NEAR-SHORE FORAMINIFERA FROM T AIWA WE BAY, NORTHLAND, NEW ZEALAND. Catherine M. Reid and Bruce W. Hayward SUMMARY

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1 Tane 36: (1997) NEAR-SHORE FORAMINIFERA FROM T AIWA WE BAY, NORTHLAND, NEW ZEALAND Catherine M. Reid and Bruce W. Hayward Auckland Museum, Private Bag 92018, Auckland SUMMARY One hundred and sity-two species of benthic foraminifera (Protozoa) are recorded from 20 shallow water (1-10.5m) dredge samples in Taiwawe Bay, Northland. Common species (in order of decreasing mean abundance) are Elphidium charlottense, Virgulopsis turris, Rosalina irregularis, Tetularia ensis, Cibicides marlboroughensis, Quinqueloculina suborbicularis, Evolvocassidulina orientalis, Gavelinopsis lobatulus, Quinqueloculina seminula, Haynesina depressula, Cassidulina carinata and Bolivina subecavata. Discrete faunal associations are not present in this small, somewhat eposed, sandy bay. Postmortem winnowing appears to have redistributed many foraminiferal tests and carried others in from offshore. Five species of unilocular foraminifera are recorded from New Zealand for the first time. Keywords: Foraminifera; Northland; Taiwawe Bay; foraminiferal associations; species diversity; post-mortem transport. INTRODUCTION Taiwawe Bay ( 'S, 'E) is a small bay within Helena Bay on the east Northland coast, south of the Bay of Islands, New Zealand (Fig. 1). The bay is m wide and 500m long with two pebbly sand beaches at its head. Oceanic swells and storms from the north pound straight into the Bay, but these are not common. Motutaniwha Island, on the east side of the mouth of Taiwawe Bay (Fig. 2), provides considerable protection from the more dominant northeast swells, although waves sweep through the channel between the island and the mainland at high tide. The hillsides and small catchment surrounding the bay are grazed farmland. A small stream flows into the bay in the middle of the southeast beach but has no effect on the normal marine salinity of the bay. A small brackish estuary in nearby Helena Bay has previously been the focus of an intertidal foraminiferal study by Hayward (1993). In contrast the Taiwawe Bay samples are all of shallow water fully marine conditions. Foraminifera from 113

2 Fig. 1. Location Map of Taiwawe Bay and dredge samples. other parts of the Northland coast have also been studied in the past. These include Tutukaka Harbour (Brook et al. 1981), Chickens Islands (Hayward et al. 1984), eastern Bay of Islands (Hayward 1981) and the Cavalli Islands (Hayward 114

3 Fig. 2. View looking north-east over Taiwawe Bay and Motutaniwha Island. 1982a). Samples were collected during the Offshore Islands Research Group's trip to the area in February Faunas and figured specimens are held in the Institute of Geological and Nuclear Sciences, Lower Hutt. METHODS Field Taiwawe Bay samples were collected with a small hand-hauled dredge (4.5 litre capacity), described by Grace and Whitten (1974). The dredge samples an area of 0.075m 2 of sea floor to a depth of c. 6cm under ideal conditions. Upon retrieval, 200ml of sediment was removed for grain size and foraminiferal analysis and the remainder passed through a 2mm sieve for macrofaunal analysis. Stations were located using a setant to measure horizontal angles between fied points on the shore and depths were measured using a lead weighted line. Sediment analysis Sediment grain size was determined by sieving the 200ml splits in the laboratory. For ease of mapping the sediment distribution patterns (Fig. 3), the following grain sizes were combined: mud and very fine sand (all < 0.125mm); 115

4 VFSand FMSand ' CSed. Fig. 3. Distribution of sediment in Taiwawe Bay as determined from grain size analyses of dredge samples. VFSand = >50% very fine sand and mud; FMSand = >50% fine to medium sand; CSed. = sand with >5% coarse sand and gravel; (Grain size limits from Folk 1974). fine and medium sand ( mm); coarse sand and gravel (> 0.5mm). Grain size terminology follows Folk (1974). Foraminiferal faunal analysis Microfaunal elements were separated from the sediment by washing out the mud fraction (through a 63^m sieve), followed by floatation of foraminiferal tests 116

