INTERTIDAL BIOTA OF THE PROPOSED NGA MOTU MARINE RESERVE, NEW PLYMOUTH Bruce W. Hayward1 and Margaret S. Morley2 1Department of Geology, University of Auckland, Private Bag 92 019, Auckland 2Auckland War Memorial Museum, Private Bag 92 018, Auckland

SUMMARY A survey of the intertidal shore within the proposed Nga Motu Marine Reserve, south New Plymouth, adds 109 additional species to existing lists for the area, bringing the current total for the combined subtidal and intertidal for the proposed reserve to 418 (including 100 gastropods, 88 fish, 50 seaweeds, 36 bivalves, 35 sponges, 28 bryozoa, 24 echinoderms, 14 crabs and shrimps, 11 chitons, 13 coelenterates, 8 ascidians, 6 barnacles). This study provides the first records from the west coast North Island of three gastropods - Cominella quoyana quoyana, Eatoniella globosa and Rissoella cystophora and extends southwards the previously known geographic range of four other gastropods and two bivalves. The diversity of intertidal life (172 species) in the rocky habitats of this area is comparable to that recorded from nearby Kawaroa Reef. These rocky shores around New Plymouth (Kawaroa Reef and Back Beach), partially sheltered by Paritutu and the Sugar Loaf Islands, contain the richest and most diverse intertidal biota of the Taranaki coast. The Taranaki coast lies adjacent to the fluctuating confluence of a south-flowing warm current and north-flowing south current. This is reflected in the coastal biota with the northernmost records of some cooler water species existing together with the southernmost records of some warmer water species.

INTRODUCTION The Sugar Loaf Islands, adjacent to Port Taranaki, New Plymouth (39°S, 174°E), and the surrounding seabed, foreshore and water (Fig. 1) are protected from mining (particularly of hydrocarbons) under the Sugar Loaf Islands Protected Area Act 1991. Using the Fisheries Act (1986), MAF gazetted regulations prohibiting commercial fishing and limiting recreational fishing in this area. Because these acts do not provide full protection for this precious piece of coast and its biota, a group of concerned locals formed the Nga Motu Marine Reserve Project Society and are campaigning for the creation of a marine reserve around part of the Sugar Loaf Islands and a strip of coastline extending to the south-west. In preparing their case for a marine reserve application, the Society is required to document the biotic values of the proposed area and thus invited the authors to New Plymouth to undertake an intertidal survey.

Taranaki coast The intertidal shore of Taranaki from Urenui around Cape Egmont to Hawera, is almost entirely boulder-lined, consisting of hard andesite boulders, cobbles and pebbles eroded out of the laharic breccias that form the low coastal cliffs. The laharic breccias were formed by lahars that flowed down from Mt Taranaki and its predecessors creating the ring plain that surrounds the mountains. These breccias consist of andesite clasts set in a matrix of relatively soft volcanic mud and sand, which in many places form a wave-cut low- to mid-tidal shore platform on which the boulders and cobbles sit. These low lying shore platforms and gravel deposits extend subtidally. The boulder beaches are interspersed with scattered sand beaches. In some places, as in the western half of the study area, sand forms a high tidal beach separated from the sea by a belt of

Fig. 1. Map of study area along the shores of the south-western suburbs of New Plymouth, Taranaki. The boundary of the present Sugar Loafs Marine Protected Area and proposed Nga Motu Marine Reserve are shown. low tidal boulders. Periodically, mobile sand is moved inshore and may bury and smother parts of the boulder shore and underlying rock platforms. North of Waitara, the north Taranaki coast consists of soft sandstone and mudstone cliffs mostly fronted by long sand beaches. At New Plymouth, Paritutu and the Sugar Loaf Islands differ from the rest of the Taranaki coast, being eroded from hard andesite intrusives. They form a group of low sea stacks and islands that provide the firmest and most stable substrate on the Taranaki coast. In the lee of the Sugar Loafs (e.g. Kawaroa Reef and Back Beach) are the most sheltered habitats on the open Taranaki coast and consequently the most diverse intertidal communities (Hayward et al. 1999).

