WHITE ISLAND NOTES. by Roger V. Grace*

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1 TANE 21, 1975 WHITE ISLAND NOTES by Roger V. Grace* SUMMARY Observations of various marine aspects of White Island were made during a week-long visit in May Sea water temperatures between White Island and Tauranga show an abrupt discontinuity, probably associated with a change from coastal to oceanic water. Volcanic activity at White Island includes subtidal hot springs and gas vents. Marine life is reduced close to the outfall of an acid stream, and high tidal limpets are severely eroded by acid from the volcano. Zonation of marine organisms on the Volkner Rocks has some features apparently peculiar to the White Island region. 55 species of marine fishes were observed, several species with strong subtropical affinities. A number of species of marine organisms that could be expected at White Island were apparently absent. INTRODUCTION In May 1974, the author visited White Island, an active volcano in the Bay of Plenty, north-eastern New Zealand, as part of an expedition to film a television documentary. The opportunity was taken to make limited scientific observations, particularly of the marine life around the island. Considerable information on the island is available in the DSIR Bulletin on White Island. 6 Apart from a few notes on special features of interest on the land, comments here will be restricted to the marine environment. SEA SURFACE TEMPERATURES Sea surface temperatures were recorded at 15 minute intervals during the trip from the entrance to Tauranga Harbour to White Island and return, except for the latter half of the trip towards White Island. Measurements were made with a mercury thermometer of reliable quality, and a bucket dipped over the stem of the boat. Results are presented in Tables 1 and 2. There appeared to be an abrupt change in temperature about half way between Tauranga and White Island. This discontinuity was probably associated with a change from essentially coastal water to oceanic water. On the outward journey, 30th April to 1st May, the coastal water was about 17.8 to 18.3 C, with the oceanic water about 18.8 to 19.1 C. On the return journey one week later, 7th to 8th May, the coastal water was about 17.3 to 17.8 C, and the oceanic water about 18.3 to 18.6 C. Thus the sea surface temperature had dropped 0.5 C during the week of the expedition with the approach of the winter months. The higher temperature of the oceanic water probably indicates that it is of subtropical origin. Subtropical water enters the southern Bay of Plenty region via the East Auckland Current and the East Cape Current. 2 > 4 There are *36 Sussex Street, Grey Lynn, Auckland. 91

2 Table 1. Sea-surface temperatures, Tauranga to White Island. 1st May, Time Temperature C Comments Tauranga Harbour entrance mile NE of Mt Maunganui % mile NE of Motiti Island Vi mile NE of Schooner Rocks Probable coastal/oceanic water boundary Readings discontinued At anchor, NW side of White Island % mile off NE side of White Island indications of a strong subtropical influence in the marine fauna of White Island, probably as a result of the maintenance of a warm water environment and continuing influx of larvae of subtropical species via the subtropical waters reaching this area. INFLUENCE OF VOLCANIC ACTIVITY ON THE MARINE ENVIRONMENT There is no large scale warming of the waters around White Island by the volcanic activity, however small warm water areas can be directly attributed to the volcanic activity. In Crater Bay, an acidic hot water stream flows into the sea, causing a large discoloured surface water layer in the bay. This layer may be up to 0.5m thick, and a measurement of the temperature indicated that the discoloured surface layer was 0.4 C higher than the clear water just outside the bay. Measurements of ph showed no appreciable lowering in the discoloured surface layer, although the ph of the stream immediately before reaching the sea was 1.5. Underwater hot springs are common around the island. An area 200 metres by 100 metres was investigated on the eastern side of the island, and was found to contain numerous underwater vents in 10 metres depth of water. Gas bubbles rose intermittently, and in steady streams, from the gravel amongst the boulder-strewn seabed. Although no measurements were taken, the water 92

3 Table 2. Sea-surface temperatures, White Island to Tauranga. 7th to 8th May, 1974, Time Temperature Comments Vi mile N of White Island Midway White Island and Volkner Rocks Volkner Rocks Volkner Rocks (departing for Tauranga) Probable coastal/oceanic water boundary milesNEof Schooner Rocks x h mile E of Motiti Island & mile E of Mt Maunganui Tauranga Harbour entrance beneath the gravel surface was hot to the touch. Patches where springs emerged were marked by distinctive deposits of an unidentified fine white powdery or crystalline substance covering the gravel and rocks over a 1 to 2 metre radius around each vent. 93

