Zooplanktonic seasonal cycles occurring in Wellington Harbour, January 1961 to August 1963, and studies on the life histories of the New Zealand Porcellanidae (crustacea, decapoda, Anomura)

Abstract

PART ONE: ZOOPLANKTONIC SEASONAL CYCLES OCCURRING IN WELLINGTON HARBOUR – 1961 to 1963. During 1961 to 1963 regular plankton tows were taken from Wellington Harbour. These plankton samples were analysed, the macroplankton fauna identified, and the abundance of each species recorded. Class Crustacea was made the subject of special study and identified larvae illustrated. A plankton calendar of the dominant macroplankton species was prepared and the characteristics of the plankton in each month described. Irregular variations are discussed. Surface water temperature variation was found to influence the abundance of numerically dominant species. Ecological factors determining the nature of the harbour population are discussed. The zooplankton of Wellington Harbour is compared with that of coastal New South Wales, Australia. PART TWO: STUDIES ON THE LIFE HISTORIES OF THE NEW ZEALAND PORCELLANIDAE (CRUSTACEA, DECAPODA, ANOMURA). The zoea and megalopa larval stages of the New Zealand Porcellanidae are described in detail. The species considered are Petrocheles spinosus Miers, Petrolisthes novaezelandiae Filhol, and P.elongatus (Milne Edwards). A key for the separation of the zoea larval stages of each species is given. Larval characters suggest that Petrocheles spinosus is close to the Galatheidae and that Petrocheles warrants generic rather than sub-generic status. The larvae of Petrolisthes elongatus conform with other described larvae of the genus Petrolisthes. On the other hand the larvae of P.novaezelandiae differ significantly from the generic larval type and can only be compared closely with those of the genus Porcellana. Consequential taxonomic implications are discussed. Keys for the separation of the zoea and megalopa larvae of the New Zealand Porcellanidae are given. The breeding cycle of Petrolisthes elongatus was determined, and compared with the abundance of larvae in the plankton samples. Juvenile crab stages of P. elongatus are briefly described.