Allometry ofUrtica urens in polluted and unpolluted habitats

The allometry ofUrtica urens (small nettle), an important medicinal plant in many countries, growing in an area near pollution sources and an area away from pollution sources was determined. The allometric coefficients were determined for nonlinear relationships between plant height, stem width, root length, petiole length, leaf dry weight, petiole dry weight, leaf length, leaf width, leaf area and specific leaf area. The slopes of the linear equations were determined for the above parameters. The results showed that there is a difference in the allometry of different parts ofU. urens growing in these two areas. Air pollutants reduced the plant height, stem width, root length and petiole length and increased leaf parameters. The same pattern of growth was reflected by comparing the slopes of the straight lines of the parts of the plants growing in the two areas.     

Limnological studies on freshwater ponds of Hyderabad,India IV. The biocenose. Periodicity and species composition of unicellular and colonial phytoplankton in polluted and unpolluted environments

Periodicity and species composition of unicellular and colonial phytoplankton was investigated for two years in three freshwater polluted and unpolluted ponds of Hyderabad, India. Periodicity of various taxonomic groups such as Volvocales, Chlorococcales, Desmids, diatoms and blue-greens was found to be related with the fluctuations of the physicochemical parameters of the ecosystem. Factors like temperature, rainfall, nitrates, nitrites, total sulfides, silica, oxidizable organic matter and basic ratio (Na + K/Ca + Mg) were observed to play an important role in the periodicity of phytoplankton. Taxonomic analysis of the commonly occurring phytoplankton resulted in the identification of 138 species.     

Clustering of water bodies in unpolluted and polluted environments based on Escherichia coli phylogroup abundance using a simple interaction database

Different types of water bodies, including lakes, streams, and coastal marine waters, are often susceptible to fecal contamination from a range of point and nonpoint sources, and have been evaluated using fecal indicator microorganisms. The most commonly used fecal indicator is Escherichia coli, but traditional cultivation methods do not allow discrimination of the source of pollution. The use of triplex PCR offers an approach that is fast and inexpensive, and here enabled the identification of phylogroups. The phylogenetic distribution of E. coli subgroups isolated from water samples revealed higher frequencies of subgroups A₁ and B2₃ in rivers impacted by human pollution sources, while subgroups D₁ and D₂ were associated with pristine sites, and subgroup B1 with domesticated animal sources, suggesting their use as a first screening for pollution source identification. A simple classification is also proposed based on phylogenetic subgroup distribution using the w-clique metric, enabling differentiation of polluted and unpolluted sites.     

Retromobilization of heavy metal resistance genes in unpolluted and heavy metal polluted soil

Abstract: Retromobilization of the nonconjugative (Tra⁻Mob⁺) IncQ vector, pMOL155, and the non-mobilizable (Tra⁻Mob⁻) vector, pMOL149, by means of the IncP plasmids RP4 and pULB113 (RP4::Mu3A), was studied in plate matings and in soil microcosms, and compared with direct and triparental mobilization. Both vectors harbour the czc genes, originating from Alcaligenes eutrophus , which code for resistance to Co, Zn, and Cd. The donor of the czc genes was Escherichia coli which did not express these genes. The recipient, Alcaligenes eutrophus , expressed the czc genes very well. Retromobilization, direct and triparental mobilization of pMOL155 was observed in sterile soil. Both the addition of nutrients and heavy metals significantly enhanced the number of (retro)transconjugants. Retromobilization was also detected in nutrient amended nonsterile soil, but the presence of the autochthonous soil biota strongly reduced the number of retrotransconjugants and also prevented their increase upon application of heavy metals to the soil. Retromobilization of the czc genes, cloned in pMOL149, by using pULB113 was also observed, yet only in sterile, nutrient amended, heavy metal polluted soil.     

Ecology of dermatophytes and other keratinophilic fungi in swimming pools and polluted and unpolluted streams

