Laminarinase induction in marine zooplankton and its variability in zooplankton samples

Abstract

Laminarinase, or β-l, 3-glucanohydrolase, is a stable and highly active catalyst of the breakdown of β-l, 3 linked polysaccharides into glucose subunits. The enzyme is apparently unique to herbivores among marine planktonic zooplankton, and its specific substrate, chrysolaminarin-a β-1, 3 linked storage product-is unique to phytoplankton. Evidence is presented to show that the enzyme is substrate inducible and that enzyme activities rise and fall in proportion to the amount of ß-1, 3-glucan in the diet. Our data from San Clemente and Santa Barbara Basins (California) showed a negative correlation between laminarinase activity and zooplankton biomass density when samples were taken at closely spaced intervals over a three day period. This result suggests that the negative correlation between phytoplankton and zooplankton which is often observed may at least in part be due to grazing activity. Implications for phytoplankton-zooplankton relationships are discussed.