Health assessment of hydro-ecosystems based on homeostasis indicators of fish: Review of approaches

Abstract

This paper reviews scientific literature concerning the possibility of using aspects of physiological responses of fish to environmental stressors and their indicators to assess vulnerability (‘health’) of hydro-ecosystems of various types. Based on the available information, the authors have found that most of these methods are quite complex, they require a researcher to have specialized skills, involve considerable time and costs, and therefore are not widely used in research on natural water bodies. These factors allowed the author to determine the aim of the paper: the analysis of the most representative and relatively simple methods of health assessment of hydro-ecosystems by using fish as biological indicators. Some of the known concepts are then discussed, demonstrating the possibility of describing and monitoring changes in hydro-ecosystems according to morphometric parameters and fish growth variability. The paper indicates that such approaches can be justified and illustrative only when the ecosystem is assessed in clearly defined local terms. The review of literature on the influence of different biotic and abiotic factors and their mutagenic action on fish suggests that the micronucleus (MN) test in fish erythrocytes is one of the most important and relatively simple assessment methods. Our research emphasizes that there is a need to pay attention in the assessment process both to the measurement units used in the presentation of research results and to their interpretation regarding the level of spontaneous mutations among fish, which differs according to various sources. The research suggests that such complications can be avoided by clarifying the levels of ontogenetic ‘noise’ for hydro-ecosystems of specific geographic zones. Taking into consideration the existing generalization of scientific facts about significant destabilization in the development of organisms when water is polluted even at low levels, the paper focuses on the opportunity to assess health of hydro-ecosystems using the fluctuating asymmetry index (FA). This study indicates that such assessments have the benefit of close correlation between the parameters of fish development stability and levels of water pollution. However there is an obvious risk of obtaining serious measurement errors in determining the level of FA. Based on the foregoing, this paper uses the registration of changes in fish homeostasis in order to expand the understanding of both the possibility of assessing the effects of combined ratings of water pollution and the background conditions in which harmful elements and compounds act. The authors substantiate the feasibility of combining several relatively simple and descriptive assessment methods and conclude that there is a need to elaborate criteria for the development of health of hydro-ecosystems within specific geographic zones.

Keywords

• pollution
• growth variability
• nuclear violations
• fluctuating asymmetry