However, this takes scientists tolerant to frustration, as I can tell from experience how easily experiments are destroyed by cyclones or other disturbances. Further experiments are surely needed to comprehend ecological processes in tropical tidal flats. Vargas detected only a negligible effect with his experimental exclusion of macropredators. Yet, while my studies on soldier crabs and on burrow infauna supported the relevance of species interactions in benthic communities of tropical tidal flats, José A.

Excluding the burrows experimentally removed their home and resulted in reduced infaunal numbers and a modified benthic assemblage ( Dittmann 1996 ).

I could show that this process is of equal importance in tropical tidal flats by investigating the burrows of severas macrobenthic species and finding associated meiofauna in all cases. However, interactions can also be promotive, as had been shown in temperate tidal flats, where certain worms provide microhabitats for associated organisms in their burrows ( Reise 1985 ). The predator-prey relationship I studied between soldier crabs and meiofauna was a case of repressive interaction. They were crabs of the genus Dotilla (Ocypodidae), forming an analogue to the Australian Mictyridae.Īll these species interact in some way and I wanted to find out whether their interactions affect benthic communities in tropical tidal flats. During more recent visits to sandflats in East Africa and Malaysia, I had a real déjà-vu, seeing herds of little crabs wandering around there.

I could show with my studies and exclusion experiments that soldier crabs (Mictyris longicarpus, Mictyridae) take up meiofauna for food and affect infaunal community composition, one example for the existence of biotic interactions in tropical tidal flats ( Dittmann 1993 ). Fiddler crab colonies give colourful sparks on the greyish mud and herds of soldier crabs roam the flats on their foraging trails, littering the sediment with pellets from their feeding activity ( Fig. These crabs are adapted to spend the low tide period out of the water, although some occasionally retreat into their burrows to replenish their gills with water. Yet, while scurrying across the mud in tropical tidal flats, I typically found decapod crustaceans active on the sediment surface. There is a lot of scope for further surveys and taxonomic efforts to investigase the biodiversity of tropical tidal flats.īringing corer, shovel and sieve into the field is essential to study tidal flat fauna, as most of the organisms are leading a secret live hidden in the sediment ( Fig. Yet, when I plotted a species-area curve it was disillusioning to see that I had not even fully assessed the species stock. Altogether I recorded nearly 500 species of benthic animals in the tidal flats of North Queensland and quite a few of them are awaiting proper names. This component of the tropical benthos had been overlooked before ( Dittmann 1995 ). This was further aggravated by my use of severas mesh sizes to separate the animals from the sediment, as finer sieves yielded more and more organisms, especially polychaete species of small individual size. Every other specimen in my samples belonged to a yet unseen new species. Soon I learned what it means to work in the tropics. Not just finding access to tidal flats through the bush or from the sea, but getting to know all the creatures in the sediment (the benthos) and the tracks they leave on the sediment surface at low tide turned into a major pastime of mine. I was heading out into uncharted territory in many ways.

Stuck in qu stuck in quicksand