A survey of freshwater fishes and their macroparasites in the ... - NINA

1 Introduction
7
NINA Report 635
The aim of the survey was to start mapping the occurrence and distribution of freshwater fish
species and their macroparasites in the rivers of ACG. This report describes the results of field
surveys performed during the rainy season of 1998 and the dry seasons of 1999 and 2001.
The species composition and distribution of the fresh water fish fauna in Costa Rica is fairly
well known in general terms, in particular through the work of Professor W.A. Bussing, University
of Costa Rica (Bussing 1985, 1987, 1998). The ACG is situated in a part of the country
where the freshwater fish fauna has received little attention. One reason may be that the fauna
is expected to contain relatively few species, due to the biogeography and immigration history
of this fauna element in this particular area (Bussing et al. 1996, Smith & Bermingham 2005).
Important factors expected to influence the occurrence of fish species in this area are e.g. the
position of rivers in relation to the major Pacific-Atlantic watershed divide (Smith & Bermingham
2005), altitude, and dry season water volume of the rivers. A survey aiming to establish
the role of these biogeographical and physical factors on the observed distribution of fish will
need to include collection on many sites (Bell 2003). Over three field periods, during the rainy
season in 1998, and the dry season in 1999 and 2001, a total of 27 localities were sampled.
The fish material has been deposited at the Museum of Zoology, University of Costa Rica, San
José, and at the Tropical Dry Forest Research Station, Santa Rosa, ACG.
In contrast to the fish fauna, the parasites of fishes in the fresh waters of Central America remain
poorly known (Watson 1976; Choudhury et al. 2002; Rodríguez-Ortíz et al. 2004a, b;
Choudhury et al. 2006; Scholz et al. 2004; Salgado-Maldonado 2008). This study is the first
comprehensive and concerted study on the parasites of a diverse assemblage of fishes from a
variety of drainages of differing hydrological and geographical characteristics in a particular
region of Central America.
The parasite material is currently in the possession of one of us (AC) and will be deposited at
the U.S. National Parasite Collection and the National Parasite Collection in Costa Rica as and
when the taxonomic work is complete. Specimens of two described species, Wallinia chavarriae
and Paracreptotrema blancoi have already been deposited at the U.S. National Parasite
Collection.
Quebrada Aserradero
(locality 4; 155
m a.s.l.).