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 1974. 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 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 Table 1. Sea-surface temperatures, Tauranga to White Island. 1st May, 1974.

Time Temperature C Comments 0010 17.8 Tauranga Harbour entrance 0020 17.7 0030 17.7 1 mile NE of Mt Maunganui 0045 17.7 0100 18.0 0115 17.8 0130 18.1 0145 18.3 0200 18.0 % mile NE of Motiti Island 0215 18.1 0230 18.1 0245 18.1 Vi mile NE of Schooner Rocks 0300 18.2 0315 18.3 0330 18.3 0345 18.3 0400 18.4 0415 18.5 Probable coastal/oceanic 0430 18.7 water boundary Readings discontinued 0800 18.9 At anchor, NW side of White Island 1000 19.1 % 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 Table 2. Sea-surface temperatures, White Island to Tauranga. 7th to 8th May, 1974,

Time Temperature Comments 1000 18.6 Vi mile N of White Island 1015 18.7 Midway White Island and Volkner Rocks 1030 18.6 Volkner Rocks 1700 18.5 Volkner Rocks (departing for Tauranga) 1715 18.6 1730 18.6 1745 18.5 1800 18.6 1815 18.6 1830 18.6 1845 18.5 1900 18.4 1915 18.4 1930 18.5 1945 18.5 2000 18.4 2015 18.4 2030 18.4 2045 18.3 2100 18.3 Probable coastal/oceanic 2115 17.8 water boundary 2130 17.8 2145 17.8 2200 17.7 2215 17.5 2milesNEof Schooner Rocks 2230 17.3 2245 17.5 2300 17.4 xh mile E of Motiti Island 2315 17.4 2330 17.6 2345 17.5 2400 17.4 0015 17.3 0030 16.9 0045 17.3 & mile E of Mt Maunganui 0100 16.4 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 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 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 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 Family Dasyatidae Dasyatis brevicaudata Short-tail stingray Family Congridae Conger wilsoni Conger eel Family Muraenidae Gymnothorax prasinus Yellow moray Gymnothorax nubilus Grey moray Gymnothorax obesus Speckled moray Gymnothorax ramosus Mosaic moray Family Exocoetidae Cypsilurus melanocercus Flying fish Family Gadidae Lotella rhacina Rock cod Family Berycidae Trachichthodes affinis Golden snapper Family Trachichthyidae Hoplostethus elongatus Slender roughy Family Serranidae Ellerkeldia huntii Redbanded perch Callanthias splendens Splendid perch Caprodon longimanus Pink maomao Polyprionum oxygeneios Hapuku Family Carangidae Caranx lutescens Trevally Decapterus koheru Koheru Seriola grandis Kingfish Family Lutjanidae Caesio sp. Blue and yellow perch Family Mullidae Upeneichthys porosus Red mullet Family Kyphosidae Kyphosus sydneyanus Silver drummer cyanea Bluefish Scorpis aequipinnis Blue maomao Atypichthys strigatus Mado Family Chaetodontidae Chelmonops howensis coralfish Family Pempheridae Pempheris adspersa Bigeye Family Histiopteridae Zanclistius elevatus Longfinned boarfish Family Aplodactylidae meandratus Marblefish Family Cheilodactylidae Nemodactylus douglasi Nemodactylus macropterus Tarakihi spectabilis

97 Family Chironemidae Chironemus marmoratus Family ciliaris Family Pomacentridae Parma microlepis Black angelfish Chromis dispilus Demoiselle Family Odacidae Coridodax pullus Butterfish Family Labridae Pseudolabrus miles Scarlet parrot fish Pseudolabrus fucicola Banded parrotfish Pseudolabrus inscriptus Green parrotfish Pseudolabrus luculentus Orange parrotfish Coris sandageri Sandager's parrotfish Verreo oxycephalic Red pigfish Halichoeres sp.A.3 Crimson cleanerfish Family Scombridae Katsuwonus pelamis Bonito Family Tripterygiidae Tripterygion varium Mottled blenny Tripterygion bucknilli Banded blenny Tripterygion sp.A.3 Blue dot blenny Tripterygion sp.B.3 Yellow/black blenny Tripterygion sp.C.3 Oblique-swimming blenny Tripterygion sp.D.3 Yaldwyn's blenny Family Blenniidae Blennius laticlavius Crested blenny Plagiotremus tapeinosoma Mimic blenny Family Scorpaenidae Scorpaena cardinalis Scorpion fish Family Alcuteridae Navodon convexirostris Leatherjacket Family Canthigasteridae Canthigaster callisternus Sharpnosed pufferfish Family Diodontidae Allomycterus jaculiferus Porcupinefish

The incidence of fish species with strong subtropical affinities is high at White Island, as at the Poor Knight Islands8'3 and the Aldermen Islands.5

RECORDS OF SPECIFIC MARINE ORGANISMS The following few records may be of interest.

Durvillea antarctica Bull Astrodiscus truncatus Fire-brick

98 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 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 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. 1971. Distribution and ecology of the crabs Cyclograpsus lavauxi and C. insularum in northern New Zealand. N.Z.Jl mar. Freshwat.Res. 5 (3&4): 415-26. 2 Barker, P.H. and Kibblewhite, A.C. 1965. Physical oceanographic data from the "Tui" cruise, 1962. N.Z.J.Sci. 8: 604-34. 3Doak, W.T. 1972. "Fishes of the New Zealand Region". Hodder and Stoughton, Auckland. 132pp. 4Garner, D.M. 1969. The geopotential topography of the ocean surface around New Zealand. N.Z.Jl mar.Freshwat.Res. 3(2): 209-19. 'Grace, R.V. 1973. A checklist of fishes of the Aldermen Islands, north-eastern New Zealand, with additions to the fishes of Red Mercury Island. Tane 19: 13-19. 6Hamilton, W.M. and Baumgart, I.L. (Eds.) 1959. "White Island". D.S.I.R. Bulletin No. 127. 84pp. 7Morton, J.E. and Miller, M.C. 1968. "The New Zealand Sea Shore". Collins, London. 638pp. 8Russell, B.C. 1971. A preliminary annotated checklist of fishes of the Poor Knight Islands. Tane 17: 81-90. 9Saies, A.B. 1973. The intertidal life of Ruamahua-iti and Middle Island (Aldermen Islands). Tane 19: 1-11.

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