Previous work Previous studies on the intertidal biota within the proposed reserve have included documentation of the main zonation patterns on Round Rock by Morton and Miller (1968, fig. 103) and a brief unpublished report on the dominant biota on the shore around the mouth of Waireka Stream (Anon 1991). The subtidal biota of the Sugar Loaf Islands, in the offshore part of the proposed reserve was documented by members of the New Plymouth Underwater Club (1989) with some specialist assistance with the identification of some groups. Their full species list includes 79 species of fish and 65 species of sponge (Department of Conservation 1996). Beyond the proposed reserve boundaries, Hayward et al. (1999) recorded a diverse biota of 180 species on Kawaroa Reef, 3km north-east of Paritutu. Further to the south, Morton and Miller (1968, fig.125) described the zonation of the boulder beach at Opunake, and a group of University of Auckland studies, undertaken as part of the Maui Development Environmental Study, documented and monitored natural change in the intertidal and shallow subtidal biota at Oaonui and Tataraimaka (Bergquist 1979, Foster 1978, Gordon 1980, Miller & Miller 1980, Miller 1982, Willan 1980a, b).

FIELD WORK The intertidal shore between Paritutu and the mouth of Tapuae Stream was surveyed by the authors during spring low tides in February 2001. This survey involved comprehensive inspection of all the available habitats, documenting all the species of macroinvertebrate, micromollusc and seaweed present. Washed up shells were also surveyed as an indication of the composition of the mollusc fauna that lives in the subtidal sediments and rocky habitats just offshore within the proposed reserve area. Qualitative assessments of the abundance of all species were made during the surveys, and are given in the species list (below).

SPECIES LIST The first four columns record species identified during our 2001 study, whereas the last two columns incorporate the records of previous studies within the proposed reserve area. This list does not include subtidal vertebrate and bryozoan records. Voucher specimens from the 2001 study are deposited in the Marine and Botany collections of the Auckland War Memorial Museum (AK). A In lee of Sugar Loaf Islands - rocky shore and boulder beach B Back Beach to Waireka beach washup C Waireka toTapuae boulder beach and rocky shore D Waireka to Tapuae boulder washup E Waireka boulder beach and rocky shore (Anon 1991) F Sugar Loafs Islands subtidal (New Plymouth Underwater Club 1989) a = abundant c = common, f = frequent, o = occasional, r= rare; d = dead, l = live, x = present Haustrum haustorium o o l l Janthina exigua d A B C D E F Lepsiella albomarginata c c l l MOLLUSCA: POLYPLACOPHORA Linopyrga rugata d d Acanthochitona violacea f l Maoricolpus roseus manukauensis d d x Acanthochitona zelandica r l Melagraphia aethiops o f l Chiton glaucus c c l Micrelenchus sanguineus c c Cryptoconchus porosus r l Nodilittorina antipodum o o l Eudoxochiton nobilis l Nodilittorina cincta r r Ischnochiton maorianus o r l Notoacmea elongata o d Leptochiton inquinatus o Notoacmea helmsi d Plaxiphora biramosa r Notoacmea parviconoidea c c Plaxiphora caelata l Notoacmea pileopsis pileopsis c o Plaxiphora obtecta r Onchidella nigricans c r Sypharochiton pelliserpentis c o l Onoba fumata d MOLLUSCA: GASTROPODA Paratrophon c. cheesemani d d Alcithoe fusus x Paratrophon c. exsculptus d Amalda (Baryspira) mucronata d Patelloida corticata c c Amphithalamus falsestea o c Penion sulcatus d d x Anabathron hedleyi d Pisinna zosterophila r Asteracmea suteri d r Pleurobranchaea maculata r Astraea heliotropium x Potamopyrgus estuarinus c Austrofusus glans d d Radiacmea inconspicua o Buccinulum linea linea d d l Risellopsis varia o o Cabestana spengleri x Rissoella cystophora r Caecum digitulum o Rissoina chathamensis d Calliostoma pellucidum l Scutus breviculus f l Calliostoma punctulatum d d l Semicassis pyrum d x Calliostoma selectum l Sigapatella novaezelandiae d d l Calliostoma tigris l Siphonaria propria o d Cantharidella tesselata c a l ? Spectamen sp. d Cantharidus opalus d l Struthiolaria papulosa d x

