The annual and seasonal successions of larvae and imagines of water beetles in a shallow, man‐made lake in Northern Sweden

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Abstract
Four years after the reflooding of a shallow, man‐made lake in the coastal region of northern Sweden the water beetle fauna was studied over a 5‐year period. Samples were taken at regular intervals using emergence traps, a sweep net and a Rzóska core sampler. Altogether 28 different species were found, 23 of which belonged to the Dytiscidae. A certain seasonal sequence in the larval stages of the most abundant species was observed. Early in summer larvae of Colymbetes striatus and Agabus fuscipennis were present, and those of A. serricornis, Rhantus exsoletus and Graphoderus zonatus at midsummer, while larvae of Hygrotus inaequalis and Ilybius subaeneus were found almost exclusively during the late summer. Larvae of Coelambus impressopunctatus occurred over a longer period of time. During the 5‐year study period the values for species number, diversity and evenness all increased. As the lake increased in age, so did habitat complexity, mainly in connection with the development of the plant community of submerse macrophytes.