Premium
The trophic role of colonial Radiolaria in oligotrophic oceanic environments 1, 2
Author(s) -
Swanberg Neil R.
Publication year - 1983
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1983.28.4.0655
Subject(s) - radiolaria , biology , trophic level , water column , photosynthesis , photic zone , chlorophyll a , pelagic zone , respiration , oceanography , botany , phytoplankton , ecology , nutrient , geology
Five species of colonial Radiolaria collected by divers on 27 cruises were used for experimental metabolic measurements. Carbon content as an indicator of colony size correlated well with cell number in three species, with approximately 50, 100, and 200 ng C per cell. Chlorophyll a per radiolarian cell (from symbiotic dinoflagellates) varied widely between colonies and could not be predicted from colony size by better than a factor of 2. Photosynthetic carbon incorporation at high levels of natural light ranged from 10 to 76 pmol C · cell −1 · h −1 . Mean respiration in two species was 5.3–5.5 µ l O 2 · mg C −1 · h −1 . Respiration is probably balanced by photosynthesis under normal light conditions. Colonial Radiolaria were present at 92% of 268 oceanic stations and very abundant at 34%. Measured abundances ranged from 0.04 to 14 colonies · m −3 in the water column and reached 540 colonies · m −3 in patches at the surface. Because the primary productivity of their symbionts is probably consumed in maintenance metabolism, colonial Radiolaria may be most important to the epipelagic oligotrophic ecosystem as gelatinous predators.