Trichosirius inornatus d

Trochus viridis l

Tugali elegans d A B C D E F Tugali suteri l Cantharidus purpureus l Turbo smaragdus o f l l Cellana ornata f c d l Xenophora neozelanica x Cellana radians a c d l x Xymene traversi c c l Cellana stellifera d r l Zalipais lissa d Cerithiopsidae 2 spp. d Zeacumantus subcarinatus l Charonia lampas l MOLLUSCA: GASTROPODA: NUDIBRANCHS Chemnitzia spp. d d Aphelodoris lactuosa l Cominella adspersa r Archidoris wellingtonensis l Cominella maculosa f l Cadlina willani l Cominella quoyana r Ceratosoma amoena l l Cominella virgata x? Chromodoris aureomarginata l Cookia sulcata d o l Doriopsis flabellifera r r? Crepidula costata d Jason miriabilis l Dicathais orbita f f l l Polycera ?maddoxi l Diloma arida a c Trapania rudmani l Diloma bicanaliculata o d l Tritonia incerta l Diloma coracina c f MOLLUSCA: BIVALVIA Diloma nigerrima o l Anomia trigonopsis d Diloma zelandica f Atrina zelandica l Eatoniella albocolumella o c Barbatia novaezelandiae d d l Eatoniella delli r r Borniola reniformis o d Eatoniella globosa? d Cardita aoteana d d l Eatoniella latebricola d Chlamys zelandiae d d l Eatoniella olivacea o o Corbula zelandica d d Eatoniella roseocincta d Diplodonta striatula d Eatonina atomaria d Dosinia subrosea d d Eatonina subflavescens o Felaniella zelandica d Epitonium jukesianum c d Gari stangeri d x Gadinia conica d Glycymeris modesta d d A B C D E F Hiatella arctica c o Haliotis australis d l Irus reflexus d Haliotis iris f f l Kellia cycladiformis d Haliotis virginea virginea l Leptomya retiaria d d Mactra discors d d Diadumene neozelanica o f A B C D E F A B C D E F Modiolarca impacta d l Isactinia olivacea o f l Modiolus areolatus d Isocradactis magna c r Myadora boltoni d Monomyces rubrum l Neolepton antipodum d d Parazoanthus sp. l Nucula nitidula d d Physalia physalis d Paphies donacina d d Solandaria racemosa l Paphies subtriangulata d Tubularia sp. l Perna canaliculus d r d l PORIFERA Peronaea gaimardi d Anchinoe sp. l Philobrya munita d Ancorina alata l Pholadidea tridens d Axinella tricalyformis l Pododesmus zelandicus l Axinellida spp. l Protothaca crassicosta f d d Biemna spp. l Pseudoarcopagia disculus d Cacospongia sp. l Ruditapes largillierti d Callyspongia ramosa l Scalpomactra scapellum d d Carteriospongia sp. l Tawera spissa d d Cinachyra sp. l Trichomusculus barbatus r Ciocalypta cf. polymastia l Xenostrobus pulex a a l Cliona celata o l MOLLUSCA: CEPHALOPODA Crella incrustans l Nototodarus sloanii l Darwinella gardineri l Octopus maorum l Desmacella dendyi l Spirula spirula d d Dysidea sp. l ECHINODERMATA Homaxinella sp. l Allostichaster polyplax o r l Hymedsmia sp. l Coscinasterias muricata o r l l Hyrtios sp. l Echinocardium cordatum l Iophon sp. l Evechinus chloroticus o c l l Latrunculia sp. l Fellaster zelandiae d Microciona coccinea r r l l Ophionereis fasciata o l Pararhaphoxya sp. l Ophiopteris antipodum l Polymastia fusca l Patiriella regularis o o l l Polymastia granulosa l Pectinura maculata l Psammocinia sp. l Pentagonaster pulchellus l Pseudoaxinella cf. australis l Stegnaster inflatus l Raspalia agminata l Stichaster australis f o l Raspalia topsenti l Stichopus mollis l Spongia sp. l CRUSTACEA: REPTANTIA Stellata conulosa l Elamena longirostris l Stellata cf. diversiraphidophora l Halicarcinus cooki f l ?Suberites axinelloides o Halicarcinus innominatus o Tethya aurantium r l l Hemigrapsus edwardsi o o Tethya australis r l Leptograpsus variegatus f d l Tethya mortoni r Notomithrax minor o POLYCHAETA Notomithrax ursus f Galeolaria hystrix o r Ovalipes catharus d o Neosabellaria kaiparaensis c Pagurus novizelandiae c c l l Salmacina australis f c Petrolisthes elongatus o f l Spirobranchus cariniferus c o l Plagusia chabrus o f l Spirorbis sp. c l CRUSTACEA: DECAPODA ASCIDIANS Alope spinifrons f o Aplidium sp. l Jasus edwardsii l Asterocarpa coerulea l Jasus verreauxi l Cnemidocarpa bicornuta l Palaemon affinis l Corella eumyota r CRUSTACEA: BARNACLES Didemnum candidum l Balanus vestitus l Didemnum densum l Chamaesipho columna a a l x Diplosoma listerianum l Chamaesipho brunnea c c x Pyura sp. r Epopella plicata c c l x Notomegabalanus decorus l Tetraclita purpurescens o f l CRUSTACEA: AMPHIPODA Hyale maroubrae o Paraweldeckia thomsoni o ISOPODA Euiodotea durvillei o COELENTERATA Actinia tenebrosa o o l Actinothoe albocincta l Alcyonium aurantium l Corynactis haddoni l Culicia rubeola l

