OSTRACOD FAUNA OF AN INTERTIDAL POOL AT KAWERUA, NORTHLAND. by Bruce W. Hayward SUMMARY

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1 TANE 27, 1981 OSTRACOD FAUNA OF AN INTERTIDAL POOL AT KAWERUA, NORTHLAND by Bruce W. Hayward New Zealand Geological Survey, P.O. Box , Lower Hutt SUMMARY The carapaces of 49 species of Ostracoda were found in four samples (of Corallina turf, gravel, sand and muddy sand) from an intertidal pool at Kawerua on the storm-swept west coast of Northland. The taxa can be divided into: a. those found living in the samples and b. those found only as dead carapaces. a. The live fauna has a low diversity (9 species) with greatest abundances on the Corallina turf and lowest in the sand. The Corallina turf fauna is dominated by Loxoconcha punctata (65%), with subdominant (7-11%) Xestoleberis cf. olivacea, "Hemicythere" sp. and Ambostracon pumila, and rare Elofsonia sp., Cushmanidea sp., Semixestoleberis sp., Neonesidea cf. amygdaloides and Semicytherura costellata. The most abundant live Ostracoda in the bottom sediments are Elofsonia sp. and Xestoleberis cf. olivacea. Live Loxonconcha punctata and Ambostracon pumila live in gravel and "Hemicythere" sp. in muddy sand. b. Forty species were not found live in the pool and most of these are thought to have been washed in from offshore sandy sediments (possibly down to 40 m depth or more). This fauna is dominated by Kotoracythere sp. and Waiparacythereis joanae, with associated common Callistocythere neoplana, Pontocythere sp., Munseyella tumida, Loxocythere crassa, Pontocythere hedleyi, Semixestoleberis taiaroaensis, Kotoracythere formosa, Copytus novaezealandiae and Cytherella polita. All but two of these common taxa are among the most common Ostracoda recorded living in inner shelf sands off Otago, 600 km to the south. INTRODUCTION The marine ostracod fauna of the New Zealand area is incompletely known with many unrecorded and undescribed species present. The main taxonomic studies on which many of the identifications in this paper are based are those of Brady (1880,1898), Hornibrook (1952) and Swanson (1979a, 1979b, 1980). Knowledge of the distribution and ecology of our recent marine ostracods is equally lacking with the only substantial study being that of Swanson (1979a) on the Otago Shelf, 600 km to the south of the present area. Hornibrook (1952) examined a 159

2 number of samples from off Northland and some of the results of thest studies were incorporated into his brief discussion on the origin and distribution of our Recent fauna but no detail was given. Study area The present study was undertaken at the Auckland University Field Club's Scientific Station at Kawerua, on the exposed west coast of Northland, 14 km south of the mouth of Hokianga Harbour (Fig. 1). Directly in front of the station, the coastline is composed of a number of basalt reefs with their associated lagoons and rocky intertidal pools. One of these pools, situated 50 m north of the track from the Station to the beach (Fig. 1) was selected for sampling. Fig. 1. Location of the intertidal Zostera pool at Kawerua on the west coast of Northland, New Zealand. The pool is at approximately mid-tidal level and has no connection to the sea for about 6 hours during every low tide. The pool is enclosed by a solid reef across the seaward western side, by low piles of boulders covering flat rock shelves to the north and south, and by a quartz sand beach on the shoreward side. The pool is approximately 30 x 15 m in size and has a water depth of 5-25 cm when not submerged. The pool contains numerous rocks (10-30 cm diameter) scattered throughout and many of these are partly covered by the turf of the red coralline alga Corallina officinalis. Much of the pool's floor is covered by a

cm thick layer of shelly, quartz sand or in places fine gravel. Small clumps of the sea grass, Zostera capricorni, occur sporadically growing in the sand.

