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45 T A N E ( 1 9 6 6 ) 12 : 4 5 - 5 5
A COMPARISON OF THE ALGAE POPULATIONS OF CAPE MARIA VAN DIEMEN AND SCOTT POINT
by I.M. Johnstone
INTRODUCTION
The aim of this study was to investigate the variation in algal communities in the North Cape region and to correlate results with hydrographic data if possible . (Refer Fig. 1.)
The main areas studied are as follows:— (I) Scott Point - the bluffs at the northern end of the Ninety Mile
Beach. (n) Cape Maria van Diemen — a small headland, four miles to the
north-west of Scott Point. (Ill) Cape Reinga, Hooper Point and Kerr Point — the rocky outcrops
on the north and east of the North Cape area, which, s ince they have similar algal flora, are considered together.
The areas were visited on three occasions — August 1965, January 1966, and March 1966.
PREVIOUS WORK Description of algae communities in the North Cape region has been
limited to that by Bergquist(1960), who studied the zonation at the southern end of Spirits Bay . There i s little literature on the hydrology of the area and most of the observations are summarized by Garnet (1959) in his article on sub-tropical convergence in New Zealand surface waters.
TERMINOLOGY
This follows Lewis (1964), unlike previous "Tane" authors (Dromgoole 1964, Sylvester 1963 and Chambers 1955) as the author prefers the more flexible system where the zones are considered to be biological entities, defined biologically rather than physically. See Fig. 2.
The following abbreviations are used to classify spec ies frequency with respect to ecological importance:
d - dominant a = abundant r = rare f = found only as drift
Only four c la s se s are used s ince the terms are employed in a manner similar to the term "sociology" in land ecological studies. Thus the term "dominant" indicates the algae was present as a continuous zone; "abundant" it was present in patches; while rare only isolated plants were observed.
METHODS Where possible a collection was made from attached material, but
species found only as drift were also recorded. The algae zones were measured at low tide using a pre — measured nylon cord.
CO LU Z < 2 LU (J <
B! LU Q-< (J
o z
o u.
EXPOSURE SHELTER
SUBLITTORAL ZONE
Flg.2 ZONATION TERMINOLOGY
Fig. 3 : THE MAIN SURFACE AND DEEP W A T E R CURRENTS OF NEW ZEALAND WATERS (after Sewell .1948 )
4 8
THE NORTH C A P E LITTORAL HABITAT
At Scott Point and Cape Maria van Dieman a heavy swell i s characteristic even during calm periods.
Cape Reinga is unique since here the tidal differences between the Tasman and the Pacific Ocean are most apparent causing strong tidal rips and undertows.
North Cape (Kerr Point) itself is only subject to a large swell when an easterly wind is blowing.
The water at all stations i s extremely clear due to the absence in the area of rivers. The lower limit of the lower sub-littoral algae i s determined by a lack of suitable substratum as the rocky coast quickly terminates in a sandy sea floor.
DRIFT
This was very plentiful on the lighthouse beach at Cape Reinga, the beach between Cape Maria van Diemen and Herangi, Tom Bowling Bay and Ohau Point. Very little was found elsewhere, this unusual distribution was probably due to a combination of prevailing winds, wave exposure and currents at the time of the v is i t s .
WATER TEMPERATURES AND CURRENTS
The two main currents in the surface waters of New Zealand are: (I) The warm sub-tropical water of the East Australian Current and
the East Cape Current (n) The cold sub-antarctic water of the West Wind Drift Deep oceanic
currents are mainly of cold water origin (e .g. Antarctic Bottom Drift) these result in cold water upwellings along the West Coast further to the north than the sub-tropical convergence. See F i g . 3
Seasonal temperature changes on the East Coast are very small (Cranwell and Moore 1938) . There is no data for the phenomenon on the West Coast north of the Kaipara Harbour, due mainly to the lack of shipping which provides the main source of information. Sea temperatures are not recorded at Cape Reinga.
