Emersion Induces Nitrogen Release and Alteration of Nitrogen Metabolism in the Intertidal Genus Porphyra

Abstract

We investigated emersion-induced nitrogen (N) release from Porphyra umbilicalis Kütz. Thallus N concentration decreased during 4 h of emersion. Tissue N and soluble protein contents of P. umbilicalis were positively correlated and decreased during emersion. Growth of P. umbilicalis did not simply dilute the pre-emersion tissue N concentration. Rather, N was lost from tissues during emersion. We hypothesize that emersion-induced N release occurs when proteins are catabolized. While the δ15N value of tissues exposed to emersion was higher than that of continuously submerged tissues, further discrimination of stable N isotopes did not occur during the 4 h emersion. We conclude that N release from Porphyra during emersion did not result from bacterial denitrification, but possibly as a consequence of photorespiration. The release of N by P. umbilicalis into the environment during emersion suggests a novel role of intertidal seaweeds in the global N cycle. Emersion also altered the physiological function (nitrate uptake, nitrate reductase and glutamine synthetase activity, growth rate) of P. umbilicalis and the co-occurring upper intertidal species P. linearis Grev., though in a seasonally influenced manner. Individuals of the year round perennial species P. umbilicalis were more tolerant of emersion than ephemeral, cold temperate P. linearis in early winter. However, the mid-winter populations of both P. linearis and P. umbilicalis, had similar temporal physiological patterns during emersion.

Variability in δ 15 N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

“…The release of both inorganic and organic compounds has been detected in several macroalgal species (Fong et al, 2004;Tyler and McGlathery, 2006). It was attributed to a response to different stressors (Young et al, 2009) and particularly to emersion (Kim et al, 2013). As far as we know, there are no reports of nitrogen release in the species considered in this study, but our results suggest that this process is enhanced in the zone with large changes in salinity.…”

“…The main intrinsic factors affecting variability of macroalgal δ 15 N are the preferential mobilization of light isotopes (isotopic fractionation) during uptake, excretion and metabolic reactions (Teichberg et al, 2008) and intra-frond variability (Carballeira et al, 2014;Raimonet et al, 2013;Savage and Elmgren, 2004;Viana et al, in review). External factors are littoral position (Kim et al, 2013) or light (Dudley et al, 2010).…”

Development of a sustainable land-based Gracilaria cultivation system

“…Studies on Chondrus crispus revealed that the first inorganic element to be depleted in tank cultures is inorganic carbon, due to rapid absorption of CO 2 /HCO 3 showed CO 2 enhancement led to increased growth in Gracilaria (Gao et al 1993), Chondrus (Craigie and Shacklock 1989), and Porphyra (Friedlander and Levy 1995, Israel et al 1999, Friedlander 2001, Figueroa et al 2010. The commonly used nutrient media for indoor cultivation of red seaweeds is von Stosch enrichment medium (VSE) (Corey et al 2012, 2013b, Redmond et al 2014. VSE contains several important nutrients including nitrate, phosphate, iron, manganese, EDTA, and vitamins (vitamin B 12 , thiamine, and biotin).…”

“…The commonly used nutrient media for indoor cultivation of red seaweeds is von Stosch enrichment medium (VSE) (Corey et al 2012, 2013b, Redmond et al 2014. VSE contains several important nutrients including nitrate, phosphate, iron, manganese, EDTA, and vitamins (vitamin B 12 , thiamine, and biotin).…”

The effects of short- and long-term freezing on Porphyra umbilicalis Kützing (Bangiales, Rhodophyta) blade viability

“…Seaweeds inhabiting the upper intertidal zone are subjected to a wide variety of temperature, light, and water stresses, most notably freezing and desiccation. It has been shown that species growing in the upper intertidal zone can survive extensive desiccation and osmotic stress with little physiological damage (Abe et al, 2001;Kim and Garbary, 2004;Kim et al, 2013;Liu, 2009;Smith et al, 1986;Zou and Gao, 2002).…”