Time Series Observations along Line P Frank Whitney Emeritus, Fisheries and Oceans Canada

Warming trend along the BC coast – Lighthouse data

Oxygen concentrations and winter mixed layer depth at OSP < “hypoxia”

Integrated nitrate and oxygen (100 to 600 m) at OSP respiration > ventilation

Oxygen sensors on Argo profilers provide near real time data from N. Pacific and N. Atlantic Data from Beaufort Sea, courtesy of R. Macdonald. It’s a Pacific issue! +

Oxygen has declined over the past 25 years in coastal and oceanic waters. The two density surfaces shown (26.5 and 26.7) represent a depth range of ~150 to 300 m. WCQCI WCVI OSP

1. Stratification increases 2. Oxygen decreases A Warming Scenario Possible result – coastal eutrophication and hypoxia, as were observed off the Oregon coast in 2002, 2003 and 2004 (e.g. Grantham et al., 2004) 3. Upwelled waters are richer in nutrients, poorer in oxygen

Effects of hypoxia on marine organisms include:  Increased respiration rates  Metabolic depression  Reduced growth and feeding  Possible affects on reproduction and development (juveniles need higher oxygen than adults)  Replacement of demersal fish by pelagics  Loss of habitat (cod avoid waters with oxygen <3.4 mg/l in Gulf of St Lawrence; D’Amours, 1993)  Loss of species (e.g. shrimp, urchins, English sole, etc. from hypoxic waters in Howe Sound; Levings, 1980)

Courtesy, Alan Sinclair, DFO Groundfish biomass is largely found between 100 and 300 m on the BC coast. A few species tolerate the low oxygen concentrations of deeper waters.

LOMAs Canada has delineated 5 Large Ocean Management Areas in which we will attempt ecosystem based management. At present, an ecosystem overview report is being revised for the BC north coast LOMA. Our hope is that new funding will allow us to answer questions arising from this review of our present knowledge. HOWEVER…

Perry, Crawford and Sinclair – LOMA overview