Revista Chilena de Historia Natural 81 (4): 501-514, 2008
RESEARCH ARTICLE
Spatio-temporal distribution of spionids (Polychaeta-Spionidae) in an estuarine system in
south-central Chile
This study is based on the identification and distribution of spionid polychaetes in relation
to abiotic characteristics of the environment at the mouth of the Valdivia-Tornagaleones estuary in south-central Chile. Four samplings
were carried out in 2005, in which eight species were identified including Aquilaspio peruana, Boccardia
polybranchia, Carazziella carrascoi, Dipolydora socialis, Minuspio patagonica, Rhynchospio
glutaea, Scolelepis quinquedentata and Spiophanes sp. As it is typical of other estuaries in south
central Chile, spionids were an important component of the macroinfauna of the Valdivia estuary. The distribution of the Spionidae
family in the system showed higher species richness in the outer reach of the estuary but higher abundance (number of specimens) at
the inner reach. The distributional pattern of the polychaetes did not vary throughout the year, exhibiting strong spatial zonation with
three significantly different assemblages. Minuspio patagonica, A. peruana and C. carrascoi contributed to the
similarity between these three groups, as well as to the formation of a general component in the macroinfauna. Sedimentological and
depth variables, as well as sedimentary organic material were only marginally related to the distribution of spionids. Results showed
that bottom salinity was the environmental variable responsible for spatial differentiation of spionids in the three groups, which permit to
differentiate the outer-reach species from those in the internal area of the estuary. The significant contribution of spionids to the total
component of macroinfauna in the studied area shows that these species are a significant component of the estuarine and transition
areas in the southwest Pacific coast.
Key words:
Polychaeta, Spionidae,
distribution, estuary, salinity, sediments, Chile
