TANE 26,1980

THE MACROBENTHOS OF THE CAVALLI ISLANDS, NORTHERN

by Roger V. Grace* and Bruce W. Haywardf * 274a Birkdale Road, Birkenhead, Auckland 10 TN.Z. Geological Survey, DSIR, P.O. Box 30-368, Lower Hutt

SUMMARY

Forty-seven dredge samples from the sea-bed to the north, west, and south of Motukawanui, the largest island in the Cavalli Group, were analysed for macrofauna, macroflora, and sediment texture. Four associations were recognised. One, inhabiting fine sand in shallow water, was characterised by Myadora boltoni and Pectinaria australis. Another, characterisec by , occurred in shelly medium to coarse sands in depths to about 10 metres. A third association, which occurred in fine to very fine sand in depths greater than 30 metres, contained Nemocardium pulchellum, but was poorly sampled. In intermediate depths, an association containing Zeacolpus pagoda, Zegalerus tenuis and juvenile Tawera spissa occurred in substrates ranging from fine sand to fine shell gravel. Algae-dominated rocky substrates were mapped in the southern part of the area with the aid of aerial photographs.

INTRODUCTION

Motukawanui is the largest island in the Cavalli Group off the east coast of Northland at latitude 35°00'S, longitude 173°57'E, and approximately 2.4 km from the mainland. Field work was carried out during the Offshore Islands Research Group trip to the Cavalli Islands during December 1978 and January 1979.The locations of the 47 dredge stations are indicated in Fig. 1, together with bathymetry of the area, based on the Royal N.Z. Navy Hydrographic Office chart number N.Z.5121, "Cavalli Passage".

METHODS

Samples were collected using a new model of a small dredge described by Grace and Whitten (1974), as used by Grace and Grace (1976). The dredge held approximately 4.5 litres of sediment, and under ideal conditions sampled an area of approximately 0.075 square metre to a depth of 6 cm. The dredge was hand-hauled from a 3.8-metre aluminium dinghy with an 18 horsepower outboard motor.

189

Upon arrival of the dredge at the surface, the volume of each sample was estimated as tenths of the dredge filled, to enable crude quantitative estimates of the biota to be made. (About 100 to 150 mis of sediment was removed for textural analysis, and for analysis of populations of foraminifera (Hayward 1979, 1980). The rest of the sample was then passed over a wire mesh sieve with 2 mm openings. Organisms retained were sorted fresh, identified where possible and counted, then returned to the sea. Some specimens were retained for subsequent laboratory identification. Estimates of the volume of residue remaining after sorting were also made, to give an indication of the quantity of sediment coarser than 2 mm particle size. Grain size analyses of the sediments were carried out in the laboratory using sieves. Stations were located using a sextant to measure horizontal angles between fixed points on the shore. Rocky bottom areas were briefly investigated using snorkel and SCUBA diving techniques, and mapped in the southern part of the area with the aid of aerial photographs. RESULTS

Lists of station data are presented in Appendices 1 and 2. Sediments (Fig. 2) Fine sands are present in the shallow Papatara and Waiiti Bays on the south-west side of Motukawanui, where maximum shelter from the prevailing east or north-east swell occurs. The study area is, however, dominated by coarse and very coarse shelly sands to the south, west, and north of Motukawanui, with even coarser shell gravel in the channel immediately south of Motukawanui. These are relatively wave-exposed areas, and with the large numbers of shells of Tawera spissa produced here, heavy deposits of shells have accumulated. Around the small islands to the south, the sediments are mainly medium sands. The finest sediments are found in deep water to the northwest, where very fine sands have accumulated in quiet conditions at over 40 metres depth. Small pockets of very fine sand also occur in shallow, very sheltered inshore parts of Papatara Bay.

Flora An important component of the "sediments" between Motukawanui and the small islands to the north, and more especially between Motukawanui and the small islands to the south, is the large number of "rhodoliths" of both living and dead coralline algae (Fig. 1). Each "rhodolith" consists of a small central nucleus of rock or shell about which has grown encrusting coralline algae in the form of numerous narrow fingers projecting radially. The diameter of the 191 "rhodoliths" measures approximately 20 to 30 mm, with each finger- like projection about 2 to 3 mm in diameter (Fig. 3). These "rhodoliths" are heavier in structure than those noted from Great Mercury Island (Grace and Grace 1976), but finer than those at Army Bay north of Auckland. Similar "rhodoliths" occur in parts of the Bay of Islands (personal observations), and "rhodoliths" have recently been found to occur extensively in deeper water off the Northland coast (K. Grange,

Fig. 2. Sediments 192 NZOI, pers. comm.). The heaviest accumulations of shells and rhodoliths impart a certain degree of stability to the sediments, allowing the development of algae attached to the larger particles. These algae include Ulva lactuca, sometimes large sheet-like plants of Gigartina circumcincta, and a variety of smaller red algae. Most of these would be temporary in occurrence, being easily destroyed in storms, but re-developing fairly rapidly during extended calm periods.

Fauna The analysis of the fauna has been approached from the classical point of view of selecting the most obvious, most numerous, or characteristic species to define benthic communities. Here the term "community" is used to apply to a recurring combination of species of organisms, in a characteristic biotope, and with a considerable degree of continuity in space. Four communities of organisms inhabiting sediments have been recognised from field observations and an examination of the data. An additional community is found on the rocky seabed. These communities are mapped in Fig. 4, and discussed below. Only those species present in more than 25% of the samples assigned to a particular community are listed, although complete data is available in Appendix 2.

1. Myadora boltoni - Pectinaria australis community.

Stations : 16, 20, 21, 22, 23, 24, 25, 27, 28 Marginal stations : 15, 26 Biotope : Sediment: fine sand to very fine sand.

Depth : low tide to 5 metres. Wave energy : low to moderate. Characterising species : No. of stations % of occurrence Myadora boltoni 6 55 Pectinaria australis 9 82 Associated species : Polychaetes 11 100 Owenia fusiformis 6 55 Amalda novaezelandiae 6 55 Myadora striata 6 55 Zegalerus tenuis 6 55 Scalpomactra scalpellum 5 45 Zeacolpus pagoda 5 45 Amphipoda 5 45 Zostera muelleri 4 36 Duplicaria tristis 4 36 Trochodota sp. 4 36 Cominella quoyana 3 27' Soletellina nitida 3 27 193 Fig. 3. Calcareous rhodoliths of algae are common in the Cavalli Passage between Motukawanui and the mainland. This community occurs in Papatara and Waiiti Bays on the sheltered south-west side of Motukawanui, from low water to about 5 metres depth. The sand-mason worm Pectinaria australis is widespread within the community. The bivalve Myadora boltoni occurs in only 55% of the stations and reaches a maximum density of 5 in the sample at station 20. Myadora striata also occurs, but is even less dense. Other species typical of fine sediments include the bivalves Scalpomactra scalpellum and Soletellina nitida. More tolerant of a wider range of sediment types are the epifaunal gastropods Amalda novaezelandiae, Zegalerus tenuis (where shells provide a hard attachment surface), Duplicaria tristis and Cominella quoyana. A bed of the eel grass Zostera muelleri occurs in part of this community in Papatara Bay, but is not well developed. Reference to aerial photographs taken at different times over the past 30 to 40 years indicates that the Zostera bed has undergone various changes in density and extent, and was at a low ebb at the time of sampling. Had this bed been well developed, it may have been appropriate to subdivide this community, distinguishing the Zostera community as a separate entity, probably with characteristic fauna. A SCUBA dive on the densest part of the bed revealed a low incidence of the following fauna often characteristic of Zostera beds, in addition to species collected in the dredge samples: Venerupis largillierti, Dosinia 194 subrosea, Pecten novaezelandiae, Struthiolaria papulosa, Echinocardium cordatum, Astropecten polyacanthus and Squilla armata. 2. Tawera spissa community

Stations: 2,3,4,14,19,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44 Marginal stations : 1,45 Biotope : Sediment: fine sand to very coarse shelly sand and shell gravel. Depth : 2 to 15 metres. Wave energy : moderate to high. Characterising species : No. of stations % occurrence Tawera spissa 21 92 Associated species : Polychaetes 18 78 Amphipoda 18 78 Rhyssoplax stangeri 17 74 Zegalerus tenuis 17 74 Hermits 16 70 Amalda novaezelandiae 14 61 Cominella quoyana 14 61 Small red algae 13 57 Notoacmea helmsi 12 52 Membraniporiform bryozoa 11 48 Serpulidae 11 48 Micrelenchus rufozonus 11 48 Owenia fusiformis 10 43 Isopoda 10 43 Rhodoliths 9 39 Dosinia maoriana 8 35 Glycymeris modesta 8 35 Trochodota sp. 8 35 Ulva lactuca 7 30 Marginella pygmaea 7 30 Zeacolpus pagoda 7 30 Trachelochismus sp. 7 30 Corbula zelandica 6 26 Liocarcinus corrugatus 6 26 Amphipholis squamata 6 26 This community is best developed between Motukawanui and Piraunui Islands, although a smaller area is occupied by a less well developed example between Motukawanui and the islands to the north. The northern area contains mainly juvenile Tawera spissa about 10 to 15 mm long, to a density of about 14 000 per square metre (station 3). Towards the east, sediments become much coarser (station 1), where the dog cockles Glycymeris modesta and G. laticostata replace Tawera spissa. The area south of Motukawanui contains large Tawera spissa between 15 and 25 mm long throughout most of the bed, with densities commonly exceeding 1 000 per square metre. Densities of large Tawera appear to be unaffected by accumulations of rhodoliths on the sediment surface (diving observation). Towards the eastern and northern boundaries of the area, the size of Tawera decreases to about

