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Effects of Heat Waves and Light Deprivation on Giant Kelp Juveniles ( Macrocystis pyrifera , Laminariales, Phaeophyceae)
Author(s) -
SánchezBarredo Mariana,
SandovalGil Jose Miguel,
ZertucheGonzález Jose Antonio,
Ladah Lydia B.,
BelandoTorrentes María Dolores,
BeasLuna Rodrigo,
CabelloPasini Alejandro
Publication year - 2020
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/jpy.13000
Subject(s) - macrocystis pyrifera , biology , kelp , photosynthesis , kelp forest , sporophyte , photoinhibition , botany , understory , shading , coral , ecology , canopy , photosystem ii , art , visual arts
Due to climate change, the incidence of marine heat waves ( MHW s) has increased, yet their effects on seaweeds are still not well understood. Adult sporophytes of Macrocystis pyrifera , the species forming the iconic giant kelp forests, can be negatively affected by thermal stress and associated environmental factors (e.g., nutrient depletion, light deprivation); however, little is known about the tolerance/vulnerability of juvenile sporophytes. Simultaneously to MHW s, juveniles can be subjected to light limitation for extended periods of time (days–weeks) due to factors causing turbidity, or even because of shading by understory canopy‐forming seaweeds. This study evaluated the effects of a simulated MHW (24°C, 7 d) in combination (or not) with light deprivation, on the photosynthetic capacities, nutrient uptake, and tissue composition, as well as oxidative stress descriptors of M. pyrifera juvenile sporophytes (single blade stage, up to 20 cm length). Maximum quantum yield ( F v / F m ) decreased in juveniles under light at 24°C, likely reflecting some damage on the photosynthetic apparatus or dynamic photoinhibition; however, no other sign of physiological alteration was found in this treatment (i.e., pigments, nutrient reserves and uptake, oxidative stress). Photosynthetic capacities were maintained or even enhanced in plants under light deprivation, likely supported by photoacclimation (pigments increment); by contrast, nitrate uptake and internal storage of carbohydrates were strongly reduced, regardless of temperature. This study indicated that light limitation can be more detrimental to juvenile survival, and therefore recruitment success of M. pyrifera forests, than episodic thermal stress from MHW s.