Chapter Ill. CHARACTERISTIC ALGAL ASSOCIATIONS AND FORMATIONS AT 
WOODS HOLE AND IN BUZZARDS BAY AND VINEYARD SOUND. 
As stated in the preceding pages, the life habits and distribution of marine algee 
are affected by a number of factors, the most important of which are temperature, 
light, depth, character of the bottom, and salinity of the water. Some or all of these 
factors, and in special calses others as well, determine, as a rule, the habitats and sea- 
sons of the different species. As a result, various alge are frequently found to be 
characteristic of particular situations, where they constitute groups or formations 
of species. 
J. G. Agardh (1836) was the first to describe regions of algal vegetation, recog- 
nizing on the Scandinavian coasts the presence of a zone characterized by green alge 
(Regnum Algarum Zoospermarum), a zone of brown alge (Regnum Algarum Oliva- 
cearum), and a zone of red alge (Regnum Algarum F loridearum). Other authors have 
attempted similar, but more elaborate, divisions of the algal flora into regions and 
zones, but none have been very satisfactory for the reason that the brown and red 
alge have species which range far outside the depth or zone which is in general most 
characteristic of their class. 
It later became apparent that the alge must be split into smaller assemblages 
than the zones of green, brown, and red alge, and Kjellman (1877 and 1878), also in 
studies on the Scandinavian coast, developed such a classification in detail, applying 
the name ‘‘formation”’ to each group and usually naming each formation after the alga 
most characteristic of it. Kjellman’s paper of 1878, ‘‘Ueber Algenregionen und 
Algenformationen im 6stlichen Skager Rack,” stands, as far as the author is aware, 
as the first algological contribution introducing the methods and terminology of 
ecology as at present practiced. Later authors have followed the methods of K jell- 
man to a greater or less degree, and among them one of the most elaborate studies 
has been that of Bérgesen (1905), ‘‘The Alge Vegetation of the Feréese Coasts.” 
The reader will find in these two papers of Kjellman and Borgesen historical treat- 
ments of the literature, which need not be repeated here, especially since they deal 
with conditions in northern waters, which are very different from those at Woods 
Hole. 
Kjellman (1877) employed the terms “‘littoral,’’% “‘sublittoral,” and “elittoral” to 
define three regions of distribution, and these terms are in wide use among botanists 
and, with certain modifications of his definitions, they have replaced earlier expres- 
sions designating regions occupied by the green, the brown, and the red alge. Kjell- 
man defined the littoral region as that between lowest and highest tide marks, the 
sublittoral region as that from the lowest tide mark to the furthest depth at which 
alge will grow (about 20 fathoms on the Scandinavian coast), and the elittoral region 
as that bottom below the sublittoral. 
@ Cf. discussion on pages 178-180, section 1, of present report. 
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