Effect of food concentration and type of diet on Acartia survival and naupliar development

Abstract

We have performed life table experiments to investigate the effects of different food types and concentrations on the larval development and survival up to adulthood of Acartia tonsa. The food species offered comprised a wide taxonomic spectrum: the pigmented flagellates Isochrysis galbana, Emiliania huxleyi, Rhodomonas sp., Prorocentrum minimum, the diatom Thalassiosira weissflogii, grown on medium offering enriched macronutrient concentrations and the ciliate Euplotes sp. initially cultured on Rhodomonas. For the ciliate species, also the functional response was studied. In order to avoid limitation by mineral nutrients, food algae have been taken from the exponential growth phase of the nutrient replete cultures. The suitability of Rhodomonas as a food source throughout the entire life cycle was not a surprise. However, in contrast to much of the recent literature about the inadequacy or even toxicity of diatoms, we found that also Thalassiosira could support Acartiadevelopment through the entire life cycle. On the other hand, Acartia could not complete its life cycle when fed with the other food items, Prorocentrum having adverse effects even when mixed with Rhodomonas and Thalassiosira. Isochrysis well supported naupliar survival and development, but was insufficient to support further development until reproduction. With Emiliania and Euplotes, nauplii died off before most of them could reach the first copepodite stages. Acartia-nauplii showed a behavioral preference for Euplotes-feeding over diatom feeding, but nevertheless Euplotes was an insufficient diet to complete development beyond the naupliar stages.

Simultaneous shifts in elemental stoichiometry and fatty acids of <i>Emiliania huxleyi</i> in response to environmental changes

“…Macronutrients were added as sodium nitrate (NaNO 3 ) and potassium dihydrogen phosphate (KH 2 PO 4 ) to achieve three N : P supply ratios, i.e., 35.2 µmol L −1 N and 3.6 µmol L −1 P (10 : 1 mol mol −1 ), 88 µmol L −1 N and 3.6 µmol L −1 P (24 : 1 mol mol −1 ) and 88 µmol L −1 N and 1.4 µmol L −1 P (63 : 1 mol mol −1 ). Vitamins and trace metals were added based on the modified Provasoli culture medium (Ismar et al, 2008;Provasoli, 1963). Initial pCO 2 of the culture medium was manipulated by bubbling with air containing the target pCO 2 .…”

Calcifying invertebrates succeed in a naturally CO<sub>2</sub>-rich coastal habitat but are threatened by high levels of future acidification

“…Rhodomonas sp. was cultured in 0.2 µm filtered seawater enriched with Provasoli seawater (PES) medium (Ismar et al, 2008), phosphate, and nitrate at a final concentration of 0.036 mmol l −1 P and 0.55 mmol l −1 N in plastic bags at 7.5 l each under constant illumination. Mean algae concentrations in the experimental aquaria were 820 ± 315 cell ml −1 .…”

Moderate seawater acidification does not elicit long-term metabolic depression in the blue mussel Mytilus edulis

“…Seawater perfusing the experimental aquaria contained a Rhodomonas suspension enabling continuous food supply. Rhodomonas were cultured in Provasolis medium II according to Ismar et al (2008) )-enriched seawater. Algae concentration was monitored at weekly intervals using a Coulter Counter (Z2, Beckman Coulter TM ).…”