11/05/2016

1

Assessing the impact of hydrocarbon

releases on tropical reef species

Andrew Negri*, Oleg Makarynskyy, Diane Brinkman, Florita

Flores, Joost van Dam, Nicole Webster, Ross Jones

AIMS: Townsville, Perth, Darwin

National Sea Simulator Outline

1. Hydrocarbons and coral reefs

2. Introduce spill modelling and ecotoxicology

3. Coral ecotoxicology examples

4. Integrating toxicity data with models

to improve risk assessments

Oil spills in tropical marine

habitats

10,000 m3 Bahia Las Minas refinery spill, Panama 1968

Corals, mangroves, seagrass > 10 year recovery

Smithsonian Inst.

Risks to reefs: blowouts

Montara (off WA, 4,500 m3)

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2

Risks to reefs: shipping

Great Barrier Reef: Shen Neng 1

� 68 000 tonnes of coal

� 950 tonnes of oil

Risks to reefs: considerations

• Weather/hydrodynamics

• Sub-surface or surface exposure

• Nature of the oil/weathering

• Other pressures (UV, thermal)

• Spill response

Response can change the risk

Norbert Wu

e.g. dispersants

Improving risk assessments for reefs

Risk = f: Exposure (concentration ; duration) x Impact (to relevant species)

• Ecotoxicology - few studies on

reef organisms

• Available data often not

reliable

Develop more relevant risk maps for regulators and industry

• Spill models – validation of

models with field data

• Masterclass Friday: MEDSLIK-II

Oleg Makarynskyy

Improved integration

Coral reef ecotoxicology has not

delivered reliable data

• Measure aromatic hydrocarbons (MAHs and PAHs)

• Concentration-response curves to derive thresholds (EC10)

Batley et al. (2014) Revision of the Method for Deriving Water Quality Guideline

Trigger Values for Toxicants. Department of Sustainability, Environment, Water,

Population and Communities. 37p.

Threshold

Need for tropical species thresholds

Why Corals?

• Ecologically important

• Economically important

• Sensitive to stress

Data used in risk modelling:

often from temperate species

tests

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3

Potential exposure: pathways

Larval development

Juvenile

Spawning

FertilisationSettlement

Q: Identify the slick

www.schmidtocean.org www.noaa.gov

Condensate (light crude)

ecotoxicology

Negri et al. (2016) Acute ecotoxicology of natural oil and gas

condensate to coral reef larvae. Nature Scientific Reports 6:21153

• Toxic threshold

103 ppb (EC10 total aromatics)

1.2 ppb (EC10 PAHs)

Normal

settlementAffected by

condensate

Settlement

Threshold

• Match the thresholds with chemicals

modelled

• Reported threshold affects risk maps…

Dispersant concentration (mg l-1)

1 10 100

Inhi

bitio

n of

set

tlem

ent (

%)

0

20

40

60

80

100

2 hour 6 hour 24 hour

Dispersant toxicity to larvae

Experiments carried out in the SeaSim in November 2015

• Coral larvae were exposed for

2, 6 or 24 hours

• Toxicity increased 5-fold from

2 – 24 hours

• Datasets useful for modelling

effects over time

Normal larvae Larvae exposed to

dispersant

Dispersant toxicity to adult corals

Increasing dispersant concentration

Dispersant concentration (mg l-1)

10 100

Col

ony

mor

talit

y (%

)

0

20

40

60

80

100

Additional pressures affect

thresholds

Condensate toxicity + co-exposure to UV

TPAH (µg l-1)

Condensate + UV

100 1000 10000

% In

hibi

tion

of s

ettle

men

t

0

20

40

60

80

100

- UV+ UV

Negri et al. (2016) Acute ecotoxicology of natural oil and gas

condensate to coral reef larvae. Nature Scientific Reports 6:21153

• Toxic threshold drops to 64 ppb (EC10 total aromatics)

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4

Sub-lethal indicators:Early warning and evidence of exposure

Control conditions

Crude oil + dispersant

Sponge larval settlement

Control

Oil only

Oil +

dispersant

• Effects on microbial communities more sensitive than settlement

Stable symbiotic community

affected by oil and dispersant

Test other threats and responses

Apply ecotoxicology criteria to other oil-related issues

• e.g. alternative sorbent products applied to soak up spills

Combining toxicity thresholds with spill

models to assess risk MEDSLIK-II

Same spill model with different

toxicity thresholds

International thresholds 10 ppbCoral (total aromatics) 103 ppb

Coral (total aromatics+UV) 64 ppb)

Coral (PAHs) 1.2 ppb

What have we learned?

(and the way forward)

Dispersant concentration (mg l-1)

1 10 100

Inhi

bitio

n of

set

tlem

ent (

%)

0

20

40

60

80

100

2 hour 6 hour 24 hour

• More threshold data needed for a diversity of tropical

species

• Improve integration between toxicology and spill

modelling to generate effective risk maps

• Including exposure duration

• Test effects of co-stressors: UV, temperature

• Develop sub-lethal indicators: early warning, validate

exposure

• What do you think is important?

Thank you

Paul Irving and AMSA

Inside the SeaSim faclity