Man-made lagoons and how their attractiveness to waders might be increased by manipulating the biomass of an insect benthos.
Abstract
The benthic invertebrate communities of 4 man-made brackish (mixo-oligohaline) lagoons in the Humber Estuary, England, were investigated. The communities showed extreme dominance by Chironomidae (Procladius choreus, Chironomus annularius, C. aprilinus, C. plumosus, C. prasinus, Glyptotendipes barbipes, Microchironomus deribae) (98% of the biomass) and were typical of disturbed or temporary habitats. The peak biomass (12.8 g m-2 dry wt) and production (65.0 g m-2 year-1 dry wt) values for these lagoons were similar to those of temperate lotic and lentic systems. The major determinants of chironomid biomass were water depth, organic content of the sediments and prey biomass. Waders consumed a relatively small proportion of the total production (12%) and of the mean annual biomass (125%), because much of the production was unavailable under the current management regime. On the lagoon with the least mean depth all the available biomass was consumed during the summer and autumn. Proposed management improvements include a new lagoon profile and a schedule for filling and emptying the lagoons to optimize biomass availability while ensuring continued colonization.