G. A. Knox

Plate tectonics and the evolution of intertidal and shallow-water benthic biotic distribution patterns of the southwest Pacific

Abstract A brief summary is given of recent information on the changing palaeogeography of the southwest Pacific region following the break-up of Gondwanaland and the parallel palaeoceanographic changes that occurred. Present intertidal and shallow-water benthic marine provinces in Australasia can be grouped into tropical—subtropical, warm-temperate, transitional warm-temperate, cold-temperate, transitional subantarctic and subantarctic regions. A notable feature is the marked faunistic attenuation that occurs with increasing latitude in most groups. Historical explanations of biotic distribution patterns fall into two classes: dispersal explanations and vicariance explanations. The problems involved in evaluating the relative roles of dispersal and vicariance in the evolution of the biota of a region are outlined and the conditions which must be met before larval dispersal across wide stretches of ocean can be successful are reviewed. It is concluded that rafting of adults is restricted to a few groups of animals and is of limited importance as a dispersal mechanism. An examination of the external relationships anddfossil record of Australasian intertidal and shallow water biota has identified a number of elements of which the predominant one is a Malayo-Pacific one comprising plants and animals of tropical affinities. The evolutionary history of the biota is re-interpreted in the light of palaeogeographic and palaeoceanographic changes with reference to a series of palaeogeographic reconstructions showing successive positions of Antarctica, Australia and New Zealand which have been used as a geographic base upon which speculative patterns of oceanic circulation and positions of oceanographic fronts have been depicted. Tectonic events, coupled with changes in circulation patterns and sea temperatures and the establishment of the Antarctic and Subtropical Convergences with a series of water masses forming belts from the poles to the tropics have been controlling influences of the distribution and evolution of the marine biota of the region. A major factor has been the migrations that have occurred in the position of the warm-water/cold-water boundary, the Subtropical Convergence. This migration coupled with changing island archipelago nature of the New Zealand land area has played a major role in speciation processes in the New Zealand region. It also led to the extraction of many warm-water genera and species as it moved north. In Australia the larger land mass extending further to the north provided opportunities for species to migrate up both the east and west coasts. This, coupled with the Pleistocene land bridges which connected Tasmania and New Guinea to Australia, led to isolation and subsequent allopatric speciation, followed by sympatry when the derived species migrated along the coast as the Subtropical Convergence retreated south to its present position and the Torres and Bass Straits barriers disappeared with rises in sea level.

Summer tide-crack phytoplankton at White Island, McMurdo Sound, Antarctica

Abstract The standing crop and succession of marine microalgae are described for blooms in the surface water of a tide crack in the permanent ice of the Ross Ice Shelf at White Island, McMurdo Sound, Antarctica. The dominant microalgae during late November were Chlorophyta (Pyramimonas sp.). Bacillariophyceae (diatoms) were dominant from early December until the end of the study in late January. Five species were most abundant: Nitzschia cylindrus, Nitzschia curta, Nitzschia obli‐quecostata, Fragilaria sp., and Synedra tabulata. The concentration of chlorophyll a was at the highest level (30.0 μg l ‐1) when Pyramimonas sp. were most abundant. Incident light and the percentage transmission of light to a depth of 1 m in the tide crack were also at maximum levels at this time. The chlorophyll a concentration decreased to below the limits of detection after the thaw in mid‐January when there was an abrupt increase in the temperature and a decrease in the salinity of the surface waters in the tide crack. The c...

Zonation of inshore benthos off a sewage outfall in Hawke Bay, New Zealand

Abstract Benthos was sampled quantitatively on a rectangular grid perpendicular to shore directly off a sewage outfall. Faunal samples were washed through a 0.5 mm sieve, and resulting species frequency data subjected to the ‘flexible’ classification. Crustacea and Polychaeta contributed most of the 100 species; most individuals were polychaetes. Five groups of species were found. Five faunal zones parallel to shore and progressively wider further offshore were distinguished. Community structure increased offshore, and faunal density decreased offshore from the second zone. Inshore zones were obviously polluted, with the capitellid Heteromastus filiformis occurring in densities up to 36 950 per square metre 500 m from shore. Furthest from shore, the fauna was more ‘normal’ with Heteromastus densities of 6000 per square metre. Unique to New Zealand shores is a dense (440 per square metre) zone of holothurians at 8–10 m depth. Deposit‐feeders dominated all stations with mean sediment sizes finer than 1.0 , ...

The Polychaetous Annelids of New Zealand Part 2: Lumbrineridae

Abstract THE species of the Family Lumbrineridae from New Zealand are reviewed and new distributional records are listed. Seven species of the genus Lumbrineris are recorded, three are refigured, and two new species Lumbrineris aotearoae and L. galatheae are described. One species of the genus Ninoe is recorded.

The key role of krill in the ecosystem of the Southern Ocean with special reference to the Convention on the conservation of Antarctic marine living Resources

Abstract The salient features of the Southern Ocean ecosystem are detailed and its special characteristics are outlined. The key role of krill (principally Euphausia superba ) is emphasized. The current state of knowledge of the living resources, with special reference to krill, squid, fish, and whales, is detailed. Information on exploitation of these resources with special reference to the past two decades is analyzed and the impact of this exploitation on the stocks of krill, fish, and whales is evaluated. Ecosystem changes following the decline in whale stocks are detailed and potential ecosystem changes that may result from intensive krill harvesting are considered. The history of the development of the Convention on the Conservation of Antarctic Marine Living Resources is outlined and the salient features of the Convention are discussed. This Convention is unique among fisheries conventions, in that it adopts an ecosystem approach to the management of living resources. The main features of this Convention are outlined and the management principles that stem from it are detailed. Problems involved in the adoption of an ecosystem-management approach are considered. Finally, the information needs for management are examined with special reference to the international BIOMASS research programme. The prospects for achieving the objectives of the Convention are considered.

The polychaetes of New Zealand Part 5. Onuphidae

Abstract The species of Onuphidae from New Zealand are reviewed and new distributional records are listed. Nine species belonging to five genera are recorded; two are refigured and two new species, Onuphis pectinata and Diopatra akarana, are described.

Biological oceanography of the Ross Sea (extended abstract)

Abstract Scientific exploration of the Ross Sea has a long history beginning with the early voyage of discovery of James Clark Ross, who gave the sea its name. A series of pioneer expeditions was followed in the early thirties by some increased activity, leading to the modern intensive period of scientific observation beginning with the IGY in 1958.

Chiltoniella elongata n.gen. et sp. (Crustacea: Cephalocarida) from New Zealand

A fourth genus of Cephalocarida is described and illustrated from two specimens taken on a shallow mud bottom in New Zealand. It differs from existing genera in its combination of characters. Comparison with other genera shows it is most similar to Hutchinsoniella. Characters distinguishing the cephalocarid genera are tabulated.

The polychaetes of New Zealand

Abstract THE species of Eunicidae from New Zealand are reviewed and distributions are recorded. Seven species of Eunice, one of Palola, one of Lysidice, four of Marphysa and one of Paramarphysa are recorded.

Taxonomic position of two lumbrineris spp.

Abstract Lumbrineris mucronata (Ehlers, 1908) and L. sulcaticeps (Benham, 1927), (Polychaeta Errantia: Lumbrineridae), previously known only from the type descriptions, are redescribed from material from Australia and New Zealand. Both species are unusual in possessing multidentate maxillae IV and bidentate posterior hooks with almost circular hoods.