Phosphate and Nitrate Uptake Dynamics in Palmaria palmata (Rhodophyceae): Ecological and Physiological Aspects of Nutrient Availability

Abstract

Uptake dynamics of dissolved inorganic phosphate (DIP) and dissolved inorganic nitrate (DIN) in young Palmaria palmata (n = 49), cultivated in a range of DIP concentrations (0.0-6.0 µmol Á L À1) and nonlimiting DIN concentration (50 µmol Á L À1) under fully controlled laboratory conditions, were quantified in a 'pulse-and-chase' approach over 5 weeks. Two different uptake rates were specified: (1) surge uptake (V S) after starvation and (2) maintenance uptake with filled nutrient pools (V M). V S for DIP of 1.57 AE 0.29 µmol Á cm À2 Á d À1 and DIN of 15.6 AE 4.3 µmol Á cm À2 Á d À1 , as well as V M for DIP of 0.57 AE 0.22 µmol Á cm À2 Á d À1 and DIN of 5.6 AE 2.1 µmol Á cm À2 Á d À1 were calculated. In addition, an absolute size of the internal storage capacity (ISC) for DIP of 22 µmol Á cm 2 and DIN of 222 µmol Á cm 2 was determined. A DIP-to-DIN uptake ratio of 1:10 under V M showed a weekly rhythmic uptake pattern, highlighted by a high correlation between DIP and DIN uptake (R = 0.943). V S for DIN did not occur under DIP depletion, but uptake rates increased with increasing DIP availability. Hence, DIP availability limited access to DIN, which was also reflected by total dissolvable protein concentrations in sporophytes, which ranged from 10.2 AE 2.5% to 24.6 AE 8.0% dry weight depending on DIP availability. Similarly, total dissolvable carbohydrate concentration ranged from 22.1 AE 3.6% to 54.3 AE 12.3% dry weight. The data presented in this study open further insight into ecological and physiological aspects of nutrient availability in P. palmata and allow for an optimization in cultivation.

Species-Specific Response of Corals to Imbalanced Ratios of Inorganic Nutrients

“…Overall, DIP enrichment (DIN:DIP 0.5 ) increased the total carbon (as carbohydrates) and nitrogen content of coral tissue without altering the internal elemental stoichiometry. These results are consistent with the notion that the availability of a limiting nutrient (especially phosphorus) promotes the uptake and/or assimilation of the other nutrients [ 52 , 53 ]. This is also consistent with a previous study showing that the carbon content in Montipora digitata symbionts increased significantly when DIP was increased in seawater [ 41 ].…”

“…The results of this study first show that changes in seawater DIN:DIP ratios can induce changes in nutrient uptake rates by the scleractinian coral T. reniformis . Uptake of DIN and DIP at different DIN:DIP ratios has been poorly studied in photosynthetic organisms and never with coral species to our knowledge (see [ 51 , 52 ] for macroalgae, [ 53 ] for cyanobacteria, and [ 54 ] for trees). This study first confirms the findings of previous studies that uptake rates are dependent on the nutrient concentration in seawater, with increased uptake rates at high nutrient concentrations (DIN:DIP 3 ) [ 51 , 52 , 53 ].…”

“…Uptake of DIN and DIP at different DIN:DIP ratios has been poorly studied in photosynthetic organisms and never with coral species to our knowledge (see [ 51 , 52 ] for macroalgae, [ 53 ] for cyanobacteria, and [ 54 ] for trees). This study first confirms the findings of previous studies that uptake rates are dependent on the nutrient concentration in seawater, with increased uptake rates at high nutrient concentrations (DIN:DIP 3 ) [ 51 , 52 , 53 ]. Furthermore, our results demonstrate that the availability of one nutrient increases the uptake rate of the other nutrient, as has been observed in phytoplankton species but not in corals [ 53 ].…”

Growth, nitrate uptake kinetics, and biofiltration potential of eucheumatoids with different thallus morphologies

“…Lubsch and Timmermans (2018, 2019) showed that Laminaria digitata and Saccharina latissima had reduced growth when cultured in a medium containing >6.0 µM phosphate and Ulva lactuca had reduced phosphate uptake when exposed to >7.0 µM phosphate. However, Palmaria palmata exhibited increased nitrate uptake rate when phosphate levels are increased (Lubsch and Timmermans 2020). In our land‐based culture, the relatively high TIP value of 1.60 ± 0.02 seems to pose no detrimental effects to the four strains of eucheumatoids since growth was observed during the entire cultivation period.…”

Een eerste verkenning van indices voor het bepalen van ecologische draagkracht t.b.v. zeewierkweek

“…Zeewier en het fytoplankton verschillen in N:P ratio wat kan leiden tot een verschil in opname, wat uiteindelijk kan resulteren in een verschil in N:P ratio in het milieu. Deze N:P ratio in het water is van belang omdat voor sommige soorten algen de opname tussen N en P gekoppeld is, zoals voor Blaaswier (Fucus vesiculosus) en Dulse (Palmaria palmata) (Perini & Bracken 2014, Lubsch & Timmermans 2020. In de afgelopen decennia heeft er reeds een grote verschuiving in deze ratio in kustwateren van de Noordzee plaatsgevonden door het aan banden leggen van stikstof en fosfor gebruik (Burson et al 2016) in onder meer de landbouw en schoonmaakmiddelen.…”