4 EFFECT OF VOLCANIC ACTIVITY ON MARINE LIFE There appeared to be little effect on the subtidal marine life. On a night dive in the hot spring area described above, a red scorpionfish (Scorpaena cardinalis) was seen resting beside a vent, the fish's body completely covered with fine white crystals deposited from the spring water. The fish appeared to be in no way distressed by this condition. Other fish did not appear affected in any way by the springs. Marine life in the vicinity appeared normal, except for an almost complete lack of large brown algae, the only large algae seen being a few specimens of Carpophyllum flexuosum. It was not determined, however, whether this lack of algae was due to the presence of the springs, or to grazing by Evechinus chloroticus which was common here. The effect of the volcanic activity on intertidal life was quite noticeable in places. Near the acid stream outlet in Crater Bay, intertidal marine life was drastically reduced. The stable boulder shore was stained rust red, and the only macrofauna seen were rare Melarapha oliveri and Nerita melanotragus, also stained rust red. 30 metres east of the acid stream, M. oliveri and N. melanotragus increased in numbers, and additional species seen were the limpet Cellana radians, and the crabs Leptograpsus variegatus and Cyclograpsus insularum. Porphyra columbina and an unidentified green algal film were also present on the brown-stained rocks. 50 metres east of the stream, an old stone jetty projects some 30 metres from the shore. On the eastern side of this jetty, a few specimens of the barnacles Elminius plicatus and Chamaesipho columna occurred, there being no barnacles closer to the stream. Risselopsis varia first appeared here, and lower on the shore the fauna was apparently normal for a shore of this rock type and degree of exposure. A comparison between the limpets Cellana radians and C. ornata from upper shore and lower shore sites here showed that those living high on the shore had their shells severely eroded (see Fig. 1), presumably by acid either from the stream or contaminated rainwater. It was not determined whether this effect occurred on parts of the island away from the influence of the acid stream, except in Wilson Bay about half a mile from the stream. Here erosion of high tidal limpets was still severe. It is quite likely that the acid levels in rainwater are high enough to cause this effect. During moderate rainfall, rainwater running off the roof of the M.V. Whai, our expedition boat, had a ph of 4.0, while rain water collected the previous day and stored overnight in an open bucket had a phof3.5. ZONATION OF SHORE ORGANISMS Zonation on a vertical rock cliff on the very exposed eastern side of the largest of the Volkner Rocks, about 8km north of White Island, is shown in Fig. 2. Verticil! distances are approximate. A number of peculiarities can be noted a common feature of zonation patterns on the outer offshore islands. 7 The presence of a dense band of the vermetid gastropod Novastoa lamellosa is a subtropical influence in the White Island fauna. The absence of Carpophyllum angustifolium and Lessonia variegata from the zonation sequence is apparently a peculiarity of the White Island area, as one or both of these species feature on offshore islands further north. The water is usually very clear, as indicated by 94

5 Fig. 1. Shells of living Cellana radians from the shore east of the stone jetty in Crater Bay, White Island. Top Photograph is of shells from the upper shore, which show severe corrosion by acid from the volcano. Bottom Photograph shows shells from the lower shore, where effects from the acid are less severe because of longer time of submergence in the sea. All approximately normal size. the depth, in excess of 45 metres, to which dense beds of Ecklonia radiata occur. Zonation patterns on White Island itself were not noted in detail. Much of the shoreline of White Island consists of boulder beaches, with dense populations of the orange crab Cyclograspus insularum on the middle shore. The absence of 95

6 S 4 Chamaesipho brunnea Chamaesipho columna unidentified brown algal turf Novastoa lamellosa and coralline paint Xiphophora chondrophylla Pterocladia lucida with patches of Xiphophora chondrophylla Ecklonia radiata with occasional plants of Carpophyllum flexuosum, to over 45 metres on gentle slopes. Fig. 2. Zonation sequence of organisms on an exposed vertical rock face at the Volkner Rocks near White Island. the common mainland species C. lavauxi is consistent with other exposed outer offshore islands, such as the Poor Knights, Aldermen and Mayor Islands. 1 ' 9 LIST OF FISHES SEEN DURING VISIT The following is a list of the 55 species of fishes seen during the visit. This is by no means a complete list of fishes for the area, as it is known that a number of other species have previously been recorded for the area, for example by Doak. 3 This list is based on a total of 9 snorkel dives, 32 day-time scuba dives, and 5 night scuba dives, by the 7 members of the expedition, a total of 46 dives in all. 96

7 Family Dasyatidae Dasyatis brevicaudata Family Congridae Conger wilsoni Family Muraenidae Gymnothorax prasinus Gymnothorax nubilus Gymnothorax obesus Gymnothorax ramosus Family Exocoetidae Cypsilurus melanocercus Family Gadidae Lotella rhacina Family Berycidae Trachichthodes affinis Family Trachichthyidae Hoplostethus elongatus Family Serranidae Ellerkeldia huntii Callanthias splendens Caprodon longimanus Polyprionum oxygeneios Family Carangidae Caranx lutescens Decapterus koheru Seriola grandis Family Lutjanidae Caesio sp. Family Mullidae Upeneichthys porosus Family Kyphosidae Kyphosus sydneyanus Girella cyanea Scorpis aequipinnis Atypichthys strigatus Family Chaetodontidae Chelmonops howensis Family Pempheridae Pempheris adspersa Family Histiopteridae Zanclistius elevatus Family Aplodactylidae Aplodactylus meandratus Family Cheilodactylidae Nemodactylus douglasi Nemodactylus macropterus Cheilodactylus spectabilis Short-tail stingray Conger eel Yellow moray Grey moray Speckled moray Mosaic moray Flying fish Rock cod Golden snapper Slender roughy Redbanded perch Splendid perch Pink maomao Hapuku Trevally Koheru Kingfish Blue and yellow perch Red mullet Silver drummer Bluefish Blue maomao Mado Lord Howe Island coralfish Bigeye Longfinned boarfish Marblefish Porae Tarakihi Red moki 97

