Zonation in the SeaStudies on the Scottish Marine Fauna: the Natural Faunistic Divisions of the North Sea asShown by the Quantitative Distribution of the Molluscs by A. C. Stephen; The Nature of theIntertidal Zonation of Plants and Animals by John ColmanReview by: Charles EltonJournal of Animal Ecology, Vol. 2, No. 2 (Nov., 1933), pp. 303-304Published by: British Ecological SocietyStable URL: http://www.jstor.org/stable/969 .

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Reviews 303

ZONATION IN THE SEA.

(1) A. C. Stephen. Studies on the Scottish marine fauna: the natural faunistic divisions of the North Sea as shown by the quantitative distribution of the molluscs. Trans. Royal Society of Edinburgh, 57, 601-16, 1933.

(2) John Colman. The nature of the intertidal zonation of plants and animals. J. Marine Biol. Ass. 18, 435-76, 1933.

(1) THE study of fisheries from an economic point of view and of the growth and numbers and migrations of fishes has far outstripped fundamental ecological work upon the animal and plant communities amongst which the fishes live and upon which they depend for food. In the end of the nineteenth century Hjort was working out the age distribution of the popula- tions of Norwegian cod. It was not until 1911 that Petersen published the first quantitative studies of marine bottom animal communities, and not until after the War that other workers (Stephen, Hagmeier, and Davis), together with Petersen, extended these preliminary surveys to cover a large part of the North Sea area. The comparatively great resources of marine fishery research have enabled these four surveys to accumulate large series of results from quantitative sampling, most of which cannot be printed, although such full publication is of great importance for a proper criticism of the work and the complete appli- cation of it to fishery problems and to ecological theory. This circumstance is creditable to the scientific workers, but not to an industry whose annual turnover in the British Isles is probably over two thousand times the amount of money spent (by the Government) on fisheryresearch. The present paper is a summary of the results of surveys inthe northern parts of the North Sea, and touches Davis's survey in the south. It deals with Mollusca, for which the author has already published important data (Trans. Roy. Soc. Edinb., 56, 291 and 521).

The work was mainly done between tide-marks, and at greater depths well beneath low- tide level, but a certain amount was done to connect these two zones of study. On the shore the main ecological divisions were found to be between sandy areas and muddy areas, sand occurring more on exposed coasts, while sand mixed with extraneous mud or interlayered with strong-smelling black mud was found in sheltered places, e.g. the Firth of Forth. On sandy habitats Tellina tenuis is the dominant lamellibranch, while on sand-cum-mud Macoma baltica and the cockle Cardium edule are the most abundant. At levels below this shore (intertidal) zone Tellina extends down to some 6 ft. below low-water mark. The author employs the term "littoral" to describe the region from high-water mark down to the limit of T. tenuis, but such a procedure seems perhaps rather arbitrary. Other molluscs have lower overlapping zones, e.g. Donax vittatus and Tellina fabula.

Coming to deeper levels, three zones or types of mollusc community are distinguished on the basis of the dominant species (meaning here the most abundant). It is not clear whether this result has been related to unpublished analysis of the zonation of the remaining members of the communities of animals, as would seem necessary if purely artificial communities are to be avoided. The coastal belt runs from littoral limits (6 ft.) down to about 120 ft. and is rich in mollusca. The offshore belt extends down to between 75 and 180 ft. and apparently is not entirely defined by its depths. The Thyasira (mollusc)-Foraminifera zone occurs in deeper waters to the north-east and again is rich in molluscs.

These results when mapped for the principal species show clearly how the shallow-water coast belts of the east of Scotland carry mollusc-zones similar to those of the Dogger Bank in the south, a fact summarised by the author in the statement that "the North Sea is best regarded as a large bay offset from the North-eastern Atlantic." He is to be congratulated on so neatly co-ordinating the results of four years intensive and arduous work with previous surveys and for clearing the way for further analysis of the extensive data already available for mapping the fish environments of the North Sea.

(2) The second survey noticed here covers in a more intensive way the relation of tidal habitats to the zonation of shore plants and animals. Four belt transects were made on Church Reef, which juts out in Wembury Bay at Plymouth. Exact profiles are published,

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304 304 Reviews Reviews

together with a description of the distribution of some of the main algae (eight species), one lichen, ten molluscs, and four Crustacea. The environment, though sheltered, is subject to surf action, which is shown to be an important factor in raising the effective height of "sea level" by 2 to 5 ft., so far as plants and animals are concerned. This splash zone is discussed in some detail, and the periodic limits of tide action are analysed in order to give accuracy to the definition of shore communities. The average curve for time and height of tide on the shore profile is somewhat complicated. The greatest numbers of species occur at low levels, and again at high levels, but the greatest concentration of the optimum ranges of species occurs in the intermediate zone. These results refer of course only to the common species studied. The author emphasises the desirability of using tidal data and not only heights as lines of reference for recording the occurrence of intertidal animals. Having thus accurately defined the zonation of various plants and animals (a thing which has seldom been properly done before, even in a small area like this), the author proceeds to discuss the problem of why the species have such definite zonation. It is pointed out that there are two modes of colonisa- tion, first by passive dispersal as in algae and many animal larvae (e.g. barnacles), and the second by active movement (as in Gasteropod molluscs). The potentialities of the latter process appear to be much restricted by the clearly marked tropisms that such species possess. These tropisms have been studied by various workers (especially on Littorina), but it is not yet clear how much the reactions are really related to the adaptive optima of the animals and how far they limit species that could otherwise range much further. There is no very clearly marked separation in habitat between species of the same genus (e.g. Littorina), the ranges being characteristic but greatly overlapping. We are left therefore with a remark- ably clear picture of an intertidal fauna, but as yet with no clearly seen reasons for the composition of the picture.

