Hypoxia and fish early-life life stages: a comparison between human-enriched and upwelling-driven systems. Outline. Oxygen Minimum Zones (OMZ)

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1 Hypoxia and fish early-life life stages: a comparison between human-enriched and upwelling-driven systems Denise Breitburg Smithsonian Environmental Research Center Lorenzo Ciannelli Oregon State University COAS OSU Outline Recent Trends, Causes and Types of coastal hypoxia Nutrient enrichment, stratification and flushing rates OMZ and upwelling-driven costal hypoxia Oxygen Minimum Zones (OMZ) Distribution, recent and expected Trends Scales of variability Persistent, seasonal, episodic, and diel cycling hypoxia Effects of coastal hypoxia on fish early life stages Co-stressors: Oxygen-salinity-temperature squeeze Fisheries exploitation CO 2 and acidification

2 Global occurrence of dead zones Hypoxic areas typically are near areas with high human footprint Diaz and Rosenberg (2008) Science 321: 926- Hypoxia and N loadings increasing Courtesy of R.J. Diaz

3 Key ingredients: Enrichment, Respiration, Stratification, Retention Hypoxic zones typically occur in enclosed estuaries and/or at mouths of polluted rivers

4 Hypoxia global problem also near eastern boundary systems Hypoxia can also occur near Oxygen Minimum Zones (OMZ) Diaz & Breitburg, 2009 Upwelling-driven coastal hypoxia Occurs in correspondence of deep Oxygen Minimum Zones (OMZ) Key ingredients: Low DO source water Upwelling intensity Dissolved oxygen units: 2 mg l -1 = 1.4 ml l -1 hypoxia ~ 57!M = 1.4 ml l -1 normal low oxygen OMZ upwelling

5 OMZ of the world O 2 distribution (!M =!mol kg -1 ) at depth where O 2 concentration is minimal Paulmier A, Ruiz-Pino (2009) Progr Oceanogr 80: m equator Vertical extent of OMZ OMZ thickness (m) 1000 m 1500 m 200 m NE Pacific equator SE Pacific Depth of upper base (m) 1000 m SE Atlantic 200 m 1000 m 1500 m From!Helly,!J.J.!and!L.A.!Levin!,!Deep!Sea"Res."I"(2004)!1159"1168

6 Factors affecting distribution, magnitude and vertical extent of OMZ Export production (patterns of primary productivity) Ventilation (patterns of global intermediate and deep ocean circulation) Boreal Summer Boreal Winter Net Primary Production (mg m -2 ) Subduction of denser and O- rich water Karstensen et al. (2008) Progr Oceanogr 77: AADW Pacific Ocean Mataer and Hirst (2003) Global Biogeoch Cycles 17(4): 1-20

7 Pacific Subarctic Intermediate Water Ocean ventilation Maximum Mixed Layer Depth (m) North Atlantic Intermediate and Deep Water Pacific 72% volume 52% subduction mostly in SP Antarctic Intermediate and Deep Water Atlantic 28% volume 48% subduction Multiple forms of hypoxia occur within systems Dissolved oxygen (mg l -1 ) Diel cycling hypoxia 20 July...30 July 2008 N Upwelling of hypoxic bottom waters (Episodic) Seasonal episodic disrupted by wind events (Patuxent) N Chesapeake Bay (data from MD-DNR eyes on the bay) Dissolved oxygen (mg l -1 ) Seasonally persistent hypoxia J F M A M J J A S O N D

8 Multiple forms of hypoxia occur within systems Persistent Seasonal-episodic ~44.5N In coastal waters movement of hypoxic water is rapid and unpredictable; early life stages are stationary or have limited mobility. July to 2001 mean! , 1972 mean Grantham et al. (2002) 429: persistent Seasonal/episodic Seasonal/episodic hypoxic systems can be more susceptible to changes in DO due to increase of nutrient loading Percent bottom area hypoxic absent/resistant N loading ( log 10 kg N km -2 surface area year -1 ) V N loading ( log 10 kg N km -2 surface area year -1 ) Breitburg et al. (2009) Ann Rev Marine Sci 1:

9 Is hypoxia/anoxia a normal feature of the Northern C Coastal System? Dissolved oxygen (ml l -1 ) Depth (m) N ~ 4000 hydrocasts 1950 to to Relatively small changes of the source water DO have resulted in larger changes of coastal DO Chan et al. (2008, Science) What to expect next? OMZ and global warming Current scenario 2680 with projected increase of CO2 Mataer and Hirst (2003) Global Biogeoch Cycles 17(4): 1-20 Reduced solulibility at subduction zones Higher temp lower solulibility, but only accounts for 15-20% of projected increase of OMZ Reduced ventilation due to shoaling and/or slowing down of meridional overturning circulation More stratification reduces primary productivity and therefore C export reduced ocean-atmosphere exchanges with net outgassing

