Comparative study of water-processing in two ciliary filter-feeding polychaetes (Ditrupa arietinaandEuchone papillosa) from two different habitats

• Published in: Marine ecology. Progress series (Halstenbek) 2002-01, Vol.229, p.113-126
• Main Authors: Riisgård, H. U., Grémare, A., Amouroux, J. M., Charles, F., Vétion, G., Rosenberg, R., Nielsen, C.
• Format: Article
• Language: English
• Subjects: adaptation to the environment; Animal and plant ecology; Animal, plant and microbial ecology; Animals; ascidian ciona-intestinalis; Autoecology; banyuls-sur-mer; biochemical-composition; Biological and medical sciences; Biological Sciences; Biologiska vetenskaper; Chemical suspensions; Cilia; Crown rump length; Ditrupa arietina; Ecology; ectoprocts bryozoa; Ekologi; energy-cost; Euchone papillosa; Fall lines; feeding structures; Filtration; filtration rates; filtration-rate; Fundamental and applied biological sciences. Psychology; Larvae; Marine; mytilus-edulis; Ocean, Atmosphere; oxygen-consumption; particle -retention mechanism; physiological regulation; Phytoplankton; Protozoa. Invertebrata; Pumping; Rhodomonas; sabella-penicillus; Sciences of the Universe; Sea water; suspension-feeding; Worms
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps229113

A comparative study of feeding rates and structures was made with the 2 ciliary filter-feeding polychaetesDitrupa arietinaandEuchone papillosafrom the Mediterranean Sea (Gulf of Lions, France) and the Gullmarsfjord (Sweden), respectively. The feeding rate (clearance) was measured as the volume of water cleared of 6 μm diameter flagellate cells (Rhodomonassp.) per unit time. Most experiments were conducted at algal concentrations equivalent to about 0.4 to 3.8 μg chlorophyllal–1. The clearance rates of ‘standard’ 1.5 mg dry wtE. papillosaand ‘standard’ 3.0 mg dry wtD. arietinashowed that the maximum weight-specific clearance rate was 114.7 ml h–1mg–1forE. papillosaand about 7 times lower, 15.7 ml h–1mg–1, forD. arietina. A relative large tentacle crown inE. papillosa, resulting in the higher specific clearance rate, may be the evolutionary result of ‘minimal scaling’ and adaptation to extremely low food concentrations. When the algal concentration was increased from 2000 to 10 000 cells ml–1a 50% decrease in the clearance rate was observed inD. arietina, presumably because the gut capacity was exceeded. A more pronounced tendency to become satiated was found forE. papillosa. No tendency to reduce the filter-feeding activity at even very low algal concentrations was noticed in the 2 polychaetes, and the filtering activity of both worms seems to be a basically continuous process. Video-microscope observations ofE. papillosashowed that suspended algal cells approaching the pinnules suddenly accelerate and move through an arc of over 180° to be delivered on the frontal side of the pinnule. The transfer takes place at a maximum distance (radius) of about 25 μm from the pinnule. Scanning micrographs show the compound lateral cilia to be 20 to 25 μm long in bothD. arietinaandE. papillosaand to consist of 1 row of 4 cilia. The feeding current is generated by these compound cilia, which, during their power stroke, catch up with the particles.