Influence of macrophyte complexity on phosphorus retention in artificial stream mesocosms

CLAUDIA FEIJOÓ; NICOLÁS FERREIRO; ADONIS GIORGI; EMILIA ZELAYA-SOULÉ

Palma de Mallorca

Congreso; ASLO 2023 Aquatic Sciences Meeting; 2023

Association of Limnology and Oceanography

Macrophytes have a key structuring role in aquatic environments, increasing habitat heterogeneity and promoting nutrient uptake when present in multispecific communities. Here, we experimentally investigated the effect of different submerged macrophyte species, with similar or distinct complexity, on phosphorus (P) retention in recirculating artificial streams. Two experiments were performed in 12 artificial channels during 3 days each. Macrophyte complexity was estimated by the fractal dimension at patch scale (FD), and P retention (k) was calculated as the slope of the relationship between P concentration (in ln) and time, and standardized by macrophyte biomass. In the first experiment, we estimated P retention in two macrophyte species (Egeria densa and Stuckenia striata) of similar complexity, alone or combined. We observed no significant differences neither in k nor in FD among treatments. In the second experiment, we compared P retention in 3 species with different complexities (Ceratophyllum demersum, Egeria densa and Elodea ernstae). We found that k differed significantly among treatments, being higher in Elodea (the species with the highest FD), intermediate in Ceratophyllum, and lower in Egeria (k = 0.0098, 0.0065, and 0.0049 1/h, respectively).Our results suggest that species that are more complex may show a higher P retention when comparing with simple species. However, physiological characteristics of each species should also influence P uptake.