CHARLES ELTON.

SOCIAL INSECTS IN THE TROPICS.

Phil Rau. Jungle wasps and bees of Barro Colorado Island (Panama). 324 pp. (With numerous figures and an Appendix by J. Bequaert, describing new species of Polybia.) Published by the author, Kirkwood, Mo., U.S.A., 1933.

THIS book is mainly the fruit of Dr Rau's five weeks' visit in 1928 to the Barro Colorado Laboratory. The most important observations are those on the Stingless Bees (Trigona spp.) and on the Social Wasps (Polybinae and Polistinae). The Stingless Bees are an almost entirely tropical subfamily of which the species are extremely abundant and still very imperfectly known in South America. Their social life and the structure of their nests are in many ways unique and any additional information is very valuable. The Polybinae, again, are a sub- family of Social Wasps which is characteristic of South America where the species are very numerous. The classical works of von Ihering and Ducke have shown that the group is an extremely instructive one from the point of view of the taxonomist. Ducke's work, in particular, has shown that biological peculiarities-especially methods of nest construction- may indicate what structural features are of importance in the recognition of genera and species. Dr Rau has described and figured the nests of several species previously undescribed. His account, however, would have been more valuable if it had been brought more into relation with previous observations.

In dealing with the Polistinae, another group of Social Wasps, Dr Rau has been able to compare the habits of the tropical ones with those of temperate America, where his own observations are already well known. He is able to bring out a number of points of contrast, suggesting that adaptation to the environment has been considerable. In some of the solitary wasps, too, the author notes how behaviour is modified in relation to the sudden heavy rains of the tropical forest.

After a number of very miscellaneous observations onArthropods encountered in Panama, there follows a chapter in which Dr Rau summarises several years' observations on the North

together with a description of the distribution of some of the main algae (eight species), one lichen, ten molluscs, and four Crustacea. The environment, though sheltered, is subject to surf action, which is shown to be an important factor in raising the effective height of "sea level" by 2 to 5 ft., so far as plants and animals are concerned. This splash zone is discussed in some detail, and the periodic limits of tide action are analysed in order to give accuracy to the definition of shore communities. The average curve for time and height of tide on the shore profile is somewhat complicated. The greatest numbers of species occur at low levels, and again at high levels, but the greatest concentration of the optimum ranges of species occurs in the intermediate zone. These results refer of course only to the common species studied. The author emphasises the desirability of using tidal data and not only heights as lines of reference for recording the occurrence of intertidal animals. Having thus accurately defined the zonation of various plants and animals (a thing which has seldom been properly done before, even in a small area like this), the author proceeds to discuss the problem of why the species have such definite zonation. It is pointed out that there are two modes of colonisa- tion, first by passive dispersal as in algae and many animal larvae (e.g. barnacles), and the second by active movement (as in Gasteropod molluscs). The potentialities of the latter process appear to be much restricted by the clearly marked tropisms that such species possess. These tropisms have been studied by various workers (especially on Littorina), but it is not yet clear how much the reactions are really related to the adaptive optima of the animals and how far they limit species that could otherwise range much further. There is no very clearly marked separation in habitat between species of the same genus (e.g. Littorina), the ranges being characteristic but greatly overlapping. We are left therefore with a remark- ably clear picture of an intertidal fauna, but as yet with no clearly seen reasons for the composition of the picture.

CHARLES ELTON.

SOCIAL INSECTS IN THE TROPICS.

Phil Rau. Jungle wasps and bees of Barro Colorado Island (Panama). 324 pp. (With numerous figures and an Appendix by J. Bequaert, describing new species of Polybia.) Published by the author, Kirkwood, Mo., U.S.A., 1933.

THIS book is mainly the fruit of Dr Rau's five weeks' visit in 1928 to the Barro Colorado Laboratory. The most important observations are those on the Stingless Bees (Trigona spp.) and on the Social Wasps (Polybinae and Polistinae). The Stingless Bees are an almost entirely tropical subfamily of which the species are extremely abundant and still very imperfectly known in South America. Their social life and the structure of their nests are in many ways unique and any additional information is very valuable. The Polybinae, again, are a sub- family of Social Wasps which is characteristic of South America where the species are very numerous. The classical works of von Ihering and Ducke have shown that the group is an extremely instructive one from the point of view of the taxonomist. Ducke's work, in particular, has shown that biological peculiarities-especially methods of nest construction- may indicate what structural features are of importance in the recognition of genera and species. Dr Rau has described and figured the nests of several species previously undescribed. His account, however, would have been more valuable if it had been brought more into relation with previous observations.

In dealing with the Polistinae, another group of Social Wasps, Dr Rau has been able to compare the habits of the tropical ones with those of temperate America, where his own observations are already well known. He is able to bring out a number of points of contrast, suggesting that adaptation to the environment has been considerable. In some of the solitary wasps, too, the author notes how behaviour is modified in relation to the sudden heavy rains of the tropical forest.

After a number of very miscellaneous observations onArthropods encountered in Panama, there follows a chapter in which Dr Rau summarises several years' observations on the North

This content downloaded from 169.229.32.136 on Wed, 7 May 2014 15:46:42 PMAll use subject to JSTOR Terms and Conditions