DIVERSITY OF LIFEFORMS AND ECOLOGICAL UNIQUENESS IN GALAPAGOS ISLAND:
The Galapagos Island contains a large number of endemic species. The notable species on this island includes-
Fauna-
The Galapagos Islands have a diverse array of bird, reptiles/amphibians and mammals. Listed below are some of the few noteworthy species on the islands:
1. Galapagos giant tortoises (Geochelone species)
The Galapagos giant tortoises are one of the most notable species on the island.11 species of endemic tortoises are found on the Galapagos:
• Five are found on Isabela Island
• Five are present on Santa Cruz, Santiago, Pinzon, San Cristobel, and
Espanola Islands. The last living Pinta tortoise, “Lonesome
George”, resides at the Charles Darwin Research Station.
2. Darwin’s Finches
These birds are one of the most studied birds on the planet for understanding the process of adaptive radiaton. 13 species of Darwin’s finches are endemic to the Galapagos Islands
• Geospiza species: Large ground finch(Geospiza magnirostris), medium ground finch (Geospiza fortis), small ground finch (Geospiza fuliginosa),sharp-billed ground finch (Geospiza dificilis), cactus ground finch (Geospiza scandens), large cactus finch(Geospiza conirostris)
• Camarhynchus species: Large tree finch(Camarhynchus psittacula), medium tree finch (Camarhynchus pauper), small tree finch (Camarhynchus parvulus),woodpecker finch (Camarhynchus pallidus), mangrove finch (Camarhynchus heliobates)
• Other species: Warbler finch (Certhidea olivacea), Vegetarian finch (Platyspiza crassirostris)
3. Waved Albatross (Phoebastria irrorata)
It the largest bird inhabiting the Galapagos and the only albatross in the tropics. This species is regarded as endemic to the Galapagos. They breed mainly on the Espanola Island.
4. Galapagos Penguin (Spheniscus mendiculus)
This endemic species of penguin is the only species of penguin found in the northern hemisphere. It has adapted to cooler water temperatures and tropical land temperatures.
5. Galapagos Petrel (Pterodroma phaeopygia)
The critically endangered Galapagos petrel is a sea bird which breeds in the Miconia zone in the highlands of SanCristobel, Santiago, Santa Cruz, and Floreana Islands of the Galapagos.
6. Land iguanas (Conolophus subcristatus and Conolophus pallidus)
Two species of endemic land iguanas are found in Galapagos:
• Conolophus subcristatus is found in the drier parts of the western and central islands, including Santa Cruz, South Plaza, Seymour , Isabela, and Baltra Islands.
• Conolophus pallidus is resides only on Santa Fe Island.
7. Sea cucumbers (Isostichopus fuscus, Stichopus horrens, and Holothuria species)
These are marine animals related to star fish and sea urchins found throughout Galapagos.A number of species can be found in Galapagos, including:
• Isostichopus fuscus
• Many Holothuria species
• Stichopus horrens
8. Rice rats (Oryzomys and Nesoryzomys species)
Six species of endemic rice rats belonging to two genera, Oryzomys and Nesoryzomys can be found on the Galapagos.
9. Sharks in Galapagos
27 species of sharks, categorized into the following three groups are native to Galapagos.
• Whale sharks (Rhincodon typus): These are rare sharks throughout Galapagos, and mainly found in open water.
• Hammerhead sharks (Sphyrna species): They are commonly found near Wolf and Darwin Islands in the northern part of the archipelago.
• Pointy-nosed sharks : This category includes Galapagos sharks (Carcharinus
galapagensis), Silky sharks (C. falciformis), white tipped (Triaenodon
obesus) and black tipped (C. limbatus) reef sharks
10. Mockingbirds (Nesomimus spp)
There are four endemic species of mockingbirds in Galapagos:
• Galapagos mockingbird (Nesomimus parvulus): Found throughout Galapagos except in areas where other species reside.
• Charles or Floreana mockingbird (Nesomimus trifasciatus): This
species is found on the islets of Champion and Gardner-by-Floreana.
• Hood or Espanola mockingbird (Nesomimus macdonaldi): Found
only on Española and the islet Gardner-by-Española.
• Chatham or San Cristóbal mockingbird (Nesomimus melanotis):
Found only on San Cristobal Island.
11.Galapagos sea lions (Zalophus wollebaeki)
Like most other species on the Galapagos, the Galapagos sea lions are also endemic to the Galapagos. They can be found hunting in the sea and on most islands of the archipelago.
Some other species found on the Galapagos include: Galapagos Green Turtle(Chelonia mydas agassisi),Flightless Cormorant(Phalacrocorax harrisi),Great Frigatebird and Magnificent Frigatebird,Blue-footed Booby(Sula nebouxii), Galapagos Hawk(Buteo galapagoensis)
Fauna-
The Galapagos Islands are native to 560 plant species, of which 180 are endemic. On the larger Galapagos Islands, four ecological zones nave been defined: coastal, low or dry, transitional and humid. In the coastal ecological zones, species such as mangrove , myrtle and saltbush are found. The incense tree, poison apple tree, carob tree, yellow cordial and chala can be found in low and dry zones. epiphytes and perennial herbs exist in the transitional zone. In the humid sector ,grow Galapagos coffee, cogojo, cat's claw, passionflower, Galapagos guava, and some varieties of moss, fungus and ferns. The three most notable plant species on the islands are mentioned below:
1. Scalesia shrubs & trees (Scalesia species)
Currently, there exist 15 recognized species and five subspecies of Scalesia endemic to Galapagos.There is great diversity between species due to adaptive radiation.
