Ecological stoichiometry of macroalgae from Sinop Peninsula coast of Black Sea, Türkiye: characterization of C:N:P

This comprehensive ecological investigation systematically analyzed the temporal and spatial variations in carbon (C), nitrogen (N), and phosphorus (P) concentrations across diverse macroalgal assemblages inhabiting the upper infralittoral zone of the Sinop peninsula. The study encompassed seasonal sampling conducted at five distinct stations between October 2019 and July 2020, targeting nine prevalent macroalgal species representing three major taxonomic groups: Chlorophyta, Rhodophyta, and Phaeophyceae. Statistical analyses revealed statistically significant (p < 0.05) variations in mean elemental concentrations across seasonal, regional, and species-specific dimensions. The elemental concentration ranges demonstrated substantial diversity, with carbon concentrations spanning from 14.73% in Corallina officinalis to 43.04% in Pterocladiella capillacea. Nitrogen concentrations exhibited remarkable variability, ranging from 0.50% in C. officinalis to 5.14% in Ceramium spp., while phosphorus concentrations varied from 0.02% in Ceramium spp. to 0.32% in Ulva rigida. The elemental ratio analyses uncovered intricate inter-specific variations, with carbon/phosphorus ratios ranging from 157 in C. officinalis to 4255 in Laurencia obtusa, nitrogen/phosphorus ratios varying from 9 to 304, and carbon/nitrogen ratios spanning from 9 to 51. Taxonomic group-level analyses revealed nuanced nutritional characteristics, with nitrogen concentrations showing slight variations across green (1.98%), brown (1.76%), and red (2.20%) algae, and phosphorus concentrations exhibiting similar patterns across these taxonomic groups. The macroalgal community presented a mean C:N:P atomic ratio of 1187:57:1, with a median ratio of 859:41:1. These stoichiometric signatures predominantly indicate phosphorus limitation across the studied macroalgal assemblages along the Sinop coastal region, with C. officinalis emerging as a notable exception.