El Niño–Southern Oscillation (ENSO) & Marine Iguanas (Difficult…
El Niño–Southern Oscillation (ENSO)
& Marine Iguanas
Snout Vent Length
A measurement of size taken from the tip of an animal's nose to the opening of the cloaca at the tail base.
A process of performing or taking place in a test tube, culture dish or outside the living organism
Rocky and uneven surface.
The fringe of land at the edge of a large body of water, such as an ocean, sea, or lake
Situated or placed higher than the surrounding area.
Exposed to warmth and light, typically from the sun.
El Niño–Southern Oscillation (ENSO) is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean
Foreshore or seashore, the area within the tidal range.
A deviation from a rule or from what is regarded as normal.
The deviation in a quantity from its expected value.
The species is experiencing high mortality in recent years especially at the Galapagos Island.
What causes a high mortality rate in this species?
Caused food source shortage & affects growth
Caused widespread starvation.
El Nino events (1982-1983)
Why Galapagos Island recorded the highest mortality rate for this species?
The El Nino event: reducing food availability and affect the reproductive system of the marine iguanas.
El Nino: disrupts the temperature of surrounding for the marine iguanas.
Oil spilled events from the grounded tanker Jessica (2001)
Mass of stomach contents of marine iguanas from 1982-1984 (Figure 8).
What is the difference of the marine iguanas (mass of stomach contents and snout vent length) during the 1991/1992 ENSO and after 1991/1992 ENSO?
The normal red algal turf disappeared, and replaced by brown algae that contains high cellulose and hard to digest.
During the event: - mass of adults iguanas' stomach contents were very light
The differences were due to the disruption of food chain .
After the event:
Sea-level and sea-water temperature in Galapagos had returned to normal.
Brown algae disappeared, while red algae dominated back .
The survival of marine iguanas recovered.
Why is the marine iguana with 400mm snout-vent length does not last after the 1991/1992 ENSO?
Sexual selection constantly favored large body sizes in male iguanas
Relationship of algal growth (Figure 4) to temperature
What is the relationship between algal growth and temperature?
Height of algal decrease as sea surface temperature increase.
Different optimum growth temperature
High temperatures cause algal growth to be slow and sometimes make the algal population to die.
Why is the temperature mostly affect the upper intertidal sample of algal?
The upper intertidal sample of algal are exposed to the air and changes of heat temperature.
Digestibility and cellulose content of algae
Does digestibility and cellulose content of algae in the Marine Iguana stomach could be taken into account on studying the history of the Santa Fe island?
Yes, it's a food source for them.
As the temperature of the sea increases, the growth of the algae decreases, causes malnutrition and starvation.
digestibility experiment of the algal samples was carried out?
To determine the nitrogen content
To determine the decrease in organic matter
Distribution of algae (1981-1984)
What is the distribution of algae from 1981-1984?
sp. show the highest number of abundance and distribution along the splash, high and low zone but very dominant at high zone. -
sp. which distributed equally in high zone and low zone whereas
sp. only distributed in low zone.
sp. show the higher distribution at high zone and low zone.
sp. which distributed more at high zone and less on low zone.
In 1981, the Green algae (
sp.) existed in large number located between the high zone and low zone followed by the Red algae (
sp.). The Brown algae (
sp.) distributed more and slightly abundance at the low zone.
Which type of algal that are most abundance in the Galapagos Island?
Marine iguana condition on Isla Santa Fe, 1981–1987
What parameters does it measure in order to determine the level of condition of Marine Iguana ?
Why the condition index of the adult female iguana is greatly decreasing in 1982 until 1983?
Decreased food source
Severe El Nino (1997-1998) at the Galapagos and the main effects were elevated air, elevated rainfall and water temperatures.
How water temperature, rainfall and air temperature cause high mortality of marine iguanas in Galapagos Island?
What are the other effects of El Nino in the Galapagos Island?
Favor development of the invasive species.
Food chains are disrupted caused extreme starvation nearly all species due to lack of nutrient-rich of primary level.
Change the feeding behaviour of some species.
Coral are stressed by the sustained higher temperature bleaching
Make the native species in the Galapagos Island to stop breeding.
How does El Nino affect marine iguana population?
Little nourishment is given, caused iguanas gave up on their normal feeding behavior
A lot of energy was used without gaining of nutrition
Food replaced by indigestible brown algae, which lead to mortality
A lot of marine iguanas died, reproduction decreased steeply.
Have to find alternative food resources.
Poor breeding seasons, due to the limited food sources
Reduction of their main food resources
Leads to unique adaptation for the marine iguana.
Which year has the highest values recorded ?
Air temperature - 1997,
Rainfall - 1983,1998
Air temperature -1997.