Surveys by various expeditions and naval ships e .g . HMNZS Lachlan (Oct. 1951) have revealed a pronounced drop in surface temperature between Spirits Bay and the Three Kings Islands (seven degrees lower). This drop i s due to cold upwellings from the Antarctic Bottom Drift. This may cause the "presence of a distinct southern element in the fauna" (Fleming 1944) at the Three Kings Islands.
Cold water upwellings along the West Coast, especially north of the sub-tropical convergence are also certain to occur, these would explain phytoplankton blooms on the West Coast (Cassie 1955). The warm East Australian Current would tend to neutralize these upwellings; but because the current swings westward in the region of the Ninety Mile Beach the same phenomenon would not occur at the Three Kings Islands.
The upwellings around the Three Kings Islands may be caused by a warm current setting from the north east (Garner 1959) that sweeps down
RANGE OF
SPECIES
SUBLITTORAL
> - t JO o
m > s c a t i in feet across
E U L I T T O R A L
traverse
L I T T O R A L
F R I N G E In z
P S e 1 m >
z
Melaraphe
Barnacles
G.alveata
Pachymenia
Durv i l lea
G/atropurpurea
Lithothamnion
Codium cuneatum
P o r p h y r a
U l v a lobata
Chnetomorpha
Entromorpha
CO O O
T J O
Z • o
? 5 s r o > ov< - cnm 2 2 °
E * z o
RANGE
OF
SPECIES
SUBLITTORAL
Lb
E U L I T T O R A L
In fea t traverse
L I T T O R A L
F R I N G E § I 81 z
o to o S i Q > m z
Melaraphe
E l m i n i u s plicatus
Chamaesipho brunnea
Modio lus neozealanics
Perna ,. canalicula
Porphyra
G a l v e a t a
C.cuneatum
Durvi l lea Gatropurpuroa
C maschalocarpum
Coral l ina
Lithothamnion
P.capilleaca
Bryopsis t o t r a s t i c h a
Gymnogongrus
Apophloea
Entromorpha
Pylaiel la
Ulva dactylifera
U l v a lobata
Chaetomorpha
2 —i o r-a.«— ai y £ en - 2
CO
O o
T J O
.o
w c
51
past the Kermadec Islands and then on to the east coast of New Zealand. This current may be the source of fauna recently found on the Poor Knights Islands with Kermadec affinities.
How this cold water affects the Cape Maria van Diemen and Scott Point region is consequently difficult to determine. The data presented below suggests that a cold water upwelling may occur at Scott Point resulting in the growth of a more southern type of algal element there, compared with that at Cape Maria van Dieman. Local currents are doubtless also a modifying factor, but little i s known of these. Possibly the most important is the strong tidal rip between Cape Maria van Dieman and Motuopao Island; which may result in a greater quantity of nutriments being available to the algae in this region.
ZONATION AT SCOTT POINT
Zonation in this area may best be described by dividing it as follows: (I) Sloping rock shelf. This shelf makes an angle of more or l e s s
45° with the sandy sea floor. Wave action here is of the extreme type, the shore being constantly washed by a heavy swell . The zonation here is sharply demarcated and the lack of a large variety of species i s marked. See Fig. 4.
(II) Rocky dissected Shore. Here wave exposure i s at a maximum, the basic pattern of large rocks causing the surf to break well before it reaches the algae of the littoral zone. Here the spray zone i s attenuated and Melarhapha oliveri covers large areas of the vertical cliff face. See Fig. 5. This latter type of shore i s to be found at the northern end of
the Ninety Mile Beach, the southern end of Twilight Beach and the innermost reaches of the several fiord-like coves around Scott Point. Elsewhere the first type of shore predominates.
ZONATION AT C A P E MARIA VAN DIEMAN
Several points of interest are apparent at this cape — (I) At the base of the near vertical cliffs are large horizontal rock
platforms that are washed by the surf at high tide and numerous rock pools are present which have been colonised by various rock pool algae.
