With the prosecution of an increasing number of local and regional studies of the New Zealand littoral (Oliver, 1923, Cranwell and Moore, 1938, Chapman, 1950, Dellow, 1950, Carnahan, 1952), most authors have recognised and described certain communities which were encountered. Others—e.g., Knox (1953), discuss the ecology of individual species. With the exception of Oliver's community descriptions, all are for restricted areas. Apart from an unpublished account by Cooper of the salt marsh at Hobson Bay, Auckland, no attempt has yet been made to correlate the information amassed in the above literature. This is most easily accomplished by means of Tables (Tables VI, VII). As is so often the case, ecological studies in this country have been hampered through insufficient knowledge of the taxonomy of the species concerned; and this applies even to a number of dominants.*
Littoral ecologists are generally agreed in the belief that the ecological units of rocky coasts are climax in nature, in spite of their small, often minute, spatial
[Footnote] * The following names used by Oliver (1923) and others have been changed as indicated in the present account:—
|Stypocaulon paniculatum||= Halopteris spicigera|
|Zonaria turnariana||= Z. subarticulata|
|Glossophora harveyi||= G. kunthii|
|Ecklonia richardsonia||= E. radiata var. richardiana|
|Caulacanthus spinellus||= Gelidium pusillum|
|Amphiroa corymbosa||= Cheilosporum corymbosum|
|Turbo smaragdus||= Lunella smaragda|
|Ostrea cucullata||= Saxostrea glomerata|
|Modiolus pulex||= Volsella neozelanicus|
|Vermilia carinifera||= Pomatoceros coeruleus|
|Hermella spinulosa||= Sabellaria kaiparaensis|
dimensions and their relatively brief duration in time. This gains expression in both the major subdivisions (formations or biomes) and in the smaller climax categories listed in Tables VI and VII. In following the schema of T. A. and Anne Stephenson (1949, p. 299) the present writer does not deny the probable validity of the formations noted previously (see Column 2 of Table VI). But for the same reason that “community” is used instead of “association”—i.e., that our basic knowledge of the true status of these divisions of the rocky shoreline is far from complete, it seems wiser at present to omit the term “formation” altogether, whilst relating each zone or subzone to its relevant section of the littoral.
To avoid confusion over upper, mid- and lower midlittoral, the Stephensons' (1952, p. 27) practice of naming each belt or zone after its chief characteristic—e.g., oyster zone, muddy zone, is perhaps the most convenient one to follow. On the other hand one finds it hard to avoid using such terms as upper, mid- and lower midlittoral (cf. Trevarthen, 1953, Fig. 3), especially where there is no conspicuous delimiting organism.
The adlittoral—i e., maritime, land vegetation on the most seaward continuous soil (Johnson and Skutch, 1928; Trevarthen, 1953) is beyond the scope of consideration of this survey.
Table VII reflects the change in ecological concepts which has taken place over the past 30 years. All New Zealand writers in this field have adopted a biotic approach, the chief improvements lying in a more precise delimitation of each unit, especially in relation to tide levels and amount of emergence and submergence, as well as in the recognition of seral groups, where they exist (Cooper, unpub.; Carnahan, 1952).
Oliver (1923) made the first genuine attempt to classify the confusing multiplicity of forms occurring between New Zealand tide marks, when the subject of littoral zonation was in its infancy. Regarding an “animal-and-plant formation” as “a biotic community with its principal ecological groups in definite combination and in definite relation to the habitat”, Oliver distinguishes between forma
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Oliver (1923)||Chapman (1950)||Trevarthen (1953)||Dellow|
|Supralittoral zone||Supralittoral zone|
|Littorina formation||Supralittoral fringe||Supralittoral fringe|
|Shelled animals formation||Upper Midlittoral|
|Barnacle formation||Mid-Midlittoral||Midlittoral zone|
|Coriaceous coated animals formation||Lower Midlittoral|
|Small emerging algae formation||Lower littoral mixed algae formation||Sublittoral fringe||Sublittoral fringe|
|Large brown kelp formation||Sublittoral brown kelp formation||Sublittoral zone||Sublittoral zone|
The scheme followed in the present work coincides with that proposed by T. A. and Anne Stephenson (1949, p. 299) except in the use of ‘sub’ for ‘infra’-littoral. (In the first two columns the relation of zones to tide levels is only approximate.)