5 from the remaining sand fraction using carbon tetrachloride. From a split of the floated specimens 100 benthic foraminiferal tests were picked and mounted on slides as a quantitative estimate of the fauna. During the benthic pick all planktic specimens found were counted to indicate the planktic percentage of the fauna. One sample (19) was also picked qualitatively after the quantitative pick to give a clearer indication of the total taonomic composition. Previous studies by Hayward and co-workers indicate that a pick of 100 benthic specimens is quite sufficient to reveal the more common species and their relative abundances. A qualitative pick is more likely to reveal rarer species that are not significant in assessment of faunal associations. SEDIMENT The dominant sediment type in Taiwawe Bay is fine to medium sand. Mud is rare to absent, and coarse sand and gravel is restricted to a few samples in the outer areas of the bay. A band of very fine sand occurs across the inner part of Taiwawe Bay (Fig. 3). This inner area is more protected from oceanic waves and currents than outer areas and therefore fine sediment brought in by ocean currents and waves, or winnowed from the outer parts of Taiwawe Bay may be deposited here. Wave action near the beach area removes very fine sediment, leaving the fine to medium sand that is present in these inner beach areas. SPECIES DIVERSITY One hundred and twenty-four species were identified from the picks of 100 benthic specimens and a further 40 species were identified in the qualitative pick of sample 19, to give a total of 164 species identified in Taiwawe Bay (Appendi I). This level of diversity is remarkably high for such a small study area with limited environmental variation. It eceeds the diversity of 144 species recorded from 56 stations in a much wider range of habitats off Stewart Island (Hayward et al. 1994), but is still somewhat less than the 195 and 221 species recorded in a wide habitat range off Great Barrier and the Cavalli Islands, respectively (Hayward and Grenfell 1994, Hayward 1982a). Diversity (Fisher a Inde, Murray 1991) in each Taiwawe Bay station is also relatively high and increases slightly in a seawards direction (Fig. 4). a values (in the range 14 to 27) are comparable to the highest levels reached in foraminiferal faunas at 20-80m depth in Wanganui Bight (Hayward et al. in prep.) and similar to the high values found in many faunas at 2-40m depth around the Cavalli Islands (Hayward 1982a). 117

6 Faunal distribution Several computer analysis techniques (e.g. Cluster Analysis, Detrended Correspondence Analysis) were applied to the quantitative counts in an attempt to recognise and hopefully map any consistent faunal distribution patterns within the study area. Despite the use of a number of different similarity coefficients 118

7 with both R and Q mode cluster analysis, no robust nor mappable classifications with clear or consistent trends or associations were produced. It therefore seems most logical to treat the faunas of all 20 stations as one slightly variable association, akin to just one of the many associations usually recognised in larger study areas (e.g. Hayward 1982a, Hayward et al. 1994). Visual evaluation of species distribution maps shows a few species are more common in shallower or sheltered areas or more prevalent in particular sediment types (Fig 5). Haynesina depressula occurs more frequently in shallow sheltered areas, and Gaudryina convea is most abundant in coarser sediment. Virgulopsis turris decreases in abundance seaward. This does not appear to be related to increasing depth but more perhaps to increasing grain size. Tetularia ensis and Elphidium charlottense have mappable abundance peaks but it is unclear what physical or biological factors are producing these. The majority of the common species show random patchy distributions that appear to be independent of depth, sediment type, or association with other species. Dominant species The twelve most abundant species in the Taiwawe Bay faunas are: pers. pers. Elphidium charlottense 7.2% 1 Evolvocassidulina orientalis 4.3% 0.85 Virgulopsis turris 6.8% 0.95 Gavelinopsis lobatulus 3.7% 1 Rosalina irregularis 6.1% 0.95 Quinqueloculina seminula 3.3% 0.95 Tetularia ensis 4.7% 1 Haynesina depressula 3.0% 0.95 Cibicides marlboroughensis 4.6% 1 Cassidulina carinata 2.7% 0.9 Quinqueloculina suborbicularis 4.5 7, 0.95 Bolivina subecavata abun. = the mean abundance of specimens across all 20 stations. pers. = persistence - proportion of stations in which each species occurs. This Elphidium charlottense- Virgulopsis turris-rosalina irregularis association is similar to that found elsewhere on the Northland east coast in shallow fully marine, moderately sheltered environments. Most of the abundant species in the Tutukaka Harbour faunas are common to abundant in Taiwawe Bay (Brook et al. 1981). This Taiwawe Bay association is intermediate in character between associations A and B that occur in sandy bays and more current swept shallow sand on the sheltered side of the Cavalli Islands (Hayward 1982a). Faunas in the deeper (> 30m) and more eposed areas of the Cavalli Islands (associations C and D) show less similarity (Hayward 1982a). It is also quite similar in composition to the Trochulina dimidiatus-rosalina irregularis association, which occurs in 3-33m in fine sand in Rangiwhakea Bay on the north east coast of Great Barrier Island (Hayward and Grenfell 1994). 119

