ISSN 0083-7903, 84 (Print) ISSN 2538-1016; 84 (Online) Foraminifera on the Continental Shelf and Slope off Southern Hawke's Bay, New Zealand by K. B. LEWIS () .T,;. � New Zealand Oceanographic Institute Memoir 84 1979 NEW ZEALAND DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH Foraminifera on the Continental Shelf and Slope off Southern Hawke's Bay, New Zealand by K. B. LEWIS New Zealand Oceanographic Institute, Wellington New Zealand Oceanographic Institute Memoir 84 1979 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ ISSN 0083-7903 Received for publication: September 1977 © Crown Copyright 1979 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ CONTENTS page LIST OF FIGURES 4 LIST OF T ABLES 4 ABSTRACT 5 INTRODUCTION 5 COLLECTIONAND PROCESSING OF SAMPLES 6 THE ENVIRONMENT 8 DISTRIBUTION OF BENTHONIC SPECIES 8 SYSTEMATIC NOTES ON BENTHONIC SPECIES 17 Suborder Textulariina ... 17 Suborder Miliolina 24 Suborder Rotaliina 26 THEFORAMINIFERAL FAUNA 39 BIOFACIES 40 ACKNOWLEDGMENTS 44 REFERENCES 44 3 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ LIST OF FIGURES page Fig. 1. Map of the continental shelf and slope off Hawke's Bay Land District showing positionsof samples 7 Fig. 2. Frequency polygons showing environmental character at 16 stations .. 9 Fig. 3. Frequency polygons showing abundance of benthonic foraminiferal fauna at each station... 41 Fig. 4. Frequency polygon showing nature of forarniniferalfauna at each station 43 LIST OF TABLES page Table 1. Position and depth of 17 ml samples 6 Table 2. Positionand depth of subsidiary samples 6 Table 3. Notationsfor foraminiferal abundance and size 10 Table 4. Weight of foraminiferaas a function of size and abundance 10 Table 5. Forarniniferaldistribution data 10 4 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Foraminifera on the Continental Shelf and Slope off Southern Hawke's Bay, New Zealand by K. B. Lewis New Zealand Oceanographic Institute, Department of Scientific and Industrial Research, Wellington. ABSTRACT Foraminiferal populations are described from a continental shelf and slope devoid of strong currents on the eastern side of North Island, New Zealand. The large numbers of living specimens per unit area suggest that productivity is high. Except on the turbulent inner shelf, the ratio of living to dead specimens correlates well with estimated rates of deposition. A method is evolved of estimating the contribution of each species to sediment acx:wnulation at each site. Six, depth-controlled biofacies are descr ibed and compared with Tertiary forarniniferal biofacies. It appears that the estimated depth of deposition of some Tertiary neritic and bathyal faunas may have been somewhat underestimated. INTRODUCTION Despite the potential value of forcrninifera for Hulme (1964) gave a detailed account of the variation closely defining the environments of deposition of of shallow water benthonic species in Manukau ancient sediments in New Zealand, the environment in Harbour. The only distribution study of benthonic which many species of benthonic foraminiferanow live species in the open ocean is by Vella (1957), who and are incorporatedinto the sediment is known in only described the foraminifera of dried dredge samples general terms. from Cook Strait and concluded that strong bottom Eade (1967) briefly reviewed studies of Recent currents had mixed faunas from different depths so that foraminifera from the seabed around New Zealand and biofacies could not be recognised. compiled a checklist of Recent New Zealand species. Most studies are either systematic descriptions or lists The following investigation is an attempt to of species, either from a single sample or from a few quantitatively define the distribution of foraminiferain closely spaced samples: distribution studies are rare. an area devoid of strong currents and thereby to Kustanowich (1963) described the distribution of provide criteria useful for the recognition of specific planktonic foraminifera in deep-sea sediments and environments in ancient, indurated sediments. 5 New Zealand Oceanographic Institute Memoir 84. 