Factors affecting the performance of basket and multiplate macroinvertebrate samplers

Abstract

The maximum number and diversity of macroinvertebrates from limestone-filled basket samplers were obtained by placing the samplers at a depth of 1 ft (0-3 m) below the water's surface for 8 weeks. The letigth ofthe exposure period had a greater effect on the number of organisms than depth of placement. The effects of longer exposure times (8 weeks, compared to 6 and 4 weeks) on Ihe number and diversity of organisms inhabiting baskets were more pronounced during cold weather. In rivers during the summer months, samples contain a variety of aquatic insects, which contributed as much as 95 % of the total number of individuals. The occurrence of some macroinvertebrate species was related to the depth of sampler placement, e.g. the caddisfly Cyrnellus fraternus was more abundant at depths exceeding 4ft {I•2 m); whereas the mayfly Stenonema interpunctatum was more abundant in samplers near the surface.The community diversity index (i) of collections on the same date varied by as much as two units depending on the depth of basket placement and length of exposure period, indicating that consistent practices in sampler installation and analysis are required for comparison of collections in water quality investigations.Baskets touching bottom accumulated greater amounts of sediments than surface satnplers and generally showed greater variability within pairs.In the Ohio River, three replicate baskets can be expected {F = 0 95) to provide an estimate ofthe true mean number of macroinvertebrates within ±20% ofthe sample mean and contain 71 % of the taxa in 10 replicates. However, estimates of sampling precision based on replicate series may vary considerably depending on time, place, number of replicates and natural history ofthe organisms.Baskets filled with 2-in. (5-1-cm) diameter porcelain spheres collect samples comparable in total abundance and diversity to baskets filled with 2-in. (5-1-cm) diameter limestone. However, the taxonomic groups occur in different proportions on the two types of substrates.Hardboard multiplates of l-ft^ (Ol-m^) surface area with -\-(0-32) or ^-in. (0-64-cm) spacings collect significantly greater numbers of individuals than porcelain multiplates with the same spacings. However, differences between samples from the same substrate type are not significant. Multiplates of the same surface area and plate spacing collect substantially the same number of taxa regardless of substrate type.Basket samplers (3-2 ft^ -0-3 m^ surface area) collect a greater abundance and diversity of organisms than the standard 1 ft^ = 0-1 m^ hardboard multiplates. The performance ofthe samplers in terms of abundance and diversity is equalized, however, by increasing the surface area of the multiplate to that of the basket. IntroductionField studies of effects of water quality on benthic macroinvertebrates are often handicapped by the problem of sampling similar, natural substrates suitable for colonization at all sampling stations. The problem is especially difficult in rivers, where fluctuations in hydrologic condition...

Methods for sampling benthic macroinvertebrates in tropical lentic systems

“…are comparable across sites (Crossman & Cairns 1974). The use of an artificial substrate circumvents this problem by providing a uniform and reproducible area for colonisation by macroinvertebrates (Mason et al 1973). Artificial substrate samplers are also relatively low in cost, easy to use and can be applied in both lentic and lotic habitats (Czerniawska-Kusza 2004).…”

Cautions on using the Before-After-Control-Impact design in environmental effects monitoring programs

“…The actual number of rocks used, their diameter, and the weight of each bag was recorded, as were the water depth and velocity (Marsh McBirney Flomate 2000 Portable Flow Meter) at each bag location. The bags were left in the river for a period of approximately 60 d (June to August), a sufficient length of time for full colonization to reach fluctuating taxa richness, abundance, and biomass (Mason et al 1973;Shaw and Minshall 1980). Once bags were retrieved the rocks were cleaned and all invertebrates and debris were preserved in 70% ethanol.…”

Macroinvertebrate colonisation of perspex artificial substrates for use in biomonitoring studies

“…Conventional benthic (surber or box) samplers have generally been favoured in swift, shallow waters (Winterbourn 1985), but these may be impractical or impossible to use in slow-flowing, deep rivers, or in rivers with a hardrock substrate. Furthermore, many investigations are handicapped by the need to sample a similar natural substrate at all sites (Mason et al 1973;Deniseger et al 1986) and in many rivers, shallow water sites suitable for conventional techniques that occur up stream, may not occur down stream. Artificial substrates can overcome these shortcomings by providing a standard substrate type and area, and can be used in situations where other techniques are unsuitable.…”

“…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.…”