Ocean Conservancy – GOMURC Workshop April 2012 Charles H. “Pete” Peterson University of North Carolina at Chapel Hill.

Ecosystem Injuries from the DeepWater Horizon Blow-out:

A Tale of Two Spills

Ocean Conservancy – GOMURC WorkshopApril 2012

Charles H. “Pete” Peterson University of North Carolina at Chapel Hill

DWH Blowout – Two Types of Oil Spills Type I - Familiar Spill

Composite of nearshore oil spillsFate:

Oil rises to the surfaceFloating oil grounds on shores

Effects:Surface organism mortality Intertidal habitats fouledShallow subtidal contaminationSublethal effects induce pop losses

Type II - Deepwater Spill Novel offshore, deep-water

blowout of oil and gasFate:

Extensive fine dispersion of oil & gas via turbulent pressurized injection into cold seawater

Retention in plumes at depthSurfacing and grounding of oilBroad deposition on sea floor

Effects:Surface organism mortality Intertidal habitats fouledBio exposures in water columnWidespread benthic mortalitiesUPINOAA

Type IIType I

well head

dispersant

accumulating oil on sediments

finely dispersed subsurface oil plume

finely dispersed oil/hydrate plume

asphaltines

oil plume

oil slick

1000 m

500 m

200 m

1500 m

1800 m

The Deepwater Horizon Spill

NearshoreEstuaryContinental shelf

Pelagic OceanicNeritic

Epipelagic

Mesopelagic

0 to 200 m

1000 m

4000 m

Bathypelagic

Ph

oti

c A

Ph

oti

c

Benthic

BathyalWind

SheensThick Oil

Dispersant

Turbulent Dispersion

Volatilization

Turbulent Dispersion

Surfacing

Current

Adsorption and Adherence to Particulates

Complex Physics and Chemistry

Oil Spill Oceanography

Legacy of the Exxon Valdez Oil SpillOf all oil spills, EVOS impacts are the most

thoroughly studied in scope, duration, and roles of ecosystem-based interconnectivity of natural resource impacts

Explicit impact studies of EVOS are relevant to the Type I components of DWH (surface and shorelines), but offer only procedural insights to guide impact assessment of DWH Type II components

EVOS helps guide the processes of impact assessment and restoration by example, good and bad

EVOS brings new insights into ecotoxicological mechanisms and processes – new paradigms only slowly incorporated into injury models

Photos: Anchorage Daily News Exxon Valdez Oil Spill = EVOS Deepwater Horizon Spill = DWH

Myths Debunked and Emerging Paradigms Created by EVOS Science

Significant toxicity is not limited to acute exposure to BTEXs, but continues for decades via exposure to buried oil sequestered in biologically accessible, but anoxic reservoirs

Toxicity of chronic exposures to PAHs occurs at ppb concentrations, much lower than the ppm water quality standards (based only on acute exposures to water-soluble fractions from fresh oil)

Clean-up and restoration responses can be more injurious than the oilbenzene, toluene, ethylbenzene, and xylenes = BTEX polycyclic aromatic hydrocarbons

= PAH

Novel Scientific Insights from EVOSSublethal impacts (affecting individual growth,

reproduction, behavior) may have serious effects at the population level and must be incorporated into the injury assessment process

Major physical effects of oil (smothering, fouling of feeding apparatus, etc.) can continue to operate independent of chemical toxicity of the oil

An ecosystem-based approach is critical to account for interactions and indirect effects that ramify through the interaction webs; this coupled with long-term monitoring is the only way to understand some delayed and long-term impacts of the oil spill

Deepwater Horizon TimelineApril 20 – well blow-out and fire @ 21:45 hApril 22 – first surface oil slick detectedMay 1 – surface application of dispersant beganMay 14 – injection of dispersant at well-head beganJuly 15 – oil and gas discharge ended (after 84 d)

Comparative Spill Oil Volumes

DWH: 4.9 million barrels of oil, 14.7 million ft3 of gas 1.8 million gallons of dispersant added

1.07 million gallons at sea surface 0.77 million gallons at the well-head

1.5 to 1.9 x more gas released than oil by mass

8

7

6

5

4

3

2

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Kuwait oil field1991

DWH2010

Ixtoc I1979

Santa Barbara 1969

Exxon1989

4.9

6 to 8

3.5

0.75

0.1

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oil

Natural Resource Injuries from the Type I Portion of the DWH Incident

The “easy” part – long agency (NOAA) experience/skills directly applicable here to surface and shoreline habitat oiling impacts

Potentially trivial compared to novel subsurface ecosystem impacts ?

