Depth influence on biochemical performance and thallus size of the red alga Gelidium corneum

Abstract

Recent declines in the foundation species Gelidium corneum (Hudson) J.V. Lamouroux in pristine coastal stretches of the Southeastern Bay of Biscay have been documented in which individuals showed a high bleaching incidence. Among the potential factorsthat may be responsible for these changes in G. corneum abundance, it has been suggested that high levels of irradiance may be imposing stressful environmental conditions for shallow populations. Given that light is reduced exponentially as depth increases, in this investigation we examined the influence of depth on the stress of G. corneum by comparing the performance of several biochemical parameters and thallus size in plants collected at three different depths. The results revealed that plants growing in shallow waters showed lower antioxidant activity, lower concentrations of photosynthetic pigments (Chl‐a, total carotenoids, phycoerythrin), lower internal nitrogen levels (higher C:N ratio) and shorter thallus lengths than those living in deeper waters. Some of these results may be an expression of photoacclimation, but the low antioxidant activity and total carotenoid concentration detected in plants living in shallow waters suggest that the photoprotective mechanisms of G. corneum may have failed to offset photodamage. If so, our findings support previous studies that suggest that recent changes in solar radiation are partially responsible for G. corneum declines. Nevertheless, given that the metabolic performance of macroalgae is determined by the inter‐play of irradiance with other factors, including temperature and nutrient availability, further research is needed to reach a better understanding of the factors causing stress in G. corneum.

Seasonal Nutritional Profile of Gelidium corneum (Rhodophyta, Gelidiaceae) from the Center of Portugal

“…To determine the best time to harvest algal biomass, depending on its intended application, it is essential to gather information about variations in the production of bioactive compounds. So far, it is known that solar radiation, water temperature, and depth, among other factors, influence the chemical composition of G. corneum [62,63].…”

The role of macroalgal habitats as ocean acidification refugia within coastal seascapes

“…https://doi.org/10.1017/cft.2023.9 Published online by Cambridge University Press Lower canopy forming algae like Gelidium corneum are also considered foundational, or habitat forming species (Quintano et al, 2017;Borja et al, 2018;Muguerza et al, 2022), particularly on some European coasts, with Gelidium canariense representing an important canopy-forming species on Macronesian islands (Alfonso et al, 2017;Hernández, 2021). While these algae are not as tall as the kelps, the canopies formed are similar in height (20 -30 cm) to some of the fucalean-dominated communities (Robertson, 1987;Quintano et al, 2018;Alfonso et al, 2021;Hernández, 2021). Smaller brown and red foliose species are usually important components of the under-story vegetation and occur both under canopies of larger brown algae as well as in the gaps between stands of taller algae.…”

“…Smaller brown and red foliose species are usually important components of the under-story vegetation and occur both under canopies of larger brown algae as well as in the gaps between stands of taller algae. However, temperate Gelidium corneum (Quintano et al, 2017(Quintano et al, , 2018Casado-Amezúa et al, 2019) and Gelidium canariense (Alfonso et al, 2021;Hernández, 2021) are both recognised as short canopy forming species in their own right.…”

Solar Radiation as an Isolated Environmental Factor in an Experimental Mesocosm Approach for Studying Photosynthetic Acclimation of Macrocystis pyrifera (Ochrophyta)

“…inside a polycarbonate box (Otter Box 3000) at 1.8-m depth in each tank. For each treatment, the diffuse downward attenuation coefficient (Kd) of PAR was calculated, following Quintano et al (2017). The Kd was determined for each experimental period by applying the Beer-Lambert law equation:…”