Feeding and fecundity of Calanus finmarchicus and Temora longicornisin Breiðafjörður, West Iceland, in 2008 and 2009

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Insights into the life cycles of zooplankton, their fecundity and energy requirements, provide essential information for better understanding of energy transfer through trophic levels in marine ecosystems. Zooplankton abundance, community composition, and developmental stages of individual species of zooplankton were monitored at two locations in Breiðafjörður, West Iceland, every 10 days in the summers of 2008–2009. In addition, egg production and gut content were measured for the two most abundant species of copepods, Temora longicornis and Calanus finmarchicus. The abundance of females of T. longicornis varied between years with annual mean abundance of 31 000 females m–2 in 2008 and 300 females m–2 in 2009. Annual mean abundance of C. finmarchicus was 6000 females m–2 and 3000 females m–2 in 2008 and 2009, respectively. Feeding of copepods was estimated based on gut content, quantified as chlorophyll a. The gut content of T. longicornis was similar throughout summer in both years, while for C. finmarchicus the gut content was fairly consistent through both summers, with occasional higher values during the second summer. The egg production of T. longicornis was on average higher in 2008 (2–14 eggs female–1 d–1) than in 2009 (42–62 eggs female–1 d–1) whereas C. finmarchicus egg production was on average similar in both years (4–60 eggs female–1 d–1 in 2008 and 14–70 eggs female–1 d–1 in 2009). This study revealed that species abundance, feeding, and fecundity of T. longicornis and C. finmarchicus were characterized by annual rather than spatial variability in Breiðafjörður.