May form the vast majority of the focus of restoration because:Better capacity to infer injuriesEcosystem values and uses to humans understoodCompensatory restoration is deemed feasiblePolitical pressure for state “wish list” projects

EPA

Press-Register

Type I Injuries: Species Oiled at Sea SurfaceSeabirds found dead in oiled areas in USFWS counts to 12/2011

gulls = 2901 brown pelican = 556 northern gannet = 441 royal tern = 233 black skimmer = 233

Sea turtles – 613 dead (incl. Kemp’s ridleys) in NOAA counts from 4/2010-4/2011

Marine mammals – 452 dolphin strandings in NOAA data base out of 625 total cetacean strandings from 4/2010-1/2012; abnormally high miscarriage rates

Fish –concerns about impacts on early life stages because of dispersed oil in fine droplets is so highly bioavailable and to nearshore demersal fish like killifish in contact with oil

Blue crab and penaeid shrimps – still under study but clearly extensive exposure to oil and dispersants

Floating Sargassum community – high risk and likely injury to habitat provider (plant) and associated fish and wildlife – incl. dead hatchling sea turtles; concern over larval & juvenile bluefin tuna, mahi, cobia, etc.

Reuters

AP

Type I Injuries: Shoreline Habitats Oiled (1053 linear miles)

Coastal marsh – especially margins, where below-ground plant mortality also fostered marsh edge erosion but low total acreage lost

Sandy ocean beaches – coatings of mousse, tarballs, and layers of buried oil at depths in the sand with intense disturbance of clean-up

Seagrass beds – some direct habitat lossOyster reefs – some mortality from smothering plus

possible oyster larval mortality; mass freshwater diversion mortality

Protected mudflats – some loss of benthic invertebrate prey for higher trophic levels

Estuarine muddy bottom and ocean floor – PAH contamination plus persistence of oiled detritus, evident during summer 2011 storms

Type I Injuries: Grounded Oil Effects on Shoreline

SpeciesGround- and low-nesting marsh birds (double jeopardy for

pelicans etc. = feeding at sea + nesting impacts).Fiddler crabs, blue crabs, and marsh nekton, esp. shrimps.Oysters by adult and juvenile mortality, larval losses, and

likely slower growth.Terrapins and marsh mammals.Nekton, including juvenile and resident fishes (killifish), that

use shallow marsh, oyster reef, seagrass habitats.Seaducks, sea turtles, and demersal fishes that eat benthic

invertebrates in shallow estuarine bottom are at risk.

AP

Collateral Injuries: from Response ActionsToxicity from chronic exposure to persistent dispersant -

alone and with oil

Fine-scale chemical dispersal of oil enhanced bio- availability and kept it sub-surface for longer, thereby magnifying impacts to zooplankton, particle feeders

Physical injuries to marsh from boom groundings and vessel groundings while deploying boom

Waterbird mortalities from “booming in” both oil and birds around marsh islands

Habitat and food-web degradation from beach “nourishment”, which kills benthic invertebrates

Oyster mortality from of freshwater diversions

Air pollution and health effects in wildlife and humans from soot creation during at sea burning

AP

Collateral Injuries: from Clean-up EffortsVehicle driving on beaches (especially at night)

destroyed nests, killed nesting birds/chicksBirds and other animals killed during uptake into oil

skimmersConstruction of coastal barrier berms killed benthic food

resources and misguided sea turtles / ground-nesting birds to nest on that rapidly eroding sand

Sea turtle mortalities from intense trawl fishing, perhaps with disabled TEDs, immediately before closures when enforcement attention was diverted

