The role of infusoria and bacteria as food for Cyclopoida in Rybinsk Reservoir [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 22(25), 37-42, 1971]

Despite the fact that it is a long time sinc e the methods of collection and quantitative estimatio n of protozoa were worked out data on the abundance of these animals in freshwaters are not very numerous. Nevertheless, Infusoria and Rhizopoda at high densities are widespread in the water and sediments of lakes and reservoirs. In order to find ou t the importance of infusoria as a food source for cyclopoids we carried out experimental investigations using C14. For this three species of cyclopoids, widely distributed in open regions of Rybinsk reservoir were selected: Cyclops vicinus, Mesocyclops oithonoides and Kesocyclops leuckarti. The data presented give evidence that the species investigated are able as predators to consume infusorian plankton arid bacteria in the form of flocs or small clumps of detritus.

Bacteria in freshwaters

An article looking at the numerical distribution of bacteria in lakes, the types most commonly present and the nitrogen-cycle, in Lake Windermere. The methodology is explained, including the sampling frequency and depths, and bacteria culturing techniques. Water bodies other than Lake Windermere were also sampled and these are detailed, including a water reservoir. A summary of the work into horizontal of bacteria is given, including a table showing the number of bacteria per millilitre at different distances from inflow into Windermere. A summary of the work into vertical distribution is also given, including two figures, one showing seasonal variation during 1938-9 in numbers of bacteria at different depths in Winderemere, and the other showing the relationship between the numbers of bacteria at 10 metres depth in Windermere and the rainfull during the previous 7 days. A summary of the types of bacteria found, as well as work on the nitrogen cycle in Esthwaite Water, Lake Windermere and Blelham Tarn are given.

Growth rates of bacteria in rivers

Three different methods for determining bacterial growth rate in rivers are described. Two of the methods are for bacteria in suspension: a recirculating experimental channel method and a radioactive tracer technique using super(35)SO sub(4). The third method is for bacteria attached to surfaces and specifically considers the surface of the common duckweed Lemna minor).

Polyphemus pediculus (L.) (Cladocera) as a possible indicator of water quality

Usually stenobiotic species are used as hydrobiological indicators of the degree of pollution in natural waters. Cladocera are eurybiotic organisms, therefore their role as specific indicators of the water quality is considered to be insignificant. However, considering new methods Cladocera at present are more and more often used as indicators of oligo- and mesosaprobic waters as well as of the presence of considerable amounts of easily degradable organic matter. Work over many years on the biology of Polyphemus pediculus, this striking representative of the order Cladocera, convinced the author of the possibility of using this species not only as an indicator of water purity but also for the estimation of the degree of water pollution as well as of water characteristics such as colour, turbidity, oxgen content and chemical composition. P. pediculus is one of the most common and abundant species of planktonic crustaceans in shallow waters of reservoirs, rivers, lakes, ponds and temporary water bodies.

Metallothionein as an indicator of water quality: assessment of the bioavailability of cadmium, copper, mercury and zinc in aquatic animals at the cellular level

The study of metallothioneins (MTs) has greatly improved our understanding of body burdens, metal storage and detoxification in aquatic organisms subjected to contamination by the toxic heavy metals, Cd, Cu, Hg and Zn. These studies have shown that in certain organisms MT status can be used to assess impact of these metals at the cellular level and, whilst validation is currently limited to a few examples, this stress response may be linked to higher levels of organisation, thus indicating its potential for environmental quality assessment. Molluscs, such as Mytilus spp., and several commonly occurring teleost species, are the most promising of the indicator species tested. Natural variability of MT levels caused by the organism's size, condition, age, position in the sexual cycle, temperature and various stressors, can lead to difficulties in interpretation of field data as a definitive response-indicator of metal contamination unless a critical appraisal of these variables is available. From laboratory and field studies these data are almost complete for teleost fish. Whilst for molluscs much of this information is lacking, when suitable controls are utilised and MT measurements are combined with observations of metal partitioning, current studies indicate that they are nevertheless a powerful tool in the interpretation of impact, and may prove useful in water quality assessment.

Detection of specific bacteria in water: implications of survival strategy

It is widely recognised that conventional culture techniques may underestimate true viable bacterial numbers by several orders of magnitude. The basis of this discrepancy is that a culture in or on media of high nutrient concentration is highly selective (either through ”nutrient shock” or failure to provide vital co-factors) and decreases apparent diversity; thus it is unrepresentative of the natural community. In addition, the non-culturable but viable state (NCBV) is a strategy adopted by some bacteria as a response to environmental stress. The basis for the non-culturable state is that cells placed in conditions present in the environment cannot be recultured but can be shown to maintain their viability. Consequently, these cells would not be detected by standard water quality techniques that are based on culture. In the case of pathogens, it may explain outbreaks of disease in populations that have not come into contact with the pathogen. However, the NCBV state is difficult to attribute, due to the failure to distinguish between NCBV and non-viable cells. This article will describe experiences with the fish pathogen Aeromonas salmonicida subsp. salmonicida and the application of molecular techniques for its detection and physiological analysis.

Persistence of viable but non-culturable bacteria during the production and distribution of drinking water

The direct measurement of in situ respiring bacteria using 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) shows that, especially for Gram-negative bacteria, large numbers of viable but non-culturable (VBNC) bacteria are present in finished water from a conventional water treatment plant, and the regrowth of bacteria along distribution networks can be seen rapidly by using this very sensitive technique. The level of bacterial inactivation with chlorine is much less important than has been previously supposed (based on experiments with non-injured laboratory strains of bacteria and classical culture techniques). Threshold values of VBNC bacteria leaving water treatment plants or regrowing along distribution systems have to be determined for better control of coliform regrowth and health- risks associated with the consumption of drinking water.

