Effects of Aufwuchs on Colonization by Simuliids (Simuliidae,Diptera)

While different studies investigated effects of surface properties on the adhesion and population dynamics of marine sessile organisms (Balanidae, Bryozoa etc.), little is known about sedentary freshwater macroinvertebrates. Artificial substrates were used to investigate the effects of Aufwuchs on density and distribution of colonizing blackfly larvae and pupae. Although, settlement of blackfly larvae often is said to be impeded by Aufwuchs or siltation, they colonized both bare substrates and those on which a thick Aufwuchs cover had developed. Often no differences in density appeared on substrates exposed for less than 6-9 d. Thus Aufwuchs apparently does not prevent initial settling of larvae. However, simuliid densities on Aufwuchs covered substrates declined after several more days of exposure, suggesting that surface properties may affect long-term settlement.