass in Ponar samples was 0 g m^-2 in June, 37 g m^-2 in August, and 32 g m⁻² in September. Maximum biomass of this taxon in one Ponar grab at this location was 289 g m^-2 in September. The alga occurred primarily in water of relatively low current velocity (11.3 cm s⁻¹) and in association with Vallisneria americana, Myriophyllum spicatum, Potamogeton richardsonii, Najas flexilis, and Elodea canadensis. Contribution 654, Great Lakes Fishery Laboratory, Ann Arbor, MI 48105, USA Contribution 654, Great Lakes Fishery Laboratory, Ann Arbor, MI 48105, USA     

The pili of Pseudomonas aeruginosa strains PAK and PAO bind specifically to the carbohydrate sequence βGalNAc(1–4)βGal found in glycosphingolipids asialo-GM1 and asialo-GM2

Pseudomonas aeruginosa employs pili to mediate adherence to epithelial cell surfaces. The pilus adhesin of P. aeruginosa strains PAK and PAO has been shown to bind to the glycolipid asialo-GM₁ (Lee et al., 1994 —accompanying article). PAK and PAO pili were examined for their abilities to bind to the synthetic βGalNAc(1–4)βGal (a minimal structural carbohydrate receptor sequence of asialo-GM₁ and asialo-GM₂ proposed by Krivan et al., 1988a) using solid-phase binding assays. Both pill specifically bound to βGalNAc(1–4)βGal. The binding of βGal-NAc(1–4)βGal-Biotin to the Immobilized PAK and PAO pili was inhibited by corresponding free pili. The receptor binding domain of the PAK pilus resides in the C-terminal disulphide-looped region (residues 128–144) of the pilin structural subunit (Irvin et al., 1989). Biotinylated synthetic peptides corresponding the C-terminal residues 128–144 of P. aeruginosa PAK and PAO pilin molecules were shown to bind to the βGalNAc(1–4)βGal-(bovine serum albumin (BSA)). The binding of biotinylated peptides to βGalNAc-(1–4)βGal-BSA was inhibited by PAK pili, Ac-KCTSDQDEOFIPKGCSK-OH (AcPAK(128–144)_ox-OH) and Ac-ACKSTQDPMFTPKGCDN-OH (AcPAO(128–144)_ox-OH) peptides. (In these peptides Ac denotes N^α -acetylation of the N-terminus, -OH means a peptide with a free a-carboxyl group at the C-terminus and the‘ox’denotes the oxidation of the sulphhydryl groups of Cys–129 and Cys–142.) Both acetylated peptides were also able to inhibit the binding of βGalNAc(1–4)βGal-biotin to the corresponding BSA-Peptide(128–144)_ox-OH conjugates. The βGlcNAc(1–3)βGal(1–4)βGlc-biotin conjugate was unable to specifically bind to either Immobilized PAK and PAO pili or the respective C-termlnal peptides. The data above demonstrated that the P. aeruginosa pili recognize asialo-GM₁ receptor analogue and that βGalNAc(1–4)βGal disaccharlde is sufficient for binding. Furthermore, the binding to βGalNAc(1–4)βGal was mediated by residues 128–144 of the pilin subunit.     

A simple periphyton sampler for algal biomass estimates in streams

• 1 A simple periphyton sampler, which is cheap and easy to construct, is described. The key component is a disposable scouring disc which also serves to adsorb detached material.
• 2 Field trials show that the scouring sampler is significantly more efficient at removing and retaining periphyton from stones in streams for biomass estimation than other commonly used techniques.
• 3 The scouring sampler requires only one operator. Its small size and speed of use facilitate replication of samples. Samples can be collected from stones as small as 30mm diameter.

