Inter-tidal Ecology at Narrow Neck Reef, New Zealand 
(Studies in Inter-tidal Zonation 3.) 1 
Vivienne Dellow 2 
INTRODUCTION 
The PLANT and attached animal communi- 
ties at Narrow Neck Reef, Auckland, have 
been studied in relation to factors that may 
be concerned with determining their vertical 
zonation. Observations were made between 
January, 1947, and July, 1948. 
Certain levels on the shore appear to be 
more critical than others in determining the 
upper and lower limits of species and of 
communities; these levels may coincide with 
heights above low water at which there is a 
sudden change in environmental conditions. 
In accordance with the general aim of this 
series, an investigation has been made into 
the number and position of levels which may 
be critical at Narrow Neck. 
Acknoivledgments: The writer wishes to 
express her sincere appreciation to Professor 
V. J. Chapman for assistance and helpful 
criticism throughout this work; to Dr. G. F. 
Papenfuss and to Miss L. B. Moore for advice 
on the text; to Mr. V. W. Lindauer for assist- 
ing with the identification of Phaeophyceae 
and Rhodophyceae; to Mr. J. E. Morton for 
identification of the animals; and to Mr. L. 
Finch for help with the compilation of the 
map. 
TERMINOLOGY 
While it is not proposed to enter into a 
lengthy discussion on the controversial topic 
1 This paper forms part of a thesis presented for 
a Master of Arts degree at Auckland University 
College (University of New Zealand) in October, 
1948. An abridged version was read before the 
Botany Division of the Seventh Pacific Science 
Congress at Auckland, in February, 1949. 
2 Department of Botany, Auckland University 
College. Manuscript received August 1, 1949. 
of marine ecological terminology, it does 
appear essential to state precisely the sense 
in which each term is employed. However, 
it seems unreasonable to me either to give 
new meanings to words now in current use 
in ecological nomenclature, or to impose a 
new series of technical terms on an already 
overburdened vocabulary. 
As the word "littoral” has been used in 
so many different ways, I prefer to call that 
part of the shore between extreme high 
water mark of spring tides and extreme low 
water mark of spring tides the "inter-tidal 
region,” where these extreme levels are the 
means of monthly extremes for the locality 
over a number of years. The area between 
Mean Extreme Low Water Spring Tide and 
Extraordinary Low Water Spring Tide ( — 
Auckland Harbour Board Datum) corre- 
sponds to Stephenson’s sublittoral fringe. Be- 
low this is the sublittoral or subtidal region, 
which is never exposed by the tide. That part 
of the shore from above Extreme High Water 
Spring Tide to the upper limit of wind-borne 
spray is regarded as the supralittoral, or supra- 
tidal region. It includes the somewhat arbi- 
trary "splash” and "spray” zones, neither of 
which is of much importance at Narrow 
Neck. 
Within the inter- tidal region exists a num- 
ber of marine biotic communities. Some 
authors consider that these should be treated 
as though they were equivalent to terrestrial 
climax communities. In general, however, 
the marine units occupy smaller areas and 
may be much less long-lived, owing to the 
shorter life-history of the component organ- 
isms and to the super-position of the tidal 
factor on the climatic complex. On the other 
hand, because of this relative impermanence 
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