Benthic resources are the key to Daphnia middendorffiana survival in a high arctic pond

TY - JOUR

T1 - Benthic resources are the key to Daphnia middendorffiana survival in a high arctic pond

AU - Cazzanelli, Matteo

AU - Forsström, Laura

AU - Rautio, Milla

AU - Michelsen, Anders

AU - Christoffersen, Kirsten Seestern

PY - 2012/3

Y1 - 2012/3

N2 - Shallow arctic lakes and ponds have simple and short food webs, but large uncertainties remain about benthic-pelagic links in these systems. We tested whether organic matter of benthic origin supports zooplankton biomass in a pond in NE Greenland, using stable isotope analysis of carbon and nitrogen in the pond itself and in a 13C-enrichment enclosure experiment. In the latter, we manipulated the carbon isotope signature of benthic algae to enhance its isotopic discrimination from other potential food sources for zooplankton. The cladoceran Daphnia middendorffiana responded to the 13C-enrichment of benthic mats with progressively increasing δ 13C values, suggesting benthic feeding. Stable isotope analysis also pointed towards a negligible contribution of terrestrial carbon to the diet of D. middendorffiana. This agreed with the apparent dominance of autochthonous dissolved organic matter in the pond revealed by analysis of coloured dissolved organic matter. Daily net production by phytoplankton in the pond (18mgCm -2day -1) could satisfy only up to half of the calculated minimum energy requirements of D. middendorffiana (35mgCm -2day -1), whereas benthic primary production alone (145mgCm -2day -1) was more than sufficient. Our findings highlight benthic primary production as a major dietary source for D. middendorffiana in this system and suggest that benthic organic matter may play a key role in sustaining pelagic secondary production in such nutrient-limited high arctic ponds.

AB - Shallow arctic lakes and ponds have simple and short food webs, but large uncertainties remain about benthic-pelagic links in these systems. We tested whether organic matter of benthic origin supports zooplankton biomass in a pond in NE Greenland, using stable isotope analysis of carbon and nitrogen in the pond itself and in a 13C-enrichment enclosure experiment. In the latter, we manipulated the carbon isotope signature of benthic algae to enhance its isotopic discrimination from other potential food sources for zooplankton. The cladoceran Daphnia middendorffiana responded to the 13C-enrichment of benthic mats with progressively increasing δ 13C values, suggesting benthic feeding. Stable isotope analysis also pointed towards a negligible contribution of terrestrial carbon to the diet of D. middendorffiana. This agreed with the apparent dominance of autochthonous dissolved organic matter in the pond revealed by analysis of coloured dissolved organic matter. Daily net production by phytoplankton in the pond (18mgCm -2day -1) could satisfy only up to half of the calculated minimum energy requirements of D. middendorffiana (35mgCm -2day -1), whereas benthic primary production alone (145mgCm -2day -1) was more than sufficient. Our findings highlight benthic primary production as a major dietary source for D. middendorffiana in this system and suggest that benthic organic matter may play a key role in sustaining pelagic secondary production in such nutrient-limited high arctic ponds.

U2 - 10.1111/j.1365-2427.2011.02722.x

DO - 10.1111/j.1365-2427.2011.02722.x

M3 - Journal article

SN - 0046-5070

VL - 57

SP - 541

EP - 551

JO - Freshwater Biology

JF - Freshwater Biology

IS - 3

ER -