An evaluation of benthic macroinvertebrate biomass methodology

Abstract

This study shows that biological assessments of water quality status using biomass estimates of wet, dry, and ash-free dry weights and counts of individual organisms from a small, headwater stream in southwestern Ohio provide essentially similar results concerning the impact of a sewage treatment plant discharge. Of the indices of biotic status for the stream segment employed for data evaluation; Diversity Index (D), Community Diversity Index (d), Trophic Condition Index (TCI), and Empirical Biotic Index (EBI), the latter two provided evaluations most consistent with benchmark water chemistry and physics information concerning the trophic status of the stream. In addition, the percent composition of macro-invertebrate taxa by pollutional category; 'clean water', 'facultative', and 'pollution tolerant', as ascribed using TCI and EBI ranges for individual taxa collected in combination of Ekman grab, rock-filled basket sampler and drift net samples, proves adequate for interpretation of biotic status.

Preservation effects on wet weight, dry weight, and ash-free dry weight biomass estimates of four common estuarine macro-invertebrates: no difference between ethanol and formalin

“…Likewise, drying temperature is known to influence biomass estimation considerably. Higher weight losses have been reported when drying temperature in preparation of DW estimation exceeded 160°C, while temperatures below 500°C have proven to result in inhomogeneous AFDW estimates (Mason et al 1983). Similarly important seem to be storage conditions.…”

“…Error bars represent 95% CI. A small offset (±1 day) has been applied between treatments with ethanol and formalin to avoid graphic overlap reported by Mason et al (1983) and Gaston et al (1996) for marine macroinvertebrates. One reason for these differing findings might be that insect larvae contain higher amounts of lipids in preparation for metamorphosis (e.g.…”

“…Centrifugation of specimens (e.g. Howmiller 1972), for example, is less likely to produce reliable results because this most likely results in the loss of fluid from body tissues of preserved specimens (Wiederholm and Eriksson 1977) which, especially in cases of repetitive WW estimation, easily results in assumed weigh losses; intensity and duration of centrifugation most likely influence the result further (Mason et al 1983). Alternatively, blotting samples with filter paper for defined time periods has been shown to be the most appropriate procedure although, the time period samples are blotted can significantly influence weight estimates (Dermott and Paterson 1973): one min of blotting has been shown to be most efficient and least error-prone.…”

“…However, some previous studies have reported that for the assessment of biomass, an important parameter describing standing crop in benthic communities, ethanol is not recommended because weight loss is higher than in formalin preserved specimens (Howmiller 1972;Dermott and Paterson 1973;Landahl and Nagell 1978;Leuwen et al 1985), while other studies could not confirm this observation (Mason et al 1983;Gaston et al 1996). Moreover, in some cases ethanol-fixed specimens continued to lose weight over time (e.g.…”

Golden Horn Estuary: Description of the ecosystem and an attempt to assess its ecological quality status using various classification metrics

“…Low species diversity is a sign of organic pollution whereas low species diversity together with low abundace an indication of acidic or toxic contamination (MASON et al, 1985). Mean species numbers of stations were not very high in all stations but extremely low at Stations 1 (1Ø0.1m…”