196 5 to 10 mm, but in places densities are very high (about 37 000 per square metre at station 40). Much of the area occupied by the Tawera spissa community contains quantities of dead shells and rhodoliths, which provide attachment surfaces not only for bryozoa, serpulid polychaetes and small algae, but also for grazers such as the small Rhyssoplax stangeri and limpet Notoacmea helmsi, and the suspension-feeding slipper limpet Zegalerus tenuis. The generally coarse sediments also provide a suitable habitat for other epifauna such as amphipods, hermit crabs, isopods, the suckerfish Trachelochismus sp., the portunid crab Liocarcinus corrugatus and small ophiuroid Amphipholis squamata. The roving carnivorous gastropods Amalda novaezelandiae and Cominella quoyana are both common throughout the area. Some of the more important species found in this community are illustrated in Fig. 5.

Fig. 5. Some important organisms from the Tawera spissa community: a, Tawera spissa; b, Venericardia purpurata; c, Gari stangeri; d, Glycymeris modesta; e, Zegalerus tenuis; f, Amalda novaezelandiae; g, Cominella quoyana; h, Rhyssoplax stangeri; i, hermit crabs; j, Serpulid worm tubes; k, unidentified polychaete; 1, algal rhodolith. 197 3. Zeacolpus pagoda - Zegalerus tenuis community.

Stations : 5,6,12,13,17,18,46,47 Marginal stations : 11,15,26 Biotope : Sediment : fine sand to very coarse shelly sand and fine shell gravel. Depth : 2 to 30 metres. Wave energy: moderate to low. Characterising species : No. of stations % occurrence Zeacolpus pagoda 11 100 Zegalerus tenuis 10 91 Associated species : Polychaetes 11 100 Tawera spissa (juveniles) 9 91 Hermits 9 91 Duplicaria tristis 6 55 Scalpomactra scalpellum 6 55 Trochodota sp. 6 55 Rhyssoplax stangeri 5 45 Felaniella zelandica 5 45 Amphipoda 5 4ft Pectinaria australis 1 36 Gari stangeri 4 36 Myadora striata 4 36 Membraniporiform bryozoa 3 27 Amalda novaezelandiae 3 27 Cominella quoyana 3 27 Notoacmea helmsi 3 27 Myadora boltoni 3 27 Nucula nitidula 3 27 Pecten novaezelandiae (juveniles) 3 27 Caprellids 3 27 Simple ascidians 3 27 This community occupies a large area to the west of Motukawanui, and appears to the south of Motukawaiti and Kahangaro Islands. In the study area it occurs adjacent to the Tawera spissa community, and to some extent intergrades with it. Although occurring at all stations, the major characterising species, the turritellid Zeacolpus pagoda, does not reach high densities. Most individuals are juveniles, suggesting that this occurrence of the community is not a fully developed example, the sediment perhaps being a little coars for high densities of large Zeacolpus pagoda as occur elsewhere (e.g. on fine sand at Mimiwhangata, Northland - personal observation, RVG). The slipper limpet Zegalerus tenuis depends upon coarse sediment particles, such as shells, for attachment, and is also an important component of the Tawera spissa community. Another strong link with the Tawera spissa community is the presence of juvenile Tawera spissa at a number of stations, particularly close to those assigned to the Tawera spissa community. Mostly the abundance of juvenile Tawera is low, but at station 46 juveniles of 5 to 10 mm length reach the 198 astonishly high density of about 63 000 per square metre . Many other species listed are shared with either the Tawera spissa community or the Myadora boltoni - Pectinaria australis community, such as Scalpomactra scalpellum, Duplicaria tristis, Rhyssoplax stangeri, Myadora striata, Pectinaria australis, Notoacmea helmsi and hermit crabs.

4. Nemocardium pulchellum community.

Stations : 7,8,9,10 Marginal station : 11 Biotope : Sediment: mainly very fine sand to fine sand. Depth: 30 to 40 metres and deeper. Wave energy : low. Characterising species : No. of stations % of occurrence Nemocardium pulchellum 2 40 Associated species : Polychaetes 5 100 Selenaria squamosa 3 60 Zegalerus tenuis 3 60 Amphipoda 3 60 Terebellidae 2 40 Spectamen plicatulus 2 40 Myadora subrostrata 2 40 Notocallista multistriata 2 40 Nucula nitidula 2 40 Saccella bellula 2 40 Hermits 2 40 Trochodota sp. 2 40

This deeper water community has not been well defined because of insufficient sampling. The presence of the bivalves Nemocardium pulchellum, Notocallista multistriata, and Saccella bellula clearly separate this community from those occurring in shallower water nearby. Other deeper water members of the fauna include Dentalium nanum, Tellina huttoni and Spectamen plicatulus.

