River-floodplain linkage determines production dynamics of detritivorous and predacious mayflies (Ephemeroptera) in a sedge-meadow wetland
Huryn, Alexander D.
published: Apr 10, 2002
ArtNo. ESP141015503006, Price: 29.00 €
The macroinvertebrate communities of riparian sedge-meadows in Maine (U.S.A.) are unusual, compared to other types of freshwater wetlands, because they are dominated by mayflies during a 1-2 mo period of spring flooding, and because one mayfly species, Siphlonisca aerodromia, is a predator of the other mayflies. The objectives of this study were to determine temporal patterns of production for mayflies inhabiting a sedge meadow along Tomah Stream in sub-boreal Maine, and to identify key factors influencing their production in this wetland. During spring flooding, mayflies contributed 80-86 % of the total macroinvertebrate biomass.Leptophlebia cupida and L. johnsoni together contributed approximately 50 % of total biomass. Arthroplea bipunctata, Eurylophella cf. prudentalis, Siphlonurus mirus, S. rapidus and S. aerodromia were also important contributors. More than 80 % of the growth of Leptophlebia, S. aerodromia and Siphlonurus occurred on the floodplain. These taxa use the stream channel primarily as a nontrophic refuge for the remainder of the year. Depending upon the year, mayfly production ranges from 1.6 to 2.3 g ash-free dry mass (AFDM)/m² of mean inundated wetland area over a 44 to 53 d period. When weighted by the length of the boundary between the sedge meadow and stream, this is equivalent to 7.5 -14.0 g AFDM/m² of stream channel. Estimates of production for similar streams indicate that this is within the range expected for total annual production by macroinvertebrates in the stream channel. Depending upon year, estimates of prey consumption by S. aerodromia ranged from 36 % to essentially all prey production. Water temperature and predation by S. aerodromia appeared to be key factors influencing the temporal patterns of mayfly production in the Tomah Stream wetland. The physical linkage of the stream and floodplain by the natural flow regime, however, is the fundamental factor determining the productivity of this unusual river-floodplain community.