The biodiversity and richness of keratinophilic fungal communities including dermatophytes were assessed in three stream sites and three swimming pools in the Nablus district in Palestine, using hair baiting (HBT) and surface dilution plate (SDP) techniques, over 8- and 6-month periods, respectively. The effect of waste water effluent and selected ecological factors on these fungi in relation to species diversity and population densities were also considered. Fifty keratinophilic fungal species were recovered from the aquatic habitats studied, of which 42 were recovered from stream sites and 22 from swimming pools. Of these fungi 6 were either dermatophytes (Microsporum gypseum, and Trichophyton mentagrophytes) or dermatophyte related species (Chrysosporium merdarium, Ch. tropicum, Ch. keratinophilum and T. terrestre). The most frequently isolated species in the three pools were Acremonium strictum and Cladosporium cladosporioides, using Sabouraud dextrose agar medium (SDA). The most abundant species were Acr. strictum, and Aspergillus flavus. However, only 4 species were isolated using the SDA medium amended with 5-flurocytosine (5-FC). The most frequent and abundant species in the three stream sites using SDA medium were Geotricum candidum, and Penicillium chrysogenum. The most frequent species in the three sites using the 5-FC medium, was Paecilomyces lilacinus. Using HBT, the most abundant and frequent species in the three stream sites were G. candidum, and Pa. lilacinus, on SDA medium, and Pa. lilacinus, and Gliocladium nigrovirens on the 5-FC medium. The 5-FC medium was more suitable for the isolation of dermatophytes and closely related species than the SDA medium; 6 were recovered on 5-FC, whereas only one on the SDA medium. Variation in the levels of keratinophilic fungal populations from the three stream sites sampled 5 times over an 8-month period, followed comparable fluctuation patterns. Waste water affected fungal population densities with the highest levels in the un-polluted stream sites, and lowest in the heavily polluted sites. Swimming pools, polluted and un-polluted stream sites were found to be rich in pathogenic and potentially pathogenic fungi.This revised version was published online in October 2005 with corrections to the Cover Date.     

Ecology of dermatophytes and other keratinophilic fungi in swimming pools and polluted and unpolluted streams

The biodiversity and richness of keratinophilic fungal communities including dermatophytes were assessed in three stream sites and three swimming pools in the Nablus district in Palestine, using hair baiting (HBT) and surface dilution plate (SDP) techniques, over 8- and 6-month periods, respectively. The effect of wastewater effluent and selected ecological factors on these fungi in relation to species diversity and population densities were also considered. Fifty keratinophilic fungal species were recovered from the aquatic habitats studied, of which 42 were recovered from stream sites and 22 from swimming pools. Of these fungi 6 were either dermatophytes (Microsporum gypseum, and Trichophyton mentagrophytes) or dermatophyte related species (Chrysosporium merdarium, Ch. tropicum, Ch. keratinophilum and T. terrestre). The most frequently isolated species in the three pools were Acremonium strictum and Cladosporium cladosporioides, using Sabouraud dextrose agar medium (SDA). The most abundant species were Acr. strictum, and Aspergillus flavus. However, only 4 species were isolated using the SDA medium amended with 5-flurocytosine (5-FC). The most frequent and abundant species in the three stream sites using SDA medium were Geotricum candidum, and Penicillium chrysogenum. The most frequent species in the three sites using the 5-FC medium, was Paecilomyces lilacinus. Using HBT, the most abundant and frequent species in the three stream sites were G. candidum, and Pa. lilacinus, on SDA medium, and Pa. lilacinus, and Gliocladium nigrovirens on the 5-FC medium. The 5-FC medium was more suitable for the isolation of dermatophytes and closely related species than the SDA medium; 6 were recovered on 5-FC, whereas only one on the SDA medium. Variation in the levels of keratinophilic fungal populations from the three stream sites sampled 5 times over an 8-month period, followed comparable fluctuation patterns. Wastewater affected fungal population densities with the highest levels in the un-polluted stream sites, and lowest in the heavily polluted sites. Swimming pools, polluted and un-polluted stream sites were found to be rich in pathogenic and potentially pathogenic fungi.     

Distribution of Clostridium perfringens in polluted lake environments

Many of the directives that relate to the prevention of pollution or the improvement of fresh water also relate to lake waters since lake waters ultimately inherit much of the pollution that enters into fresh water. In order to determine the influence of the water depth on Clostridium perfringens, we utilised a new medium, lactose-sulfite (LS) broth, suggested for rapid enumeration and identification of C. perfringens. Duplicate samples were collected at each one of the following sites of the polluted station: surface, 60 cm, 90 cm and bottom (1.18 cm). Membrane filtration equipment was used. All samples were alternatively passed through two membrane filters, the first (20-25 microm pore size) was used for retention of the abundant phytoplankton and the second (porosity 0.45 microm) for C. perfringens. Membranes were placed into the first tube of ten-fold dilutions from 10(1) to 10(4) and incubated aerobically in a waterbath at 46 degrees C for 24 h. The numbers of C. perfringens fluctuated depending on the water depth. Vegetative forms were found only in the bottom sampling; they were never found in surface, 60 cm and 90 cm sampling sites. Sporulated forms were found in all sampling sites with the exception of the surface sampling. Clostridium perfringens as an anaerobic bacterium never occurred in the surface waters in vegetative or spore forms, even if the waters were extremely polluted by domestic or industrial activities. Vegetative forms occurred only in the bottom samples but spore forms which are more resistant to various environmental effects occurred in all depths except for the surface.     

Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean samples

Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 microgram of one of a set of chemicals selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmid DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.     

Bacteriophages and genetic mobilization in sewage and faecally polluted environments

Bacteriophages are one of the most abundant entities on the planet and are present in high concentrations within humans and animals, mostly in the gut. Phages that infect intestinal bacteria are released by defecation and remain free in extra‐intestinal environments, where they usually persist for longer than their bacterial hosts. Recent studies indicate that a large amount of the genetic information in bacterial genomes and in natural environments is of phage origin. In addition, metagenomic analysis reveals that a substantial number of bacterial genes are present in viral DNA in different environments. These facts support the belief that phages can play a significant role in horizontal gene transfer between bacteria. Bacteriophages are known to transfer genes by generalized and specialized transduction and indeed there are some examples of phages found in the environment carrying and transducing genes of bacterial origin. A successful transduction in the environment requires certain conditions, e.g. phage and bacterial numbers need to exceed certain threshold concentrations, the bacteria need to exist in an infection‐competent physiological state, and lastly, the physical conditions in the environment (pH, temperature, etc. of the supporting matrix) have to be suitable for phage infection. All three factors are reviewed here, and the available information suggests: (i) that the number of intestinal bacteria and phages in faecally contaminated environments guarantees bacteria–phage encounters, (ii) that transduction to intestinal bacteria in the environment is probable, and (iii) that transduction is more frequent than previously thought. Therefore, we suggest that phage‐mediated horizontal transfer between intestinal bacteria, or between intestinal and autochthonous bacteria in extra‐intestinal environments, might take place and that its relevance for the emergence of new bacterial strains and potential pathogens should not be ignored.     

Activity and heavy metal resistance of non-specific esterases in leaf beetle Chrysomela lapponica from polluted and unpolluted habitats

We compared the general activity and heavy metal resistance of non-specific esterases in two populations of the leaf beetle Chrysomela lapponica from habitats severely contaminated by heavy metals (mostly Ni and Cu) and two populations from unpolluted habitats. Concentrations of Ni and Cu in adult beetles from the most polluted site were 7.7 and 3.6 times higher that in beetles from unpolluted habitats. Larval esterases showed higher activity and lower susceptibility to heavy metals than esterases of adults. Larval esterase activity did not differ between populations from polluted and unpolluted sites, but adult beetles from polluted localities had lower esterase activity than beetles from unpolluted habitats. Both Cu and Ni sulfates in millimolar concentrations in vitro suppressed esterase activity of larvae from unpolluted habitats, but caused no negative effect on esterases of larvae from polluted sites. Similarly, inhibition of adult esterase activity by Ni was stronger in beetles from unpolluted localities than in beetles from polluted localities. This indicates that resistance of non-specific esterases to heavy metals is higher in leaf beetle populations from contaminated environment.     

Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean samples.

Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 microgram of one of a set of chemicals selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmid DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.     

Ecological studies on macroinvertebrate populations associated with polluted kelp forests in the North Sea

Summary 1. The English Counties of Midlothian and Durham are situated on the North Western Edge of the North Sea. Both counties have a high population density and a variety of industries located in them.2. The coastal seas adjacent to these areas are heavily polluted.3. In one of these industrial areas, County Durham, the coastal waters have been polluted for 150 years — from the beginning of the Industrial Revolution.4. Two gradients of pollution, one estuarine and one off the open coast, are described. The intervening sea coast has little or no pollution.5. A comparative method of pollution surveying is presented which makes use of the epifauna in the holdfast or hapteron of the large brown algaLaminaria hyperborea (Gunn.)Fosl.6. The size of the habitat is measured in cubic millilitres and called ecospace.7. The rate of invertebrate colonisation is measured in ecoperiods.8. Statistical investigation reveals similar habitats in clean and polluted water.9. The normal sequence of habitat colonisation by invertebrates is described for clean waters. It contains species groups commonly found on rocky sublittoral kelp forests elsewhere in the North Atlantic.10. Ecological comparison is made of the community development described for clean and polluted stations.11. Results indicate that in polluted water, invertebrate succession is retarded; the species composition of the community is simplified, 43 % of the species are lost, rates of habitat colonisation by individuals of pollution tolerant species are speeded up; the polluted community undergoes neotenous development i.e. retaining juvenile characteristics throughout development to community maturity.12. Functional aspects of new (pollution present) and old (pollution absent) communities are discussed.13. The marginal presence of some species in polluted water is also discussed.15. Two ecological barriers to normal community development in the polluted environment are postulated.