La pollution bacterienne de la lagune et de la mer autour d'Abidjan

The total coliforms, fecal coliforms and fecal streptococci were counted over 1 year at 33 stations in the Ebrié Lagoon near Abidjan (Ivory Coast). Most of the waters show high numbers of bacteria, (D category of the American standards). For the sea-beaches, high numbers of fecal germs are found where the human population is abundant.

Using eye lens diameter as age indicator of young Lithognathus mormyrus and Diplodus vulgaris

Eye lens diameter was analyzed in two sparid fish species, Lithognathus mormyrus and Diplodus vulgaris, in order to determine the possibility of using these data for age determination. The results showed that the technique could be adopted for determining the age of the two species when the specimens are very young. The method is especially useful for age determination when otolith or scale rings are not visible or when false rings may give erroneous readings.

Physico-chemical factors and bacteria in fish ponds

Analyses of pond water and mud samples show that nitrifying bacteria (including ammonifying bacteria, nitrite bacteria, nitrobacteria and denitrifying bacteria) are in general closely correlated with various physico-chemical factors, ammonifying bacteria are mainly correlated with dissolved oxygen; denitrifying bacteria are inversely correlated with phosphorus; nitrite bacteria are closely correlated with nitrites, nitrobacteria are inversely correlated with ammoniac nitrogen. The nitrifying bacteria are more closely correlated with heterotrophic bacteria. Nitrobacteria are inversely correlated with anaerobic heterotrophic bacteria. The correlation is quite weak between all the nitrite bacteria which indicates that the nitrite bacteria have a controlling and regulating function in water quality and there is no interdependence as each plays a role of its own. The paper also discusses how the superficial soil (pond mud down to 3.5 cm deep) and different layers of the mud affect the biomass of bacteria. The study shows that the top superficial layer (down to 1.5 cm deep) is the major area for decomposing and converting organic matter.

Heterotrophic marine bacteria as supplementary feed for larval Penaeus monodon

The findings are presented of a study conducted to use autochthonously obtained, nonpathogenic heterotrophic marine bacteria as a substitute feed for microalgae in rearing larval Penaeus monodon. Eleven strains were isolated: Micrococcus (MCC), Staphylococcus, Streptococcus, Bacillus (two strains; BAC-1, BAC-2), Pseudomonas (two strains; PSM-1, PSM-2), Vibrio parahemolyticus, V. fluviatilis, Moraxella (MOR) and Flavobacterium. Six nonhemolytic strains were then chosen for the Penaeus monodon larval feed trials: BAC-1, BAC-2, PSM-1, PSM-2, MCC and MOR. The study demonstrates that bacterial biomass could be further investigated as a partial substitute for microalgae in penaeid shrimp larval rearing.

Incidence of human pathogenic bacteria in shrimp feeds - a study from India

The incidence of various human pathogenic bacteria in commercially available and home-made shrimp feeds used on some farms in India was analyzed. The Total Heterotrophic Bacteria in the commercial feed samples ranged between 103–105 cfu g-1 and those in the farm-made feeds between 106-107 cfu g-1. No bacteria of significance to human health were found to be associated with any of the commercial feed samples analyzed, while farm-made feeds analyzed during the study showed a high incidence of various human pathogens such as Vibrio parahaemolyticus, V. cholerae, Escherichia coli and Staphylococcus aureus. Possible modes of contamination in feeds and ways to prevent them are discussed.

Relative pleopod length as an indicator of size at sexual maturity in slipper (Scyllarides squammosus) and spiny Hawaiian (Panulirus marginatus) lobsters

Body size at gonadal maturity is described for females of the slipper lobster (Scyllarides squammosus) (Scyllaridae) and the endemic Hawaiian spiny lobster (Panulirus marginatus) (Palinuridae) based on microscopic examination of histological preparations of ovaries. These data are used to validate several morphological metrics (relative exopodite length, ovigerous condition) of functional sexual maturity. Relative exopodite length (“pleopod length”) produced consistent estimates of size at maturity when evaluated with a newly derived statistical application for estimating size at the morphometric maturation point (MMP) for the population, identified as the midpoint of a sigmoid function spanning the estimated boundaries of overlap between the largest immature and smallest adult animals. Estimates of the MMP were related to matched (same-year) characterizations of sexual maturity based on ovigerous condition — a more conventional measure of functional maturity previously used to characterize maturity for the two lobster species. Both measures of functional maturity were similar for the respective species and were within 5% and 2% of one another for slipper and spiny lobster, respectively. The precision observed for two shipboard collection series of pleopod-length data indicated that the method is reliable and not dependent on specialized expertise. Precision of maturity estimates for S. squammosus with the pleopod-length metric was similar to that for P. marginatus with any of the other measures (including conventional evidence of ovigerous condition) and greatly exceeded the precision of estimates for S. squammosus based on ovigerous condition alone. The two measures of functional maturity averaged within 8% of the estimated size at gonadal maturity for the respective species. Appendage-to-body size proportions, such as the pleopod length metric, hold great promise, particularly for species of slipper lobsters like S. squammosus for which there exist no other reliable conventional morphological measures of sexual maturity. Morphometric proportions also should be included among the factors evaluated when assessing size at sexual maturity in spiny lobster stocks; previously, these proportions have been obtained routinely only for brachyuran crabs within the Crustacea.