Geography Reference
In-Depth Information
Expanding Environmental Problems
In the Galápagos, the direct impacts of a growing economy based on tourism are
still limited. Tourism is tightly regulated in the National Park with a restricted
number of visitor sites and inter island quarantine. The indirect effects of growth
have had the greatest impact on the archipelago's biodiversity. Negative indirect
impacts include the introduction of invasive species, including diseases (Fig.
6.2
)
and pollution. Table
6.1
gives a summary of the origins of various taxonomic
groups. To date, nearly 1,500 new species are known to have been introduced into
the Galápagos, many in the last 40 years. Earlier on, many introductions, such as of
edible species, were deliberate; but now, most species arrive unintentionally as a
result of increasing human traffic. Recently detected introductions include the
Mediterranean fruit fly and the big headed ant. Bird malaria has been found in
penguins, and dengue fever and its host mosquito are both now present.
Although the total number of species in Galápagos is relatively low, endemism
is high (Table
6.1
). High endemism is related to the archipelago's isolation; histori-
cally, new species arrived infrequently and irregularly. Species that did arrive and
survived have had the opportunity to evolve to suit the new environment without
much competition. For this reason, such island systems are less resilient to inva-
sions than continental systems (Lonsdale
1999
). Furthermore, naturalization rates
of introduced species in Galápagos also appear to be exceptionally high. Of the 888
plants introduced to Galápagos, approximately 34% have become naturalized, that
is, are able to reproduce without cultivation (Trueman et al.
2010
). This is a very
high rate of naturalization even among islands.
Once new species are naturalized, it has proved almost impossible to eradicate
them. Preventing negative impacts on both human and biological systems involves
expensive and perennial control programs. It is much more cost effective to prevent
new arrivals than to control existing ones. As part of the Galápagos Special Law, an
Inspection and Quarantine service was set up in 1999. Its aims are: (1) to intercept
new species before they arrive in the Galápagos in mainland ports or airports; (2) to
detect introduced species on the islands before they become naturalized; and (3) to
Table 6.1
Number of known endemic, native and introduced Galápagos species in main
taxonomic groups (
Source:
Charles Darwin Foundation databases, September 2008)
Taxonomic group
Native species
Of which endemic
Introduced species
Vertebrates except fish
117
69
55
Fish
396
51
2?
Terrestrial invertebrates
3,000
1,560
543
Marine invertebrates
1,384
362
?
Vascular plants
378
238
888
Non vascular plants (lichens,
bryophytes, algae), but
excluding fungi
986
184
?
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