5. Ecklonia radiata - Carpophyllum spp. community.

No detailed investigation of this community has been carried out here, but it appears typical of the shallow water rocky bottom community occurring generally on the Northland coast and offshore islands. This community is usually found adjacent to hard shorelines where rocks extend from the shore into sublittoral areas, but isolated rocky outcrops on the seabed are also colonised where light levels are sufficient to support large algae. The species of Carpophyllum found with the widespread Ecklonia radiata depends largely on the degree of wave action. C. angustifolium

199 occurs only in very shallow water in the most wave-exposed areas. C. maschalocarpum and C. plumosum occur in moderate exposure to moderate shelter, whereas C. flexuosum occurs subtidally in more sheltered conditions, such as between Waiiti and Papatara Bays. A great variety of also inhabit this community. For a general discussion of this community see Morton and Miller (1973), and Ayling (1975a, 1975b).

Diversity of species. The number of species of animals in each sample is indicated in Appendix 1. For this purpose all polychaetes are grouped and considered as one species, as are all nemertea, and all bryozoa. The pattern of species numbers is illustrated in Fig. 6, and bears a remarkable similarity to that shown by the distribution of the communities in Fig. 4. The number of species is highest in the Tawera spissa community, with an average of 20 species per sample, and a maximum of 34 at station 44. The Zeacolpus pagoda - Zegalerus tenuis community averages 14 species per station. Both the Myadora boltoni - Pectinaria australis community and the Nemocardium pulchellum community have relatively low diversity, with an average of 8 and 9 species per sample respectively. The higher numbers of species correspond in general to coarser sediments and a greater degree of water movement and wave action, provided that sediment stability is maintained. Coarser sediments offer more opportunities for shelter and attachment, particularly for epifauna, and the greater water movement brings with it a good supply of food for filter-feeding organisms. The resulting diversity of life- forms provides opportunities for a variety of carnivores.

DISCUSSION AND CONCLUSIONS

Comparison with other areas in New Zealand. The major work which attempts to summarise benthic communities of the New Zealand continental shelf is that by McKnight (1969). He recognised 5 major groups of communities, divisible into a total of 17 communities based on the larger infaunal bivalves and echinoderms. These communities he regarded as provisional and worthy of more detailed examination. The communities recognised at the Cavalli Islands can be related, with varying degrees of certainty, to those recognised by McKnight (1969) for the New Zealand shelf. Closer parallels may exist between the Cavalli examples and associations recognised by other workers in specific areas, but this brief comparison is by no means intended to be exhaustive.

200 Fig. 6. Number of species per sample. 201 1. Myadora boltoni - Pectinaria australis community. Grace and Whitten (1974) distinguished a Myadora boltoni - Scalpomactra scalpellum community on medium to fine sand in shallow water (5 to 15 metres) at Slipper Island. This community was similar in many respects to a Pupa kirki - Pectinaria australis community at Great Mercury Island (Grace and Grace, 1976), as well as to the Myadora boltoni - Pectinaria australis community at the Cavalli Islands. The Cavalli's example, however, is in shallower water (0 to 5 metres), lacks Puka kirki, and Echinocardium cordatum is all but absent (1 specimen at station 15, although it was found by diving near station 25). A clear-cut parallel with McKnight's communities is difficult to uphold. Grace and Whitten (1974) suggested that their Myadora boltoni - Scalpomactra scalpellum community may be a shallow water variation of McKnight's Scalpomactra scalpellum - Maorimactra ordinaria community. The difficulty of relating the above communities to McKnight's communities is probably complicated by the fact that nearly all McKnight's stations are in much deeper water than the series of stations reported in Grace and Whitten (1974), Grace and Grace (1976), and in the present paper. There is likely to be more variation in the shallowest parts of the shelf than in deeper waters, and the deeper parts are therefore likely to support communities with greater uniformity over larger areas, simplifying recognition of major associations. McKnight did note, however, that there was some variation in the composition of samples listed for his Scalpomactra scalpellum - Maorimactra ordinaria community.

