TY - JOUR

T1 - Ecophysiological traits of mixotrophic Strombidium spp.

AU - Maselli, Maira

AU - Altenburger, Andreas

AU - Stoecker, Diane K.

AU - Hansen, Per Juel

PY - 2020

Y1 - 2020

N2 - Ciliates represent an important trophic link between nanoplankton and mesoplankton. Many species acquire functional chloroplasts from photosynthetic prey, being thus mixotrophs. Little is known about which algae they exploit, and of the relevance of inorganic carbon assimilation to theirmetabolism. To get insights into these aspects, laboratory cultures of three mixotrophic Strombidium spp. were established and 35 photosynthetic algal species were tested as prey. The relative contributions of ingestion and photosynthesis to total carbon uptake were determined, and responses to prey starvation were studied.Ciliate growth was supported by algal species in the 2–12 μm size range, with cryptophytes and chlorophytes being the best prey types. Inorganic carbon incorporation was only quantitatively important when prey concentration was low (3–100 μgCL−1), when it led to increased gross growth efficiencies. Chla specific inorganic carbon uptake rates were reduced by 60–90% compared to that of the photosynthetic prey. Inorganic carbon uptake alone could not sustain survival of cultures and ciliate populations declined by 25–30% during 5 days of starvation. The results suggest thatmixotrophy in Strombidium spp. may substantially bolster the efficiency of trophic transfer when biomass of small primary producers is low.

AB - Ciliates represent an important trophic link between nanoplankton and mesoplankton. Many species acquire functional chloroplasts from photosynthetic prey, being thus mixotrophs. Little is known about which algae they exploit, and of the relevance of inorganic carbon assimilation to theirmetabolism. To get insights into these aspects, laboratory cultures of three mixotrophic Strombidium spp. were established and 35 photosynthetic algal species were tested as prey. The relative contributions of ingestion and photosynthesis to total carbon uptake were determined, and responses to prey starvation were studied.Ciliate growth was supported by algal species in the 2–12 μm size range, with cryptophytes and chlorophytes being the best prey types. Inorganic carbon incorporation was only quantitatively important when prey concentration was low (3–100 μgCL−1), when it led to increased gross growth efficiencies. Chla specific inorganic carbon uptake rates were reduced by 60–90% compared to that of the photosynthetic prey. Inorganic carbon uptake alone could not sustain survival of cultures and ciliate populations declined by 25–30% during 5 days of starvation. The results suggest thatmixotrophy in Strombidium spp. may substantially bolster the efficiency of trophic transfer when biomass of small primary producers is low.

U2 - 10.1093/plankt/fbaa041

DO - 10.1093/plankt/fbaa041

M3 - Journal article

VL - 42

SP - 485

EP - 496

JO - Journal of Plankton Research

JF - Journal of Plankton Research

SN - 0142-7873

IS - 5

ER -