Original scientific paper

ENVIRONMENTAL IMPACTS OF TUNA AQUACULTURE IN THE ADRIATIC SEA

Damir Kapetanović ; Institut Ruđer Bošković, Zagreb, Hrvatska
Irena Vardić ; Institut Ruđer Bošković, Zagreb, Hrvatska
Damir Valić ; Institut Ruđer Bošković, Zagreb, Hrvatska
Zlatica Teskeredžić ; Institut Ruđer Bošković, Zagreb, Hrvatska
Emin Teskeredžić ; Institut Ruđer Bošković, Zagreb, Hrvatska

Abstract

Aquaculture including tuna fattening, increased public interests in the possible impact on the environment in recent decades. Influences of cultivation of economically important fish species are numerous, but not in regard to assessment of microbial influences, particularly in the context of tuna. The aim of this study was to assess the effects of tuna fattening (Thunnus thynnus) in the sense of the environmental monitoring of microbial indicators of seawater quality at tuna farm in the central Adriatic, and to compare the achieved results with the results of research on a tuna farm in the Mediterranean. The quality of sea water was analyzed at two sites; one site was at the
tuna farm, and the other at a distance of about 500m from the farm, the control point. Sampling was conducted in two seasons (spring / autumn), in 2007 and 2008. During this study, the basic physico-chemical (temperature, salinity, transparency) and microbiological parameters of seawater quality (total number of bacteria, Vibrio, total coliforms, Escherichia coli, faecal coliforms, enterococci) were analyzed. For microbiological analysis of seawater; samples were serially diluted with PBS solution (Merck). To determine the total number of heterotrophic bacteria, spread plate method was used on Marine agar (BBL) and Trypticase soy agar (BBL) supplemented with 1% NaCl-a (Kemika), as well as substrate method using SimPlate test (IDEXX), all in duplicate. To determinate total coliforms and E. coli, and enterococci substrate tests Colilert (IDEXX) and Enterolert (IDEXX) were used in duplicate. Number of heterotrophic bacteria, which indicate the effects of the farm on the eutrophication, was less than the number determined in similar study in the Mediterranean. Number of E. coli and enterococci were not significantly different between farm and control point, but these values are higher than those from research in the Mediterranean. Increased numbers of enterococci, on the farm and control point, were indirect consequence of improper nutrition technology, which attracted a colony of seagulls. These results suggest that changes in seawater quality in relation to tuna fattening, depend on the broader ecological context. Therefore, location and environmental impact of tuna fattening on the environment must be considered within the broader context of ecological areas.

Keywords

Thunnus thynnus; heterotrophic bacteria; Vibrio; total coliforms; faecal coliforms; enterococci; seagulls

Hrčak ID:

66721

URI

https://hrcak.srce.hr/66721

Publication date:

20.12.2010.

Article data in other languages: croatian

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