3 cm thick layer of shelly, quartz sand or in places fine gravel. Small clumps of the sea grass, Zostera capricorni, occur sporadically growing in the sand. The macrofauna and flora of this pool has been described and illustrated by Hayward (1979), together with the foraminiferal microfauna of the four samples used in this study. Methods One sample of Corallina turf (sample A) and three of sediment (samples B-D) taken from the upper 2 cm covering the bottom of the pool (Table 1) were collected in January The samples were preserved in 10% ethanol and on return to the laboratory were thoroughly washed over a 200 mesh sieve and dried. A measured volume (100 cc of Corallina turf and gravel-samples A, D; 50 cc of sandsamples B, C) of each sample was taken and the ostracod carapaces concentrated by floating off in carbon tetrachloride. All Ostracoda in these floats were then picked, mounted, identified and counted (Appendix 1) and articulated carapaces containing preserved soft parts were noted separately as having been alive when collected. Table 1. Samples from intertidal Zostera pool at Kawerua used in ostracod studies. Sample N.Z. Geological Substrate No. Survey No. A F Clumps of Corallina turf growing on rocks B F Muddy sand beneath Zostera clumps C F Clean, medium-coarse sand between rocks D F Sandy gravel between rocks LIVE OSTRACOD FAUNA (Fig. 2, 3) Only nine of the 49 species of Ostracoda recorded were found as live specimens (Appendix 1, Fig. 2). Fauna of Corallina turf (sample A) The greatest abundance of live Ostracoda was in the Corallina turf, where 45% of the total fauna was alive. The carapaces of dead Ostracoda in this sample were all trapped, together with some foraminifera and sand, amidst the dense basal portion of the turf. All nine living species were found on the Corallina turf. The most abundant species (65% of the live fauna) is the reticulatelyornamented, subovate ostracod, Loxoconcha punctata (Fig. 3a), with three subdominant species (7-11% of live fauna) present - Xestoleberis cf. olivacea, "Hemicythere" sp., Ambostracon pumila (Fig. 3b, c, d). Of the remaining five species (each represented by a single live specimen), four were only found live on the Corallina turf - Cushmanidea sp., Semixestoleberis sp., Neonesidea cf. amygdaloides and Semicytherura 161

Fig. 2. Diagram illustrating the intertidal pool habitat at Kawerua, with the live ostracod fauna of Corallina turf illustrated above and of the pool bottom sediments illustrated below.

4 Fig. 2. Diagram illustrating the intertidal pool habitat at Kawerua, with the live ostracod fauna of Corallina turf illustrated above and of the pool bottom sediments illustrated below. costellata (Fig. 3e-h), whereas the fifth - Elofsonia sp. (Fig. 3i) is more common in the sediment samples. Fauna of sediments (samples B, C, D) Five species were found living in the three sediment samples with greatest abundance (7% of the total fauna) and diversity in the gravel sample (D) and lowest (only 2% of total fauna) in the sand samples (B, C). The two most common live ostracod species in these sediments are the small, weakly-ornamented Elofsonia sp. (Fig. 3i) and the inflated, smooth Xestoleberis cf. olivacea (Fig. 3b). Two of the most common species living on Corallina turf - L. punctata and A. pumila (Fig. 3a, d) also occur live in the gravel sample (D) and a third "Hemicythere" sp. (Fig. 3c) was found living in the muddy sand around the base of Zostera clumps (B). Standing crop is a measure of density of live Ostracoda. The intertidal pool muddy sand, medium-coarse sand and sandy gravel samples have standing crops of 4 400, and live Ostracoda per square metre of bottom respectively. DEAD OSTRACOD FAUNA (Fig. 4, 5) The total fauna (dead plus live) is listed in Appendix 1 and the dominants graphically displayed in Figure 4. Carapaces (both dead 162

Fig. 3. Live ostracod fauna of the intertidal pool. a. Loxoconcha punctata (F201680, OP1096), x 35. b. Xestoleberis cf. olivacea (F201680, OP1097), x 60. c. "Hemicythere" sp. (F201681, OP1098), x 70.

5 Fig. 3. Live ostracod fauna of the intertidal pool. a. Loxoconcha punctata (F201680, OP1096), x 35. b. Xestoleberis cf. olivacea (F201680, OP1097), x 60. c. "Hemicythere" sp. (F201681, OP1098), x 70. d. Ambostracon pumila (F201680, OP1099), x 35. e. Cushmanidea sp. (F201681, OP1100), x 70. Semixestoleberis sp. (F201680, OP1101), x 60. g. Neonesidea cf. amygdaloides (F201680, OP1093), x 35. h. Semicytherura costellata (F201680, OP1094), x 60. i. Elofsonia sp. (F201683, OP1095), x 100. plus live) of the nine species found living comprise 58% of the total present in the Corallina turf sample and 18%, 17% and 33% of the total in sediment samples B, C and D respectively. When this "live" fauna is discounted, there is a large background assemblage of 40 ostracod species not found living, which is remarkably uniform in taxonomic composition and abundances between all samples. The two dominant species (8-35% of total fauna) are the weaklyornamented, elongate forms Kotoracythere sp. and Waiparacythereis joanae (Fig. 5a, b). A suite of subdominant species (mostly 3-7% of total fauna) consists of Callistocythere neoplana, Pontocythere sp., Munseyella tumida, Loxocythere crassa, Pontocythere hedleyi, Semixestoleberis taiaroaensis, Kotoraythere formosa, Copytus novaezealandiae and Cytherella polita (Fig. 5c-k). In addition there are a further 29 species, each of which comprises less than 2% of the total fauna, and in many cases is represented only by a single carapace. DISCUSSION The total ostracod fauna of this intertidal pool can be divided into: 163

