El Nino
impacts
wind pattern and ocean current shift in Pacific
reduction in cold water upwelling in western area of Archipelago
warm waters will replace productive and nutrient rich cold water - breaks down food chain
increase of land precipitation - boosts plant production and therefore some insect and animal species higher in the food chain like snakes
new conditions are difficult for most species to adapt to - islands normally dry
Examples
excessive rains caused collapse of Opuntia cacti
shallow roots anchored in loose mud could not sustain the weight of cactus body which was overloaded with excess fluids
Galapagos Giant Tortoise
nests become too wet to maintain their eggs at the correct temperature - reduced reproduction and population numbers
encourages introduced species to become established
invasive ants and wasps
are able to expand their ranges of tolerance during El Nino
how is El Nino different to climate change
more short lived effects - usually last around 1 year
climate change is longer and more permanent
they are linked - as climate change advances, El Nino events may become more frequent and intense
Effects on specific habitats on Galapagos
Terrestrial Ecosystems
'The humid zone' - most biologically diverse
higher precipitation alters vegetation growth rates and therefore the forest structures
water saturated soils increases soil erosion so trees cannot survive as roots can't penetrate to sustain growth
increased temperatures force species to higher elevations so get restricted at tree and mountain tops
Marine Ecosystems
Upwelling Zones - deep water currents carrying nutrient rich water to sustain food chains
upwelling areas may be reduced due to ocean warming
El Nino led to dramatic decline in productivity
Coral Reef Ecosystems
warm and cold water currents create precise conditions for tropical and deep water corals to survive
rising ocean temps threaten them - ocean acidification may limit coral growth
rising temperatures may force cold water corals to be replaced by warm tolerant species
Mangrove Forest - coastal transition from ocean to land that creates a nursery for juvenile fish important in commerce on the island
threatened by rising sea levels - more coastal flooding and erosion