Conklin, D. J., Mowbray, R. C., and Gingerich, W. H., 1992, Effects of chronic
exposure to soft, acidic water on gill development and chloride cell numbers in
embryo-larval brook trout, Salvelinus fontinalis: Aquatic Toxicology, v. 22, no. 1, p.
39-52.

Abstract

In order to evaluate the effects of acid exposure on the respiratory and ionoregulatory
systems of  developing brook trout, Salvelinus fontinalis , differences in gill
morphology and numbers of chloride cells were  compared between groups of
developing embryo-larval fish continuously exposed to moderately hard well water 
(130.0 mg/l as CaCO sub(3), pH 7.94) or to reconstituted soft, acidic water (4.4 mg/l
as CaCO sub(3), pH 5.25)  designed to mimic acidic waters of northern Wisconsin
acidified lakes. Exposures were maintained for up to 48  days (82 days after
fertilization) during critical periods of growth and differentiation of branchial
structures.  The second right gill arch of each fish was examined for changes in the
development of filaments and lamellae  and for differences in numbers of chloride
cells. Gills of fish that developed in soft, acidic water contained  greater numbers of
normal and degenerating chloride cells, exhibited hyperplasia of primary epithelium
and  multiple fusions of adjacent filaments and lamellar epithelium than the gills of
control fish. Filament and  lamellar lengths and numbers of lamellae per filament were
significantly less (P < 0.05) in fish that developed in  soft, acidic water than in fish
exposed to well water.

Keywords

acidity, freshwater-fish, developmental-stages, gills, osmoregulation, toxicity-tests,
acids, morphology, Salvelinus-fontinalis, cell-morphology, water-quality;
chronic-toxicity; hardness-; chloride-cells