1979 ISSN 0083-7903 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ COLLECTION AND PROCESSING OF SAMPLES Sixteen samples (Table 1; Fig. 1) were collected for 0.17 mm, 0.12 mm, 0.08 mm and 0.06 mm. The sieves detailed quantitative ana�sis. The two shallowest sort grains, including foraminifera, according to their samples were collected with an orange-peel grab, the width, so that foraminifera on the bottom sieve have remainder with a short gravitycorer of 47 mm internal widths ranging from 0.08 mm to 0.06 mm. diameter, care being taken with both grab and core Each sieve fraction was examined on a water-filled samples to prevent washing of the surface sediment. counting tray because many fragile specimens are For a more detailed description of techniques see Lewis destroyed by drying. Further, many foraminifera are (1970). The area sampled by the corer was about translucent when wet so that stained protoplasm is 1700 mm2 and a similar area was sampled at the two shallowest stations by pressing a piece of core liner into easily visible. All benthonic foraminifera on randomly selected squares on the tray were identified and the surface of each grab sample. The same volume of counted until between 100and 200specimens had been sediment, 17 ml, representing a layer about 10 mm counted. The total number of specimens and thick, was removed from the surface of each core and grab sample and preserved with 90% ethyl alcohol. percentage of planktonic specimens in the fraction was then calculated. Each living specimen in the whole In the laboratory each sample was washed on a sieve fraction was identified and counted. Thus, in each with a mesh aperture of 0.06 mm, thereby removing fraction, the number of living and dead specimens of alcohol and all material of silt and clay grade, including each benthonic species is known. The number in the some juvenile and small foraminifera. The washed whole sample was found by adding the numbers in each sample was steeped for 12-24 hours in Rose Bengal in fraction. order to stain protoplasm (Walton 1952), thereby showing which specimens were alive when coll�cted. Thirteen subsidiary samples (Table 2; Fig 1) were The stained sample was washed again on the 0.06 mm collected by similar techniques but the volume of each sieve and soaked in water for 12-24 hours to remove sample was not accurately measured and stained excess stain from the surface of foraminiferaltests. The fractions were examined dry. The presence of living sample was then washed through a nest of seven sieves and dead specimens of each benthonic species was with mesh apertures of 0.50 mm, 0.33 mm, 0.25 mm, noted. TABLE 1. Position and depth of 17ml samples . NZOI Latjtude Longitude Sample Stn s E Depth Zone TABLE 2. Position and depth of subsiruarysamples. 1 F662 39• 49' 177" 08' 18m NZOI Latitude Longitude inner 2 F630 40· 37' 176" 26.3' 18 m Sample Stn s E Depth Zone shelf 3 F661 39" SO' 177• 02.5' 48 m A B865 40• 13.8' 176" 48.8' 40 m inner 4 F636 40· 38.5' 177" 30' 71 m B B863 40• 31.6' 176" 39.S' 42m shelf outer F660 39• SO' 177" OS' 91m s shelf 6 F659 39• SO' 177" 09' 130m C B866 40· 15.5' 176" 54.2' 113m outer D B867 40• 16.6' 176" 58.2' 186m shelf 7 F861 40• 01.5' 177" 22' 329 m bank E B154 40• 21' 177" 12' 142m Madden 8 F609 40• 45' 176" 40' 304m F B153 40• 37' 177" 02' 183m Banks upper 9 F601 40• SO' 176" 44' 375m slope 10 F863 40· 02' 177" 16.S' 479 m G B868 40• 17.8' 177" 01.8' 276m upper H B881 40· 22.0' 176" 50.2' 427m slope 11 FS99 40• 52' 176" 58' 1 240 m I B869 19.0' 177" 05.6' 625m mjd 40• 12 F673 40• 11' 177" 51' 1 419 m slope 13 F683 40• 08' 177" 32' 1646m J B884 40· 27.8' 177" 03.8' 1 439m mjd slope 14 F679 40• 22' 177" 55.3' 2 329m K B885 40• 35' 177" 16' 2 028m lower lower 15 FS92 40• SO' 177" 42' 2 432m L FS94 40• 56.S' 177" 14' 2 063m slope slope 16 FS90 40· 59' 177" 59' 2 469 m M F862 40• 13' 177" 45' 2 127m 6 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ y , . :···.··_. ·:····· ... ..,· . .... • • 6 .• . $ · .··· ,: ... , . .... C i R;H ... ;,;)7•'••!:'./ JO ·.:·. �.·..... ·. .... ·· .$ � ·:·· .. · . ·, ......�.� ··· ··BANK.MADDEN· .·· .. · q.� ;.'. :.·.· _:_ , : : ,: . :: -�·· :: '40°30' s :· .·. .:. : ,. · . , .•. ·.. .·· ... .. ··_:: . s. : 0 10 20 30 .' · .9 //· ....· ···· .... Kilometres �� ···· · · . II�/ . .. · "# . :::-- "' . : _·:· j 15 · ..' :;, · .. / ·· � � .::•, ASTLE POINT .. · . .... � . .• . · . : . ·· 17'7° 30' E Flo. 1. Map of the continental shelf and slope off Hawke's Bay Land District showing positions of 16 samples used for quantitative analysis (numbers) and 13 subsidiary samples {letters). Depths are in metres.