8 Fig. 5. Contoured distribution and abundance patterns of selected common Taiwawe Bay species. Values are percentages of each species in the quantitative counts of benthic foraminiferal faunas in each sample. 120

9 This bay has a similar aspect and level of eposure to Taiwawe. The Taiwawe Bay fauna is also similar to that occurring in medium to coarse sand at 4-10m off the southwest coast of Little Barrier Island (Hayward 1982b). Less than 1km along the coast from Taiwawe Bay, the foraminiferal fauna in the mouth of Owai Stream estuary is, not surprisingly, very similar to ours and probably contains many tests that have been carried in by the strong tidal currents (Hayward 1993). Biogeography Species diversity of shallow water benthic foraminifera decreases from the tropics to the poles (Boltovskoy and Wright 1976). Around New Zealand this is epressed as decreasing diversity from north to south. Taiwawe Bay, at the north of the North Island, has at least 12 species that appear to be restricted to the north or northeast coast of the North Island. These include Tetularia fistulosa, T. torquata, Nummoloculina sp., Quinqueloculina cultrata, Pyrgo comata, Siphonaperta sp., Buliminoides williamsonianus, Discorbinita lepida, Neoconorbina pacifica, Pileolina calcarata, P. harmeri and Rugidia simple. POST-MORTEM TRANSPORT OF BENTHIC FORAMINIFERAL TESTS Taiwawe Bay's location in shallow water on a relatively eposed coast makes the seafloor sediment and associated live and dead foraminiferal tests prone to disturbance by waves, tidal currents and storm events. This has potential to cause considerable post-mortem miing and homogenisation of the foraminiferal fauna. As well as transport and miing of tests within the bay, it could be epected that the shells of some species may be carried in from outside. Small numbers of several usually deeper water (>40m), fine sediment species are present in Taiwawe Bay faunas and have probably been transported in by currents and storms. These include Anomalina spherica, Astacolus spp., Epistominella vitrea, Fissurina spp., Globocassidulina minuta, Discorbinella bertheloti, Lagena spp., Lenticulina spp., Oolina spp., Parafissurina spp., Pyrgo spp., Siphouvigerina vadescens, and Uvigerina sp. This undoubtedly contributes to the high diversity values discussed above. To investigate wave and current transport of foraminiferal tests, we looked at the distribution within Taiwawe Bay of the various foraminiferal test shapes (e.g. miliolid, bolivinid, globular, plano-conve, biconve). No clear mappable patterns of distribution are apparent. We also looked at the distribution of the various sizes of foraminiferal test. The number of tests in each size class (using same size divisions as the sediment) were counted in each sample. When the test size classes were mapped a similar distribution pattern to that of sediment grain 121