8 Family Chironemidae Chironemus marmoratus Family Latridae Latridopsis ciliaris Family Pomacentridae Parma microlepis Chromis dispilus Family Odacidae Coridodax pullus Family Labridae Pseudolabrus miles Pseudolabrus fucicola Pseudolabrus inscriptus Pseudolabrus luculentus Coris sandageri Verreo oxycephalic Halichoeres sp.a. 3 Family Scombridae Katsuwonus pelamis Family Tripterygiidae Tripterygion varium Tripterygion bucknilli Tripterygion sp.a. 3 Tripterygion sp.b. 3 Tripterygion sp.c. 3 Tripterygion sp.d. 3 Family Blenniidae Blennius laticlavius Plagiotremus tapeinosoma Family Scorpaenidae Scorpaena cardinalis Family Alcuteridae Navodon convexirostris Family Canthigasteridae Canthigaster callisternus Family Diodontidae Allomycterus jaculiferus Kelpfish Blue moki Black angelfish Demoiselle Butterfish Scarlet parrot fish Banded parrotfish Green parrotfish Orange parrotfish Sandager's parrotfish Red pigfish Crimson cleanerfish Bonito Mottled blenny Banded blenny Blue dot blenny Yellow/black blenny Oblique-swimming blenny Yaldwyn's blenny Crested blenny Mimic blenny Scorpion fish Leatherjacket Sharpnosed pufferfish Porcupinefish The incidence of fish species with strong subtropical affinities is high at White Island, as at the Poor Knight Islands 8 ' 3 and the Aldermen Islands. 5 RECORDS OF SPECIFIC MARINE ORGANISMS The following few records may be of interest. Durvillea antarctica Astrodiscus truncatus Bull kelp Fire-brick starfish 98

9 Knightaster bakeri Yellow starfish Diadema palmeri Long-spined sea-urchin Centrostephanus rodgersi Purple-spined sea urchin Tripneustes gratilla Orange-pink sea urchin Holopneustes inflatus "Tennis ball" sea urchin Xenophalium royanum Large helmet shell Also noted was a seven-armed forcipulate starfish, 20 to 30cm in diameter, with markings in brown, grey and blue. The species is awaiting determination in Wellington, and was fairly common on rocky ground from low water to a depth of 37 metres. NOTABLE ABSENCES A number of species and groups which might be expected at White Island were conspicuous by their absence. Although we could not be certain about the long-term absence of any species based on a visit of only a few days, this list is added so that perhaps other visitors may keep a special watch for these species. Lichens: No lichens were found on the island, probably because of high concentrations of sulphur dioxide and acid fumes in the air. Algae: Lessonia variegata Carpophyllum maschalocarpum Carpophyllum augustifolium Invertebrates: Steganoporella neozelanica Bryozoan Pustolopora sp. Bryozoan Bugula dentata Green bryozoan common on northern offshore islands Cyclograpsus lavauxi Crab Fishes: Myliobatus tenuicaudata Eagle ray Reporhamphus ihi Piper Zeus faber John dory Caesioperca lepidoptera Butterfly perch Arripis trutta Kahawai Chrysophrys auratus* Snapper Girella tricuspidata Parore Pseudolabrus celidotus Spotty Parapercis colias Blue cod Gilloblennius tripennis Spectacled blenny Reptiles: No reptiles were seen on the island. *Although no snapper were seen during this visit, it is understood that large solitary specimens can be found in shallow water in summer (personal communication with spearfishermen). 99

10 ACKNOWLEDGEMENTS I would like to thank the Directors of Marine Movie Films Ltd., Sigmund Spath and Brian Horton, for the opportunity to visit White Island. I also wish to thank them and my other colleagues on the expedition for their companionship and helpful observations. REFERENCES 'Bacon, M.R Distribution and ecology of the crabs Cyclograpsus lavauxi and C. insularum in northern New Zealand. N.Z.Jl mar. Freshwat.Res. 5 (3&4): Barker, P.H. and Kibblewhite, A.C Physical oceanographic data from the "Tui" cruise, N.Z.J.Sci. 8: Doak, W.T "Fishes of the New Zealand Region". Hodder and Stoughton, Auckland. 132pp. Garner, D.M The geopotential topography of the ocean surface around New Zealand. N.Z.Jl mar.freshwat.res. 3(2): 'Grace, R.V A checklist of fishes of the Aldermen Islands, north-eastern New Zealand, with additions to the fishes of Red Mercury Island. Tane 19: Hamilton, W.M. and Baumgart, I.L. (Eds.) "White Island". D.S.I.R. Bulletin No pp. 7 Morton, J.E. and Miller, M.C "The New Zealand Sea Shore". Collins, London. 638pp. 8 Russell, B.C A preliminary annotated checklist of fishes of the Poor Knight Islands. Tane 17: Saies, A.B The intertidal life of Ruamahua-iti and Middle Island (Aldermen Islands). Tane 19: