The rate of colonization by macro‐invertebrates on artificial substrate samplers

Abstract

The influence of exposure time upon macro-invertebrate colonization on modified Hester-Dendy substrate samplers was investigated over a 60-day period. The duration of exposure affected the number of individuals, taxa and community diversity.Tlie numbers of individuals colonizing the samplers reached a maximum after 39 days and then began to decrease, due to the emergence of adult insects. Coefficients of variation for the four replicate samples retrieved each sampling day fluctuated extensively throughout the study. No tendencies toward increasing or decreasing coefficients of variation were noted with increasing time of sampler exposure.The number of taxa colonizing the samplers increased throughout the study period-The community diversity index was calculated for each sampling day and this function tended to increase throughout the same period. Tliis supports the hypothesis thai an exposure period of 6 weeks, as recommended by the United States Environmental Protection Agency, may not always provide adequate opportunity for a truly representative community of macro-invertebrates to colonize multiplate samplers.Many of the taxa were collected in quite substantial proportions after periods of absence or extreme sparseness. This is attributed to the grov^^h of periphyton and the collection of other materials that created food and new habitats suitable for the colonization of new taxa.

Macroinvertebrate colonisation of perspex artificial substrates for use in biomonitoring studies

“…In an unstable South Island braided river, Sagar (1983) considered recolonisation of previously dry channels to be completed after 33 days in winter, and 15 days in summer. This is in contrast to the results of Meier et al (1979) in the United States, who found that diversity and number of taxa continued to increase throughout a 60-day study period. This, they suggested, occurred as new niches were created with increasing periods of exposure as a result of adult emergence and periphyton growth.…”

“…Additional taxa served only to decrease the percentage contribution of these two taxa and as aresult, reduced equitability. In contrast, Meier et al (1979) found that the equitability of colonisation on multiplate samplers initially decreased, butlevelled off after 24 days, as aresult of a high dominance of Chironomidae and Trichoptera species at all times. The contrasts between colonisation studies outside New Zealand and the present study reflect the fundamental characteristics of the New Zealand aquatic fauna.…”

“…Meier et al (1979) concluded that the 6-week period generally recommended (Mason 1981; APHA1985) may not always provide adequate opportunity for a truly representative community to develop. Exposure times of other studies have varied from 3 5 to 84 days.…”

“…Various factors can influence the composition of the colonising fauna, such as depth in the water column and exposure period (Mason et al 1973;Meier et al 1979;. Sufficient time must be allowed for a community to develop before retrieval of artificial substrates from the watercourse.…”

Qualidade Da Água Do Rio Das Pedras, Oeste Do Paraná, Utilizando Macroinvertebrados Bentônicos Como Bioindicadores

“…Os manuais práticos de coleta de invertebrados bentônicos para biomonitoramento aconselham que os litter bags permaneçam incubados por um período de 42 a 56 dias (GIBBONS et al, 1993;APHA, 1998), porém, tem sido considerado inadequado por alguns autores (MEIER et al, 1979). Segundo Rosenberg e Resh (1982) e Mackay (1992), o tempo ideal de incubação depende do desenho amostral, da estação do ano, da localização geográfica e a medida de equilíbrio considerada.…”