Histological effects of the inert suspended clay kaolin on the gills of juvenile rainbow trout, Salmo gairdneri Richardson

Abstract

Juvenile rainbow trout were exposed to 36, 171, 1017 and 4887 mg/1 of suspended kaolin clay for 64 days. Gills were analysed quahtatively and quantitatively using histology. Branchial pathology was absent at all sample times in fish exposed to 36,171 and 1017 mg/! kaolin, althoughintracellularkaotinwas visible within filament and lamellar epithelium in gills exposed to 171, 1017 and 4887 mg/1 kaolin at 4, 8, 16, 32 and 64 days. Lesions were found in gills exposed to 4887 mg/I kaolin at 16 and 32 days but the marked lamellar proliferation was associated with moderate to large numbers of protozoa identified as Ichthyobodo necator. Gills regained normal architecture by 64 days despite continued exposure to kaolin. It is suggested that while the gill lesions were probably a direct result of protozoan infection, kaolin was indirectly responsible for creating a favourable environment for protozoan colonization. The recovery of normal architecture and reduction of protozoan numbers between 32 and 64 days was probably a function of increased mucus secretion, immune response and turnover of branchial epithelium. The authors conclude that exposure to prevailing levels of this inert clay particle, even for periods as long as 64 days, probably has little direct effect on gill structure at the light microscope level. The action of noninert and organic particles remains to be investigated.

Effects of a cationic detergent on the gills and blood chemistry of rainbow trout Salmo gairdneri

“…( X 500) irritants (Mallatt 1985). This is not surprising in light of the fact that gill lesions pathognomonic for particular agents or toxicants are rare (Goldes et al 1988).…”

Effects of Sedimentation and Turbidity on Lotic Food Webs: A Concise Review for Natural Resource Managers

“…For species that remain in the disturbed area, elevated levels of sediment may have an adverse effect on fish health. Increased sedimentation and turbidity can reduce dissolved oxygen in the water column, and in extreme cases may cause a thickening of the gill epithelium and reduced respiratory function (Horkel and Pearson, 1976;Goldes et al, 1988;Waters, 1995). Increased mortality has been associated with increased suspended sediment for arctic grayling (T. arcticus), Atlantic silverside (Menidia menidia), rainbow trout (0. mykiss), fourspine stickleback (Apeltes quadracus), white perch (Morone americana), yellow perch (Perca flavescens), American shad (Alosa sapidissima), striped bass (M. saxatilis), coho salmon (0. kisutch), chinook salmon (0. tshazuytscha), chum salmon (0. keta), striped killifish (Fund&s majalis), sheepshead minnow (Cyprinodon variegatus), and even carp (Cyprinus caqio) (Newcombe, 1994;Newcombe and Jensen, 1996).…”

Paramoeba pemaquidensis (Sarcomastigophora: Paramoebidae) infestation of the gills of coho salmon Oncorhynchus kisutch reared in sea water

“…Goldes et al (1988) reported moderate to severe gill infestations by the ectoparasitic flagellate Ichtyobodo necator in rainbow trout exposed to high levels of inert suspended solids in the form of clay kaolin, whereas fish kept in otherwise identical conditions were not infested. Many coho salmon with prominent Paramoeba infestations in our study were also infected with a microsporidium (Loma salmonae) or a monogenean (Laminiscus strelkow~].…”