The Role of Body Size in Complex Food Webs: A Cold Case - Advances in Ecological Research - page 193

feed on alive prey of higher trophic levels but also at lower trophic levels
(i.e. plants and detritus).
A third group was made up of herbivorous crawling benthic predators

(n ¼ 34), swimming omnivorous benthopelagic (n ¼ 1) and swimming pelagic

predators (n 23): this included all those species that feed on lower trophic

levels (i.e. plants and detritus).
The fourth groups were omnivorous crawling benthic predators and sca-
vengers (n

¼

¼ ¼ ¼

75), swimming benthopelagic (n 40), swimming pelagic (n 22)

¼

and swimming land-based (n 4) omnivorous benthic predators and scaven-

gers, which included all those species that feed on alive prey but also recently
killed prey items.
Finally, there was a fifth group that included herbivorous/detritivorous
crawling benthic grazers (n

¼ 39), swimming herbivorous/detritivorous pelag-

ic grazers (n ¼ 12) and sessile herbivorous/detritivorous benthic suspension

feeders (n 112).

There was not a significant relationship between a species body mass and
trophic level across all consumer species ( Figure 3 ). However, if we separated
the data using the feeding classifications listed above, it became clear that
there were certain functional groups in which a relationship exists, and others
where it was absent. The relationship between trophic level and body size
was significant in all true carnivorous predator types (carnivorous pelagic
predators r 2 : 0.46, p: 0.0056; carnivorous benthic predators r 2 : 0.49,
p: 0.0527) and in all land-based predator types (carnivorous land-based
predators r 2 : 0.49, p: 0.0453) ( Figure 4 , Table 2 ). In all other trophic types,
especially omnivorous predator/scavenger types as well as detritivorous

¼

5

4

3

2

1

- 10 0 1

Mean mass (log 10 )

Figure 3 Pairwise relationships between body mass and trophic position across all
species of the high Antarctic Weddell Sea.