tions on rock and those on sand and mud. Thus a community on the above definition is equivalent to a wider unit embracing several “associations”, the latter corresponding approximately with the communities described in the ensuing text. Although the information in his paper is presented in such general terms, he describes a number of “formations” and “associations” which are prominent in the Hauraki Gulf, particularly those in Auckland Harbour and at Takapuna. His lists of subordinate species remain of considerable value to the littoral ecologist, but there is a need with our increased knowledge in this field for relating of the communities more precisely to their habitat. This has been achieved to a certain extent by later writers, for restricted localities.
Cranwell and Moore (1938, p. 380) take an association to be composed of species which “form an interdependent unit in equilibrium with the existing environment” the dominants having power to “exclude all invaders of similar life form and requirements”. These writers have contributed a sufficiently detailed account of the Poor Knights littoral communities to provide a basis of comparison with the present survey of the Hauraki Gulf. The concept of single dominance is still upheld; however, in the Nemastoma, Xiphophora, Durvillea, Carpophyllum elongatum and Lessonia associations. Like later writers (cf. Table VII), Cranwell and Moore have not been able to decide with certainty the status of certain groups which fall outside their definition of the littoral, in this case of lichens and Cyanophyceae; and so they have used the noncommital term “community”. Their employment of terms such as biocoenose, epibiose and hypobiose, used also by several European authors, has not been followed here.
Chapman, Beveridge, Dellow and Carnahan have carried the process of classifying the groups further by defining them more accurately in terms commonly used in climax land ecological terminology, while Carnahan and Cooper give due recognition to the seral nature of Zostera and Avicennia, together with several algal “socies” densely clothing mangrove stems and pneumatophores, dominated by Caloglossa, Catenella, Rhizoclonium and sometmes also the barnacle Elminius modestus. The fact that the mangrove swamp is seral in nature is considered sufficiently valid grounds for treating the associated algal groups in a like manner.
Owing to longer periods of observation on each area, the above-mentioned studies have shed more light on seasonal aspect communities. Following on this segregation of different types of community one could proceed almost indefinitely with the recognition of different units, whether one prefers to call them fasciations, sociations, clans, families, or similar terms; in fact the number of subdivisions made to date has appeared to depend at least partly on the length of time each writer spent in studying a particular locality, as well as on his or her chief interest. The fact remains that our knowledge of the majority of littoral communities comes from purely subjective observation; and until dominance is placed on a statistical basis we cannot be sure of the exact ecological status of a given assemblage. To avoid further multiple usage, therefore, the present writer feels it necessary to abandon the previous practice of attaching a narrowly defined term to a seemingly distinct littoral group of species.
Obviously, some communities will be more restricted in time and space than others, and certain dominants will hold sway according to minor variations in the habitat. It is not to be expected that any one community will be found in
|Author||Oliver (1923)||Cranwell & Moore (1938)||Chapman (1950)||Beveridge & Chapman (1950)||Dellow (1950)||Carnahan (1952)|
|Locality||New Zealand||Poor Knights||Stanmore Bay||Piha||Nerrow Neck||Rangitoto|
|Associations||Caulacanthus; Bostrychis Porphyra; Ulva Corallina-Hormosira Corallina; Xiphophora Carpophylaum-Lessonia Durvillea Helaraphe Cellana-Monodonta Cellans-Monodonta Cellans-Nerita E. Plicatus; C. columns Vermilia; Modiolus Ostrea; Mytilus Corella; Cynthis||Chthamalus, Apophloea- [ unclear: ] Novastoa-encrusting coralline Xiphophora Carpophyllum elongatum Rhodophyceae Lessonia||Melaraphe-Lichina. Chamaesipho-Volsella-(Apophloea) Vermilis-Saxostrea Hormosira-Corallina Carpophyllum-Ecklonia||Lichina pygmaea-Melaraphe Chamaesipho Modiolus-C. columns Vermilia-Hermella Durvillea-Mytilus Mytilus-attached algae Cladhymenia-Schizymenia Vidalia-Melanthalia-Pterocladia lucida||Calothrix-Melaraphe Enteromorpha-Gelidium-Volsella Chamesipho-Klminius-Saxostrea Hermella-Vermilia Corallina-Hormosira Encrusting coral line Carpophyllum-Ecklonia||Melaraphe-Lichina Chamesipho-Apophloea Chamaesipho-Saxostrea Corallina-Hormosira Carpophyllum-Ecklonis|
