9780521861724htl 1..2

two, the 12 8 C difference in temperature between normal and warmed commun-

ities had no significant effect (Fig.13.2, Table13.2), and in analysis three there

was no apparent effect of the different temporal patterns of temperature varia-

tion (Fig.13.3, Table13.3).

Community consequences of body size – results

The slope of the relationship between total density and mean cell mass was

0.93 in analysis one (Fig.13.4),0.81 in analysis two (Fig.13.5) and0.35 in

analysis three (Fig.13.6). Again, results were therefore more similar in commun-

ities that contained species from multiple trophic levels (analyses one and two)

compared with communities containing only one trophic level. The exponent for

all communities in analysis one was not different from unity, indicating that the

2 species

6 species

10 species

14 species

18 species

–8

0

2

4

6

–7 –6 –5 –4 –3 –2

Log 10 (Cell mass (mg))

Log

10

(Density per ml)

(a)

–8

0

2

4

6

–7 –6 –5 –4 –3 –2

Log 10 (Cell mass (mg))

Log

10

(Density per ml)

(c)

Expt. 1

Expt. 2

Expt. 3

Autotroph

Bacterivore

Omnivore

–8

0

2

4

6

–7 –6 –5 –4 –3 –2

Log 10 (Cell mass (mg))

Log

10

(Density per ml)

(b)

Figure 13.1Size-abundance

relationship for analysis one, which tests for

influence of (a) species richness, (b) species

trophic position, and (c) experiment on the slope

of relationship.

252 O.L. PETCHEYET AL.