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Central Labrador Sea

Response on Canadian Atlantic Shelves related to forcing (represented by NAO) over the Labrador Sea Response of bottom temperature; Response of fish communities, data from fisheries-independent surveys, 1970-2006 from Cape Hatteras to mid-Labrador Shelf (27,224 sets). Central Labrador Sea.

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Central Labrador Sea

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  1. Response on Canadian Atlantic Shelves related to forcing (represented by NAO) over the Labrador Sea Response of bottom temperature; Response of fish communities, data from fisheries-independent surveys, 1970-2006 from Cape Hatteras to mid-Labrador Shelf (27,224 sets)

  2. Central Labrador Sea Sta. 27 Nfld (dot) Emerald Basin, SS (triangle) Prince 5, Bay of Fundy (square) (a) 1 year; (b) 3 run y

  3. Unnormalized Annual Mean Temperature differences of Negative NAO (mild winters) run* years – Positive NAO (severe winters) run years *years with at least 2 previous years with the NAO having the same sign,shown as large dots below. NAO time series

  4. Individual Species Response: 2 examples of mobile species Severe winters over Lab-Nfld Shelf Mild winters over Lab-Nfld Shelf

  5. Severe winters over Lab-Nfld Shelf Mild winters over Lab-Nfld Shelf

  6. Fish Community Response: all observed species Annual average bottom temperature and Cumulative Species Diversity versus latitude from 35oN (Cape Hatteras) to 55oN (Mid-Labrador Shelf). Long term there is a strong relationship between number of species and bottom temperature Cumulative Species Diversity Latitude

  7. Temporal Variability If fish can respond quickly to T changes then: Positive NAO years: severe winters over Lab Sea; colder than normal btm shelf T and fewer species in north, warmer with more species in south; steeper (more negative) latitudinal diversity gradient. Negative NAO years: mild winters over Lab Sea; warmer than normal btm shelf T and more species in north, colder with fewer species in south; shallower latitudinal diversity gradient.

  8. Observed response using all years: Qualitatively fits with expectations (LDG range corresponds to 42 species; Rapid fish community response to T variations; Affects fish community dynamics through top predator replacement (another species ready to assume role), resiliency (ability to return to earlier state; to cope with higher exploitation levels).

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