9780521861724htl 1..2

diversity assemblage structure varied with the mesh sizes of the sieves used to

extract the animals from the sediment. Within an apparently homogeneous area

of coarse intertidal sand in the Isles of Scilly, UK, samples were extracted using a

standard range of five mesh sizes (63, 125, 250, 500, 1000mm), with the sample

areas and distances between samples scaled to the mesh size. All metazoans in

each of the sample sets were identified to species level. Diversity and dominance

patterns showed a dramatic stepwise change between the 250mm and 500mm

mesh-size samples, being relatively constant in the< 500 mmand> 500 mmcate-

gories, with diversity higher in the former (Figs.11.7 & 11.8 ). This suggested a

fractal structure within but not between the< 500 mmand> 500 mmbody-size

categories (cf.Schmid & Schmid-Araya, this volume). This clear meiofauna/

macrofauna dichotomy, Warwicket al.(2006 ) argued, supports the view that the

important relationships are those between body size and various biological char-

acteristics such as feeding behaviour, reproductive mode and life history as they

are affected by the spatial and temporal structure of the environment.

Syllidae <8 setigers

Nephtyiidae

Nereidae <7 setigers

Polydora sp.

Streblospio

benedicti

Prionospiop sp.

Capitellidae

Orbiniidae

Cirratuldae

Clymenella

torquata

Terebellidae

Oligochaeta <1 mm

Nereidae 8–12

setigers

Oligochaeta >1 mm

Amphipoda

Bivalvia

(shell broken)

Nematoda

Enhydrosoma sp.

Other harpacticoid

copepods

Acoel B

Convoluta sp.

Turbellarian A

Macrostomum

beaufortensis

Archiloa wilsoni

Neochildia fusca

1 mm

MEIOFAUNA LARVAL MACROFAUNA

sp.

Figure 11.4The meiofaunal and

young macrofaunal diets of two

species of meiobenthic

turbellarians,Neochildia fuscaand

Archiloa wisoni. All animals drawn

to scale. Note the large size of

many prey items relative to the

body size of the predators (after

Watzin, 1985 ).

BODY SIZE AND DIVERSITY IN MARINE SYSTEMS 217