Repeated mortality of benthic invertebrates and consequent loss of prey from demersal surf fishes and shorebirds after beach excavations to remove buried tarballs and oil layers and raking up wrack

U.S. Coast Guard

AP

Injuries: Type II Oil Spill Impacts (Subsurface including Deep Ocean)

By far the hardest aspect of the DWH spill to assess, requiring new research on interdisciplinary oil-spill oceanography

Possibly largest portion of the ecosystem impacts of the hydrocarbon release

Effective restoration depends on scientific advances to understand direct and indirect ecosystem impacts and service losses in meso-pelagic, bentho-pelagic, and deep-bottom communities

Failures by government and industry to conduct necessary science for readiness

NOAA

NOAA

Subsurface Ecosystem Consequences of a Deep-water Blowout

3 broad categories of subsurface impacts from the DWH1. Toxicity of oil and dispersant (includes physical smothering and

fouling) – pelagic particle feeders and all guilds of benthos2. Implications of organic carbon loading (perhaps 0.5-3.0 x annual

production over the spill area) with resultant intense microbial heterotrophic production and CO2 injection into seawater

3. Indirect effects of food web disruption – likely a widespread fracture of the food-chain linkage from particle feeders to higher trophic levels – including (?) species like sperm whales

2 ecological compartments outside familiar scope of NRDA1. pelagic (mostly deep) water column2. deep benthos

Type II Effects of DWH Oil Spill:Glimpses of Pelagic Impacts

Extensive mortality by fouling the feeding and respiratory organs of pelagic particle feeders such as copepods, salps, and appendicularians, thereby fracturing the food chain linkages to higher trophic levels

Massively elevated heterotrophic microbial production and consequent oxygen sags detected in petroleum hydrocarbon plumes trapped at a pycnocline in 800-1,100 m, but oxygen not depleted enough to induce hypoxia

Microbial production has been associated with marine snow and slime that helped aggregate oil droplets with organic particles and induce transport the oil to the deep sea floor

Study of higher trophic levels could integrate impacts to food chains, taking opportunity to use the spill as an oceanographic experiment

The high likelihood of large indirect food-web effects from DWH oil implies that delayed injuries will emerge, detectable only if focused ecosystem-based injury assessments continue over sufficient time

M. Joye

Type II Effects of DWH Oil Spill:Glimpses of Deep Benthos Impacts

Deposition of dark, hydrocarbon-rich sediments mm-cm thick onto sedimentary bottoms appears to have caused widespread mortality of resident soft-bottom benthic invertebrates, perhaps by smothering (Joye)

Some emergent hard-bottom areas exhibit apparent cover by a similar dark material and exhibit mortality of soft corals, sea fans, brittle stars, and other inverts (Fisher)

After the early bloom of heterotrophs, microbial activity now appears grossly suppressed on the sedimentary seafloor

Guiding Principles for GoM Ecosystem Restoration from 2011 Pew Report

Recognizing that past human and natural perturbations have compromised Gulf ecosystem function and resilience

Acknowledging that dramatic environmental change is inevitable and must be integrated into restoration plans

Treating the Gulf as one interconnected network of ecosystems from the shoreline to the deep sea

Realizing that ecosystem productivity, health, and sustainability of the Gulf and human welfare are intrinsically codependent

AP

NCEAS Working Group:Sean Anderson, Gary Cherr, Rich Ambrose, Shelly Anghera, Steve Bay, Michael Blum, Rob Condon, Tom Dean, Monty Graham, Michael Guzy, Stephanie Hampton, Samantha Joye, John Lambrinos, Bruce Mate, Doug Meffert, Sean Powers, Ponisseril Somasundaran, Bob Spies, Caz Taylor, Ron Tjeerdema, Charles Peterson : paper now posted on-line in BioScience May 2012.

Ocean Conservancy Team:Stan Senner, Jeff Short, Chris Haney, Bob Spies, Lisa Suatoni, Paul Kemp, Dennis Kelso, Charles Peterson

Acknowledged Contributors