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Seasonal dynamics of macroinvertebrate assemblages in the benthos and associated with detritus packs in two low-order streams with different riparian vegetation (2000)

Murphy, John F. ; Giller, Paul S.

Oxford, UK : Blackwell Science Ltd

Freshwater biology 43 (2000), S. 0

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ISSN: 1365-2427

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: 〈list style="custom"〉1The seasonal dynamics of the benthic macroinvertebrate assemblage, and the subset of this assemblage colonising naturally formed detritus accumulations, was investigated in two streams in south-west Ireland, one draining a conifer plantation (Streamhill West) and the other with deciduous riparian vegetation (Glenfinish). The streams differed in the quantity, quality and diversity of allochthonous detritus and in hydrochemistry, the conifer stream being more acid at high discharge. We expected the macroinvertebrate assemblage colonising detritus to differ in the two streams, due to differences in the diversity and quantity of detrital inputs.2Benthic density and taxon richness did not differ between the two streams, but the density of shredders was greater in the conifer stream, where there was a greater mass of benthic detritus. There was a significant positive correlation between shredder density and detritus biomass in both streams over the study period.3Detritus packs in the deciduous stream were colonised by a greater number of macroinvertebrates and taxa than in the conifer stream, but packs in both streams had a similar abundance of shredders. The relative abundance of taxa colonising detritus packs was almost always significantly different to that found in the source pool of the benthos.4Correspondence analysis illustrated that there were distinct faunal differences between the two streams overall and seasonally within each stream. Differences between the streams were related to species tolerances to acid episodes in the conifer stream. Canonical correspondence analysis demonstrated a distinct seasonal pattern in the detrital composition of the packs and a corresponding seasonal pattern in the structure of the detritus pack macroinvertebrate assemblage.5Within-stream seasonal variation both in benthic and detritus pack assemblages and in detrital inputs was of similar magnitude to the between-stream variation. The conifer stream received less and poorer quality detritus than the deciduous stream, yet it retained more detritus and had more shredders in the benthos. This apparent contradiction may be explained by the influence of hydrochemistry (during spate events) on the shredder assemblage, by differences in riparian vegetation between the two streams, and possibly by the ability of some taxa to exhibit more generalist feeding habits and thus supplement their diets in the absence of high quality detritus.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00548.x

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Spatial scale and the aggregation of stream macroinvertebrates associated with leaf packs (1998)

Murphy, John F. ; Giller, Paul S. ; Horan, Margaret A.

Oxford, UK : Blackwell Science Ltd, UK

Freshwater biology 39 (1998), S. 0

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ISSN: 1365-2427

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: 1. An experimental field study examined the aggregation of stream macroinvertebrates associated with leaf packs over different spatial scales (several metres–km) (extent), at different patch sizes (grain) and temporal scales (2 and 4 weeks).2. Standardized leaf packs were constructed and set in eighteen blocks of nine equally spaced packs in glide areas over a 2 km stretch of a wooded stream. The distribution of macroinvertebrates colonizing the artificial leaf packs was investigated to examine the extent of both intraspecific and interspecific aggregation across leaf packs.3. All major colonizing taxa were intraspecifically aggregated across the leaf packs. Aggregation decreased with increasing patch size (grain) (from pack to block), and also decreased with decreasing spatial extent (from 2 km stretch to within-block scale) with patch size held constant. Interspecific associations among all major taxa were not common on most occasions at the short temporal scale, although the proportion of significant associations tended to increase somewhat over time and with spatial scale, but did not exceed 42% of all possible associations. The vast majority of significant associations were positive rather than negative.4. The influence of heterogeneity in a number of environmental variables measured for each leaf pack (accumulated detritus and sediment, leaf mass, flow and depth) on the distribution of invertebrates was considered, but this could only partially explain the variation in macroinvertebrate abundance across leaf packs.5. The roles of intrinsic aggregation and stochastic processes were examined as alternative explanations for the distribution patterns observed. It is apparent from this study that intrinsic aggregation, in concert with resource partitioning, influences the community structure of stream macroinvertebrates associated with leaf packs. These findings may also have implications for the distribution of taxa in the benthos as a whole.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2427.1998.00284.x

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Induction of resistance in tomato against cucumber mosaic cucumovirus by plant growth-promoting rhizobacteria (2000)

Zehnder, Geoffrey W. ; Yao, Changbin ; Murphy, John F. ; [et al.]

Springer

BioControl 45 (2000), S. 127-137

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ISSN: 1573-8248

Keywords: Bacillus amyloliquefaciens ; Bacillus pumilus ; Bacillus subtilus ; induced resistance ; induced systemic resistance ; Kluyvera cryocrescens ; plant defense

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Studies were done to evaluate specific strains of plant growth promoting rhizobacteria (PGPR) for induced resistance against cucumber mosaic cucumovirus(CMV) in tomato. In greenhouse experiments where plants were challenged by mechanical inoculation of CMV, the percentage of symptomatic plants in the most effective PGPR treatments ranged from 32 to 58%,compared with 88 to 98% in the nonbacterized, challenged disease control treatment. Field experiments were conducted in 1996 and 1997 to evaluate 4 PGPR strain treatments based on superior performance in the greenhouse studies. In the 1996field experiment, tomato plants treated with 3 PGPR strains exhibited a significantly lower incidence of CMV infection and significantly higher yields, compared with nonbacterized, CMV-challenged controls. In 1997, the overall percentages of plants infected with CMV in the control and PGPR treatments was higher than in 1996. CMV symptom development was significantly reduced on PGPR-treated plants in 1997compared with the control, but the percentage of infected plants and tomato yields were not significantly different among treatments. These results suggest that PGPR-mediated induced resistance against CMV infection following mechanical inoculation onto tomato can be maintained under field conditions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009923702103

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Making RMP hazard assessment meaningful (1998)

Murphy, John F. ; Zimmermann, Keith A.

New York, NY [u.a.] : Wiley-Blackwell

Process Safety Progress 17 (1998), S. 238-242

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ISSN: 1066-8527

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology

Notes: The Brazoria County Petrochemical Council, 13 companies that are working together to enhance relations between industry and the community, united in a joint effort at complying with the EPA's Risk Management Program. One of the significant issues the group had to address was the need to develop meaningful hazard assessment for presentation to the public. The EPA's “Table Look-Up Approach” found in the Offsite Consequence Analysis Guidance document is certainly a good tool; however, the built-in conservatism results in over-estimates of potential hazard areas. Much more meaningful results are shown to be obtained using one of the hazard release models.The value of using a credible scenario with realistic meteorological data is demonstrated through the consistently smaller areas predicted by the PHAST Model for planning purposes. Realistic scenarios/failure modes and realistic model parameters are important so that the risk to the public is not overstated. Proprietary models such as PHAST are invaluable in providing more meaningful consequences for planning purposes.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prs.680170404

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