|Consociations||Bostrychia arbuscula Gigartina alveata Pachymenia himantophora Gigartina marginifera||Calothrix Melaraphe Enteromorpha Volsella C. columns E. modestus Saxostrea||Hormosira|
|Fasciations||Klminius-Scytothamnus||Caloglossa-Catenella Myxophyceae Klminius-Modiolus Mytilus canaliculus-Tunicate|
|Communities||Lichen Verrucaria & Cyanophycae (+ Melaraphe)||Fresh-Water seepage||Brackish water||Mytilus-attached, algae|
|Aspect Societies||Chthamalus-Porphyra||Nemastoms oligarthra Splachnidium Scytosiphon lomentaria Colpomenia sinuosa Myriogloia lindauerii Ilea fascia||Porphyra-Bangia Myriogloia Helminthocladia Splachnidium||Enteromorpha bulboss-Monostroma|
another ecologically similar locality exactly as it is described here. Nevertheless widening experience of the behaviour of intertidal biota shows the remarkable selectivity of a certain organism (or organisms) for a particular type of environment. The occurrence of Bostrychia arbuscula and B. mixta on southerly, moist and shaded rock faces near high water may be cited as an algal example; and the restriction of Tethya fissurata, the golf ball sponge, to caves and the undersides of overhangs is an instance of animal preference.
The question arises whether there is any such concrete entity as a community on the rocky shore. It is true that we might grow accustomed in zonation studies to thinking of belts or zones of individuals rather than of communities as basic units. It is not proposed to discuss the community concept in detail here, but it should be mentioned that most New Zealand writers on intertidal ecology, and indeed, many from overseas (e.g., Feldmann, 1938; Gislén, 1943, 1944; Womersley, 1947, 1948) have regarded the grouping of plants and animals which they observed as being composed of communities, chiefly of associations. T. A. and Anne Stephenson (1949, p. 301) see no objection to calling a subzone of, say, the “infralittoral” fringe a community, although they have not adopted the system, generally speaking. They do point out, however, that our present knowledge of the status of such groups is by no means clear.
For the purposes of this work the definition of Dice (1952, p. 15) appears to be a suitable one. He considers an ecologic community to be “an assemblage of ecologically related organisms composed of two or more species”. If only one species is present, as in several seasonal units on the seashore, the term “society” should be applied.
The time factor in connection with the community status is one which needs further investigation. On a brief visit to the rocky coast one is confronted by a community complex which represents a seasonal cross section of a reticulation formed by the origin, growth, decline and regeneration of each unit. An analogy comes to mind from the complex vascular structure of a dictyostelic fern. A cross section at a particular level portrays only an incomplete impression of the structure of the whole, and yet is a considerable aid in understanding the fundamental anatomy of the stele. The concept of a community complex as a cross section of a reticulate system is infinitely more complex, nevertheless it is a necessary one before a complete picture of intertidal (and also land) biota can be obtained. In other words one should be familiar with the geological age of a particular shore, with the time during which ecological factors (both tidal and climatic in this case) have undergone no major change, and with the seasonal appearances and fluctuations in abundance of the constituent organisms.
After consideration of all previous accounts of biotic communities in the littoral region of the Hauraki Gulf, the writer has attempted in the following list to note each unit in terms of its general occurrence, in preference to repeating the more detailed descriptions already published for the majority of communities from restricted localities. A generalised picture of dominance has been aimed at, rather than an exhaustive list of the many component species. No account has been taken of the biota beneath overhangs or below movable boulders. Information arising out of the Hauraki Gulf survey has been summarized from a more extensive account (Dellow, unpub.).*
[Footnote] * Ph.D. thesis, 1953.