METAMORPHOSIS OF CONCHOLEPAS-CONCHOLEPAS (BRUGUIERE, 1789) INDUCED BYEXCESS POTASSIUM

Planktonic larvae of Concholepas concholepas Bruguiere underwent compl ete metamorphosis in response to excess K+. The effect was dose-depend ent and optimal at approximately double the normal concentration of K in 0.45 um membrane-filtered seawater. Increasing concentration over 25 mM K+ produced a decline in survival, suggesting toxicity. Metamorp hosis began with propodium attachment to the substratum and subsequent deciliation and destruction of the velum, followed by the emergence o f cephalic tentacles from the larval shell margin. Velar loss, induced by K+, began with the detachment of large ciliated cells at the velar margin. Field-collected larvae, from different localities along the C hilean coast, presented a positive response to excess K+, and almost 8 0% of the larvae metamorphosed in 1 to 2 days. The induction of metamo rphosis of Concholepas concholepas larvae by K+, provides a useful bio technological tool for the cultivation of this socio-economically impo rtant marine resource of the southeastern Pacific Ocean.