Nutritional and related experiments on laboratory maintenance of three species of symbiont-bearing, large foraminifera

Abstract

Abstract. Factors were examined that affect survival and growth of two common species of large foraminifera from the Red Sea, Amphisorus hemprichii Ehrenberg and Amphistegina lobifera Larsen, 1976. The former is host for dinoflagellate and the latter for diatom zooxanthellae. Experimental conditions were modeled on conditions at 25 m during spring at Wadi Taba, Gulf of Elat, Israel, the season and site where the experimental organisms were collected between 1983 and 1988. The two species responded quite differently in nutritional experiments.A. hemprichii grew, on average, 0.270 mm in diameter in 3 mo on a diet of Nitzschia subcommunis Hustedt, Chlorella sp. (clone AT) or Cylindrotheca closterium Rabenhorst isolated from their native habitat. Unfed controls did not grow. In contrast, unfed populations of A. lobifera grew as well or better than those that were fed unialgal diets. Growth of both species was enhanced on particular mixed algal diets. Both species required photosynthetically active symbionts. Even when fed weekly and supplied with nutrients, neither species survived in the dark. All individuals of A. hemprichii died after 8 wk incubation in the dark; A. lobifera survived longer, but all were dead by 13 wk. The highest growth rate of A. hemprichii (0.037 mm wk-1) was obtained when they were fed, the medium was enriched, and the medium was changed weekly. All other conditions being the same, growth rate dropped to 0.009 mmwk -1 when the medium was changed every 3 wk. In contrast, A. lobifera grew fastest when the medium was changed every 3 wk. Food or enrichment with nitrate or phosphate did not stimulate growth (0.03 mm wk-1) over that of the controls. Specimens of Marginopora kudakajimensis Gudmundsson from Japan, another dinoflagellate-bearing species, were also tested. They grew best (0.02 mm wk-t) when cultured in light, in media enriched with nitrate and phosphate changed weekly, and fed. All three species withdrew nitrate and phosphate from the medium in chemostat experiments.

Ocean acidification induces biochemical and morphological changes in the calcification process of large benthic foraminifera

“…Thus, although symbionts play an important role in providing energy to their respective hosts [61], we suggest that the differences in responses observed between A. lessonii and M. vertebralis are owing more to differences in calcification mechanisms rather than symbiont type. figure 4a,c).…”

Interactive effects of climate change and eutrophication on the dinoflagellate-bearing benthic foraminifer Marginopora vertebralis

“…Both the diatom-bearing species Amphistegina lobifera and the Symbiodinium-bearing species Amphisorus hemprichii showed no growth response to nitrate or phosphate enhancement in static experiments (Lee et al 1991). In separate experiments, growth in those species (Kuile ter et al 1987) and two other diatom-bearing species (Röttger et al 1980) increased somewhat under inorganic nutrient addition when compared to starved individuals.…”

Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers

“…Furthermore, cultured foraminifers were not fed during the experiments. Lee et al (1991) showed that food availability did not influence growth rates of symbiont-bearing perforate (hyaline) foraminifer (Amphistegina lobifera), whereas imperforate (porcelaneous) foraminifers (Amphisorus hemprichii and Marginopora kudakajimensis) grew better in fed conditions than in unfed conditions. Therefore, all these variables might have not been optimum conditions for cultured foraminifers.…”