6 a. those species that live in the pool b. those that occur only as dead carapaces and are most likely exotic. It is most probable that the majority of the "dead" ostracod fauna Loxoconcha punctata Waiparacythereis joanae Kotoracythere sp. Xestoleberis cf. olivacea Cytherella polita Hemicythere sp. Ambostracon pumila Pontocythere hedleyi Loxocythere crassa Kotoracythere formosa Copytus novaezealandiae Kotoracythere sp. Waiparacythere is joanae Callistocythere neoplana Pontocythere s p. Elofsonia Sp. MunseyeIla tumida Loxoconcha punctata Semixestoleberis taiaroaensis Hemicythere sp. Cushmanidea. sp. Pontocythere hedleyi Kotoracythere sp. Waiparacythereis joanae Elofsonia sp. Loxocythere crassa Pontocythere Sp. Loxoconcha punctata Cushmanidea sp.. Pontocythere hedleyi Munseyella tumida CaIlistocythere neoplana Semixestoleberis taiaroaensis Kotoracythere sp. Waiparacythereis joanae Xestoleberis cf*. olivacea Loxoconcha punctata Munseyella tumida Elofsonia sp. Callistocythere neoplana Cushmanidea sp. Pontocythere sp. Pontocythere hedleyi Hemicythere sp. Copytus novaezealandiae percentage of total ostracoda living Fig. 4. Histograms of common ostracod species (>3%) in total faunas (dead plus live) in samples from the intertidal pool at Kawerua. 164

Fig. 5. Common species of the exotic ostracod fauna, only found dead in the intertidal pool. a. Kotoracythere sp. (F201680, OP1102), x 70. h. Waiparacythereis joanae (F201680, OP1103), x 30. c.

7 Fig. 5. Common species of the exotic ostracod fauna, only found dead in the intertidal pool. a. Kotoracythere sp. (F201680, OP1102), x 70. h. Waiparacythereis joanae (F201680, OP1103), x 30. c. Callistocythere neoplana (F201681, OP1104), x 60. d. Pontocythere sp. (F201682, OP1105), x 70. e. Munseyella tumida (F201681, OP1106), x 70. f. Loxocythere crassa (F201680, OP 1107), x 60. g. Pontocythere hedleyi (F201680, OP1108), x 70. h. Semixestoleberis taiaroaensis (F201680, OP1109), 70. i. Kotoracythere formosa (F201680, OP1110), x 70. j. Copytus novaezealandiae (F201688, OP1111), x 40. k. Cytherella polita (F201680, OP1112),x35. has been washed into the pool from surrounding areas where they live, as the Kawerua coast is notorious for its rough weather, large swells and onshore winds. These ostracod carapaces, together with other faunal debris and sediment, could have been carried in from several kilometres or more away and from depths reaching 40 m plus. It is to be expected however, that the majority of the well-preserved carapaces have not been transported far and are derived from faunas living within 500 m offshore. Thus the "dead" ostracod fauna of the intertidal pool is probably a good reflection of what is living in the sands offshore on the inner part of the continental shelf. A similar, though less-marked, situation was found in the foraminiferal faunas (Hayward 1979), with an in-situ live benthic fauna 165

