Chapter 1 - Núria BONADA

Chapter 3
Chile and SAustralia have 2 common stoneflies (Austroperlidae and Eustheniidae) absent in
other med-regions.
Many connections are found between north and southern hemisphere, as Noteridae or
Platycnemidae in Med-Basin and South Africa, or Corylidae in South Africa, Chile and
California. A relationship between northern hemisphere and South Africa or Chile is noticed,
with some coldstenoterm families in fast flowing waters as Heptageniidae, Lepidostomatidae or
Goeridae only in South Africa, California and Med-Basin; or as for example Perlidae,
Psychomyiidae and Limnephilidae in the northern hemisphere and Chile. Other linkages
between both Hemispheres are recent because the human introductions of Mollusca (Physidae
in Australia, Hydrobiidae in Med-Basin, Corbiculiidae in California) or Crustacea (Cambaridae
in Med-Basin and Grapsidae in California and Med-Basin).
When the list of taxa is analyzed for each med-region according to several multimetric indexes
(Figure 4a-h), a differential composition among med-regions is found (Figure 4d-h).
Communities from northern hemisphere have higher richness in Ephemeroptera, Plecoptera
and Trichoptera, while in the southern hemisphere Coleoptera, Heteroptera, Diptera and non-
Insect are more abundant. Taxa richness (as number of taxa) is slightly higher in Med-Basin
(125), California (119), South Africa (104) and SAustralia (120), compare with Chile (92) and
SWAustralia (98). However, even though this similarity in richness, taxonomical composition
between med-regions is different (Figure 4b-h). Number of EPT appears to be high in Med-
Basin, California, Chile and SAustralia (Figure 4b), because a major number of Plecoptera
(Figure 4f), while is low on South Africa and SWAustralia with only one stonefly family
(Notonemouridae and Gripopterygindae, respectively) (Annex 1). On the other hand, the low
value of EPT/OCH in Australia would indicate that although having a high EPT value, the
OCH are more important than in other med-regions (Figure 4h). In general, in southern
hemisphere the percentage of non-insect taxa is higher, because of the presence of many
crustacean families (Figure 4d). This phenomenon is more important in Australia and South
Africa than in Chile, because in this last region the community is mainly composed by
Ephemeroptera, Plecoptera and Trichoptera, being more similar to the northern hemisphere
one at order level (Figure 4e-g).
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