Burrow morphology and dynamics of mudshrimp in Asian soft shores

Mudshrimps are important soft shore bioturbators but research on the ecology of tropical species has received less attention when compared with their temperate counterparts. The mudshrimp Austinogebia edulis is common on Asian soft shores and lives in burrows for its entire adult life. Epoxy resin casting of A. edulis burrows showed that they were approximately Y-shaped, with an upper U-part and the lower central shaft part. The burrows had two openings extending to the surface; the mean distance between the two openings was 11.0 cm in Hong Kong and 26.4 cm in Taiwan. Openings of the burrows had small chimneys. The tunnels of the burrows were circular, narrow and with a smooth surface (tunnel diameter corresponded to shrimp carapace width). Each burrow was inhabited by a single shrimp and burrows were inter-connected during the mating and reproductive season. Each burrow had four to 12 spherical chambers, which were free of detritus. The chambers were thought to be used for suspension feeding, current generation and as turning points. The depth of burrows was up to 1.1 m. Multivariate analysis on various burrow parameters showed that burrows collected on a mud flat in Taiwan were deeper, had a wider distance between the openings and a larger volume than burrows collected from a sandy shore in Hong Kong, suggesting that burrow architecture is variable between shore types. Burrow architecture, however, did not vary between tidal levels, seasons and shrimp density on the shores in Hong Kong, indicating that the burrows were quite stable within the substratum and were not affected by environmental and biological factors.