The Distribution of Some Cladocera and Free‐Living Copepoda in British Columbia

105

The species composition of limnetic zooplankton communities in 27 Colorado lakes has been determined on the basis of 148 vertical series of plankton-trap samples. Each such series consisted of three or more evenly spaced samples taken from surface to bottom in the limnetic area. Comparable quantitative data for 42 selected lakes in other parts of the world are also considered, such samples having been taken with the plankton trap, pump, Clarke-Bumpus sampler, closing net, etc.Momentarily, the great majority of Colorado limnetic communities contained one or two species of copepods, one to three species of cladocerans, and three to seven species of rotifers. Comparable data for other small to medium-sized lakes of the world were one to three copepods, two to four cladocerans, and three to seven rotifers. From a species standpoint, therefore, these limnetic communities are remarkably simple. Depending on the complexities of cyclic and seasonal abundance, however, the individual species making up Ihcsc communities change from one time of the year to another. The most common and widely distributed North American species are contained in the following genera: Cyclops, It is unusual to find more than one species in the same genus in a limnetic community at the same time, at least when ordinary quantitative sampling methods are used. But when two spccics in the same genus do occur together, one is usually 20 or more times as abundant as the other. These and other phenomena arc discussed with particular reference to the "niche" concept.In spite of the cyclic waxing and waning of populations of individual zooplankton species, the great majority of limnetic communities are characterized at any one time by one numerically dominant species of copepod, one dominant cladoceran, and one dominant rotifer. Thus, adequate sampling in "typical" lakes shows that, on the average, 80 per cent of all limnetic copepods belong to one spccics, 78 per cent of all cladocerans belong to one species, and 64 per cent of, all rotifers to one species.

Section: Communitiesmentioning

confidence: 99%

Species Composition of Limnetic Zooplankton Communities1

Pennak

1957

105

“…Of the species associations reported in our study, only the associations of D. stagnaZis and D. sanguineus in temporary ponds (Wilson and Moore 1953) and D. Zeptopus and D. nudus (Wilson 1958) have been reported previously. As most records of congeneric associations arc based on a few scattered collections ( Carl 1940;Whittaker and Fairbanks 1958) and not on samples collected successively over a period of time, there is little previous evidence of coexistence of the species reported here. Of the mechanisms for congeneric associations suggested by Sandercock ( 1967), coexistence of some of the species pairs in this study on the basis of vertical segregation would be most difficult to explain.…”

Section: Discussionmentioning

confidence: 58%

“…The size differences observed among coexisting species of Diaptomus by Carl ( 1940) were elaborated on by Hutchinson ( 1951), Cole ( 1961), andSandercock ( 1967) as possible reasons for the lack of competition among these species. Fryer ( 1957) Seasonal separation of congeneric spetics is important in this study.…”

Section: Discussionmentioning

confidence: 99%

“…According to the principle of competitive exclusion (Hardin 1960) implied by Darwin's work and known by many names since that time, two closely related species cannot coexist in the same habitat and utilize the same resources, On the basis of evidence from his own extensive Colorado lake studies ( Pennak 1955( Pennak , 1957) and Carl's (1940) British Columbia lake surveys, Pennak ( 1957, p. 227) concluded that, with few exceptions, this was the case among the Calanoid copepods. He stated that: "When two limnetic calanoids are found together it is very seldom that they are both species of Diaptomus, rather it is one Diaptomus and an additional species of Limnocalanus, Epischura or SeneceZla."…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

SEASONAL SUCCESSION AND CONGENERIC ASSOCIATIONS OF DIAPTOMUS SPP. (COPEPODA) IN SOME SASKATCHEWAN PONDS1

Hammer

Sawchyn

1968

“…Before Hrbacek, species distributions were discussed in terms of such physicochemical factors as gradients of salinity (Moore 1952;Whittaker and Fairbanks 1958;LaBarbera and Kilham 1974), altitude and temperature (Dodds 1919;Carl 1940), or of trophic status of the lake (Patalas and Patalas 1966), to give a few examples from a large literature.…”

mentioning

confidence: 99%

Body size patterns in arctic and temperate zooplankton1

Dodson

1979

Do zooplankton species occur in discrete associations of large and small species? In 36 arctic tundra ponds near Barrow, Alaska, there were 21 examples of a large species association, 9 of a small association, and 6 intermediate associations. Statistically, the species do show evidence of nonrandom association. The literature of comparative examples is used to investigate the significance of intermediate species associations in the arctic ponds and elsewhere. Intermediates are found to occur, and in some cases make up a high proportion of the observed cases. Distinct associations are the result of a constellation of the proper chemical, physical, and biological factors and, for that reason, distinct associations are expected to be uncommon.