Factors affecting fledging weight of Adelie penguin (Pygoscelis adeliae) chicks: a modeling study

Salihoğlu, Barış
Hofmann, EE
An individual-based model is developed to examine mechanisms that potentially underlie the observed constancy in fledging weight (2.8-3.2 kg) of Adelie (4Pygoscelis adeliae) penguin chicks, in spite of large variability in the abundance of Antarctic krill (Euphausia superba), the primary food source. The model describes the energetic requirements of the chick. with growth resulting from the difference between assimilated energy and respiration. Parameterizations of these metabolic processes are based upon experimental and field observations. Ingestion of Antarctic krill by the chick is dependent on the frequency of food delivery to the chick by the adults, which is based on measured foraging times. The mass, size, and size frequency distribution of Antarctic krill fed to the chick are specified using empirical data. The energy content of the Ant arctic krill provided to the chick is taken to be constant or allowed to vary with size. The simulations show that food availability is most critical in the latter portion of chick development, when growth rates and food demands are high. Low food availability during this time must be compensated by either feeding chicks with larger krill of higher caloric value or by increased assimilation efficiency. Periods when small krill with lower caloric value dominate require more frequent. feeding of the chicks in order to attain their observed fledging weight. Thus, although the total food energy given to the chick is the main factor determining chick growth, the distribution of food availability relative to chick size (i.e., different net growth rates) and food quality are also factors influencing the fledging weight of penguin chicks. The simulations provide insight into the compensating effects of food delivery, food quality, and metabolic processes that allow Adelie penguin chicks to reach their observed fledging weight in spite of considerable environmental variability in food supply.


Biochemically based modeling study of Antarctic krill Euphausia superba growth and development
Fach Salihoğlu, Bettina Andrea; Wolf-Gladrow, Dieter; Bathmann, Ulrich (2008-01-01)
A biochemical model of Antarctic krill Euphausia superba was developed to investigate the physiological mechanisms which enable krill to survive winter, when food is scarce. In this modeling approach data sets on the biochemical composition of krill and its food sources are combined into a model that takes food quality into account rather than just food availability during different seasons. Krill is defined in terms of protein, neutral lipid, polar lipid, carbohydrate, chitin, and ash content, and the mode...
Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part II. Krill growth and survival
Fach Salihoğlu, Bettina Andrea; Murphy, Eugene J. (2006-06-01)
A time-dependent, size-structured, physiologically based krill growth model was used in conjunction with a circulation model to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia are sustained by import of individuals from upstream regions. Surface phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal Zone Color Scanner (CZCS) measurements and sea ice biota concentrations were calculated from sea ice concentration ...
Karakuş, Onur; Fach Salihoğlu, Bettina; Salihoğlu, Barış; Department of Oceanography (2018-11-19)
In this study, a three dimensional, coupled ocean ecosystem model (FESOMREcoM2) is used to investigate the impact of krill on the ecosystem dynamics of the Southern Ocean in modeling studies. A new, second zooplankton group defined to be Antarctic krill is added to an already existing and validated setup of the modelling system. This species was chosen because it is a key organisms in the Southern Ocean. The effect of grazing on net primary production and export production due to the addition of Antarctic k...
Modeling studies of antarctic krill Euphausia superba survival during transport across the Scotia Sea
Fach Salihoğlu, Bettina Andrea; MURPHY, EUGENE (2002-01-01)
Antarctic krill Euphausia superba spawned on the outer continental shelf of the west Antarctic Peninsula can be entrained into the Southern Front of the Antarctic Circumpolar Current and transported across the Scotia Sea to South Georgia. A time-dependent, size-structured, physiologically based krill growth model was used to assess the food resources that are needed to sustain Antarctic krill during transport across the Scotia Sea and to allow them to grow to a size observed at South Georgia. Initial Lagran...
Implementation of Antarctic Krill into the Ocean-Ecosystem Model FESOM-REcoM-2 and its Effects on Southern Ocean Biogeochemistry.
Karakus, Onur; Hauck, Judith; Völker, Christoph; Fach Salihoğlu, Bettina Andrea; Hagen, Wilhelm (2020-01-16)
In this study, a three-dimensional, coupled ocean ecosystem model (FESOM- REcoM2) is used to investigate the effect of krill on the biogeochemistry of the Southern Ocean. The implementation of Antarctic krill in the model was done in three steps. 1) A second zooplankton group was implemented, which grazes on diatoms, mesozooplankton and nanophytoplankton (in order of descending preference). 2) A new detritus group was added to the model, which represents faster-sinking krill faecal pellets. 3) The grazing i...
Citation Formats
B. Salihoğlu and E. Hofmann, “Factors affecting fledging weight of Adelie penguin (Pygoscelis adeliae) chicks: a modeling study,” POLAR BIOLOGY, pp. 328–337, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/30103.