2. Opuntia cactus (Multiple Opuntia species)
Also known as prickly pear cacti, this species are a commonly found in the arid lowlands of Galapagos. Six species of Opuntia cacti are found in Galapagos.
3. Galapagos rock-purslane (Calandrinia galapagosa)
This perennial herb grows is endemic to only the San Cristobal island of the archipelago. There exist two varieties of the Galapagos rock-purslane- one with purple leaves and pink flowers and the other with green leaves and white flowers.
BIOLOGICAL INTERRELATIONSHIP AMONG THE LIFEFORMS-
There exists complex interaction between the species inhabiting the Galapagos. Listed below are some of the many interactions between the living species on Galapagos:
• Opuntias serve as source of food in arid zones of Galapagos. Land iguanas and turtles eat the pads, fruits are consumed by doves, mockingbirds and iguanas. Many species of Darwin’s finches consume the fruits, seeds and flowers and derive water by from the pads of Opuntia. Insects get nectar from the flowers. In return, all these species help in the propagation of Opuntia by dispersing its seeds.
• Opuntia serves as a nesting place for the Floreana mockingbird.
• Darwin’s finches consume seeds, flowers and insects (mites and ticks from iguanas and tortoises). Sharp-billed Ground finches feed on the blood of seabirds. Mangrove and Woodpecker finches can also dig insects out of holes in dead trees with help of spines of cactus or twigs.
• Mangroves away from the sea serve as habitats for mangrove finches.
• Birds in Galapagos help reptiles by removing ticks and parasites from their bodies.
• Algae, small snails, invertebrates, waste materials and sand are food for sea cucumbers.
• Sea cucumbers help other aquatic life forms by recycling nutrients for their use.
• Rice rats feed on grasses, seeds and fruits.
• Sharks, being the top predator in the food chain help in the process of natural selection by consuming slow and weak fishes, including smaller sharks and rays.
• Remoras (cleaning fish) accompany sharks and other large marine animals and remove parasites.
• The Galapagos sea lion feeds on fishes and squids.
HUMAN INTRUSION THREATENING GALAPAGOS:
Human activities in and around the area has threatened the rich biodiversity of the Galapagos.
• The Galapagos tortoise was overhunted by pirates in the past which led to a rapid decline in its population
• The human population in Galapagos has recorded a 40 fold increase in 50 years leading to increased competition with the indigenous flora and fauna for limited resources.
• Agricultural lands have replaced highlands leading to habitat loss for a large number of animals inhabiting Galapagos.
• The international demand for sea cucumbers has increased its fishing in the waters surrounding Galapagos leading to decline in their population.
• The popularity of Galapagos as a tourist destination has increased. This has lead to the development of infrastructure on the archipelago.
• Increased travel in and around the area has contributed to climate change and pollution.
• Invasive species like feral cats, goats, etc. introduced on the islands by humans has threatened the existence of the native flora and fauna of Galapagos.
• Climate change as a result global warming and pollution due to human activities in other parts of the world has also affected the species.
• Increased occurrence of eye infection in sea lion pups, appearance of dead fish, sea urchins and algae had been reported following the oil spill from tanker Jessica in January 2001 near the island of San Cristobel.
EFFORTS FOR PRESERVATION-
To protect the rich biodiversity of the Galapagos, many steps have been taken up the government of Ecuador and NGOs like the Charles Darwin Foundation.
• 97.5% of the land area has been declared as National Park to protect the species inhabiting Galapagos.
• Long line fishing has been prohibited in areas around the Galapagos to protect its marine life.
• The Charles Darwin Foundation has successfully removed a number of invasive species (goats, donkeys, pigs, cats, fire ants, etc)in some parts of the islands to protect the native flora and fauna and in currently involved in projects to remove other species.
• The Charles Darwin Foundation is also involved in protecting the last Pinta Tortoise (Lonesome George) and breeding it to restore the species.
• A census of all the species inhabiting the area is maintained and factors affecting the existence of various species are recorded to help preserve the endangered species.
ADDITIONAL MEASURES REQUIRED-
• Complete eradication of invasive species on the islands to minimize competition and predation of native species.
• Control of traffic in and around the archipelago to control pollution and climatic changes.
INDIVIDUAL MEASURES-
• Understand the importance of protecting the biodiversity and donate to non-profit organizations like the Charles Darwin Foundation dedicated to the preservation of biodiversity in the Galapagos.
• Individuals can volunteer to take part in conservation activities on the island.
IMPACT OF LOSS OF BIODIVERSITY-
If the intrusion in Galapagos goes unchecked, native species on the island will be lost. Even if one of the species is lost, it can adversely affect the existence of other species and lead to ecological imbalance. Hence it is very important to check intrusion in the Galapagos.
Sources-
1. http://www.darwinfoundation.org/en/
2. http://www.galapagos.org/2008/