Sean J. Handley

Aquaculture trials of the New Zealand bath‐sponge Spongia (Heterofibria) manipulatus using lanterns

Abstract A submarine lantern system was trailed in the aquaculture of explants of the endemic New Zealand bath‐sponge Spongia (Heterofibria) manipulatus (Demospongiae: Dictyoceratida: Spongiidae) at four New Zealand sites, two in the Marlborough Sounds and two off Coromandel Peninsula. The main objectives were to compare growth rates of explants at different sites, compare these with those of control sponges, and to assess the utility of these lanterns for the culture of this species. After a period of 13 months, sponges at exposed Bonne Point in the Marlborough Sounds were on average 73% larger in estimated volume than at the start of the experiments. Growth rates of explants at exposed Port Charles, Coromandel, showed no significant change over the study period, although positive growth over spring 2003 was evident. Sponge explants at sheltered Wairangi Inlet and Kennedy Bay, in the Marlborough Sounds and Coromandel, respectively, did poorly, with most explants regressing in size and becoming moribund. Growth rates varied considerably between individuals at each location. Implications of the growth rate characteristics of S. (H.) manipulatus, and the design and construction of the aquaculture lantern, for the future commercial production of this species are discussed.

First record of the Australian ascidian Eudistoma elongatum in northern New Zealand

Abstract A colonial ascidian was first reported by marine farmers in Houhora Harbour, Northland, New Zealand in early 2005 and subsequently found on oyster racks in Parengarenga Harbour and the Bay of Islands. The Northland ascidian was identified with a combination of morphological characters and DNA cytochrome c oxidase I (COI) sequence data, as Eudistoma elongatum, a species native to Australia, where it is found from northern New South Wales to Northern Queensland, and distinguished from Eudistoma circumvallatum, the only reported species in this genus from New Zealand. Ascidian larvae are weak dispersers and long distance dispersal of E. elongatum is likely to be enhanced by vectors such as oyster barges and/or movement of cultured oysters. In its native range, E. elongatum is restricted to areas with a minimum winter sea temperature of 16°C. Assuming similar biological limitations apply in New Zealand, the spread of E. elongatum might be restricted to northern New Zealand (north of latitude 37°S).

Annual pattern of brooding and settlement in a population of the flat oyster Ostrea chilensis from central New Zealand

Abstract Temporal patterns of larval brooding and settlement were investigated in a flat oyster (Ostrea chilensis) population in Tasman Bay, central New Zealand. The proportion of the population brooding larvae and larval settlement rates were monitored over 26 months. A peak period of brooding activity began in late spring and continued through summer. Maximum rates of 17% and 23% of adult oysters brooding larvae occurred in November and December, and an estimated 55–78% of adult oysters incubated larvae over the entire summer breeding period. These proportions of brooders are higher than those previously reported for Tasman Bay. A very low level of brooding activity (1%) occurred during winter. Temporal trends in larval settlement closely tracked brooding patterns. Settlement was greatest between November and January, and there were very low rates in winter. The seasonal breeding pattern in the population was intermediate between northern and southern populations, confirming a latitudinal gradient of reproductive behaviour for O. chilensis in New Zealand. Results are useful in optimising the timing of substrate deployment in an enhancement programme for the oyster fishery.

The colonial ascidian fauna of Fiordland, New Zealand, with a description of two new species

A total of 17 species from the families Styelidae, Polyclinidae, Polycitoridae, Pseudodistomidae, Ritterellidae and Didemnidae are described for the first time in collections from remote fiords with steep-sided walls, high rainfall and high tidal flow on the south-west coast of New Zealand. The Fiordland ascidian assemblages are composed of endemic species, species with trans-Tasman affinities, species found in southern New Zealand and species found New Zealand wide, some of which have global distributions. Two Australian native species, Diplosoma velatum Kott, 2001 and Didemnum jucundum Kott, 2001 from South Australia are new records to New Zealand and a further eight species remain undescribed. Two new colonial ascidians Aplidium coronum sp. nov. and Trididemnum shawi sp. nov. are described in this paper. http://zoobank.org/urn:lsid:zoobank.org:pub:5ADC2C9D-28AC-4348-8B4D-F26-2A43DEA66