Biogeography

Dr. Ana Širović (asirovic@ucsd.edu)

SIO 133: Marine Mammal Biology

Is the ocean homogenous?

Tagging of Pacific predators (TOPP)

Yellow: females Red: males • Northern elephant

seal distribution:

– Pupping on beaches

– Foraging in open ocean

Biogeography

• Determined by:

– Evolutionary biology: historical range

– Ecology: food availability, temperature

Plate tectonics & early records

From Berta et al. 2006

1 – early cetaceans 2 – early sirenians

Evolutionary biogeography: cetaceans Geologic events | Marine mammal events | Location

From Berta et al. 2006

Tethys

Southern hemisphere

N Pac. Arctic N Atl.

Evolutionary biogeography: pinnipeds Geologic events | Marine mammal events | Location

From Berta et al. 2006

Walrus | Sea lion | Phocid

N Pac. equator S Pac.

N Pac. Pan. seaway N Atl.

Ocean zones

Seasonal variability of ocean zones • Temperate region

– Wind important factor

Seasonal variability: coastal upwellings

• California Current system

Bailey et al. 2010

Blue whale tracks

Seasonal variability: coastal upwellings

• California Current system

Bailey et al. 2010 Block et al. 2011

Blue whale tracks

Seasonal variability: polar region

• Light important

– Productivity high in summer

• Seasonal presence common

Prey aggregation • Affected by oceanographic features: fronts,

eddies, ocean bottom

From Tynan et al. 1998

Blue whale catches Krill concentration

Species distribution

• Cosmopolitan species

– E.g. Killer whales (Orcinus orca)

From Hoelzel 2002

Blue whale stocks

From McDonald et al. 2006

Species distribution

• Anti-tropical distribution

– E.g.: Long-finned plot whales (Globicephala melas)

From Hoelzel 2002

Anti-tropical distribution

From Hoelzel 2002

Species distribution

• Pan-tropical species

– E.g. Spinner dolphins (Stenella longirostris)

From Hoelzel 2002

Species distribution

• Circumpolar species

– E.g. Beluga whales (Delphinapterus leucas)

From Hoelzel 2002

Species distribution • Endemic species

– E.g. River dolphins

From Hoelzel 2002

Coastal species • E.g. Porpoises

From Hoelzel 2002

Gender-variable distribution

• E.g. Sperm whales (Physeter macrocephalus)

Source: whaletrackers.com

Migratory species

• Prey driven: Most rorquals

• Ice driven: polar species – e.g. beluga, narwhal, bowhead

Block et al. 2011

Month of year

Temperature-defined distribution

• E.g. Short and long-finned pilot whales

Source: Duke University, OBIS-SEAMAP

Major reason for anthropogenically driven climate change

Results of climate change in the ocean I

• Increased acidity

Metabolic consequences

Calcification issues

Results of climate change in the ocean II

• Reduced productivity – positive feedback

(stratification)

Effects of sea ice reduction on marine mammals

From Moore 2006

Effects of sea ice reduction on Arctic marine mammals I

• Walrus, polar bear: longer foraging routes, crowding on shore (walrus)

• Ringed seal: decrease in subnivean lairs

• Longer presence by migrating species

Ringed seal lair

Effects of sea ice reduction on Arctic marine mammals II

• Change in timing of migration (presence & food availability mismatch)

– Grey whales: move south later

– Belugas: arrive coastally sooner

– Bowheads: linger along route

Antarctic marine

ecosystem

Effects of sea ice reduction on

Antarctic marine mammals

krill seals & whales • Sea-ice From Atkinson et al. 2004

Krill versus salps

From Atkinson et al.

2004

Other effects of climate change on marine mammals

• Distribution shifts – temperature driven

From MacLeod

et al. 2005

Other effects of climate change on

marine mammals

• Distribution shifts – prey driven

From Kerosky et al. 2012

Results of climate change IV

• Rising sea level

– Loss of breeding habitat

Hawaiian monk seal

Possible cumulative effects on

marine mammals

• Predator-prey interactions: – Polar bear & ringed seal

– Loligo squid and short-finned pilot whales & Risso’s dolphins

Other possible effects on marine mammals

• Toxins

– Increased occurrence of harmful algal blooms

(HAB)?

• Disease – 2012 die-off in Peru? Common dolphin &

Burmeister’s porpoise

Brevetoxin: Flewelling et al. 2005