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Effects of the Discharge of Iron Ore Tailings on Subtidal Rocky-Bottom
Communities in Northern Chile
Sergio A. González†, Wolfgang Stotz†‡, and Domingo Lancellotti§
†Departamento de Biología Marina
Facultad de Ciencias del Mar
Universidad Católica del Norte, Casilla 117
Coquimbo, Chile

‡Centro de Estudios Avanzados en Zonas Aridas (CEAZA)
Raúl Bitrán s/n
La Serena, Chile

ABSTRACT
Some of the many mining operations that exist in northern Chile dispose their mine tailings directly into the sea. Little is known about the effects of these tailings on shallow rocky subtidal communities. This study
reports these effects for an iron ore pelletization plant that has discharged
for ca. 23 years in the intertidal of a cove on the exposed rocky coast of
northern Chile, generating high turbidity in the water column and deposit
of sediments on the bottom. A nonparametric multidimensional scaling
(nMDS) ordination analysis for the species of the rocky subtidal communities, based on the Bray-Curtis dissimilarity index, showed great differences, the affected communities being dominated by incrusting invertebrates, whereas the unaffected areas at the same depth had kelp beds. The
effects were observed only close to the discharge and were not observed
in the more shallow water communities, which in affected and unaffected
areas consisted of barren grounds dominated by calcareous algae and sea
urchins. The effect on the vertical zonation pattern of communities did
not produce differences in the effective diversity, which turned out to be
similar among affected and control sites. This occurred because of the replacement, more than the elimination, of species on affected sites. This
type of study, in which information is generally maintained in reports only
seen by industry and governments, needs to be published to contribute to
a more comprehensive database for the improvement of decision-making
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§Departamento de Salud Pública
Facultad de Medicina
Universidad Católica del Norte, Casilla 117
Coquimbo. Chile

processes regarding coastal subtidal rocky communities and the effects of
human activities on these environments.
ADDITIONAL INDEX WORDS: Mining activities on the coast, discharge
of suspended solids, effect of turbidity, marine assemblages, kelp beds, barren
grounds, Chilean coast.
INTRODUCTION
The human population inhabiting coasts around the world comprises
one thousand million people (23% of the total human population), being
in average three times denser (112 persons/km2) than the global average
population density (Small and Nicholls, 2003). This exerts great pressure
on the natural ecosystems, which can be altered by activities such as introduction of pollutants to the environment, alteration of the physiography, and addition or removal of organisms (Benedetti-Cecchi et al., 2001;
Lubchenco et al., 1991). These activities can directly or indirectly affect
the species composition, alter interspecific interactions within affected
communities, and change the flow of natural or anthropogenic materials
through the system. At present, no single site in the marine environment
has been unaffecte d. The most intense effects have been along the coasts,
Latin America being no exception (Halpern et al., 2008). Chatwin and Rybock (2007) have calculated a Threat Index for Latin American counties,
which is highest for the Brazilian coast, the coast of northern Peru, and

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