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Ökologische Studien an Populationen von Makro-Invertebraten auf verunreinigten Seetang-Wäldern in der Nordsee

Kurzfassung Die Arbeit berichtet über erste Ergebnisse einer ökologischen Untersuchung an verschmutzten Küstengewässern im Bereich der Grafschaften Durham und Midlothian (im Nordosten Englands). Die untersuchten Küstenstreifen enthalten sowohl städtische als auch industrielle Gebiete, während die dazwischenliegende Landmasse weitgehend landwirtschaftlich genutzt wird. Die Küstengewässer in Durham sind seit über 100 Jahren verschmutzt, d. h. seit dem Beginn der industriellen Revolution. Das Ausmaß der Verschmutzung wird kurz umrissen. Es wird eine Methode beschrieben, die einen Vergleich der in den verschmutzten Seetang-Gebieten gewöhnlich anzutreffenden Invertebraten-Epifauna ermöglicht. Repräsentative Proben der auf dem Haftorgan der BraunalgeLaminaria hyperborea lebenden Fauna wurden gesammelt und mit Proben aus unverseuchten Gewässern verglichen. Die Ergebnisse deuten an, daß in verschmutzten Gewässern die Artenfolge, die Geschwindigkeit der Aufeinanderfolge, die Häufigkeit der Individuen und die trophische Struktur der Lebensgemeinschaft verändert sind. In verschmutzten Gewässern ist die Entwicklung zu komplexen Lebensgemeinschaften verlangsamt; es entstehen neotene Gemeinschaften. Gründe, welche einer Entwicklung zu einer normalen Lebensgemeinschaft im Wege stehen, werden herausgestellt.

     

Ecological studies on Oligochaeta inhabiting depositing substrata in the Irwell, a polluted English river

SUMMARY. Oligochaete worms dominate the macroinvertebrate fauna of the River Irwell, in north west England. The river is polluted by domestic and industrial wastes. Tubificids constituted 86.8% of the worm fauna, with three dominant species; Tubifex tubifex (Müller), representing 43.1% of the total oligochaetes, Limnodrilus hoffmeisteri Claparède, representing 26.8% and Limnodrilus udekcmianus Claparède, representing 16.7%. The Naididae were the next most abundant worms, representing 6.1% of the oligochaete fauna, with Nais elinguis Müller comprising 5.0%.
T. tubifex and L. hoffmeisteri were abundant along the length of the river, but reached their greatest numbers in the organically polluted lower reaches at Agecroft and Salford. The density of L. udekemianus was low in the Irwell above the entry point of the heavily polluted River Roch, but high below this point. N. elinguis was abundant above the Roch entry point and scarce below it.
In the three dominant tubificids, the main population recruitment occurred during the summer months (April to September for T. tubifex , May to November for L. hoffmeisteri and June to October for L. udekemianus ). In N. elinguis , there was massive recruitment in April.     

Food web modularity and biodiversity promote species persistence in polluted environments

Pollution represents a major threat to biodiversity. A wide class of pollutants tends to accumulate within organisms and propagate within communities via trophic interactions. Thus the final effects of accumulable pollutants may be determined by the structure of food webs and not only by the susceptibility of their constituent species. Species within real food webs are typically arranged into modules, which have been proposed to be determinants of network stability. In this study we evaluate the effect of network modularity and species richness on long‐term species persistence in communities perturbed by pollutant stress. We built model food webs with different levels of modularity and used a bioenergetic model to project the dynamics of species. Further, we modeled the dynamics of bioaccumulated and environmental pollutants. We found that modularity promoted the stability of food webs subjected to pollutant stress. We also found that richer food webs were more robust at all modularity levels. Nevertheless, modularity did not promote stability of communities facing a perturbation that shared most features with the pollutant perturbation, but does not spread through trophic interactions. The positive effect of both modularity and species richness on species persistence was cancelled and even reversed when the structure of food web departed from a realistic body size distribution or a hierarchical feeding structure. Our results support the idea that modularity implies important dynamic consequences for communities facing pollution, highlighting a main role of network structure on ecosystem stability.     

Ecological studies in the plankton of certain freshwater ponds of Hyderabad-India III. Zooplankton and bacteria

Summary Zooplankton Cladocerans were more abundant than copepods, rotifers or ostracods in all the ponds investigated. The pond harbouring Chara and Nitella had a dense population of Chydorus. Thermocyclops grew abundantly in oxygen-rich water. The pulses of zooplankton preceded those of phytoplankton and the grazing effect was very well marked in one of the ponds. Bacteria Ponds smaller in dimension harboured denser population of bacteria. Higher concentrations of phosphate, dissolved solids, and oxidizable and nitrogenous organic matter favoured their multiplication. Bacterial pulses almost coincided with those of phytoplankton — more precisely with chlorophyll-a. Possibly microbes fed on the freshly liberated materials from the phytoplankters.