2. Tawera spissa community. Communities with Tawera spissa as one of the most important infaunal bivalves are common and widespread on the New Zealand continental shelf. Other occurrences of this, or a very similar, community are noted by Powell (1937) for the Hauraki Gulf, Grace (1966, 1972a) for the entrance to the Whangateau Harbour, Grace and Whitten (1974) for Slipper Island, Grace and Grace (1976) for Great Mercury Island, and Ballantine et al (1973) at Mimiwhangata, Northland. McKnight (1969) has recognised a number of communities of this type, his Tawera spissa - Venericardia purpurata community probably most resembling this Cavalli Islands example. Although Venericardia purpurata is rare in the Cavalli samples, this is consistent with McKnight's comment that Tawera tends to dominate in shallower samples. Two other "Tawera" communities recognised by McKnight occur mainly in southern New Zealand. 202 3. Zeacolpus pagoda - Zegalerus tenuis community. There appears to be no published record of this or any similar community for the New Zealand area. Personal observations (RVG) at Mimiwhangata, Northland, have been made of a Zeacolpus pagoda community developed on medium to fine sand in 8 to 10 metres, where adult Zeacolpus pagoda reached densities in excess of 1 000 per square metre. The present example, however, is not as well developed, and seems to be more a fringe development around the Tawera spissa community. McKnight (1969) discussed "Turritella" communities, but recognised only the Maoricolpus roseus - Nucula hartvigiana community occurring in the Manukau Harbour. Clearly, communities with Zeacolpus pagoda dominant can now be recognised as other local examples of "Turritella " communities.

4. Nemocardium pulchellum community. McKnight (1969) recognised three local communities in which Nemocardium pulchellum is important. The one closest to the Cavalli Islands example appears to be the Nemocardium pulchellum - Pleuromeris zelandica community, which occurs mainly from 20 to 130 metres on muddy sand, mud, or sometimes sand. Because of the few samples from the Nemocardium pulchellum community at the Cavalli Islands, clear parallels are difficult to determine. Grace and Grace (1976) considered their Caryocorbula zelandica - Pleuromeris zelandica community at Great Mercury Island as possibly an inshore variation of one of McKnight's "Nemocardium" communities.

5. Ecklonia radiata - Carpophyllum spp. community. This community, or variations of it, is widespread on shallow rocky bottoms along the coastline of New Zealand, particularly in the north. Discussions of this community are given by Ayling (1975a, 1975b), Doak (1971), Grace (1972b), Morton and Miller (1973), Grace and Puch (1977), and others.

ACKNOWLEDGEMENTS

The authors wish to thank several colleagues on the trip for assistance with sorting of some of the samples. Dr Richard Willan kindly identified some molluscs. Special thanks to Dr W.J. Ballantine of the Marine Research Laboratory at Leigh for the loan of a portable SCUBA air compressor, and to Mrs D.A. Sales for the loan of the outboard motor.

REFERENCES

Ayling, A.M. 1975a: Habitat: coastal kelp forests. New Zealand Nature Heritage 21: 579-83. 203 Ayling, A.M. 1975b: Offshore kelp forests. New Zealand Nature Heritage 22:605-609. Ballantine, W.J., Grace, R.V. and Doak. W.T. 1973: "Mimiwhangata marine report". Limited circulation report for New Zealand Breweries Ltd. 98p. Doak, W.T. 1971: "Beneath New Zealand seas". Reed, Wellington. 113p. Grace, R.V. 1966: The bottom communities of the entrance to the Whangateau Harbour. Tane 12:63-70. Grace, R.V. 1972a: "The benthic ecology of the entrance to the Whangateau Harbour, Northland, New Zealand". PhD thesis, University of Auckland. 205p. Grace, R.V. 1972b: Sublittoral zonation of dominant organisms at Red Mercury Island, north-eastern New Zealand. Tane 18:57-66. Grace, R.V. and Grace, A.B. 1976: Benthic communities west of Great Mercury Island, north-eastern New Zealand. Tane 22:85-101. Grace.R.V. and Puch, G.F. 1977: Intertidal and sublittoral patterns of of the Moturoa Islands, north-eastern New Zealand. Tane 23:51-65. Grace, R.V. and Whitten, R.F.. 1974: Benthic communities west of Slipper Island, north• eastern New Zealand. Tane 20:4-20. Hayward, B.W. 1979: Planktic foraminifera in surface sediments around the Cavalli Islands, northern New Zealand. Tane 25:149-155. Hayward, B.W. 1980: New records of warm-water foraminifera from north-eastern New Zealand. Tane 26: 183-188. McKnight, D.G. 1969: Infaunal benthic communities of the New Zealand continental shelf. New Zealand Journal of Marine and Freshwater Research 3(3): 409-444. Morton, J.E. and Miller, M.C. 1973: "The New Zealand sea-shore". 2nd edition. Collins, London. 653p. Powell, A.W.B. 1937: communities of the sea-bottom in Auckland and Manukau Harbours. Transactions of the Royal Society of New Zealand 66: 354-401.

APPENDIX 1. Station data.