     

Production of presumptive humoral haematopoietic regulators in canine cyclic haematopoiesis

Abstract. Conditioned media (CM) were prepared according to previously published techniques from the bone marrow of dogs with cyclic haematopoiesis (CH). CM prepared from day 9 marrows inhibited mouse bone marrow CFU-s proliferation rate while CM from day 10 marrows were stimulatory and also contained an erythroid stimulating factor which appeared to be erythropoietin. In addition a highly significant trend from CM containing CFU-s inhibitory materials to media with CFU-s stimulatory activity was observed through cycles day 1 to 8. These studies further support the concept that CH is due to a defect in factors controlling stem cell proliferation and suggest that a major event occurs in CH dog marrow on days 9 and/or 10 of the cycle. Bone marrow transplantation studies (Dale & Graw, 1974; Weiden et al., 1974; Jones et al., 1975b) have indicated that canine cyclic haematopoiesis (CH) is probably due to a disorder in the multipotential stem cells. Morphological evidence (Scott et al., 1973) and the almost synchronous cycling of CFU-e, CFU-c and diffusion chamber progenitor cells (DCPC) (DUM et al., 1977, 1978a, b) lend support to such a theory. However, efforts to identify the mechanisms controlliig multipotential stem cell proliferation in dogs have been handicapped by the lack of suitable techniques to study these cells in the canine. Recently, Wright and co-workers (Wright & Lord, 1978, 1979; Wright et al., 1979; Lord et al., 1979), on the basis of previous observations (Frindel et al., 1976; Frindel & Guigon, 1977), described the preparation of species non-specific, bone marrow conditioned media (CM) which are capable of influencing the proliferation rate of murine colony forming units-spleen (CFU-s). The studies now reported were designed to determine if CM prepared from canine CH marrow would influence the proliferation rate of murine bone marrow CFU-s. The results indicate that a major event, possibly related to the in vivo control of stem cell proliferation in dogs with CH, occurs on days 9–10 of the cycle; day 1 being the first day when the peripheral blood neutrophil count falls below-1600 mm³.     

Assessment of two mesh sizes for interpreting life cycles, standing crop, and percentage composition of stream insects

Using Surber-type samplers and dip-net samplers, we assessed the efficiency of nets having pore sizes of 720 μm and 320 μm for determining standing crop and percentage composition of the stream fauna, and for collecting representative size-class specimens of Ephemeroptera and Plecoptera to be used in life-cycle studies. Except for one species, samples collected with either the 720-μm or 320-μm dip-net led to the same general inferences about the species' life cycle. Of fifty possible sample comparisons, there were twelve samples where the size-class frequencies of particular species collected in the 720-μm dip-net were significantly different from the size-class frequencies of the 320-μm dip-net; for five of these samples a deficit of large nymphs (> 5.0 mm) in the 320-μm net mainly contributed to the significant χ² values. On one date, we used double-bag samplers with both th e 720-μm and 320-μm nets attached to either the Surber or dip-net sampler. Approximately 50% of the insects by numbers passed through the 720 fxm mesh ofeach sampler, but only 5% by volume-biomass. Shape of the insect as well as body length was important in assessing mesh-size efficiencies. The 720-μm mesh of the double-bag dip-net sampler retained most of the Nemoura dnctipes (having stout appendages) and Epeorus longimanus (flattened) nymphs 2.0 mm in body length and larger; whereas most Baetis (streamlined) nymphs smaller than 3.0 mm and all Paraleuctra (needle-like shape) nymphs passed through the 720-μm mesh.     

Bouchardia rosea,a vanishing brachiopod species of the Brazilian platform: taphonomy,historical ecology and conservation paleobiology

Dead-live faunal comparisons can offer powerful data to detect natural or human-induced population changes in the late Holocene. Here, we document dead–live comparisons for death assemblages of the brachiopod Bouchardia rosea in nearshore (0–45 m) environments along the northern coast of São Paulo State, Brazil. The sampling programme included 30 stations (14 at Ubatuba, 16 at Picinguaba bay). The bottom was sampled via Van Veen grab sampler, and also dredged. Out of 30 stations, 22 yielded brachiopods. The fidelity estimates were obtained by direct comparisons of live biota with dead shells. A total of 6627 brachiopods were recovered, 5339 (80.6%) from Ubatuba and 1288 (19.4%) from Picinguaba. Out of these, 6621 (99.9%) were empty, dead shells, while only six individuals (0.1%) were found alive, all in the Picinguaba Bay. These results suggest extremely poor dead–live compositional fidelity for B. rosea assemblages. The spatial data suggest that the distribution of B. rosea accumulations has been highly patchy in the region, whereas the great scarcity of live brachiopods may point to a recent decline in local populations. Several lines of evidences indicate that changes in water temperature, nutrient availability, population history and even pollution, may have all affected spatio-temporal dynamics of B. rosea populations.     

