4.3 Name of the Indicator: Number of introduced or invasive species
1. Description of the indicator (objective, methodological general aspects and
utility):
This indicator evaluates changes in the presence and abundance of introduced or invasive
species reported in the MPA. It is particularly relevant for oceanic islands, which are usually
highly vulnerable to the effect of a biological invasion, due to their biological characteristics
shaped through natural evolution processes in geographic isolation.
Definition of terms:
Native species: species, subspecies or inferior taxon, which occurs inside its potential space for
dispersal, e.g.: within the space that would occupy naturally without direct or indirect human
introduction or care
Introduced species: exotic species, non-native, but not necessarily invasive. It is any species
that occurs outside of its natural space and of the space of potential dispersal, i.e.: in a space
that in theory it would not exist without direct or indirect human intervention. Includes a part, a
gamet or a propagule of the species that could survive and reproduce
Invasive species: a species introduced or native, that under particular biophysical conditions
shows an aggressive reproductive behavior and settlement, which allows it to push out other
species thus producing significant changes in the structure of the biological community already
established in the area
2. Measurement unit of the indicator:
- Number of introduced or invasive species in the MPA classified by taxa
- Number of estimated individuals of the introduced or invasive species (applies particularly to
mobile fauna)
- Percentage (%) cover of the introduced or invasive species (applies particularly to plants and
benthic sessile marine organisms)
3. Methodological description:
3.1. Process to calculate the indicator (steps):
1. Inventory of fauna and flora species or revision of the existing base line
2. Inventory of biodiversity of taxonomic groups such as insects, herbaceous plants, worms, that
can have species that are more readily introduced accidentally by human activities. The
number, target groups and frequency of the inventories will depend on the characteristics of the
MPA and the availability of human and economic resources. It is important to identify migratory
species.
3. Temporal comparison of species richness in the taxonomic groups evaluated and
establishment of new species.
4. Once identified, the species that are introduced and/or with potential of becoming invasive
species, specific studies should be carried out to estimate their population size, population
dynamic and distribution of those species. Ideally, monitoring programs for those species
should be implemented, considering at least three issues: a) population dynamics, b)
interactions with other species of the MPA, particularly in terms of competence and predation, c)
Control of possible entry routes, in the case of introduced species.
3.2. Formula of the indicator (in case this is useful to simplify the indicator
measurement):
Where:
3.3. Presentation of the results (graphs, figures, tables, etc. that allow visualizing
the results clearer):
-
Spread sheets of classified species with population numbers for the different years
-
Graphs that show number of species introduces and/or invasive per taxon evaluated
-
Geographic Information Systems (GIS) to help visualize changes in cover and areas
occupied by species.
If the number or population size of any introduced or invasive species grows, management
measures must be implemented immediately.
3.4. Possible methodological limitations of the indicator:
- Incomplete or inexistent baseline information about the biodiversity of the MPA. This will
hinder identification of introduced species and the establishment of the time when it was
introduced.
- The indicator demands high investment of specialized human resources to carry out biological
inventories of several taxa and to carry out monitoring to estimate population sizes
- Frequency of updating the information will most probably be based on the availability of
resources than on manager’s needs
- The beginning of a biological invasion by an introduced species can be caused by
environmental changes that could be very subtle, which added to the low frequency of updating
the information, can limit the probability of early detection, making more difficult to implement
effective management measures.
4. Variation and influence ranges:
4.1. Relation with other indicators:
This indicator can be related, both directly and indirectly, with other indicators such as:
- Number of visits to the protected area and its sites
- Abundance of key species
- Percentage of solved cases and complaints formally presented
- Percentage of trained personnel, economical resources and operational infrastructure for the
management of marine tourism basing on optimal conditions
5. Data availability:
5.1. Are there available data? (Yes) (No) In which format/state are they? (Printed,
digital, field data sheets, analyzed, published, etc):
There is only available information for Galapagos National Park, which corresponds to the entire
protected land area of the archipelago. Data is published. There is no data for the Galapagos
Marine Reserve.
6. Responsible institutions of the indicator (including potential ones):
MPA management authorities
7. References related to the indicator:
Mack, R.N., D. Simberloff, W.M. Lonsdale, H. Evans, M. Clout y F. Bazzaz. 2000. Invasiones
Biológicas: Causas, Epidemiología, Consecuencias globales y Control. Issues in Ecology.
Issue 5. 22 p.
Chairman’s Report. Norway/UN Conference on Alien Species. The Trondheim Conference on
Biodiversity. 1-5 July 1996. Norwegian Institute for Nature Research, Trondheim, Norway.
UICN. 1999. Borrador de guías para la prevención de pérdidas de diversidad biológica
ocasionadas por invasión biológica. Cuarta reunión del órgano subsidiario de
asesoramiento científico, técnico y tecnológico. Montreal, Canadá. Documento de base.
Cronk, C.B. y J.L. Fuller. 1995. Plant invaders (1a Ed.). WWF-International. Chapman & Hall.
241 p.
McNeely, J.A. et. al. 2001. A Global Strategy on Invasive Alien Species. Global Invasive
Species Programme (GISP) – IUCN. Gland, Suiza.
Calderón-Sáenz, E. 2003. Plantas invasoras en Colombia: una visión preliminar. Programa de
Biología de la Conservación, Línea “Especies Focales”. Instituto Alexander-von-Humboldt.
8. Comments (methodological limitations included):
Several international codes are available on-line about practice, treaties and agreements about
prevention, control and eradication of exotic species
Fecha: Febrero 2007
…………………………………
Autor: Luis Chasqui Velasco, Isaac
Chinchilla, Eddy Araujo, Pilar Herrón
E-mail: lchasqui@hotmail.com