Arctic Zooplankton Community Structure: Exceptions to Some General Rules

. Commonly,accepted theories of zooplankton,species distribution hold that: 1) large-bodied zooplankton,species are excluded by fish predation and so are found only in lakes and ponds without fish; and,2) because small-bodied species are unable to compete,successfully against large ones and also are preyed upon,heavily by invertebrate predators, they exist primarily in lakes with fish. This pattern is not followed in a group of lakes and ponds in arctic Alaska. Some of these lakes were found to support,both large and,small zooplankton,species along with populations of facultative planktivorous,fish. Other lakes that ,had,no,fish had,a small-bodied zooplankton,species Co-existing with,a more,typical large-bodied community.,Close analysis,of these,unusual,distributions reveals that the mechanisms,affecting zooplankton,community,dynamics,are more,subtle and,complex,than genedly recognized, particularly in such harsh environments as the Arctic. RgSUMk. La théorie generalement,reconnue,sur la ,repartition des espkces,de 1) les poissons prédateurs excluent les espkces de zooplancton de grand taille et donc