The use of transgenic and naturally occurring mutants to understand and manipulate tomato fruit ripening

In the years since we last reviewed the use of mutants to study tomato fruit ripening ( Grierson et al. 1987 ), considerable information has been gained by the cloning, sequencing and identification of many mRNAs implicated in this developmental process. Genes involved in cell wall degradation, colour change and ethylene synthesis have been cloned, and antisense techniques have been developed and used to produce genetically engineered mutant fruit deficient in these aspects of ripening (see Gray et al. 1992 ). Recently, a previously cloned ripening gene has been used to complement a naturally occurring fruit colour mutant, yellow flesh ( Fray & Grierson 1993a ), and a ripening impaired mutant, ripening inhibitor, has been used to identify several new ripening-related mRNAs ( Picton et al. 1993b ). The chromosomal region bearing the ripening inhibitor mutation has been subjected to high-resolution mapping ( Churchill, Giovannoni & Tanksley 1993 ) and chromosome walking experiments are in progress to identify this gene.     

Dispersal of Pseudocercosporella herpotrichoides Spores from Infected Wheat Straw

Evidence from spore samples collected amongst infected straw spread on fallow ground supported the conclusion that spores of Pseudocercosporella herpotrichoides are dispersed mostly by rainsplash. Most spores travelled a short distance in the larger ballistic splash droplets, although some may have travelled further in smaller airborne droplets. Weekly spore counts from microscope slides under rainshields, a funnel and an impinger, evaluated as samplers for spores of P. herpotrichoides, showed a similar seasonal pattern. The funnel, as the largest sampler, generally collected most spores, but the impinger collected more spores per unit area of sampling surface. Slides sometimes collected spores when none was recovered from other samplers. Young wheat plants, exposed with the samplers and changed weekly, subsequently developed eyespot symptoms for most of the season.     

Airborne pollen grain concentrations at two different heights

The present study describes the airborne pollen grain concentrations at two different heights (1.5 m and 15 m, respectively). The survey was carried out in 1991 and 1992, using two Burkard spore-traps, both set up at the University of Córdoba, Faculty of Sciences. Generally, and for all herbaceous plants, pollen detection started and ended around the same date on both samplers. However, in the case ofOlea europaea, the pollen was detected in advance by the sampler located at 1.5 m compared with the one located at 15 m, probably due to the fact that olives growing close to the low sampler flower before the great olive plantations located some 60 km south of the city. No significant differences between the counts of both samplers have been observed, except in the case of Urticaceae, where the sampler situated on top of the building recorded higher pollen concentrations in both years. Similar annual peaks of Urticaceae are probably due to the buoyancy of their small, light grains and the explosive pollination mechanism which liberates pollen grains from the anthers of the Urticaceae family, includingUrtica andParietaria.     

EVOLUTIONARILY STABLE MORPHOLOGIES IN PEA POPULATIONS

We investigated the hypothesis that plant form can dramatically affect plant competitive ability, and that forms with dense canopies can invade populations of plants with more open canopies regardless of initial relative frequencies. Under controlled field conditions, we examined the effects of plant form on growth rate, size variation, mortality, and reproduction in high-density monocultures and mixtures of two morphologically distinct varieties of peas. These two varieties differ genetically at only the afila locus. In high-density monocultures and mixtures, peas with finely dissected, minute leaflets (af/af) grew more slowly and produced fewer seeds than Af/—individuals with large leaflets that cast more shade on neighbors. After as few as four generations, mixtures begun with 10% Af/— peas would be expected to evolve to Af/— monocultures. We conclude that an increase in morphological complexity (e.g., virtually leafless to leafy) can have dramatic ecological and evolutionary impacts on plant population dynamics.     

Modifications of the Ekman Sampler

Many types of sediment samplers have been designed for specific purposes and for sampling in different aquatic environments. The objective of this technical note has been to introduce two specific improvements of the traditional Ekman grab sampler, which is a well-known apparatus for sampling of soft sediments, especially in bottom faunistic contexts. The two new modifications concern the automatic closing mechanism. The jointed quadrant and the jointed, hooked axis, both made of brass, provide a much handier and more reliable operation than, e.g., the traditional automatic mechanism.     

