Search

This study aims to determine the influence of the quality of food on specific dynamic action (SDA) in the ascidian Ciona intestinalis and thereby if respiratory measurements of SDA can be used to monitor the quality of a potential food source. Weight specific rates of filtration, ingestion and respiration of C. intestinalis were examined using two different experimental methods. Two food sources were selected, the flagellate Rhodomonas sp. representing a high-quality food source and the eelgrass Zostera marina representing a potentially low-quality food source. In spite of insignificant differences in weight specific rates of filtration and ingestion of Rhodomonas sp. and Z. marina, significant differences in weight specific respiration rates and weight specific ingestion rates of C. intestinalis at different particle concentrations of the two food sources were found. Ingestion of Rhodomonas sp. resulted in a SDA coefficient of 20%, whereas the respiratory increase after ingestion of Z. marina was insignificant. From the experimental results it is concluded that SDA of C. intestinalis is strongly dependent on the quality of the food ingested. [ABSTRACT FROM AUTHOR]

The functional response of the appendicularian Oikopleura dioica was investigated with a unialgal diet (Isochrysis galbana, 0–1,600 µg C l–1) and with additions of specific concentrations of algae either smaller than the incurrent filter mesh size (Rhodomonas baltica, 90 µg C l–1; Thalassiosira weissflogii, 60 µg C l–1) or larger algae (Ceratium lineatum, 8 µg C l–1; C. tripos, 52 µg C l–1). Clearance ranged from 0.13 to 3.3 ml µg C–1 h–1 and followed a Michaelis–Menten curve corresponding to a maximum filtration rate (particles collected by both animal and house), FRmax=164 ng C µg C–1 h–1 and Km=64 µg C l–1. Maximum pellet production was 9 pellets ind–1 h–1 and occurred at 100 µgC l–1. Pellet production was proportional to filtration rate below this level, but declined at higher concentrations. House production ranged from 0.5 to 5.5 houses ind–1 day–1 and the corresponding curve fit resulted in Hmax=4.6 houses ind–1 day–1 and Km house=32 µg C l–1. Addition of edible small algae caused increased internal clogging of the houses, evidenced by significantly higher pigment concentrations in abandoned houses than in houses produced with I. galbana as a single food. House production was not affected. In contrast, larger algae caused a significantly higher house production, but the algae were not collected on the houses. Increased levels of edible algae will not have negative effects on O. dioica at ecologically realistic concentrations. Ambient bloom concentrations of larger algae may, however, have a negative effect on the growth of O. dioica populations, owing to the compensatory increased house production. [ABSTRACT FROM AUTHOR]

Provides information on a study which determined the beat frequency of the lateral cilia in the openings of the branchial sac of the ascidian Ciona intestinalis. Materials and methods used on the study; Results; Discussion.