Station1 Depth(m) Sediment2 Sample vol.1 Residue vol.* No. of Community* species8 1 6 v.crs.sh.s 8 800 14 (T) 2 6 v.crs.sh.s 6 1050 23 T 3 6 v.crs.sh.s 7 700 24 T 4 7 v.crs.sh.s 6 1250 15 T 5 10 ms 7 200 11 Z 6 25 v.crs.sh.s 6 800 16 Z 7 36 v.crs.sh.s 6 100 9 N 8 41 vfs 5 50 6 N 9 41 vfs 9 50 10 N 10 34 fs 8 140 14 N 11 29 v.crs.sh.s 7 300 7 (Z.N) 12 22 v.crs.sh.3 6 1200 20 Z 13 17 f.sh.gr 6 1000 13 z 14 10 fs 6 400 14 T 15 2 fs 9 20 6 (M,Z) 16 1 fs 5 5 3 M 17 6 fs 8 800 20 Z 18 6 fs 9 600 17 Z 19 8 fs 8 900 29 T 20 3 fs 8 100 10 M 21 3 fs 9 50 7 M 22 0.8 fs 9 14 7 M 23 1 vfs 10 5 12 M 24 1.8 fs 6 150 9 M 204 25 2.5 fs 6 200 6 M 26 3 f.s 9 200 17 (M,Z) 27 3.5 fs 9 150 11 M 2H 1.5 vfs 7 150 4 M 29 4 fs 9 600 14 T 30 5.5 v.crs.sh.s 7 - ? T 31 7 crs.sh.s 5 1000 20 T 32 7 crs.sh.s 7 500 20 T 33 6.5 ms 6 1500 25 T 34 5.5 ms 8 - ? T 35 6 sh.m-fs 5 2000 25 T 36 •1 ms 9 50 8 T 37 6 ms 6 1400 23 T 38 7 ms 7 • ? T 39 8 sh.ms 7 900 25 T 40 10 v.crs.sh.s 9 - ? T 41 10 v.crs.sh.s 5 1200 11 T 42 9 f.sh.gr 5 1600 10 T 43 9.5 v.crs.sh.s 7 2300 27 T 44 2.5 v.crs.sh.s 7 1300 34 T 45 1 s.gr 9 1800 21 (T) 46 10 fs 8 300 17 Z 47 3 ms 8 400 13 Z 'Samples from stations 30, 34, 38 and 40 were quickly examined in the field only for gross faunal character. No data on residue volume or number of species is available. 'Key to sediment code: vfs = very fine sand; fs = fine sand; ms = medium sand; sh.m-fs = shelly medium to fine sand; sh.ms — shelly medium sand; crs.sh.s = coarse shelly sand; v.crs.sh.s = very coarse shelly sand; f.sh.gr = fine shell gravel; s.gr = sandy gravel. 'Sample volume estimated as tenths of the dredge filled. Full dredge = 4.5 litres. 'Estimate of residue volume, after sieving and sorting, in millilitres. Includes volume of "rhodoliths". 'Species of fauna only. All polychaetes are grouped and considered as one species, as are all nemertea, and all bryozoa. 'Key to community code : M = Myadora boltoni • Pectinaria australis community; T = Tawera spissa community; Z = Zeacolpus pagoda • Zegalerus tenuis community; N = Nemocardium pulchellum community; ( ) = marginal for community or communities specified. APPENDIX 2. Species counts. Note: For each species, the station at which that species occurs is given, followed in brackets by the number of individuals occurring in the sample. Where no figures in brackets are given, information is qualitative only. ALGAE Caulerpa hypnoides 13 Gigartina circumcincta 32(1) Ulva lactuca 2,18,29,31,32(1),33,35,39 Unidentified small red algae 2,3,13,19,27,29,31,32,33,35,37,39,40,41,43 Coralline "rhodoliths" 2(150mls),4(50mls),13(100mls),30(100mls),31(20mls) 32(3mls),33(200mls),35(900mls),38(10mls), 43(2200mls) Coralline turf 24,32,45 ANGIOSPERMS Zostera muelleri 20,21,25,27(rhizomes only) PORIFERA Red encrusting 32(3) 205 COELENTERATA Unidentified anemone 12(1),19(1),26(1),27(1),37(1),44(1),45(6) PLATYHELMINTHES Unidentified polycladida 9(1) NEMERTEA Black 19(1),37(1),43(1),45(1) Orange 4(1),5(1),10(1),47(1) Other 3(1),14(1),23(1),35(1) BRYOZOA Selenaria squamosa 7(14),10(1),11(5) Membraniporiform 1,2,3,12,13,19,31,32,33,35,37,41,43,46 SIPUNCULOIDEA 7(1),39(1),45(1) POLYCHAETA Armandia mac a lata 19(1) Euchone sp. 18(2),28(7),39(15) Eunicidae 41(6) Glycera sp 