Nitrogen and phosphorus ecophysiology of coralline algae
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23RD INTERNATIONAL SEAWEED SYMPOSIUM, JEJU
Nitrogen and phosphorus ecophysiology of coralline algae Hang T. T. Nguyen 1,2
&
Daniel W. Pritchard 1,3 & Christopher D. Hepburn 1
Received: 27 July 2019 / Revised and accepted: 11 December 2019 # Springer Nature B.V. 2020
Abstract The characteristics of nutrient uptake in macroalgae are generally well known but surprisingly little is known about nutrient uptake in coralline algae despite their ecological importance and extensive depth distribution. This study provides the first information on nitrate, ammonium and phosphate storage and uptake by articulated and crustose coralline algae that are dominant features of temperate subtidal rocky reefs. A comparison was made between an articulated coralline alga, Arthrocardia sp. in the Corallinales and crustose coralline spp. within the Hapalidiales. Seawater nutrient concentration and nutrient storage by coralline algae were monitored between June 2016 and November 2017 in a kelp forest in southern New Zealand. Time-course nutrient depletion experiments were conducted to determine appropriate incubation times for multiple-flask experiments and evaluate maximal uptake of nitrate, ammonium, and phosphate over time in winter and summer. The uptake of ammonium exhibited a saturable kinetics with Vmax of Arthrocardia sp. (2.07 ± 0.32 μmol gDW−1 h−1) significantly higher than that of crustose coralline spp. (0.58 ± 0.17 μmol gDW−1 h−1). A linear relationship with concentration was observed in nitrate and phosphate uptake by both coralline algae. Ammonium was considered a preferred nitrogen source for these corallines compared with nitrate in both summer and winter. Morphological difference is suggested to be an important factor resulting in the difference in nitrogen and phosphorus uptake rates and kinetic parameters of these corallines. Further research is required to understand if these differences are general attributes of the functional ecology of crustose and articulated corallines. Keywords Coralline algae . Rhodophyta . Kinetics . Morphology . Nutrient . Uptake
Introduction Macroalgae must take up and assimilate nitrogen and phosphorus, limiting nutrients for macroalgal growth, from seawater to support their primary productivity (Harrison and Hurd 2001). In seawater, nitrate (NO3−) and ammonium (NH4+) are the primary forms of nitrogen available for uptake, while phosphorus is found as phosphate (PO43-) (Dugdale and Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10811-019-02019-w) contains supplementary material, which is available to authorized users. * Hang T. T. Nguyen [email protected]; [email protected] 1
Department of Marine Science, University of Otago, PO Box 56, Dunedin 9054, New Zealand
2
University of Agriculture and Forestry, Hue University, 102 Phung Hung,, Hue City, Vietnam
3
Te Ao Tūroa, Te Rūnanga o Ngāi Tahu, PO Box 799, Dunedin 9054, New Zealand
Goering 1967; Jackson and Williams 1985; White and Dyhrman 2013). These nutrients
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