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Simon Geist

Dr. Simon Joscha Geist

Leibniz Center for Marine Tropical Ecology Bremen (ZMT)
Department: Fisheries Biology

Fahrenheitstra├če 6, 28359 Bremen, Germany

Phone: -49-421-23800-24

E-mail: simon.geist@we dont want spamzmt-bremen.de



Simon Geist has succesfully finished his Ph.D. program within the GENUS project. He defended his thesis in Aug. 2013:

"Trophic positions and physiological adaptations of early life stages of pelagic fish of the Northern Benguela Current Upwelling System".

Congratulations!

Simon now works as a postdoc in GENUS II.

Supervisors:

Dr. Werner Ekau, Dr. Andreas Kunzmann, Prof. Dr. Ulrich Saint-Paul

Scope of the thesis:

The Benguela Current (BC) off the southwest African Atlantic coast, is one of the major upwelling systems on earth. Upwelling systems are characterized by a high primary production sustaining large stocks of small pelagic fish (Sardine, anchovy) and commercially important fisheries. In terms of biomass upwelling areas are the most productive fishery grounds worldwide.
In the northern part of BC, small pelagic stocks suffered a harsh decline since the 1970s, mainly due to overexploitation. In contrast to the southern subsystem, stocks could never recover significantly in the last decades, but reasons are not yet understood.
Early life stages of fish are extremely vulnerable to changing environmental conditions. Possible factors for the failed recovery of small pelagic fish stocks in the BC could be, among others, a change in the composition of food organisms and/or increased occurrence of hypoxic zones in the water column. These conditions may favor jellyfish, krill or other fish species such as horse mackerel, pelagic goby or myctophids, which in turn can act as competitors and predators for small pelagics during their early life stages.
Embedded in the GENUS project (http://genus.zmaw.de/), the aim of my doctoral thesis is to quantify trophic relationships and physiological adaptations of early life stages of important pelagic fish species of the northern BC and thus to contribute to a better understanding of their population dynamics.

Main target species:

Sardines (Sardinops sagax, Sardinella aurita), anchovy (Engraulis encrasicolus), horse mackerel (Trachurus trachurus capensis), pelagic goby (Sufflogobius bibarbatus)

Intended Methods:

Trophic position: Stomach content analysis, SI, FAME
Growth and Fitness: Otolith analysis and lipid content
Metabolic needs and adaptations: Respiratory experiments and key enzyme activities

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