A B C D E F BRACHIOPODA Calloria inconspicua r d l ALGAE Ballia scoparia? o Bryopsis plumosa l Capreolia implexa l Carpophyllum angustifolium o o Carpophyllum flexuosum o o Carpophyllum maschalocarpum a a l Caulerpa sedoides nz l Chaetomorpha aerea o Chaetomorpha sp. o Chordaria cladosiphon o o Colpomenia sinuosa o o l Corallina officinalis a a l l Cystophora torulosa c c Dasya sp. o Dasyclonium incisum o o Dictyota dictotoma? o Dictyota sp? o Enteromorpha ?compressa o l Enteromorpha sp. o Gigartina cranwelliae l Gigartina livida o o Glossophora kunthii c Griffithsia traversii o o Haliptilon roseum o o Halopteris virgata o o Helminthocladia densa? o o Herposiphonia ceratoclada o Heterosiphonia tessellata o o Hildenbrandia crouani l Hormosira banksii o c l Jania micrarthrodia o o Landsburgia quercifolia o Laurencia thyrsifera o o l Metamorphe colensoi o o Microzonia velutina o c Notheia anomala o Petalonia fascia o o Plocamium costatum l Plocamium microcladioides o o Polysiphonia sp. l Porphyra columbina o Pterocladia lucida o l Pterocladiella capillacea o l Rhodymenia linearis ? o Rhodymenia obtusa ? o o Scytothamnus australis c c Splachnidium rugosum f c Ulva lactuca o LICHEN Lichina confinis c FISHES Acanthoclinus quadridactylus l Trachelochismus pinnulatus o c

ECOLOGICAL NOTES In the lee of the Sugarloafs One hundred and sixteen species were found living intertidally on or under the rocks and cobbles in the lee of Snapper and Round Rocks and in the small, partly sheltered bay between Round Rock and Paritutu (Fig. 1). The sheltered, south-east facing andesite faces of Snapper and Round Rocks have a full intertidal zonation (Fig. 2) from the high tidal black lichen Lichina confinis and limpet Notoacmea pileopsis, down through bands of the barnacles Chamaesipho brunnea and C. columna, flea-mussel Xenostrobus pulex, pink coralline turf and paint, to the low tidal seaweed belt dominated by Carpophyllum maschalocarpum. Also common on these intertidal rock faces are the limpets Cellana ornata, C. radiata, and Notoacmea parviconoidea, leathery slug Onchidella nigricans, oyster borer Lepsiella albomarginata, chiton Sypharochiton pelliserpentis, ribbed barnacle Epopella plicata, and orange seastar Stichaster australis. At the time of our visit a thick build-up of sand had recently smothered a rich low-tidal boulder habitat on the sheltered side of Snapper Rock. Still largely free from sand was a similar area of large and small boulders and cobbles around mid to low tide level at the foot of Paritutu. This contained the richest and most diverse intertidal community within the proposed reserve area - a result of the partial shelter provided by Round Rock, the diversity of habitats on the top, sides and beneath the boulders, and the lack of smothering sand. Here at low tidal Carpophyllum maschalocarpum is joined by a number of other less abundant seaweeds, such as C. angustifolium, C. flexuosum, Cystophora torulosa, Gigartina livida, Haliptilon roseum, Laurencia thyrisifera, Microzonia velutina and many others. On boulders and in pools slightly higher on the shore are other more scattered, often seasonal, seaweeds such as Neptunes necklace Hormosira banksii, Porphyra columbina, Scytothamnus australia, Splachnidium rugosum, and Ulva lactuca.