10 size is seen (Fig. 6). Some species occur preferentially in particular size classes. Adult specimens of Bolivina pseudoplicata, B. subecavata and Virgulopsis turris are common in the very fine shell size class along with juvenile specimens of all species. Virgulopsis turris is more common inshore and decreases seaward as grain size increases, however B. pseudoplicata and B. subecavata do not show any clear distribution pattern when they are mapped individually or together. Larger specimens of Trochulina dimidiatus, Notorotalia zelandica and Quinqueloculina seminula, are the most common tests in the coarse shell class. These species do not show a greater concentration in coarser grained areas when mapped individually as they are represented by a range of shell sizes from small juveniles to large adults. As the fauna as a whole is generally randomly distributed by species but shows a relationship between sediment grain size and foraminiferal shell size it would appear that post-mortem winnowing and sorting according to shell size play a major role in the distribution of dead shells within the sediment. The mappable distribution patterns of at least some species that appear to be independent of grain size (Fig. 5) suggest that post-mortem test transport mechanisms are not fully destroying the original live distribution patterns. Faunal analysis of live foraminifera only, might perhaps reveal discrete faunal associations within Taiwawe Bay. However a study of this type is likely to be strongly affected by seasonal abundance variations and by temporary local abundance peaks (clumping). Meaningful documentation of the live fauna would require monthly (or bimonthly) sampling of a number of stations over at least one and preferably several years - a task well beyond this initial survey. PLANKTIC FORAMINIFERAL FAUNA Total planktic percentage of the foraminiferal fauna ranges between 1 and 7 % - fairly typical values for a moderately eposed, shallow water location on the east coast of Northland (e.g. Hayward and Grenfell 1994). Two smaller species dominate the planktic fauna, Globigerina falconensis and G. quinqueloba. These are well known as the dominant planktics of near-shore neritic waters around New Zealand (Hayward 1983). The eight rarer species have probably been transported shorewards while still floating, from their preferred oceanic habitats. FIRST NEW ZEALAND RECORDS The following species are recorded from New Zealand for the first time: 122

11 Taiwawe Bay VFShell FMShell CShell Fig. 6. Distribution of foraminifera in Taiwawe Bay according to the characteristic shell size of the fauna in each dredge sample. The median thickness of each shell was measured, or the diameter in the coiling plane for planispiral/trochospiral forms. VFShell = >50% shells finer than 0.125mm; FMShell = >50% shells between mm; CShell = >5% shells larger than 0.5mm * Fissurina crassiannulata Collins; ALBANI & YASSINI 1989, figs.5n-0. This paper Fig. 7c-d. 123

12 Fig. 7. Selected unilocular foraminifera from Taiwawe Bay, both new records and those previously recorded in New Zealand, a-b, Fissurina cf. curvitubulosa (FP4497); c-d, Fissurina crassiannulata (FP4498); e-g, Lagenosolenia prolata (e,f, FP4499; g, FP4500); h-i, Parafissurina discalis (FP4501); j, Fissurina cf. southbayensis (FP4502); k-1, Fissurina semialata (k, FP4503; 1, FP4504); m-n, Fissurina evolutiquetra (FP4505); o-p, Palliolatella lacunata paucialveolata (o, FP4506; p, FP4507); q-r, Lagena sulcata spicata (q, FP4508; r, FP4509); s, Lagena dovayensis (FP4510); t-u, Oolina heagona (t, FP4511; u, FP4512); v, Oolina melo (FP4513); w, Oolina lineata (FP4514). Scale bar = 0.1mm. 124

13 * Fissurina evolutiquetra McCULLOCH 1977, pi.58, figs.21,24. This paper Fig. 7m-n. * Lagena peculiariformis Albani & Yassini; YASSINI & JONES 1995, figs , 339. * Lagenosolenia prolata McCULLOCH 1977, pi.60, fig.9,16. This paper Fig. 7e-g. * Parafissurina discalis McCULLOCH 1977, pi.70, fig.5. This paper Fig. 7h-i. ACKNOWLEDGEMENTS We are indebted to Roger Grace who dredged the samples in Taiwawe Bay, accompanied by BWH; Jan de Visser, who made preliminary identifications and counts of common taa; the University of Auckland for use of their scanning electron microscope; and Hugh Grenfell for suggesting improvements to the draft manuscript. This research was started by BWH while at the New Zealand Geological Survey, Lower Hutt, and completed at the Auckland Museum. REFERENCES Albani, A.D. & Yassini, I. 1989: Taonomy and distribution of shallow-water Lagenid Foraminiferida from the south-eastern coast of Australia. Australian Journal of Marine and Freshwater Research 40: Boltovskoy, E. & Wright, R. 1976: "Recent foraminifera". Junk Publishers, The Hague, 515pp. Brook, F.J., Grace, R.V. & Hayward, B.W. 1981: Soft-bottom benthic faunal associations of Tutukaka Harbour, Northland, New Zealand. Tane 27: Campbell, H.J. 1988: The epression of doubt in the nomenclature of fossils (open nomenclature). Geological Society of New Zealand Newsletter 81: Folk, R.L. 1974: "Petrology of Sedimentary Rocks". The University of Teas, Hemphill Publishing Co. Austin, Teas. 182pp. Grace, R.V. & Whitten, R.F. 1974: Benthic communities west of Slipper Island, north-eastern New Zealand. Tane 20: Hayward, B.W. 1981: Foraminifera in nearshore sediments of the eastern Bay of Islands, northern New Zealand. Tane 27: Hayward, B.W. 1982a: Associations of benthic foraminifera (Protozoa : Sarcodina) of inner shelf sediments around the Cavalli Islands, north-east New Zealand. New Zealand Journal of Marine and Freshwater Research 16: Hayward, B.W. 1982b: Foraminifera and Ostracoda in nearshore sediments, Little Barrier Island, northern New Zealand. Tane 28: Hayward, B.W. 1983: Planktic foraminifera (Protozoa) in New Zealand waters: a taonomic review. New Zealand Journal of Zoology 10: Hayward, B.W. 1993: Estuarine foraminifera, Helena Bay, Northland, New Zealand. Tane 54: Hayward, B.W., Grace, R.V. & Bull, V.H. 1984: Soft bottom macrofauna, foraminifera and sediments off the Chickens Islands, northern New Zealand. Tane 30: Hayward, B.W. & Grenfell, H.R. 1994: Foraminiferal associations around northern Great Barrier 125

