MALFORMATIONS IN NORTH-SEA PELAGIC FISH EMBRYOS DURING THE PERIOD 1984-1995

Malformation rates in embryos of dab, whiting, cod, flounder, and plai ce in the southern North Sea have been monitored between 1984 and 1995 by quantitative investigations of developmental defects in eggs immed iately after capture. Incidences were highest in near-coastal waters k nown to receive high pollution loads. For all species and all areas in vestigated, synchronous trends were found with intermediate incidences in 1984, maxima in 1987 and significant decreases thereafter. The var iations are compared with trends in organochlorine residues in dab and plaice from the German Eight collected over the same period. Trends v ary for different organochlorine substances, but the overall picture i ndicates elevated levels in the period 1984-1987 and decreasing concen trations thereafter. Although the general pattern is consistent with t he trend in incidences, significant correlations were only found for m alformations of dab and concentrations of p,p'-DDE. Trends in concentr ations of nutrients and hydrographic factors were also investigated, i ndicating a significant negative linear correlation between surface wa ter temperature and incidence of malformed embryos of dab. The hypothe sis is put forward that low temperature may predispose developing fish embryos to the impact of organochlorines. (C) 1996 International Coun cil for the Exploration of the Sea