Fig. 2. Intertidal ranges of dominant zoning organisms on the intertidal landward face of Round Rock, Sugar Loaf Islands. Drawings by Margaret Morley.

Common grazing gastropods at mid and low tide levels are Diloma arida, D. coracina, Melagraphia aethiops, Cantharidella tesselata (on seaweed), Micrelenchus sanguineus (on seaweed), and beneath cobbles small paua Haliotis iris, the large black “slug” Scutus breviculus, and the chitons Chiton glaucus and Ischnochiton maorianus. Common carnivorous gastropods are Dicathais orbita and Xymene traversi. The commonest crabs are the small hermits Pagurus novizelandiae, masking crab Notomithrax ursus, purple rock crab Leptograpsus variegatus and pillbox crab Halicarcinus cooki. The large, multi-coloured anenome Isocradactis magna is common, as is the encrusting tubeworm Spirobranchus cariniferus. A rare find intertidally were several specimens of the small red brachiopod Calloria inconspicua attached to the underside of a boulder. The wentletrap Epitonium jukesianum was common sieved alive in sandy pools near its host the large anemone Isocradactis magna.

Western boulder shore (Fig. 3) At the time of our visit, the most striking aspect of the western half of the surveyed shore was the enormous build-up of sand which had clearly buried and smothered most of the low and mid tidal boulder habitats along the whole stretch of coast. In places where the boulders sit on an intertidal rock platform of eroded laharic breccia, the platform was almost everywhere completely buried. In several places the sand had been swept clear of small portions of previously buried platforms and they were completely bare of any life forms save for the white colour of the dead coralline paint. In places longer seaweed straps of Carpophyllum and Cystophora torulosa had just their tips sticking out from the sand drifts. In several places the sand had driven all the kina Evechinus chloroticus, from their normal grazing grounds and they were clustered together in their hundreds, probably starving, around the sand ensheathed bases of the larger protruding boulders. Other mobile members of the fauna (e.g. gastropods) were also found concentrated in artificially high numbers in small refuges around large boulders or in partially sand-filled tidal pools. From these refuges we were able to determine the overall character of the biota that lives intertidally along this stretch of coast during the long intervals when it is relatively free from sand build-ups. One hundred and ten species were recorded living here. Most of the high-mid tide zone was occupied by a wide strip of sand beach. Near Wairere Stream mouth the laharic breccia rock platform protrudes above the sand and is home to occasional periwinkles Nodilittorina antipodum and N. cincta, barnacles Chamaesipho brunnea, C. columna and Epopella plicata, limpets Cellana radians and C. ornata, dark red anenome Actinia tenebrosa, and the encrusting dark red seaweed Apophloea sinclairii. On the sides of stable boulders at mid and low tide levels are common encrusting flea- mussels Xenostrobus pulex and barnacles Chamaesipho columna, and their predator the oyster borer Lepsiella albomarginata, together with occasional clumps of sand tubeworms Neosabellaria kaiparaensis and the calcareous tubeworm Spirobranchus cariniferus. In and around the few remaining pools are the common whelk Cominella maculosa, Cook’s turban Cookia sulcata, hermit crabs, and the anenome Isactinia olivacea. Living under smaller, but stable cobbles and boulders sitting on a rock platform at low tide are common chitons Chiton glaucus, Acanthochitona violacea and Ischnochiton maorianus, the suckerfish Trachelochismus pinnulatus and multicoloured anenome Diadumene neozelanica. Perfectly camouflaged, the nudibranch Doriopsis flabellifera adheres closely to its prey, an orange encrusting sponge. Low tidal seaweeds attached to the boulders are dominated by C. maschalocarpum, C. torulosa, Microzonia velutina, Glossophora kunthii, Landsburgia quercifolia, Pterocladia capillacea and P. lucida. Higher on the shore, often attached to the underlying rock platform are Neptune’s necklace Hormosira banksii and seasonal seaweeds

