English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The ascidian Pyura stolonifera (Heller) is an important component of the filter-feeding community off the coast of South Africa. Scanning electron microscopy of the inhalant siphon, pharyngeal basket and gut contents of freshly-collected ascidians suggests that the food supply comprises a muted resource of phytoplankton cells of 3 to 5pm diameter, particulate detritus and diatoms. There is a progressive concentration of cells of 3 to 5 km diameter during passage through the pharynx, and these form a dominant component of the material taken into, and lysed in the gut. Some diatoms and detritus are also ingested, but to a large extent pass through the gut undigested. Digestive enzyme activity in the endostyle was negligible, but protease, chitinase, laminarinase and cu-amylase were of importance in the gut. Very little cellulase activity occurred in the gut, and there was no evidence of significant bacterial involvement in the decomposition of complex polysaccharides. This indicates that phytoplankton is likely to be of more significance in the diet of P. stolonifera than the refractory components in the water column. The relatively high specific activity of carbohydrases in the gut results in a large energetic gain relative to estimated carbon losses through respiration. P. stolonifera thus appears to be well-adapted to exploit the eplsodic phytoplankton availability which characterises the southern Benguela upwelling system, and in this respect resembles the mussel Chorornytilus meridionalis which, together with P. stolonifera, forms the major suspension-feeding component in the kelp beds off the west coast of the Cape Peninsula. It therefore seems likely that the particulate matter which dominates the water column in kelp beds enters the decomposer pathway and does not represent a nutritional resource which is exploited directly by the filter-feeding community.

Exploitation of phytoplankton as a food resource by the kelp bed ascidian Pyura stolonifera