The influence of environmental features in the content of mycosporine‐like amino acids in red marine algae along the Brazilian coast

Abstract

Mycosporine-like amino acids (MAA) are ultraviolet screen substances synthesized by marine algae. The physiological function of these substances is related to cellular protection against UV radiation and as a protective mechanism against oxidative stress. These substances can be found mainly in the ocean, among red seaweeds. Its concentration in organisms has been related to ultraviolet radiation and availability of inorganic nitrogen in the environment. We start our study of MAA content in different species to understand if environmental conditions influence the concentration of MAAs in red seaweeds. The Brazilian coast presents abiotic factors that interact to create different physical-chemical features in the environment. We collected 441 samples from 39 species of red seaweed easily found in the intertidal zone, in low tide, during the summer of 2015. The sampling encompassed a latitudinal gradient (3° S to 28°5' S) at 23 points along the coast. We quantified and identified the content of MAAs in species through the method of high performance liquid chromatography. We detected for the first time the occurrence of MAAs in certain species of red algae that have not been reported to contain MAAs before. We confirmed that some environmental factors influenced the content of MAAs. Enhanced MAA contents, for example, were found in environments with a basic pH, a high ultraviolet index, and high concentrations of phosphate and nitrate. Salinity, dissolved oxygen and variations of sea surface temperature also influenced, in a secondary way, MAA content in algae in their natural environments.

Dual influence of terrestrial and marine historical processes on the phylogeography of the Brazilian intertidal red alga Gracilaria caudata

“…The genetic break revealed in G. caudata thus fits nicely with the sharp abiotic environmental break detected between tropical and subtropical regions (Briani et al. ).…”

“…It is possible that the genetic structure is currently maintained by the combination of the low dispersal capacity of the species, the existence of various barriers to gene flow and adaptation to sharp changes in environmental conditions (e.g., salinity, sea surface temperature, oxygen and nutrient concentration; Briani et al. ). In seaweeds with low dispersal capacity, even weak and/or transient barriers can easily promote and maintain strong genetic divergence (Montecinos et al.…”

“…Possible ecotypic differentiation may have arisen along the G. caudata distribution range, linked to local adaptation to habitats specific to the north‐east and the regions of lower latitude (such as MAAs content, see Briani et al. ). These results were also confirmed by the Mantel test that showed a significant correlation between genetic and geographic distances, suggesting that the population structure and the subsequent occurrence of ecotypic differentiation could be explained by an isolation‐by‐distance model.…”

“…Although we did not observe the gradient of admixture and/or clines of allele frequencies expected in this contact zone, more extensive sampling in this zone is required to clarify the size of the contact zone and level of introgression between the two main lineages. It is possible that the genetic structure is currently maintained by the combination of the low dispersal capacity of the species, the existence of various barriers to gene flow and adaptation to sharp changes in environmental conditions (e.g., salinity, sea surface temperature, oxygen and nutrient concentration; Briani et al 2018). In seaweeds with low dispersal capacity, even weak and/or transient barriers can easily promote and maintain strong genetic divergence (Montecinos et al 2012).…”

“…Such patterns of reduced gene flow, if congruent with contrasted environmental conditions, may also initiate ecotypic differentiation. Briani et al (2018) reported that the content of mycosporine-like amino acids (MAAs) in 39 different red algae including G. caudata varies sharply between the north-east and south-east of the Brazilian coast. Algae MAAs content varied mainly according to the level of UV and irradiance, however, other environmental factors such as pH and phosphate and nitrate concentrations in the water column also had some influence (Briani et al 2018).…”