10 Recent global trends Climatological mean dissolved oxygen concentrations (µmol kg 1 shown in color) at 400 m depth Dissolved oxygen concentration (µmol kg 1 shown in color) maps versus time ( ) and pressure Stramma et al. (2008) Science 320: Effects of hypoxia on fish early life history stages Hypoxia Duration, spatial extent (scale) Advective vs local depletion Predictability Proximity to refuges Species/stages Tolerance Mobility Effectiveness of avoidance behaviors Co-stressors Hypoxia-tolerant predators Fisheries exploitation Acidification Oxygen-salinity-temperature squeeze

11 Crassostrea virginica DO level at which 50% of individuals die Zoea stages of Cancer irroratus DO levels of sublethal responses Gadus morhua (Atlantic cod) Exposure time for 50% lethal responses Platichthys flesus (flounder) Vaquer-Sunyer and Duarte (2008) PNAS 105(40): Upwelling-driven coastal hypoxia and fish early life stages Ekau and Verheye 2005 Afr J Mar Biol 27(3): Sampling: February-March 2002

12 Ongoing studies: A Johnson presentation Latitude (N) Multinet Beam Trawl Methot LB NH SR WK SH CH Sampling 2008 Columbia R. Lincoln City Newport Yachats Bottom dissolved oxygen (averaged for April to Sept 2007) Longitude (W) Courtesy of PISCO Make a contour map from our files For 2008 Shifts in food web interactions under seasonal hypoxia hypoxia favors gelatinous zooplankton tolerant of low oxygen Chesapeake Bay Chrysaora quinquecirrha Mnemiopsis leidyi Seto Inland Sea Aurelia aurita o o o + sea bream larvae naked goby Gobiosoma bosc Breitburg et al 2003, Decker et al Kolesar et al in prep Shoji et al 2005

13 The effect of low dissolved oxygen can be very different in different habitats within the same system - Proportional density bay anchovy eggs 12-LC 50 = 2.8 mg/l Bottom dissolved oxygen (mg L -1 ) proportion total eggs buoy site surface pycnocline bottom JI Patuxent River Bay anchovy eggs sink into the bottom layer into lethal DO concentrations in the mesohaline Patuxent River, but are retained in the surface layer of the more strongly stratified mainstream Bay. Keister et al., Breitburg et al., see also North & Houde. Co-stressor: Salinity-oxygen squeeze Depth Salinity - Oxygen Cod eggs cannot survive when DO < 2ml/l or when salinity < 11 psu From: Valling & Nissling (2000). Fish Res. 49: 21

14 Co-stressor: Salinity-oxygen squeeze + fisheries effect Salinity too low for spawning Depth Depth Acceptable oxygen and salinity Lethal oxygen concentration Salinity - Oxygen From: Valling & Nissling (2000). Fish Res. 49: 21 Hypoxia, CO 2 and acidification Feely et al. (2008) Science 320 Distribution of the depths of the undersaturated water (aragonite saturation < 1.0; ph < 7.75) on the continental shelf of western North America Vertical sections of (A) temperature, (B) aragonite saturation, (C) ph, (D) DIC, and (E) pco2 on transect line 5 off Pt. St. George, California.

15 A big unknown: Effects of acidification and hypoxia as co-stressors Dorsal view of sagittal otoliths of 7-day-old white sea bass grown at (A) 430, (B) 1000, and (C) 2500 µatm p(co2)seawater In an acidified world Mean ratios and their associated uncertainties (3) are plotted. The control level p(co2)seawater was ~430 µatm [p(co2)atmosphere ~ 380 µatm], for which otolith area ratio = 1 Checkley et al. (2009) Science 324 Digital x-ray photographs of live European flounder (Platichthys flesus) showing formation of gut carbonates in unfed fish after transfer from fresh water to seawater Wilson et al. (2009) Science 323

16 In an acidified world Resting metabolism ph = 7.8 Maximum swimming metabolism Aerobic scope control Munday et al. MEPS (In press) At high CO2 (lower ph) fish decrease their aerobic scope. Summary Global trends indicate rapid increases of hypoxic regions in both closed systems and open ocean coastal environments Increasing temperature will likely cause a decrease of dissolved oxygen and an increase of fish oxygen demand Importance of spatial and temporal scales of hypoxia to predict effect of climate change, nutrient loading and consequences on fish ELS Presence of co-stressor interact with low oxygen level to modify its effects on fish early life stages A big unknown: interactions with CO 2 and acidification

17 Thank you PISCO (Partnership for Interdisciplinary Studies of Coastal Oceans) Francis Chan, Dafne Eerkes-Medrano Oregon State University Jack Barth, Angela Johnson COAS Ship Operation Elakha crew NOAA, NWFSC Ric Brodeur, Chris O Toole, Waldo Wakefield