Freshwater species distribution

Figure SI-2 Species Sensitivity Distribution for TBT-Sn based on the data for 29 marine and freshwater species...

Wheeler et al. (2002) established acute freshwater and saltwater SSDs for 21 substances, including ammonia, metals, several pesticides, and narcotic substances. Using HC5 calculations and curve slope, they found freshwater species were either more sensitive (ammonia, copper, nickel, or zinc) or less sensitive (chlordane, endosulfan, pentachlorophenol) than saltwater species. In some cases, the distributions were very similar however, the taxonomic compositions of the freshwater and saltwater data sets were not always comparable. Maltby et al. (2005) analyzed SSDs for 16 insecticides and inter alia compared SSDs based on saltwater and freshwater species. They concluded (page 379) that the taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard, but the habitat and geographical distribution of the species do not. Differences in freshwater and saltwater SSDs were primarily driven by taxonomy (e.g., both crustaceans and insects are present in freshwater, but only crustaceans are found in seawater). Correcting for the disparity in taxonomy removed habitat differences. 

The order Perciformes is the largest and most diverse of all fish orders, encompassing about 8,000 species. Distributed worldwide, fish of this order exist in both marine and freshwater habitats and represent species of diverse sizes, habitats, and behaviors. This order is broken into 150 families and 1,370 genera. 

For two freshwater species, the crayfish Pacifastacus leniusculus) and the snail Juga silicula) whole-body concentration ratios of 1.6 and 41, respectively, were obtained when 9.imTc04 was used as a tracer. Tissue distribution data showed that 79-100 % of the crayfish body burden was in the exoskeleton and digestive gland, whereas the soft tissues of the snails contained 82-96 % of the whole-body activity [70]. 

All these data prove that both the soil and the freshwater species (or freshwater groups of species) are not distributed randomly in the world. 

In conclusion, it is still not clear what kind of geographic pattern is really true and important for the continental free-living nematodes, nor if there is a geographic parallelism between the soil and the freshwater species, nor if vicariance or dispersion are the main biogeographic factors. We can only foresee that new field collections and DNA data, that many laboratories are collecting with a constantly increasing speed, will permit us to define a picture of nematode distribution and history one which is vaster and more correct than any we can conceive at present. 

Stacey, N.E. Cardwell, J.R. 1995. Hormones as sex pheromones in fish widespread distribution among freshwater species. In Proceedings of the Fifth International Symposium on the Reproductive Physiology of Fish (Ed. by F.W. Goetz P. Thomas ), pp 244-248. Austin TX Fish Symposium 95. 

Northern pike (Esox lucius), an esocidae species, is considered one of the most widely distributed freshwater fish [57]. It is a piscivorous species, consisting its diet on common carp (Cyprinus carpio) and roach Rutilus rutilus). Nevertheless, in the absence of prey fish, invertebrate feeding could be important for this species [58, 59]. 

Inorganic ligands in aqueous solutions, and in particular in natural freshwaters, include, in addition to H2O and OH, the major ions carbonate and bicarbonate, chloride, sulfate and also phosphate [29], The distribution of metal ions between these ligands depends on pH and on the relative concentrations of the ligands. The pH is a master variable with regard to the occurrence of hydrolysed species and to the formation of carbonate and bicarbonate complexes. 

Gakstatter, J.H. The uptake from water by several species of freshwater fish to p,p -DDT, dieldrin, and lindane their tissue distribution and elimination rate. PhD Dissertation, Univ. of North Carolina, Chapel Hill (1966)... 

Wheeler, J.R., Leung, K.M.Y., Morrit, D., Sorokin, N., Rogers, H., Toy, R., Holt, M., Whitehouse, P. and Crane, M. (2002). Freshwater to saltwater toxicity extrapolation using species sensitivity distributions. Environmental Toxicology and Chemistry, 21, 2459-2467. 

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