Marine WP 2: Linking primary producers to top predators ...
Transcript of Marine WP 2: Linking primary producers to top predators ...
Marine WP 2: Linking primary
producers to top predators: The role of capelin and sandeel in the
Godthåbsfjord area Peter Grønkjær (PI), Martin Blicher,
Rasmus Hedeholm, Malene Simon and Nathalie Danielsen
Small zooplanktivorous fishes
• Small zooplanktivorous fishes are the primary mediators of energy flow from low trophic levels to top-predators in many marine systems.
• These fishes are often fast-growing, short-lived and their condition & population dynamics respond quickly to environmental change.
Capelin & Sandeel
• In Greenlandic waters capelin is known as an important prey for a number of marine fishes, marine mammals and birds.
• In contrast, knowledge on the sandeel in Greenlandic waters is sparse, despite their privotal role in other north Atlantic ecosystems.
Sandeel lifecycle
Van Deurs, 2009
Aim
• To investigate how oceanographic conditions impact feeding, growth and energy accumulation in capelin and sandeel in the Fylla Bank & Godthaabsfjord area.
• To infer how changes in capelin and sandeel dynamics may influence their value as prey for higher trophic levels.
Gicacomo Nathalie
Sampling in May, August and September
Capelin
Sandeel
Analyses
• Age & growth - otoliths
• Diet
• Lipid content – muscle & total
• Energy density
• Stable isotope signatures
Diet
Zooplankton biomass strongly
influences growth of sandeel on the
Faroe Shelf
Eliasen 2012
Increasing winter temperatures decrease nutritional value of sandeel.
Eliasen 2012
Sandeel condition impact cod growth
Eliasen 2012
…and kittiwake breeding success
Eliasen 2012
Some perspectives
• Sandeel (and capelin) are sensitive indicator species for environmental change.
• Their growth and nutritional value can be used to gauge the productivity on the banks or fjords.
• The sandeel (and capelin) can be used to predict the productivity onhigher trophic levels.