Seabird guano enhances phytoplankton production in the Southern Ocean

• Published in: Journal of Experimental Marine Biology and Ecology
• Main Authors: Shatova, O, Wing, SR, Gault-Ringold, M, Wing, L, Hoffmann, LJ
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2016
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; Guano; Southern Ocean; Antarc*; Snares Islands
• Online Access: https://doi.org/10.1016/j.jembe.2016.07.004; http://ecite.utas.edu.au/113759

Six incubation experiments were carried out to investigate the phytoplankton biomass response to seabirdguano-enrichment under different nutrient regimes. Study locations included Antarctic waters of the Ross Seaand sub-Antarctic waters offshore of the Otago Peninsula, both being characterized by iron limitation of phytoplanktonproductivity in summer, the Sub-Tropical Frontal Zone offshore of the Snares Islands,which is generallymicronutrient-replete, and the island wakewaters of the Snares Islands,which have a high nutrient supply fromland. In all of the experiments the increase of phytoplankton biomass was higher in the treatments with guanoaddition compared to the controls. Guano additions were compared to Fe and macronutrients treatments(both added in quantities similar to those in the guano treatment) to shed light on which constituent(s) ofguano are responsible for the observed increases in phytoplankton biomass. Macronutrients increased the phytoplanktonbiomass in the Sub-Tropical Frontal Zone, however, the response was less prominent than in theGuano treatment, suggesting synergetic effects of nutrients in seabird guano on phytoplankton production. Itwas also found that the pattern of response varied between the water masses with 610 days lag phase in theSub-Antarcticwater mass and no lag phase in Sub-Tropical Frontal Zone. The calculations presented here suggestthat micro- and macronutrients delivered from seabird colonies on some of the sub-Antarctic islands may providea significant amount of limiting nutrients to the nutrient budget of the surrounding coastal waters, potentiallysufficient to sustain a local phytoplankton bloom. Findings of the present study indicate that biologicalrecycling of nutrients by seabirds likely supports marine primary production and enhances productivity of associatedfood webs in the vicinity of islands.