Lecture 7 Flashcards
(28 cards)
what is toxicokinetics?
the description of both what rate a chemical will enter the body and what occurs to excrete and metabolize the compound once it is in the body
what is exposure?
any direct contact between a toxicant and an
individual, whether by touching, breathing or swallowing material from a source
what is dose?
the amount of a toxicant
inhaled or ingested, not all of which
is actually absorbed
What factors play a role in contaminant
exposure for marine mammals?
- diet
- habitat
- breathing
- skin/contact
what is the diet/characteristics of a baleen whale (Mysticetes)?
- feed on large prey aggregations
- grazing-type behaviours
- feed lower in the trophic levels
- two blow holes
- life span range ~30-100 years
- bowhead whale estimated to live up to 200 years
what is the diet/characteristics of toothed whales?
- feed on individual large prey items
- hunting-type behaviours
- feed higher in the trophic level
- one blow hole
- life span range ~35-50 years
- sperm whales can live up to 70 years
what is the difference in PCB concentrations between baleen and toothed whales?
toothed whales have a 30 fold increase in PCB concentrations
what are the trophic levels of common marine mammals?
- Baleen whales and sea otters (3.2 – 3.4)
- Most pinnipeds and odontocete whales
(3.8 – 4.4) - Killer whales (4.5 – 4.6)
how do oil spills impact filter feeding species?
Filter feeding species could trap oil in their baleen plates which would lead to ingestion of residual amounts of oil
how do oil spills impact benthic feeding species?
Benthic feeders (e.g., Sea otters, Bearded seals, Walrus, Grey Whales) can ingest sunken oil while feeding in areas of contaminated sediment
- Example: Repeated exposure of sea otters to oil through their benthic foraging behaviour was identified as the cause of protracted recovery and chronic mortality from the Exxon Valdez Oil Spill, Alaska
how do whales and dolphins breathe and how does oil affect this?
Whales and dolphins breathe at
the surface, where oil floats. Unlike
humans, who have noses that serve
as air filters, dolphins blow holes
connect almost directly to their
lungs. This creates a more direct
pathway for toxic oil to enter their
bodies.
what is the inhalation pathway for dolphins?
1: vapours inhaled through blowhole
2: enter lungs
3: enter circulatory system through pulmonary circulation, travel to heart
4: enter arterial circulation and travel to entire body, intact
what was the deep water horizon oil spill (2010)?
- Largest marine oil spill in the history of
the petroleum industry - Caused in the aftermath of a blowout
and explosion on the Deepwater Horizon
oil platform - Estimated the total discharge at
780,000 m^3 - Oil flowed for 87 days
- 1,141 dolphins died from March 2010
through July 2014 - Photographic surveys of live dolphins
from 2010 through 2014 showed low
survival and poor reproductive success
for dolphins from Barataria Bay and
Mississippi Sound - Additionally, the stranding network
documented high numbers of perinatal
strandings since the spill, especially in
2011.
what was the Exxon Valdez oil spill (1989)?
- Occurred in Alaska’s Prince
William Sound - Oil supertanker owned by Exxon
Shipping Company was bound for
Long Beach, California and hit
Prince William Sound Bligh Reef - 37,000 tonnes of crude oil was
spilled - 2,100 km of coastline was affected
- Long-term impacts associated with the Exxon
Valdez oil spill were observed in two killer
whale populations in Alaska resulting in
population depression in one, and the loss of
all potentially reproducing individuals, leaving
the group functionally extinct - Several thousand sea otters and several
hundred harbour seals died in the immediate
aftermath of the accident
how does oil impact the skin?
- Prolonged contact with oil can
lead to long-term coating that
may interfere with swimming
ability in seals - Oiling has been linked to
hypothermia, absorption and
irritation to skin and mucous
membranes, and mortality
How do we measure contaminants and
characterize exposure in marine mammals?
- Marine mammal (individual) – proxy for exposure, what is
retained, net accumulation - Prey – stable isotopes, fatty acids, stomach contents
- Habitat use – telemetry (tagging), observations
- Habitat – sediment, water, air
- Alternatives: individual and population-based models
How do we characterize contaminants in marine mammals?
- feces: POPs, hormones -> hours to days
- skin: Hg, Omics -> years
- blow: hormones, omics -> hours to days
- blubber: POPs, hormones, omics -> years
- whiskers: Hg, hormones -> days to months
- blood: POPs, Hg, hormones, omics, immune markers -> hours to days
how are harvested animals and carcasses used to characterize contaminants?
- Jaw (canine tooth) – Aging, stable isotopes, Hg
- Blubber – POPs
- Skin – Stable isotopes
- Blood
- Liver - PFASs
- Muscle – Hg, Stable isotopes
- Claw – Hg, Stable isotopes
- Fecal
- Whiskers – Stable isotopes, Hg
what are the pros and cons of using harvested animals vs. carcasses?
harvested: pros - fresh tissue, healthy individuals, age/sex information, reproduction, unlimited tissue
carcasses: pros - age/sex information, unlimited tissue, reproduction
cons - decomposition, not normal (death due to starvation, disease, emaciation)
what can you test for with free ranging blubber-skin biopsies?
- skin: mercury (Hg), stable isotopes, genetic analysis
- blubber: POPs, fatty acids
what information can you gather with fecal samples?
- mercury
- POPs
- PFAS
- stable isotopes of carbon and nitrogen
- % lipid
- protein content
- genetic analysis
how does genetic analysis work?
- Using a DNA sequencer we can obtain the
sequences at 68 different SNP locations. - At each location we get the DNA sequence on
a chromosome that came from the particular
killer whale’s mother, and the chromosome
that came from the father - Compare the pattern of DNA SNP sequences
to our database that contains almost all
Southern Resident killer whales and a
majority of Northern Resident killer whales
what are the pros and cons of using fecal samples vs. a biopsy?
fecal: pros - age/sex information, cons - minimal material, more challenging to match with a specific individual
biopsy: pros - known individual, age/sex information, healthy individuals, cons - minimal material, loss of lipid, depth of biopsy
what contaminants are retained, lost, and what is the exposure pathway?
retained: contaminants in the lipids or proteins
lost: contaminants in the urine, feces, or air
exposure pathway: food, water, sediments, air
