Effect of Seasonal Changes on Predictive Model Assessments of Streams Water Quality with Macroinvertebrates

In this study we investigate how seasonal variability in aquatic macroinvertebrate communities affects the performance of a predictive model developed to assess environmental quality. Macroinvertebrates were sampled from nine not visibly disturbed sites located in different streams of the Mondego catchment across a full year. Organisms were identified to the lowest practicable taxonomic level and their abundances recorded at three taxonomic levels (order, family and lowest level). The seasonal samples were examined with regard to seasonal variation using three predictive models at order, family and lowest taxonomic level. The models showed increasing effect of seasonal changes across taxonomic levels, from order to the lowest level. When using the current models samples should be taken in the same season as the reference sites were sampled. Furthermore, data from more reference sites should be added to the model in order to encompass sufficient natural variation and allow the use of the model in different seasons. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

An investigation into some aspects of the biology of the Hirudinoidea

Bibliography: p. 124-128

Baseline incidence of mouthpart deformities in Chironomidae (Diptera) from the Laurentian Great Lakes, Canada

Larval chironomid mouthpart deformities are used as indicators of anthropogenic stress. However, there are limited data on the incidence of naturally occurring deformities. Chironomid larvae were collected from 252 reference sites throughout the Great Lakes by Environment Canada from 1991 through 1993. Overall incidence of mentum deformities was 2.27% for Procladius (SE = 0.46, n = 1055), 2.15% for Chironomus (SE = 0.51, n = 839), 1.27% for Heterotrissocladius (SE = 0.57, n = 393), 1.38% for Tanytarsus (SE = 0.61, n = 363), and 3.25% for Polypedilum (SE = 1.07, n = 277). The most common deformity was one missing tooth in the mentum. Deformity frequency was highest in Northern Channel and Georgian Bay of Lake Huron. However, incidences were homogeneous among regions (G-test, p \u3e 0.05). In examining contaminated conditions, a result greater than one 95% confidence interval above these reference deformity frequencies should be considered significantly elevated from baseline levels

Development in Hidrology : Aquatic Oligochaete Biology VI

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Sediment quality in Rio Guadiamar (SW, Spain) after a tailing dam collapse: Contamination, toxicity and bioavailability

10 páginas, 5 figuras, 6 tablas.An integrated assessment of sediment quality in the Guadiamar River after a mining spill was conducted. The concentration of different metals and other conventional parameters were measured in sediments located along the river. Four sediment toxicity tests (Hyalella azteca 28-day survival and growth test; Chironomus riparius 10-day survival and growth test; Hexagenia spp. 21-day survival and growth test; and Tubifex tubifex 28-day reproduction and survival test) were carried out to determine the effects associated with the accidental spill. The geochemical fractions of 6 metals (Fe, Mn, Zn, Cu, Pb, and Cd) were determined to establish the bioavailability of the metals. The relationship found in the concentrations of metals associated with the mobile fractions of the sediments in the sites studied is similar to the toxic mud from tailing pond and confirms that the toxic effects are associated with the metals Zn and Cd originating from the spill.The chemical speciation approach was supported by grant REN2002-01699 and CTM2005-07282-C03-C01/TECNO from the Spanish National Plan for research, innovation and development (Ministerio de Ciencia y Tecnología).Peer reviewe