Malpigmentation is common in hatchery-reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels sufficient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular-side skin follows the normal blind-side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery-reared flatfish. 2000 The Fisheries Society of the British Isles

Seasonal variation in lipid content and composition was studied in deposit-feeding amphipods from a Baltic archipelago. In Monoporeia afinis, which is more active and has a higher respiration rate, lipid levels were low in winter and early spring, rose to 27% of the dry mass in late summer, then declined in autumn. In Pontoporeia femorata, which regulates its oxygen consumption, lipid levels were 20-23% of the dry mass. In October, maturing male P. fimorata had a significantly lower lipid content than females. Triacylglyccrol and phospholipid accounted for -90% of lipids. Phospholipid dominated in M. afinis in March, but triacylglycerol accumulated and became the main lipid after the spring bloom. Triacylglycerol was always the main lipid in P. femorata, but also accumulated after the spring diatom bloom. Both species seem to assimilate and store food resources from the diatom bloom. The higher feeding rate of M. afinis may explain its greater accumulation of lipid. Lower metabolic costs in P. femorata may allow it to maintain steady lipid levels for most of the year.

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The effect of 1-year-old Monoporeia (=Pontoporeia) affinis on the survival and growth of young of the year was studied in laboratory experiments. Amphipods were kept in jars with sediment and a continuous supply of cooled water for 3 months. Adults or juveniles were added to a control density of juveniles. Juvenile mortality increased at higher total densities, and was greater when adults were present. The mean length and dry weight of juveniles decreased at higher densities, but adults did not have a greater effect than juveniles. These density-dependent effects are probably caused by competition for food within and between year classes. Thus, a high abundance of juveniles or adults could reduce the recruitment of juveniles into the adult year-class the following year, and the suppression of juvenile growth could lower fecundity. The results of this experiment support the hypothesis, inferred from field data from the Baltic Sea and Swedish lakes, that intraspecific interactions contribute to fluctuations in the abundance of populations of M. affinis.

Article Descriptors profoundly mentally handicapped students; multiply handi capped students; prelanguage communication skills; interac tive communication behaviors; communication programming; communication awareness skillsThe purpose of this study was to ascertain the effec tiveness of specific prelanguage communication pro gramming techniques on the development of com munication awareness behaviors of four profoundly mentally handicapped students. Results indicate that the procedures were effective and that, in the majority of cases, the communication awareness behaviors generalized to other situations and individuals. Prob lems related to defining communication awareness behaviors and communicative stimuli, as well as issues pertaining to generalization, are discussed.