(H) A wide band of algae in the sub-littoral i s visible, but lack of aqualung equipment at the time of the visit prevented an investigation in detail being made. This zone is probably the source of much of the drift found around the Cape with such types as Vidalia colensoi, Pterocladia lucida, Melanthalia abscissa, Plocambium angustum, Halopteris hordacea, Sargassum sinclairii, Caulerpa hypnoides, var flexis /. novaezealandiae. See Fig. 6.
(IH) The filamentous algae Pylaiella fulvescens i s found in the eu-littoral zone as well as being a major rock pool component.
(IV) The dominant phaeophycean marking the upper limit of the sub-littoral changes with wave exposure. Wherever exposure i s extreme Durvillea antarctica i s found to be dominant; but wherever exposure i s reduced Carpophyllum maschalocarpum
RANGE
OF
SPECIES
Melaraphe
Nerita melanotragus
Barnacles
Porphyra
Scytothamnus
Cadherans
U l v a lobata
Ulva dactylifera
J a n i a
C o r a l l i n a
Entromorpha
P y l a i e l l a
Apophloea
Splachnidium
D u r v i l l e a
|C. maschalocarpum
Petrospongium berkleyi
G y m n o g o n g r u s
Lithothamnion
Chaetomorpha
S U B L I T T O R A L
w Iso
CA
in a
UL
p m 33
> S c a l e
c
in
m >
f t *
60° Slope
E U L I T T O R A L
t r b
x > H •z c in
versje
w 20° Slope
L I T T O R A L
F R I N G E
o -a
o o *" 7* 3
§ > m cn
> £ in m "0 in
1 1
5 3
becomes the dominant plant. Refer Fig. 6.
ZONATION AT C A P E REINGA. HOOPER POINT AND KERR POINT.
As time did not permit a detailed study of these local i t ies , a spec ies list i s provided so that comparison may be made with the other two stations.
SPECIES LISTS
N.B. Epiphytes were not recorded (I) Scott Point
Phaeophyceae: Durvillea antarctica d Carpophyllum maschalocarpum r Lessonia variegata f Pylaiella fulvescens a
Rhodophyceae: Pachymenia himantophora d Gigartina alveata d Apophloea sinclairii d Porphyra columbina d Gigartina atropurpurea a Pterocladia capillacea a Gymnogongrus (nodiferus?) f Corallina officinalis a Lithothamnion sp. d
Chlorophyceae: Codium cuneatum f.striatissimum d Bryopsis tetrasticha r Viva dactylifera a Ulva lobata a Enteromorpha intestinalis a Chaetomorpha sp. a
(H) Cape Maria van Diemen Phaeophyceae:
Carpophyllum maschalocarpum d Durvillea antarctica d Splachnidium rugosum d Scytothamnus australis a Petrospongium berkleyi d Sargassum sinclairii f
Ecklonia radiata f Lessonia variegata f Halopteris hordacea f Pylaiella fulvescens d Xiphophora chondrophylla
var minus f Rhodophyceae:
Porphyra columbina d Apophloea sinclairii d Pterocladia capillacea a Gymnogongrus (nodiferus?) a Gigartina alveata a Jania natalensis a Champia novae-zealandiae a Pterocladia lucida Vidalia colensoi Plocambium angustum Gigartina atropurpurea Melanthalia abscissa Corallina officinalis Lithothamnion sp. d
Chlorophyceae". Caulerpa hypnoides var flexis
f .novae-zealandiae f Enteromorpha intestinalis a Viva dactylifera a Viva lobata a Chaetomorpha sp. a (III) Cape Reinga, Hooper Point,
Kerr Point N.B. Due to the large area included,
it is not possible to give in this list an indication of ecological importance.
54
Phaeophyceae: Ecklonia radiata Lessonia variegata Glossophora kunthii Hormosira banksii Notheia anomala (epiphytic on
Hormosira) Carpophyllum plumosum Scytothamnus australis Colpomenia sinuosa Splachnidium rugosum Carpophyllum maschalocarpum Dictyota dichotoma Petrospongium berkleyi Halopteris hordacea Sargassum sinclairii Landsbergia quercifolia Xiphophora chondrophylla var
minus Petalonia fassia
Carpophyllum flexuosum Cystophora torulosa Pylaiella fulvescens
Rhodophyceae: Melanthalia abscissa Apophloea sinclairii Porphyra columbina Pterocladia lucida Corallina officinalis Lithothamnion sp. Laurencia botryoides Vidalia colensoi Champia novae-zealandiae Gigartina alveata Plocambium angustum Ralfsia verrucosa Hymenia sp.
