Modeling studies of antarctic krill Euphausia superba survival during transport across the Scotia Sea

Download
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 Lagrangian simulations provide trajectories that are followed by particles released on the west Antarctic Peninsula shelf. Pelagic phytoplankton concentrations along these trajectories are extracted from historical Coastal Zone Color Scanner measurements from the Antarctic Peninsula-Scotia Sea region and are input to the growth model. The results of these simulations show that pelagic phytoplankton concentrations are not sufficient to support continuous growth of Antarctic krill during the 140 to 160 d needed for transport to South Georgia. The inclusion of a supplemental food source during part of the transport time, such as sea ice algae (up to 80 mg chl a m(-3)), does not significantly alter this result. Survival and growth of larval krill during modeled transport is, however, enhanced by encounters with mesoscale patches of high chlorophyll concentrations (1 mg m(-3)), while subadults and adults benefit less from these conditions. Further simulations show the importance of an additional food source, such as heterotrophic food, for the survival of subadult and adult Antarctic krill. For all planktonic food scenarios tested, krill that begin transport at the Antarctic Peninsula did not reach the smallest age group often observed at South Georgia, the 2+ group, during the 140 to 160 d of transport. Including the effect of increasing temperature across the Scotia Sea on krill growth rate does not significantly alter these results, since the maximum increase in growth due to increased temperature obtained in the simulations was 1.0 mm for both 2 and 22 mm Antarcic krill. These simulations suggest the possibility of alternative transport scenarios, such as Antarctic krill beginning transport at the Antarctic Peninsula in austral summer and overwintering under the sea ice that extends northward from the Weddell Sea into the Scotia Sea. Such an interrupted transport would allow the Antarctic krill to overwinter in a potentially better food environment and begin transport again the following year, growing to a size that is within the range observed for Antarctic krill populations at South Georgia.
MARINE ECOLOGY PROGRESS SERIES

Suggestions

Krill transport in the Scotia Sea and environs
Hofmann, Eileen E; Klinck, John M; Locarnini, Ricardo A; Fach Salihoğlu, Bettina Andrea; Murphy, Eugene (1998-12-01)
Historical observations of the large-scale flow and frontal structure of the Antarctic Circumpolar Current in the Scotia Sea region were combined with the wind-induced surface Ekman transport to produce a composite Bow field. This was used with a Lagrangian model to investigate transport of Antarctic krill. Particle displacements from known krill spawning areas that result from surface Ekman drift, a composite large-scale now, and the combination of the two were calculated Surface Ekman drift alone only tra...
MODELING THE IMPACT OF CLIMATE VARIABILITY ON ANCHOVY OVERWINTERING MIGRATION IN THE BLACK SEA
Güraslan, Ceren; Fach Salihoğlu, Bettina; Department of Oceanography (2016-10-21)
Black Sea anchovy (Engraulis encrasicolus ponticus) undertake extensive (~1000km long) overwintering migration in autumn from northern spawning grounds to the overwintering areas located at the south-eastern coasts of the Black Sea. When arriving at the Anatolian coast, they support important fisheries in Turkey. Black Sea anchovy is known to experience stock variability quite frequently including stock collapses, which are believed to be closely linked with environmental conditions. Therefore, it is of imp...
Modeling the influence of hydrodynamic processes on anchovy distribution and connectivity in the black sea Karadeniz'deki hamsi dağılımı ve bölgeler arası bağlantısı üzerine hidrodinamik proseslerin etkisinin modellenmesi
Fach Salihoğlu, Bettina Andrea (2014-01-01)
Dispersal mechanisms of Black Sea anchovy larvae (Engraulis encrasicolus ponticus) across the Black Sea were studied with an individual based anchovy larvae model embedded in a Lagrangian model using surface currents calculated from daily dynamic height topography maps of altimeter data during a period of three years (2001-2003). Particles representing anchovy eggs were released at different sites during June to August and their movement was tracked over time. Drifters were advected for 36 days, representin...
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 ...
Basement structure and architecture of the Black Sea Basin
Kaymakcı, Nuretdin; Horn, Brian (null; 2018-01-28)
Black Sea consists of two separate back arc basins which opened at different times during the Cretaceous in response to northward subduction of the Neo-Tethys Ocean. The paucity of well data, complex geometries and seismic imaging challenges mean that questions remain regarding the basement architecture though most authors accept that, at least in part, both these basins are floored by oceanic crust, even though there are no magnetic stripes. Interpretation of deep, long offset seismic data (imaging to more...
Citation Formats
B. A. Fach Salihoğlu and E. MURPHY, “Modeling studies of antarctic krill Euphausia superba survival during transport across the Scotia Sea,” MARINE ECOLOGY PROGRESS SERIES, pp. 187–203, 2002, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32304.