8 and many exotic benthics thought to have been washed in from offshore together with an unusually large percentage of planktic foraminifera. Comparison with the ostracoda of the Otago Shelf Swanson (1979a) recognised five ostracod assemblages on the Otago Shelf; two of which occur in sand and muddy sand on the inner shelf (0 - c. 40 m depth). There is considerable similarity between the dominant taxa of these two assemblages and those of the exotic (or "dead") Kawerua fauna. As dominants they have in common Waiparacythereis joanae, Callistocythere neoplana, Munseyella tumida, Loxocythere crassa, Pontocythere hedleyi, Semixestoleberis taiaroaensis, Kotoracythere formosa and Copytus novaezealandiae. In addition Loxoconcha punctata and Ambostracon pumila (both abundant in the "live" Kawerua fauna) are among the dominants on the inner Otago Shelf. Only two of the abundant taxa in the inner Otago Shelf assemblages (Hemicythere munida, Munseyella brevis) are absent from the Kawerua fauna, and only two of the dominants of the exotic Kawerua fauna (Kotoracythere sp., Pontocythere sp.) are not recorded from Otago. Whereas the dominants of the Kawerua and inner Otago Shelf ostracod faunas have a good deal in common, the total taxonomic composition is greatly different. Of the 49 taxa found in the Kawerua pool, only 17 (35%) were in the faunas of the Otago Shelf, km to the south (Swanson 1979a). This difference partly reflects the lack of similar shallow sampling stations in the Otago study, but also reflects considerably the biogeography of New Zealand ostracods, as many of the Kawerua species not found on the Otago Shelf are present in shelf samples from off Northland studied by Hornibrook (1952). ACKNOWLEDGEMENTS I should like to thank Norcott Hornibrook for his encouragement and assistance with the taxonomy of these ostracoda and together with George Scott and Kerry Swanson for a critical appraisal of the manuscript and suggested improvements. The SEM photographs were taken by Hugh Morgans and printed by Lloyd Homer. The manuscript was typed by Patricia Hodgson. REFERENCES Brady, G.S. 1880: "Report on the Ostracoda dredged by H.M.S. Challenger during the years " Report on the Scientific Results of the voyage of H.M.S. Challenger , Zoology 1(3). 184 p. Brady, G.S. 1898: On new or imperfectly known species of Ostracoda, chiefly from New Zealand. Transactions of the Zoological Society, London 14(8): Hayward, B.W. 1979: An intertidal Zostera pool community at Kawerua, Northland and its foraminiferal microfauna. Tane 25: Hornibrook, N. de B. 1952: Tertiary and Recent marine Ostracoda of New Zealand. New Zealand Geological Survey, Paleontological Bulletin 18:82 p. 166

9 Swanson, K.M 1979a: The marine fauna of New Zealand: Ostracods of the Otago Shelf. New Zealand Oceanographic Intitute Memoir p. Swanson, K.M. 1979b: Recent Ostracoda from Port Pegasus, Stewart Island, New Zealand. New Zealand Journal of Marine and Freshwater Research 13(1): Swanson, K.M. 1980: Five new species of Ostracoda from Port Pegasus, Stewart Island. New Zealand Journal of Marine and Freshwater Research 14(2): APPENDIX 1 - Ostracoda from the intertidal Zostera pool at Kawerua. Key: Arabic numerals = total count of valves present (i.e. one articulated specimen gives count of 2); italic numerals = numbers of live specimens (i.e. each articulated specimen gives count of 1). Counts are for specimens found in 100 cc of Corallina turf and gravel (samples A J)) or 50 cc of sand (samples B,C). A B C D Ambostracon pumila (Brady) Bradleya sp. 3 1 Bythocythere sp. 2 Callistocythere murrayana (Brady) 7 Callistocythere neoplana Swanson Callistocythere obtusa Swanson 6 Callistocythere cf. obtusa Swanson 2 Callistocythere sp. 4 Copytus novaezealandiae (Brady) Cushmanidea sp. 2 i Cytheralison fava Hornibrook 2 Cytherella lata Brady 1 i Cytherella polita Brady Cytheropteron cf. fornix Hornibrook 2 Cytheropteron cf. wellingtoniense Brady 2 Cytheropteron sp. 4 Elofsonia sp Eucythere sp. 4 Hemicythere cf. kerguelensis (Brady) 2 "Hemicythere" sp Hemicytherura quadrazea Hornibrook 2 Kangarina sp. 2 2 Kotoracythere formosa Swanson Kotoracythere sp Loxoconcha punctata Thomson Loxocythere crassa Hornibrook Loxocythere kingi Hornibrook 1 4 Munseyella tumida Swanson Munseyella 2 spp. 3 2 Neonesidea cf. amygdaloides (Brady) 2 1 Neonesidea cf. fusca (Brady) 2 1 Neonesidea sp. 1 Paradoxostoma antarcticum Muller 2 Paradoxostoma hypselum Muller 1 Polycope sp. 1 Pontocythere hedleyi (Chapman) Pontocythere sp Pterygocythereis cf. cristatella Brady 6 Quadracythere biruga Hornibrook 1 Quadracythere mediaruga Hornibrook 1 Quadracythere truncula (Brady)

10 Sclerochilus sp. 1 Semicytherura cf. clausi (Brady) 2 Semicytherura costellata (Brady) 2 1 Semixestoleberis taiaroaensis Swanson Semixestoleberis sp Waiparacythereis joanae Swanson Xestoleberis cf. olivacea Brady

PLANKTIC FORAMINIFERA IN SURFACE SEDIMENTS AROUND THE CAVALLI ISLANDS, NORTHERN NEW ZEALAND. by Bruce W. Hayward SUMMARY

TANE 25, 1979 PLANKTIC FORAMINIFERA IN SURFACE SEDIMENTS AROUND THE CAVALLI ISLANDS, NORTHERN NEW ZEALAND by Bruce W. Hayward New Zealand Geological Survey, P.O. Bo 30368, Lower Hutt SUMMARY Planktics