Geoscience Reference
In-Depth Information
(a)
95
15
90
54
3
6
2
1
8
1
10
9
85
7
12
13
80
14
75
0
100
200
Number of species
(b)
90
1
4
3
5
12
10
6
2
9
11
7
85
8
80
13
15
75
70
14
65
0
100
200
300
Number of species
Figure 14.2
Funnel plots of delta
+
for the EPT data from (a) bank habitats and (b) channel habitats. The numbers
indicate the salinity categories (Table 14.1). Too few EPT species were recorded in category 16, which was excluded
from both plots.
for the bank habitat (Table 14.1). Although such
manipulation is common (but quite tedious) when
comparing species data collected with different
amounts of sampling effort, less of the data from
sites with large numbers of samples are used
and some uncertainty surrounds values that rely
on extrapolation. Delta
Both the study by Kefford
et al
. (2011) and this
one present a different picture of the effect of
salinity on diversity of aquatic insects in south-
eastern Australia (based on field data) than that
presented by Hart
et al
. (1991); they suggested that
field records of salinity indicated that a threshold of
about 1.6 mS cm
−
1
existed, above which diversity
of aquatic insects declined markedly. The current
study does not show a marked threshold at this
salinity level (category 8) either for all insect species
or just for the EPT species. Kefford
et al
. (2011)
showed that species richness of aquatic insects
does not depend on
extrapolation, can be calculated after minimal
manipulation of the raw data, and has been used
successfully to identify disturbed sites from datasets
of marine biota (Clarke and Warwick, 2001) and
benthic insects from rivers (Marchant, 2007).
+
