Tropical Tidal Flat Benthos Compared Between Australia an Central America
277
valid within tropical latitudes by comparing species with similar ecological roles, looking especially at those roles implying interactions between species.
We faced several constraints for the comparison: The studies carried out in
tidal flats of Australia and Central America had not been designed for a
comparative analysis and differed in their respective aims, durations as well
as in the methods used. We therefore restrict most of the comparison to the
macrofauna size fraction retained on a 500-l1m sieve, leaving out the smaller
mesofauna (Dittmann 1995). Furthermore, the taxonomy of benthic invertebrates is much better known from Central America than from northern Australia. Because of this and the few available studies on tropical tidal flats in the
Pacific, a detailed biogeographic comparison of benthic diversity remains a
future endeavor. Throughout the comparison we indicate research demand
for tropical tidal flats. Mangroves and seagrass beds, which also occur in the
intertidal of tropical coasts, were excluded from the comparison.
13.2 Tropical Tidal Flats in Australia and Central America
Tidal flats can develop where a tidal range of greater than 1 m occurs in combination with an appreciable distance between high and low water line and a
prevalence of soft sediments (Veenstra 1976). At the study sites in Australia
and Central America compared here, tides were semidiurnal with average
tidal ranges of about 2-3 m (Table 13.1). However, tidal ranges can vary from
1 to >9 m along the coast of northern Australia (Lane 1987).
The following sites were used for the comparison (Fig. 13.1). Data on
macrobenthos from tidal flats in tropical Australia were available from Wells
(1983) for the Bay of Rest in West Australia and from Dittmann (1995, 1996,
2000) for Hinchinbrook Channel and the Haughton River estuary in North
Queensland. Further records were available from Alongi (1987, 1988) and
Pepping et al. (1999). In Central America, tidal flats in the Estero de Jaltepeque
(El Salvador) were surveyed for Polychaeta by Hartmann-Schroder (1959)
and her sites were re-sampled by Molina in 1990-1991 (Molina 1992; Molina
and Vargas 1994, 1995). In the sheltered location of the Gulf of Nicoya (Costa
Rica), Vargas (1987, 1988, 1989, 1996) studied a mudflat at Punta Morales and
a further site (Cocorocas) located nearby. Further records were available from
foreshore tidal flats in Panama (Kaufman 1976; Lee 1978).
The studied sites differed in their areal extent and comprised different
types of tidal flats. While tidal flats on the Pacific coast of Central America
often cover a few square kilometers, and are more scattered and isolated
coastal habitats, large coherent tidal flats exist in West Australia. The north-
277
valid within tropical latitudes by comparing species with similar ecological roles, looking especially at those roles implying interactions between species.
We faced several constraints for the comparison: The studies carried out in
tidal flats of Australia and Central America had not been designed for a
comparative analysis and differed in their respective aims, durations as well
as in the methods used. We therefore restrict most of the comparison to the
macrofauna size fraction retained on a 500-l1m sieve, leaving out the smaller
mesofauna (Dittmann 1995). Furthermore, the taxonomy of benthic invertebrates is much better known from Central America than from northern Australia. Because of this and the few available studies on tropical tidal flats in the
Pacific, a detailed biogeographic comparison of benthic diversity remains a
future endeavor. Throughout the comparison we indicate research demand
for tropical tidal flats. Mangroves and seagrass beds, which also occur in the
intertidal of tropical coasts, were excluded from the comparison.
13.2 Tropical Tidal Flats in Australia and Central America
Tidal flats can develop where a tidal range of greater than 1 m occurs in combination with an appreciable distance between high and low water line and a
prevalence of soft sediments (Veenstra 1976). At the study sites in Australia
and Central America compared here, tides were semidiurnal with average
tidal ranges of about 2-3 m (Table 13.1). However, tidal ranges can vary from
1 to >9 m along the coast of northern Australia (Lane 1987).
The following sites were used for the comparison (Fig. 13.1). Data on
macrobenthos from tidal flats in tropical Australia were available from Wells
(1983) for the Bay of Rest in West Australia and from Dittmann (1995, 1996,
2000) for Hinchinbrook Channel and the Haughton River estuary in North
Queensland. Further records were available from Alongi (1987, 1988) and
Pepping et al. (1999). In Central America, tidal flats in the Estero de Jaltepeque
(El Salvador) were surveyed for Polychaeta by Hartmann-Schroder (1959)
and her sites were re-sampled by Molina in 1990-1991 (Molina 1992; Molina
and Vargas 1994, 1995). In the sheltered location of the Gulf of Nicoya (Costa
Rica), Vargas (1987, 1988, 1989, 1996) studied a mudflat at Punta Morales and
a further site (Cocorocas) located nearby. Further records were available from
foreshore tidal flats in Panama (Kaufman 1976; Lee 1978).
The studied sites differed in their areal extent and comprised different
types of tidal flats. While tidal flats on the Pacific coast of Central America
often cover a few square kilometers, and are more scattered and isolated
coastal habitats, large coherent tidal flats exist in West Australia. The north-