46(3) Hyalinoecia sp. 8(1) Hydroides norvegicus 32(5) Lumbriconereis sphaerocephala 46(2) Maldanidae 46(2) Orbinia papillosa 29(1) Owenia fusiformis 19(1),20(5),21(6),25(4),26(4),27(1),28(5),29(5),32(2), 33(1),36(1),37(20),39(8),41(1),43(1),44(2) Pectinaria australis 10(1),14(1),17(2),18(2),20(11),21(14),22(1),23(12), 24(4),25(10),26(1),27(2),28(1),29(11),46(2) Polynoda 39(1) Sabellidae 42(1) Serpulidae 2(13),3(4),4(1),13(1),14(1),31(7),32(12),33(46),35(11), 37(32),39(2),43(3) "Spirorbis" 14,17,35,40,42(3) Terebellidae 7(1),11(1),33(1),37(2),43(1) Unidentified 1(3),2(12),3(3),4(7),5(5),6(7),7(18),8(4),9(16),10(4),11(3) 12(4),13(4),14(19),15(7),16(2),17(44),18(30),19(12), 20(13),21(6),22(7),23(1),24(5),25(16),26(26),27(5),28(1) 29(19),31(3),32(2),33(26),35(21),36(13),37(16),39(11), 42(5),43(14),44(15),45(64),46(10),47(1) AMPHINEURA Acanthochitona zelandica 4(1),33(1),44(1) Craspedochiton rubiginosus 37(3),39(1),41(7),44(3) Ischnochiton maorianus 14(1),37(1),39(1),44(8) Notoplax cuneata 31(2),32(1),44(1),45(1) Onithochiton neglectus neglectus 1(1),2(1),6(1) Rhyssoplax stangeri 1(14),2(108),3(112),4(21),6(1),12(8),13(2),14(22),17(6), 19(43),31(47),32(36),33(79),35(39),37(17),39(45),40, 42(1),43(32),44(17),45(3),46(1) Terenochiton inquinatus 44(3) SCAPHOPODA Dentalium nanum 9(1) GASTROPODA Amalda australis 23(1) A. novaezelandiae 1(1),2(5),3(2),4(1),10(2),12(1),14(4),16(1),18(2),19(6), 22(1),23(5),24(1),25(1),27(1),32(4),35(2),36(2),37(2), 39(1),43(2),44(2),45(3),46(2) Antisolarium egenum 46(1) 206 Cantharidus purpureus 37(1),45(2) Cominella adspersa 3(1),19(3),29(1),31(1),44(1) C. quoyana quoyana 2(2),3(4),4(1),13(1),14(4>,17<4),19(6),22(1),24(1),25(3), 29(1),32(1),33<2),35(6),36(1),37(2),39<4),40,44(6),45(4), 46(13) Cylichna thetidis 26(1),32(1) Dendrodoris sp. 19(1) Duplicaria tristis 5(1),13(1),14(17),18(1),19(6),23(2),25(2),26(5),28(1), 29(17),35(1),43(1),46(10),47(3) Epitonium jukesianum 45(1) E. minora 24(1),43(1),44(1) Fossarina rimata 44(2) Lucerapax angustatus 8(1) Maoricolpus roseus 33(1),35(1) Marginella pygmaea 23(1),31(2),32(1),35(1),36(4),39(8),41(1),44(3),45(20) M. tryphenensis 1(2),2(3),3(2) Micrelenchus rufozonus 2(l)i3(15),4(6),6(l),19(20),31(9),33(l),35(l),37(19),40, 41(31,43(1) Microvoluta marginata 10(4) Muricopsis octagonus 41(1) Neoguaraleus lyallensis tenebrosus 36(1) N. sp. 19(1) Notoacmea kelmsi 17(1),19(73),29(1),31(7),32(8),33(32),35(29),37(40), 39(8),41(1),43(1),44(14),45(1),46(1),47(2) Peculator hedleyi 2(11,44(6) Proxiuber australe 2(1) Pupa kirki 10(2) Rissoina aupouria 2(4),3(5),4(1),7(2),19(1) R. chatamensis 44(11),45(13) Scrinium neozelanicum 44(1) Sigapatella novaezelandiae 35(2),37(2) Spectamen plicatulus 8(1),10(2) Struthiolaria vermis 19(1) Terebra circumcincta 6(1) Trochus tiaratus 19(1),31(2),33(1) Unidentified Turridae 14(1) Xymene ambiguus 3(2),19(3),33(1),37(5),43(1) X. traversi 33(1),43(1),44(1) Zeacolpus pagoda pagoda 5(7),6(12),11(2),12(5),13(8),14(1),15(2),17(29),18(9), 19(1),20(2),22(1),23(2),26(14),29(1),31(1),35(5),39(9), 43(1),.46(10),47(15) Zegalerus tenuis 1(5),2(18),3(8),4(9),5(5),6(4),7(2),10(1),11(2),12(32), 13(8),14(5),17(56),18(32),19(13),20(1),23(1),24(1), 26(6),27(4),28(1),29(11),31(8),32(6),33(27),35(17), 36(6),37(58),39(20),42(2),43(14),44(4),46(2),47(1) Corbula