14 Island, New Zealand. Records of Auckland Institute and Museum 31: '. Hayward, B.W., Hollis, C.R. & Grenfell, H.R. 1994: Foraminiferal associations in Port Pegasus, Stewart Island, New Zealand. New Zealand Journal of Marine and Freshwater Research 28: Hayward, B.W., Grenfell, H.R. & Reid, CM. in prep: Foraminiferal associations in Queen Charlotte Sound and Wanganui Bight, New Zealand. McCulloch, I. 1977: "Qualitative observations on recent foraminiferal tests with emphasis on the eastern Pacific". 3 vols. University of Southern California, Los Angeles. Murray, J.W. 1991: "Ecology and palaeoecology of benthic foraminifera". Longman Scientific and Technical, Esse. 397pp. Yassini, I. & Jones, B.G. 1995: Recent Ostracoda and Foraminifera from estuarine, inner, middle and outer shelf environments of the southeastern coast of Australia. University of Wollongong Press. 484 pp. APPENDI I: Percentage counts of foraminiferal species in the quantitative picks of Taiwawe Bay samples, denotes species occurring in qualitative pick only.? denotes an uncertain identification of either species or genus (following Campbell 1988) TETULARIDS Cribrostomoides jeffreysi 1 Gaudryina convea Siphotetularia blacki 1 1 Siphotetularia mestayerae 1 Siphotetularia! sp. 3 Tetularia ensis Tetularia fistulosa 1 Tetularia proispira Tetularia torquata 1 Tetularia sp. 2 1 Trochammina ochracea 1 Trochammina sorosa MILIOLIDS Cyclogyra involvens 1 Miliolinella subrotundata Miliolinella vigila Miliolinella sp. 2 Nummoloculina l sp Pyrgo anomala Pyrgo comata 2 Pyrgo depressa Pyrgo ezo Pyrgo aff. ezo 1 Pyrgo sp. 1 Quinqueloculina agglutans Quinqueloculina ariminensis

15 Quinquelocutina auberiana Quinqueloculina bicostoides I 1 1 Quinqueloculina colleenae Quinquelocutina cooki 1 1 Quinquelocutina cultrata) 2 Quinqueloculina delicatula I Quinquelocutina lata Quinqueloculina neosigmoilinoides 1 Quinqueloculina patagonica Quinqueloculina seminula " 7 Quinqueloculina suborbicularis (i Quinqueloculina tasmanica 1. Quinqueloculina tenagos 1 Quinqueloculina triangularis! Quinqueloculina sp.! Sigmoilopsis wanganuiensis Siphonaperta sp. Spiroloculina disparilis Spiroloculina sp. Triloculina tricarinata Triloculina cf. trigonula 1 ROTALIDS Ammonia beccarii Anomalina spherica Anomalinoides sp. Astacolus australis Astacolus crepidula Astrononion novozealandicum Bolivina cf. ana 1 Bolivina compacta Bolivina pseudoplicata Bolivina spathulata Bolivina subecavata Bolivina sp Buccella frigida 1 2! Bulimina gibba 1 0 Bulimina marginata Buliminella madagascarensis Buliminoides williamsonianus Cassidulina carinata Cassidulina sp. I 1 Cibicides cf. deliquatus 1 Cibicides marlboroughensis Cibicides ungerianus Cibicides cf. ungerianus I

