Rates of sediment ejection were recorded from 20 burrows of the echiuran worm Maxmuelleria lankesteri at monthly intervals over a 13-month period. Environmental parameters, numbers of ejecta mounds and the spatial persistence of burrows were also monitored. All 20 marked burrows retained signs of occupation over the study year. Sediment turnover was recorded in all months, with no cessation of activity over the winter. Volumes of sediment expelled during each 2-day measurement period were extremely variable, up to a maximum of similar to 97 g dry weight burrow(-1) day(-1). Over the year, the mean ejection rate from 20 burrows was 7.53+/-5.24 S.D. g burrow(-1) day(-1), with peaks of activity recorded in December and April. The superficial sediment (on which M. lankesteri feeds) was very rich in organic matter, with monthly values of 11.7-16.7% sediment dry weight. Thermally labile organic matter, determined by combustion at 250 degrees C, comprised 16.7-71.4% of the total organic content, with highest and lowest values in April and August, respectively. There was no significant correlation between monthly sediment ejection rate and total sediment organic content, but a highly significant correlation was found between ejection rate and the percentage of labile material in the sediment organic matter. Ejection rate remained constant at labile fractions below similar to 50%, but increased sharply above this threshold. Topographic relief and numbers of feeding traces at the site suggested that activity level was lowest in late summer (August-September). Burrows appeared to be static, and the animals sedentary in habit. Individual ejecta mounds could persist for up to 15 months. There was no evidence that the worms alternated the functions of the feeding and ejection openings of their burrows. This burrow stasis contrasts with the pattern seen in some deep-sea echiurans, a behavioural difference probably determined by the nutritional status of the respective habitats. (C) 1999 Elsevier Science B.V. All rights reserved.
|Number of pages||15|
|Journal||J EXP MAR BIOL ECOL|
|Publication status||Published - 1999|
- Marine & Freshwater Biology
- BIKINI ATOLLS
- SHRIMP CALLIANASSA-SUBTERRANEA