Fish biomarkers from a different perspective: evidence of adaptive strategy of Abramis brama (L.) to chemical stress

Abstract

Background: A prerequisite for long-term survival of populations under multi-stress conditions is their capacity to set up efficient adaptive strategies. However, changes in the activity of molecular biomarkers have been for decades considered as early signals of the deterioration of the fish health and evidence of stress-related adverse biological effects. The aim of this study was to show that such changes actually represent adaptive response of fish to chemical stress. Gene expression and enzyme activity level in liver and brain of specimens from two populations of Abramis brama from contrasted habitats (nature reserve and urban) were examined. Selected parameters included biomarkers of general stress, antioxidative defence, xenobiotic metabolism, endocrine disruption, glucose homeostasis, iron homeostasis, and neurotoxicity. Results: Exposure of A. brama population from urban area to chemical stress was confirmed by assessment of chronic toxic pressure at fish habitats using Toxic Unit approach. The most pronounced response to chemical stress is observed through the activation of antioxidative defence mechanisms in brain and liver at gene and enzyme activity level, high biotransformation capacity of liver, and activation of mechanisms that will meet energy demands and compensate for the metabolic costs of the response to toxicants (higher expression of genes related to glucose homeostasis in the exposed population). Higher hepatosomatic index in the exposed population implies liver hypertrophy due to increased functional load caused by pollution. Body condition factors indicate good overall condition of both fish populations and confirm high efficacy of mobilized adaptation mechanisms in the exposed population. Conclusions: The study provided the first data on basal expression of a number of genes in A. brama, potentially valuable for biomonitoring studies in absence of clear pollution gradient and/or reference sites (conditions). The study highlights importance of newly identified roles of various genes and proteins, typically considered as biomarkers of effects, and shows that changes in these parameters do not necessarily indicate the deterioration of the fish health. Such changes should be considered as adaptive response to chemical stress, rather than direct proof of ecological impact of pollution in situ.

Metal accumulation in relation to size and body condition in an all-alien species community

“…Previous literature showed, however, that this relationship can be highly variable (Alhashemi et al 2012;Luczynska et al 2016;Dragun et al 2016;Rakocevic et al 2018). One possible explanation is that fish could have physiological mechanisms that reduce the impact of metals on body condition (Tenji et al 2020). It should also be noted that the Fulton factor is correlated with the body fat content (Schloesser and Fabrizio 2017), which can vary between individuals and species, and that metal accumulation can be positively or Table 1 Results of the significant linear models with log 10 -transformed metal concentration as response variable and length (CTL, cephalothorax length for crayfish; TL, total length for fish) and Fulton factor (K) as predictors Asterisks refer to the significance level: p < 0.05 (*); p < 0.01 (**); p < 0.001 (***) negatively related to the lipid content, depending on the metal (Sassd 2011;Charette et al 2021).…”

Impact of habitation conditions on metabolism in the muscles, liver, and gonads of different sex and age groups of bream

“…Indices of the physiological condition of fish may reflect the health and wellbeing of individuals and be criteria for evaluating the living conditions of hydrobionts (Teubner et al, 2015;Arame et al, 2020;Khillare & Khandare, 2020;Tenji et al, 2020). The indices of physical conditions are considered to positively correlate with the content of lipids in the organism of fish (Salam & Davies, 1994;McPherson et al, 2011;Pradhan et al, 2015;Ahmed & Sheikh, 2017).…”

Age and growth of two bream species in the Tudakul reservoir of Uzbekistan

“…The bream found a favorable environment, started natural reproduction and spread in the middle and low streams of the river, including the Tudakul reservoir. Recently, the species has the status of a commercial fishery in all water bodies of the Zarafshon River basin [4,6]. In Uzbekistan, the biology of European bream, including growth and maturation, was studied until the 1980s; there have been virtually no studies since the early 1990s [4].…”