Nutrient availability to marine macroalgae in siliciclastic versus carbonate-rich coastal waters

摘要: Abundant populations of frondose epilithic macroalgae from a variety carbonate-rich tropical waters were significantly depleted in phosphorus relative to carbon and nitrogen when compared temperate siliciclastic waters. Percent (C) percent (N) dry weight contents similar between tissues the carbonate environments (means 22.6% vs. 20.1% 1.0% 1.2%, respectively), but (P) levels two-fold lower (0.15% 0.07%) systems. Accordingly, molar C:N tissue ratios comparable sites (mean 29.2 23.1), whereas large differences observed for C:P 430 976) N:P 14.9 43.4). In addition, alkaline phosphatase activity was low often undetectable habitats 7.3 μM PO4 3− released g wt−1 h−1) seven-fold higher rates (52.5 Seawater samples taken adjacent benthic contained relatively high dissolved inorganic with concentrations soluble reactive (SRP), showed elevated N:SRP (mean=36) <3). These data support precept that availability N limits productivity but, conversely, suggest P, rather than N, may be paramount importance limiting primary production