Fig. 3. Common and characteristic organisms of the intertidal western boulder beaches, west of the Sugar Loaf Islands. Drawings by Margaret Morley and Morton and Miller (1968).

Colpomenia sinuosa and Splachnidium rugosum. The bivalve Hiatella arctica is common in algal holdfasts. An attractive striped form of the limpet Notoacmea helmsi was found living on intertidal cliff faces at Pukearuhe, North Taranaki (Hayward et al. 1997). Several shells were found washed up on the beach and undoubtedly it lives within the proposed reserve. This appears to be a local variant, as specimens elsewhere do not have contrasting stripes. Another small limpet Radiacmea inconspicua was found alive on a cat’s-eye shell.

Beach wash-up Seventy-three species of mollusc shell were found washed up on the beaches within the proposed reserve. These are a mix of species that live: a. intertidally on rocks or seaweed within the reserve (30 species, 13 recorded live), e.g. Cellana radians, C. ornata, Perna canaliculus, Protothaca crassicosta; b. subtidally on rocks within the reserve (14 species, 10 recorded live at Sugar Loafs), e.g. Calliostoma punctulatum, Cantharidus opalus, Sigapatella novaezelandiae, Cardita aoteana, Chlamys zelandiae; c. in shallow subtidal sand as infaunal surf clams within the reserve (3 species), e.g. Mactra discors, Paphies donacina plus the sand dollar Fellaster zelandiae; d. on or in offshore sediment, possibly within the reserve (27 species), e.g. Amalda mucronata, Austrofusus glans, Struthiolaria papulosa, Corbula zelandica, Glycymeris modesta, Nucula nitidula, Scalpomactra scapellum, Tawera spissa; or e. pelagically and wash ashore dead (2 species), e.g. Janthina exigua, Spirula spirula (internal shell of cuttlefish). The only live inhabitant of the beach sands observed was the swimming crab, Ovalipes catharus.

MOLLUSCAN BIOGEOGRAPHIC NOTES This study extends the recorded geographic ranges of nine mollusc species (below). Powell’s (1979) published ranges have been used when commenting on extension of range, because Spencer and Willan (1996) give zoogeographic provinces only. These provinces (Powell 1955) are used to summarise the known range of each species (A = Aupourian, C = Cookian, F = Forsterian, M = Moriorian, An = Antipodean). Additional records from the collections of Auckland Museum(AK) and Margaret Morley (MM) are cited where they extend the published range. Cominella quoyana quoyana A. Adams, 1854 Previously recorded from the northern part of New Zealand from the Bay of Islands to East Cape (Powell 1979). The live specimen recorded here is the first west coast record of this species, although we know of additional specimens from Destruction Gully and Whatipu, at the entrance to the Manukau Harbour (AK). These extend the species range to A and C provinces. Eatoniella latebricola Ponder, 1965 Previously recorded from Muriwai, west coast Auckland, under Durvillaea holdfasts (Powell 1979) and Raglan (Hayward et al, in prep.). The New Plymouth specimen found dead in algal wash (AK 105403) provides an extension of range south of Raglan. Owing to the difficulty accessing its restricted habitat, it is seldom collected alive. The species range is A and C provinces. Eatoniella globosa Ponder, 1965 Previously recorded from the north and east coasts of Northland, this New Plymouth specimen (AK 105398) is the first record on the west coast of the North Island. Its range is now A and C provinces. Rissoella cystophora (Finlay, 1924) Previously recorded from the east coast of the North, South, Stewart and Chatham Islands, these specimens (AK 105401) found in algal washes, are the first published record on the west coast of the North Island. We know of additional records from algal washes at Ahipara, west coast Northland, and Dusky Sound, Fiordland (MM). The species range is now A, C, F and M provinces.

