TY - JOUR
T1 - Light-induced changes on the feeding behaviour of the calanoid copepod Clausocalanus furcatus (Brady, 1883)
T2 - Evidence from a mesocosm study
AU - Isari, Stamatina
AU - Zervoudaki, Soultana
AU - Calbet, Albert
AU - Saiz, Enric
AU - Ptacnikova, Radka
AU - Nejstgaard, Jens C.
AU - Sousoni, Despoina
AU - Berger, Stella A.
AU - Ptacnik, Robert
PY - 2014/9/1
Y1 - 2014/9/1
N2 - Light and nutrient availability are assumed to largely control the dynamics and trophic efficiency of marine planktonic food webs, and are expected to be influenced by climate change (i.e. changes in stratification due to global warming). During an 8-day mesocosm experiment, we investigated the propagation of light energy up to the copepod trophic level in ultra-oligotrophic Eastern Mediterranean waters. Using mesocosms with light treatments corresponding to ca. 40% (L1) and 4.5% (L4) of the incident light intensity (simulating light conditions at 10 and 50-60 m depths, respectively), we assessed the feeding behaviour of the dominant copepod Clausocalanus furcatus every second day. We hypothesized that increased availability of copepod food at higher light levels would result in increased copepod ingestion rates and selectivity. Our results showed that copepod prey (microbial biomass>5 μm) had only a small increase in the L1 and daily rations (DRs) of C. furcatus were similar among treatments (usually <15% of body carbon). Nevertheless, microplankton was clearly selected in L1, having double the contribution in the DR of C. furcatus compared with L4. A more balanced selective feeding pattern was observed in L4, with nanoplankton also being important in the diet. An increase in the copepod stock in the L1 compared with L4, observed at the end of the experiment, is likely associated with the light-mediated effects on C. furcatus feeding behaviour. We suggest that the importance of light availability on the efficiency of the marine planktonic food web should be further considered by climate change predictive models.
AB - Light and nutrient availability are assumed to largely control the dynamics and trophic efficiency of marine planktonic food webs, and are expected to be influenced by climate change (i.e. changes in stratification due to global warming). During an 8-day mesocosm experiment, we investigated the propagation of light energy up to the copepod trophic level in ultra-oligotrophic Eastern Mediterranean waters. Using mesocosms with light treatments corresponding to ca. 40% (L1) and 4.5% (L4) of the incident light intensity (simulating light conditions at 10 and 50-60 m depths, respectively), we assessed the feeding behaviour of the dominant copepod Clausocalanus furcatus every second day. We hypothesized that increased availability of copepod food at higher light levels would result in increased copepod ingestion rates and selectivity. Our results showed that copepod prey (microbial biomass>5 μm) had only a small increase in the L1 and daily rations (DRs) of C. furcatus were similar among treatments (usually <15% of body carbon). Nevertheless, microplankton was clearly selected in L1, having double the contribution in the DR of C. furcatus compared with L4. A more balanced selective feeding pattern was observed in L4, with nanoplankton also being important in the diet. An increase in the copepod stock in the L1 compared with L4, observed at the end of the experiment, is likely associated with the light-mediated effects on C. furcatus feeding behaviour. We suggest that the importance of light availability on the efficiency of the marine planktonic food web should be further considered by climate change predictive models.
KW - Clausocalanus furcatus
KW - copepods
KW - eastern mediterranean
KW - feeding
KW - light
KW - selection
UR - http://www.scopus.com/inward/record.url?scp=84908297816&partnerID=8YFLogxK
U2 - 10.1093/plankt/fbu054
DO - 10.1093/plankt/fbu054
M3 - Article
AN - SCOPUS:84908297816
VL - 36
SP - 1233
EP - 1246
JO - Journal of Plankton Research
JF - Journal of Plankton Research
SN - 0142-7873
IS - 5
ER -