16 Discorbinella bertheloti l l Discorbinella complanata 1 Discorbinella subcomplanata Discorbinella vitrevoluta Discorbinella sp. Discorbinita lepida 1 0 Dyocibicides sp Elphidium advenum Elphidium charlottense Elphidium ecavatum f. clavatum Elphidium ecavatum n.f Elphidium ecavatum f. williamsoni 1 Elphidium novozealandicum Entomorphinoides opposita Epistominella vitrea 1 Evolvocassidulina orientalis Fissurina baccata Fissurina claricurta Fissurina clathrata 1 Fissurina crassiannulata 1 1 Fissurina evolutiquetra Fissurina lucida 1 1 Fissurina quadrirevertens 1 Fissurina semialata 1 Gavelinopsis lobatulus Gavelinopsis sp. 1 Gavelinopsis sp. 1 Glabratella margaritaceus Globocassidulina canalisuturata Globocassidulina minuta Guttulina bartschi Guttulina irregularis 1 Guttulina silvestrii 1 Gypsina vesicularis Haynesina depressula Heronallenia pulvinulinoides Lagena doveyensis Lagena peculiariformis Lagena spiratiformis Lagena sulcata spicata Lagenosolenia prolata Lenticulina antarctica Lenticulina australis 2 Lenticulina tasmanica 1 Mychostomina sp. 1 Neoconorbina pacifica

17 Neoconorbina sp Notorotalia depressa Notorotalia finlayi Notorotalia cf. zelandica 1 Oolina globosa 1 Oolina heagona Oolina lineata 1 Oolina melo l Palliolatella lacunata paucialveolata Parafissurina acarinata 1 Parafissurina discalis Parafissurina procidua 1 Parafissurina sp. 1 Patellinella inconspicua Pileolina calcarata 1 Pileolina harmeri Pileolina patelliformis Pileolina radiata 1 2 Pileolina zelandica Planoglabratella opercularis Planorbulina acervalis Procerolagena sp. Ramulina! sp. 1 Rectobolivina columellaris Rosalina bradyi Rosalina irregularis Rosalina paupereques 1 Rugidia simple Saidovina karreriana Sigmavirgulina tortuosa Siphouvigerina vadescens 1 Spirillina denticulo-granulata 1 Spirillina vivipara 1 1 Tretomphalus sp. Trifarina angulosa Trifarina n.sp Trochulina dimidiatus Uvigerina sp. 1 1 Vaginulina vertebralis Vaginulina sp. Virgulopsis turris Zeaflorilus parri PLANKT1CS Globigerina bulloides 1 1 Globigerina falconensis Globigerina quinqueloba

18 Globigerinita glutinata Globigerinoides ruber Globorotalia hirsuta Globorotalia inflata Globorotalia truncatulinoides % Neogloboquadrina dutertrei APPENDI II: Taiwawe Bay dredge sample data. station cat. no. planktic % depth inn diversity grain size * shell size ** (Fisher inde) 1 F FMSand FMShell 2 ' F VFSand VFShell/FMShell 3 F VFSand VFShell/FMShell 4 F VFSand VFShell 5 F FMSand FMShell 6 F FMSand FMShell 7 F FMSand FMShell 8 F G FMShell 9 F sg CShell 10 F (g)fmsand CShell 11 F FMSand FMShell 12 F sg CShell 13 F VFSand FMShell 14 F VFSand VFShell/FMShell 15 F VFSand FMShell 16 F FMSand VFShell 17 F FMSand FMShell 18 F FMSand FMShell 19 F FMSand FMShell 20 F FMSand FMShell * grain size - VFSand = > 50% very fine sand and mud, FMSand = > 50% fine to medium sand, (g)fmsand = > 50% fine to medium sand and a minor amount of gravel, sg = sandy gravel, G = gravel. ** shell size - VFShell = > 50% shells finer than mm, FMShell = > 50% shells between mm, Cshell = > 5% shells larger than 0.5 mm. 130