zelandica 2(2),3(1),12(2),30,39(1),41(2),43(3) Diplodonta globus 8(1),14(1) Dosina zelandica 17(1) Dosinia maoriana 1(1),3(2),4(2),17(1),32(5),37(2),39(1),43(1),44(2),47(1) D. subrosea 21(1),26(1) Felaniella zelandica 17(7),18(2),20(1),26(4),46(1),47(1) Gari hodgei 26(1),46(1) G. stangeri 2(1),5(2),7(1),12(1),13(1),19(4),20(1),41(1),47(1) Glycymeris laticostata 1(1) 207 G. modesta 1(8),2(7),3(5),4(6),5(1),12(1),.37(2),39(2),43(2),44(2) Hiatella arctica 12<1),31(1),32(1),33(6),35(1),43(1) Longimactra elongata 12(1) Mesopeplum convexum 12(1) Myadora antipodum 10(1) M. boltoni 6(1),16(1),17(3),20(5),22(2),23(1),26(3), 27(3),29(1) M. striata 17(3),18(1),20(1),23(1),24(1),26(3),27(2),28(1),46(1) M. subrostrata 4(2),6(1),7(1),11(3),12(2),44(1) Nemocardium pulchellum 7(D,9(1) Notocallista multistriata 8(1),10(1) Nucula nitidula 9(1),10(2),12(1),19(2),24(1),31(1),32(1),44(1),46(1), 47(1) Pecten novaezelandiae 12(8),13(1),17(2),43(1) Pleuromeris sp. 10(1),12(1) Saccella bellula 8(1),9(3) Scalpomactra scalpellum 1(1),5(2),15(2),17(6),18(7),20(1),21(3),26(2),27(1),47(2) Soletellina nitida 15(1),22(1),23(1) Talabrica bellula 2(2) Tawera spissa 2(118),3(779),4(21),5(3),6(3),12(3),13(7),14(139), 17(30),18(5),19(269),26(2),29(77),30,31(122),32(226), 33(60),34,35(8),36(73),37(21),38,39(114),40(2500), 41(1),42(6),43(12),44(57),46(3800),47(39) Tellina huttoni 9(1) Thracia australica novozelandica 35(1),39(1) Venericardia purpurata 2(1),31(1),39(3),42(1) Venerupis largillierti 33(1) CRUSTACEA Amphipoda 1(3),2(7),3(6),6(2),9(2),10(2),11(1),13(4),14(4),17(10), 18(1),19(5),21(2),23(1),24(1),25(1),27(1),29(2),31(7), 32(1),33(40),35(12),36(1),37(15),39(5).41(1).42(2), 43(30),44(10),45(15) Caprellidae 1(1),17(6),18(5),19(2),26(2),29(2),44(3),45(1) Isopoda 2(1),3(2),6(2),18(1),21(1),31(1),33(2),35(2),37(1),39(1), 42(2),43(2),44(2) Paranthura sp 17(2),18(2'),19(1),22(2),45(1) Tanaidacea 3(1),45(4) Natantia 33(2) Galatheidae 33(2) Unidentified hermits 1(3),2(7),3(6),4(3),5(1),6(10),7(3),11(4),12(1),13(5), 14(1),17(7),18(2),19(40,20(1),21(1),29(4),31(1),33(4), 35(15),37<5),39(10),42(11),43(13),44(9),45(4),46(8), 47(1) Petrolisthes novaezelandiae 35(1) Elamena producta 33(1),45(2) Halicarcinus varius 24(1),25(1) Liocarcinus corrugatus 2(1),32(1),33(1),35(1),37(2),39(1) Notomithrax minor 19(1),29(1),39(1),45(1) ECHINODERMATA Trochodota sp. 5(1),6(1),9(1),10(1),17(3),18(6),19(2),20(1),21(5),26(5), 27(2),29(2),31(1),32(2),35(1),43(1),44(1),45(4),46(1) Unidentified holothurian 15(1),39(1),43(1) Apatopygus recens 6(1),13(1) Echinocardium cordatum 15(1) Evechinus chloroticus 44(1) Astropecten polyacanthus 9(1),27(1) 208 Coscinasterias calamaria 35(2) Amphipholis squamata 3(2),32(2),33(2),39(1),43(1),44(4) Amphiura sp. 12(1) Unidentified Ophiuroids CHORDATA 3(1),4(1),42(1),43(6),44(1) Balanoglossus australiensis 3(3), 18(5), 26(4), 27(2)

Balanoglossus australiensis 3(3),18(5),26(4),27(2) Corella eumyota 37(1) Unidentified simple ascidian 2(2),6(1),17(1),18(1) Didemnum sp. 32(16),35(2),39(5) Sigillinaria arenosa 24 Unidentified compound ascidians 31(1),33(41) Epigonichthys hectori 26(1),42(1) Trachelochismus sp. 3(3),19(1),33(1),37(1),42(1),43(1),44(1)

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