Revista de biología marina y oceanografía
On-line version ISSN 0718-1957
CANETE, Juan I; LEIGHTON, Gerardo L and SOTO, Eulogio H. Environmental monitoring index based on the temporal fluctuations in the abundance of two species of benthic polychaetes from Quintero Bay, Chile. Rev. biol. mar. oceanogr. [online]. 2000, vol.35, n.2, pp. 185-194. ISSN 0718-1957. http://dx.doi.org/10.4067/S0718-19572000000100007.
An Environmental Monitoring Index based on the temporal variations in the abundance of two benthic polychaetes (Nepthys impressa Baird, 1871 and Prionospio peruana Hartmann-Schröder 1962a) is proposed. Three replicated samples were collected in four subtidal stations at Quintero Bay (32º45' S, 71º29' W; 6 to 13 m deep), central Chile, with a Van Veen grab 0,1 m-2; the sampling campaigns were carried out in March and November 1995 and 1996, April, August and November 1997 and March 1998. This study allowed to evaluate the use of population parameters of the benthic component in environmental impact programs according to the technical requirements of DGTM and MM (Chilean Navy). Nepthys impressa (Ni) is a common species whose abundance (N) varied in one order of magnitude and occurred in sediments with low percentage of organic matter, MO (< 1%). Instead, Prionospio peruana (Pp) is an opportunistic species, uncommon, with its abundance varying four orders of magnitude. This species was associated to altered sediments, moderately enriched in terms of organic matter (» 3%). The temporal variations in the abundance of both species allows to propose the Environmental Monitoring Index (IVA): IVA = Log [(NNi/(NPp + 1))* 100], The index identified three phases at subtidal sediments: a) a moderate enrichment in March, 1996 (3% MO; IVA<1) with important population development of P. peruana, b) a recuperation of habitual conditions (< 1% MO; IVA » 3) in seven months retourning to the dominance of N. impressa, and c) after March 1996 IVA showed lower values than those obtained before the event of enrichment (IVA > 3). The use of this index in other Chilean bays is discussed. Other eighteen species of benthic polychaetes were collected in the shallow sandy bottom in the study area.
Keywords : Polychaeta; Marine Pollution; Quintero; Nepthys impressa; Prionospio peruana.