Performance of the Coriolis air sampler,a high-volume aerosol-collection system for quantification of airborne spores and pollen grains

The Coriolis δ air sampler manufactured by Bertin Technologies (France) is a continuous air sampler, dedicated to outdoor monitoring of airborne spores and pollen grains. This high-volume sampler is based on patented Coriolis technology delivering a liquid sample. The air is drawn into a conical vial in a whirling type motion using suction; particles are pulled against the wall by centrifugal force. Airborne particles are separated from the air and collected in a liquid medium. This innovative solution allows rapid analysis by several techniques including PCR assay and serological assay in order to measure the antigenicity/allergenicity of pollen grains and fungal spores. Also, traditional counting of pollen grains or taxa identification by optical microscopy can be done. A study has been carried out by the Health Protection Agency (HPA), Porton Down, UK, to measure the physical efficiency of the Coriolis air sampler. The physical efficiency of the sampler for collection of micro-organism-laden particles of various sizes has been compared with that of membrane filter samplers using the techniques described by ISO 14698-1. The Coriolis was operated simultaneously with membrane filter samplers in a controlled room where they were challenged with uniform-sized particles of different diameters containing bacterial spores. For the larger particle sizes, it was found that the physical efficiency of the Coriolis was 92% for 10-μm particles. The biological performance of the Coriolis in the collection of airborne fungal spores and pollen grains was evaluated in comparison with a Hirst spore trap (one-week tape-on-drum type sampler) which is one of the most frequently used traps in the measurement of outdoor pollen grain concentrations. The advantages and limitations of both technologies are discussed. The Coriolis was operated simultaneously with a Hirst spore trap in the sampling station of Réseau National de Surveillance Aérobiologique, France (RNSA); the pollen grain and fungal spore counts were analysed by optical microscopy. The pollen grain count m⁻³ collected was compared for both devices. The dispersion values were obtained and statistical analysis was carried out. This study shows that the Coriolis air sampler provided equivalent recovery of pollen grain and fungal spores compared with the volumetric trap standard method (not significantly different, W test, α = 0.05). Nowadays, the French-led project, acronym MONALISA, with financial support from the European Commission––Life-Environment (LIFE05 ENV/F/000068), is testing this innovative air sampler in order to measure the antigenicity/allergenicity of the main aeroallergen particles, i.e. Betula (birch), Poaceae (grasses), Parietaria (pellitory), Olea spp (olive tree), and Artemisia (mugwort) pollen grains, and Alternaria (fungal spores) to validate a new approach of monitoring instead of quantifying pollen grains by their morphology. The robustness and efficiency of the MONALISA system is being demonstrated at a national level throughout Europe in eight different countries with different bio-climatic and topography characteristics: France, UK, Finland, Poland, Spain, Portugal, Switzerland, and Italy.     

A NEW FRESHWATER CENTRIC DIATOM MICROSIPHONA POTAMOS GEN. ET SP. NOV.1

A new centric diatom, Microsiphona potamos gen. et sp. nov. (family Coscinodiscaceae), is described from the Little Miami River, Cincinnati, Ohio, where it occurred at cell densities ranging from 29 to 20,140/ml in surface grab samples during the period May 18–December 14, 1966, contributing an average of 11% and a maximum of 35% of the centric diatoms. This species has been observed in grab samples from rivers throughout the United States. The cells are 3–4 μ in diameter, 4–8 μ long, and contain 2 to several plate-like chromatophores. They occur singly, or arc held together in short chains by the old girdle bands and by numerous apiculi that connect the opposing valves of adjacent daughter cells.     

News & Notes: Comparison of Methods to Enumerate Bacteria in Dental Unit Water Lines

Millipore HPC samplers are simple, self-contained test devices that can be used by personnel in dental offices who do not have microbiologic training to easily and economically monitor dental unit water quality without laboratory support. This study evaluated the correlation of HPC samplers to R2A agar for enumerating planktonic bacteria in dental unit treatment water. Eight different dental units were sampled. Five replicates were performed for each media at each dilution. The Pearson correlation coefficient between the R2A agar and HPC sampler is 0.89. These data suggest HPC samplers correlate with conventional laboratory-based R2A culture techniques for determining dental unit water line contamination. Received: 16 June 1998 / Accepted: 31 August 1998