Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster E71
Erpur Snær Hansen
Náttúrustofa Suðurlands
Kynnir / Presenter: Erpur Snær Hansen
Tengiliður / Corresponding author: Erpur Snær Hansen (erpur@nattsud.is)
The complete pole netting harvest record (1880-2014) of Atlantic Puffins in the Westman Islands, Iceland, is negatively correlated to seasonal sea surface temperatures (SST). Ringing recoveries show that pole netting is age selective with ~80% of the harvest being immatures. Variation in harvest reflects past production until age of maturity & colony attendance of immature birds, both reflecting availability of the key prey, the Lesser Sandeel. The relationship between Puffin harvest & SST is hypothetically explained by sandeel population control by temperature dependent metabolic rate. Sandeel life history is composed of summer growth period in May-July, and dormant winter period in August-April spent buried in sand. In winter, increased SST accelerates the sandeel’s metabolism & their rate of reserve depletion, but reduces energy allocation to growth & reserves during summer. A critical sandeel length threshold Lth was calculated annually for the sandeel dormancy period, which the 0-group sandeels need to attain to “survive” the SST profile of the following winter [1]. Mean annual summer temperature was also calculated. The 3 variables were prewhitened & split into regimes by a sequential t-test [2]. The regime timing & level of change of the three variables was compared. Three main production crashes were identified in 1890, 1932 and 2005, and three regimes of growth <1880, 1968 and 1990. The combination of three warm winter regimes with Lth > 7.5 cm & two warm summer regimes correspond to the observed production (harvest) regime pattern. This analysis supports the metabolic hypothesis & advocates a further analysis. 1. Mikael van Deurs, Martin Hartvig, & John Fleng Steffensen (2011). Critical threshold size for overwintering sandeels (Ammodytes marinus). Marine Biology 158: 2755-2764 2. Sergei N Rodionov (2004). A sequential algorithm for testing climate regime shifts. Geophysical Research Letters 31: L09204