This New Plymouth study extends the range of three gastropods and two bivalves south of Kawhia on the west coast of the North Island (Morley et al. 1997): Doriopsis flabellifera (Cheeseman, 1881) (AK 105274); Linopyrga rugata rugata (Hutton, 1886) (AK 105402); Tugali elegans Gray, 1843 (AK 105454); Myadora boltoni E.A. Smith, 1880 (AK 105397); Kellia cycladiformis (Deshayes, 1834).

DISCUSSION Offshore Taranaki lies at the fluctuating confluence of two surface water currents - the cooler, north-flowing Durville Current and the warmer, south-flowing West Auckland Current. The exact current patterns are not fully understood and are believed to vary seasonally (Adams 1994). The effects of the northern flowing Durville Current are reflected by molluscs which have northern and southern variants or subspecies. The siphon whelk Penion sulcatus found at in the proposed marine reserve at New Plymouth is the southern form without nodules on the whorls. The small grazing gastropod Eatoniella roseocincta found in algal wash, were all pink and white banded which is the southern form. Northern variants of the same species are uniformly rose-pink (Powell 1979). The muricid, Paratrophon cheesemani exculptus, the southern subspecies, was found at New Plymouth but not the northern subspecies P. cheesemani cheesemani. Both subspecies were found in a survey of North Taranaki (Hayward et al 1999). The effects of the southward flowing West Auckland Current are shown by molluscs present at New Plymouth usually found further north. The orange nudibranch Doriopsis flabellifera, the pyramidellid Linopyrga rugata and the fissurellid Tugali elegans are recorded for the first time south of Kawhia (Morley et al 1997). A total of 418 marine and intertidal species are now recorded from the proposed Nga Motu Marine Reserve. 218 of these species are recorded here from the intertidal. Forty-six of these are washed-up shells of subtidal or pelagic molluscs. Thus 172 species are so far recorded living intertidally on the rocky shorelines of this area. The census is incomplete for amphipods, isopods, sponges and smaller invertebrates, and obviously will be supplemented periodically by finds of rarer taxa or new colonisers. This diversity is comparable with the 180 species recorded (Hayward et al. 1999) from the intertidal rocky habitats of Kawaroa Reef, also partially sheltered by the Sugar Loaf Islands, but to the east of them (Fig. 1). This and the previous study of north Taranaki clearly show that the rocky shores around New Plymouth (Kawaroa Reef and Back Beach), partially sheltered by Paritutu and the Sugar Loaf Islands, contain the richest and most diverse intertidal biota of the Taranaki coast. In selecting sites for potential marine reserves, various criteria need to be considered. A long-term goal of a marine reserve network is to protect in perpetuity the richness and full diversity of our marine biota. To achieve this requires protecting the best representative examples of the complete diversity of marine habitats in each coastal region, so that breeding populations of all the biota survive to reseed areas beyond the reserve boundaries. Thus on the west coast of the North Island, a sound argument could be made to establish a marine reserve that protected at least part of the most sheltered section of rocky coast at New Plymouth with its consequent high diversity of microhabitats and biota. If a reserve is established in this area, it should be recognised that natural sand build-up on the coast will periodically impact upon and kill off much of the biota. Once the sand recedes the previous diversity of intertidal life could be expected to recolonise and return within a few years, reseeded from unimpacted refuges locally and more distant. At the present time, it appears that Kawaroa Reef is less affected by periodic sand accumulation than the proposed Nga Motu Reserve area, possibly because sand moving northwards along the coast is first captured in Port Taranaki, dredged out and dumped out to sea.

ACKNOWLEDGEMENTS We thank the committee of the Nga Motu Marine Reserve Project Society for the invitation to undertake the survey and for the hospitality during our visit. We particularly thank Anne and Brian Scott for providing accomodation and helpful advice. Brett Stephenson and Doug Rogan assisted with crustacean and seaweed identifications respectively.

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