Tropical Tidal Flat Benthos Compared Between Australia an Central America
281
species accounted for 95 % of the individuals, leaving 2/3 of the species
represented with few specimens (Vargas 1987). Such a low species frequency
was found in other tropical tidal flats as well (Reise 1991; Wolff et al. 1993a;
Pepping et al. 1999). The high number of rare species implies the need for
more extensive sampling programs to assess also those species with low
population densities. It also poses questions as to the co-existence of the
many species and the availability of niches in tropical tidal flats.
13.3.2 Similarity in Taxonomic Compositions
The macrofauna in the tropical tidal flats in Australia and Central America is
mainly composed of polychaete, crustacean and mollusc species (Fig. 13.2).
Polychaeta account for about half of all species both at the Central American
sites and the Hinchinbrook Channel in Australia. At the other Australian sites,
molluscs or crustaceans were richer in species.
To compare taxonomic similarity, the taxa in common were counted and
the S0rensen index QS (S0rensen 1948) calculated for each taxonomic level
(Table 13.2). This comparison gives a first idea on taxonomic similarity at
Table 13.2. Similarity in the taxonomic composition of macrobenthos recorded from several tropical tidal flats in Australia and on the Pacific coast
of Central America. Records are based on unpublished species lists of the
authors and records by Jones and Morgan (1994), Hartmann-Schroder
(1959) and Molina and Vargas (1994). The values are based on the present
state of taxonomic descriptions and could change with ongoing taxonomic
work and revisions
Australia
America Taxa in common
Qsa
Entire macrobenthos
Phyla
14
11
11
0.88
Class
17
16
16
0.97
Order
34
29
28
0.89
Family
94
65
53
0.67
Genus
203
135
41
0.24
Species
336
173
0
0
Polychaeta
Order
14
12
12
0.92
Family
41
32
30
0.82
Genus
103
66
26
0.31
Species
184
86
0
0
a QS=S0rensen index (2 xC/(A+B), where A and B are the taxa in each area
and C the number of taxa in common).
281
species accounted for 95 % of the individuals, leaving 2/3 of the species
represented with few specimens (Vargas 1987). Such a low species frequency
was found in other tropical tidal flats as well (Reise 1991; Wolff et al. 1993a;
Pepping et al. 1999). The high number of rare species implies the need for
more extensive sampling programs to assess also those species with low
population densities. It also poses questions as to the co-existence of the
many species and the availability of niches in tropical tidal flats.
13.3.2 Similarity in Taxonomic Compositions
The macrofauna in the tropical tidal flats in Australia and Central America is
mainly composed of polychaete, crustacean and mollusc species (Fig. 13.2).
Polychaeta account for about half of all species both at the Central American
sites and the Hinchinbrook Channel in Australia. At the other Australian sites,
molluscs or crustaceans were richer in species.
To compare taxonomic similarity, the taxa in common were counted and
the S0rensen index QS (S0rensen 1948) calculated for each taxonomic level
(Table 13.2). This comparison gives a first idea on taxonomic similarity at
Table 13.2. Similarity in the taxonomic composition of macrobenthos recorded from several tropical tidal flats in Australia and on the Pacific coast
of Central America. Records are based on unpublished species lists of the
authors and records by Jones and Morgan (1994), Hartmann-Schroder
(1959) and Molina and Vargas (1994). The values are based on the present
state of taxonomic descriptions and could change with ongoing taxonomic
work and revisions
Australia
America Taxa in common
Qsa
Entire macrobenthos
Phyla
14
11
11
0.88
Class
17
16
16
0.97
Order
34
29
28
0.89
Family
94
65
53
0.67
Genus
203
135
41
0.24
Species
336
173
0
0
Polychaeta
Order
14
12
12
0.92
Family
41
32
30
0.82
Genus
103
66
26
0.31
Species
184
86
0
0
a QS=S0rensen index (2 xC/(A+B), where A and B are the taxa in each area
and C the number of taxa in common).