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New Zealand Journal of Marine and Freshwater Research abstractsNOTES ON THE ECOLOGY AND PALEOECOLOGY OF NEOTHYR1S, AN ENDEMIC NEW ZEALAND BRACHIOPODV. E. NeallGeology Department, Victoria University of WellingtonAbstract Neothyris lecticularis (Deshayes, 1839) live mainly south o'f 44°S in waters 90-180 m (extremes 18—384 m) deep where bottom temperatures are always >7°c. Fossil N. "avails" (Hutton, 1886) in the early Pleistocene limestone at Castlepoint (41 °S) are associated with an assemblage of animals generioally the same as the living N. lenticularis assemblage o'f Foveaux Strait. The granular substrate occupied by the living animals is similar to the matrix of the Castlepoint limestone. Thus the early Pleistocene marine climate in 90-180 m at 43°S may have been about 5°c cooler than it is today; the possible use is mentioned of the presence of the fossil assemblage in studies iotf palaeoelimates.Population analysis of living and fossil stocks show a constant bias toward the older age-groups; this finding is discussed. Various ecological observations are recorded. Introduction The articulate brachiopod Neothyris lenticularis (Deshayes, 1839) is found living only in New Zealand and subantarctic waters. The species has been dredged from an area extending from the southern part of the Campbell Plateau (52°65'S, 196° 23'E) to as far north as Three Kings Islands (34° 10'S, 172° 10'E), although it is rare in the north of this area. Fossil specimens occur abundantly throughout the New Zealand Upper Tertiary and Quaternary, and their presence may mark the spread of cooler climate northwards across New Zealand. The distribution of living Neothyris lenticularis is summarised in Fig. 1; optimum environmental conditions appear to exist in Foveaux Strait and around Stewart Island, where the largest and most prolific populations are known. This may be accounted for by the currents which sweep along the shelf bottom from the east and west (current data from Cullen 1967). The larvae evidently settle on a substrate of small stones or fragments of shell large enough to support only the juvenile individual. Few specimens trawled from Foveaux Strait and examined by the author are found with pedicle attachment areas greater than a few millimeters in diameter. With growth some individuals become too large for the original holdfast and may become free, and some adult specimens have been observed rolling along the bottom of Foveaux Strait in the brisk bottom currents (Bowen 1968). They appear able and strong enough to withstand the current action.
N.Z. Jl mar. Freshwat. Res. 4: 117-25
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