Gammarus pulex Watercress Farming · •Human health benefits. Watercress (Nasturtium officianale...
Transcript of Gammarus pulex Watercress Farming · •Human health benefits. Watercress (Nasturtium officianale...
Gammarus pulex&
Watercress Farming
Chalk Stream Headwaters Forum Oct 09
Melanie Dixon & Pete Shaw
Gammarus pulex (L.)
Bourne Rivulet – Gammaridae
Data courtesy of Environment Agency
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• PEITC
• Produced by crucifers e.g. watercress, broccoli, cabbage, rocket, kale.
• Plant defence against herbivores.
• Human health benefits.
Watercress (Nasturtium officianale (R.Br.))
Isothiocyanates
Gammarus pulexreproduction
• Exposed Gammarus pulex breeding pairs to PEITC solution or watercress wash water.
• Measured separation of pairs within a 2 hour period.
G. pulex precopular pairs
Response during 2h exposure
Pairsseparated
%
PEITC (1µl/l)
Wash water
Control
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After Exposure
• Were pairs able to re-form after return to clean water?
• Transient effect?
Watercress in flower
Pairs re-forming after 24h in clean water
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Washwater PEITC Control
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pairs re-formed after 24h
pairs at exposure end
Management to improve water quality
• E.g. settlement tank, parabolic screens, chlorine wash ceased.
• De-silted East channel, de-culverted discharge.
• Redirected factory wash water through watercress beds.
Parabolic screen above outfall
Survival in factory effluent
• Cages upstream & downstream of watercress bed.
• Factory wash water supplied bed.
• Borehole water supplied bed (control).
Gammarus pulex - Acute effect
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Re-direction of factory effluent
• ‘Treatment’ of wash water by passing though watercress beds before discharge is a positive measure
• Recent biological surveys indicate invertebrate populations recovering
Watercress farm outfall (Spring 08)
Bourne Rivulet – Gammaridae
Data courtesy of Environment Agency
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We gratefully acknowledge the support of the Vitacress Conservation Trust and use of facilities at the Environment Agency Biological Effects Laboratory.
Vitacress Salads Ltd, Hampshire, UK