Chlorophyceae (most spec ies not recorded)
Ulva lactuca Enteromorpha intestinalis
THE THREE KINGS ISLANDS
The marine algae of these Islands, as recorded by Chapman (1954) differ considerably from those above especially with respect to the dominant Phaeophyceae.
Notable large phaeophycean algae absent from the Three Kings Islands are as follows:
1 Durvillea antarctica l i s ts 1, 2 2 Lessonia variegata l i s ts 1, 2, 3 3 Splachnidium rugosum l i s t s 2, 3 4 Scytothamnus australis l i s ts 2, 3 5 Hormosira banksii l ist 3
Thus the areas are by no means identical.
CONCLUSION Although the information submitted i s incomplete with respect to the
sub-littoral species some broad conclusions may be drawn. (I) The dominants in the eu-littoral are essentially different: Splachnidium and Scytothamnus at Cape Maria van Dieman; Pachymenia and Gigartina alveata at Scott Point.
5 5
(II) Durvillea i s dominant on the limit of the sub-littoral in all aspects at Scott Point, but at Cape Maria van Dieman it only grows where wave action is excess ive . Elsewhere one finds Carpophyllum maschalocarpum. Since the rest of the algal flora is essentially different at these two stations a temperature phenomenon probably operates in association with the wave exposure. Scott Point i s favourable for the growth of Durvillea in respect to both temperature and exposure; while at Cape Maria van Dieman the author considers the water temperature is generally unsuitable for the growth of Durvillea. Consequently this algae grows only in the exposed positions where C. maschalocarpum will not grow successfully.
(in.) The cold water which upwells around the Three Kings Islands may explain the absence of several North Cape spec ies .
SUMMARY
It is found that the cessation in dominance of D.antarctica at Cape Maria van Dieman is accompanied by a complete change in the algal community composition compared with that at Scott Point. This could be explained by climatic change, caused by
(a) the absence of any cold upwelling water at Cape Maria van Dieman and/or
(b) influence of warm water currents. These warm water currents could come from a main current flowing in from the north east, which would not affect the Three Kings Islands or Scott Point.
R E F E R E N C E S
"Notes on the Marine algal ecology of some exposed rocky shores of Northland, New Zealand". Bot.1(3/4),
86. "Population studies on the Toheroa." "Marine Zonation on Marotiri Island". Tane 7. "Algae of the Three Kings Islands, New Zealand". Rec. Auck. Inst. Mus. Vol.4, No.4. 199-204.
"Intertidal communities of the Poor Knights Islands New Zealand". Trans. Roy. Soc. N.Z. 67:375 "The Ecology of the Sub-littoral Boulder Beaches at the Little Barrier Island". Tane 10. "Molluscan evidence of Pliocene Climatic change in New Zealand". Trans. Roy. Soc. N.Z. 74-207 "The Sub-tropical convergance in New Zealand Surface waters". N.Z. J.Geol. Geop. 2:315 "The Ecology of Rocky Shores". E.U.P. "An Introductory Study of the Marine Algal Ecology of Open Coast Area at Leigh". Tane 9. "The free swimming plankton Copepoda — geographical distribution John Murray expdn. 1933-34". Sci. Repts. B.M.(N.H.)8, 321-592.
Bergquist P.L. 1959
Cassie R.M. 1955 Chambers T.C. 1955 Chapman V.J. 1954
Cranwell L.M. & Moore L.B. 1938
Dromgoole F.I. 1964
Fleming C.A. 1944
Garner D.M. 1959
Lewis J.R. 1964 Sylvester M.B. 1963
Sewell R.B.S. 1948
