Histopathological alterations in Astyanax bifasciatus (Teleostei: Characidae) correlated with land uses of surroundings of streams

ABSTRACT This study evaluated gills and liver of Astyanax bifasciatus as histological biomarkers for biomonitoring of streams along areas with different land uses. The fish were collected by electrofishing in six streams in the basin of the lower Iguaçu River. The objective was to correlate the presence and degree of histopathological alterations of gills and liver with the environmental variables among streams along different land uses. The low frequency of histopathological alterations found in fish from the forest streams suggested normal organ functioning. In fish from the rural and urban streams, the histopathological alterations occurred were in higher frequency, indicated light to moderate damage in gills and liver of fish from the rural streams, and moderate to severe damage in liver of fish from urban streams. The histopathological alterations in gills (lamellar aneurysm) and livers (vascular congestion) verified in impacted streams were significantly more frequent and severe. It was possible to distinguish streams along different land uses, suggesting that these histopathological alterations can be used as biomarkers for biomonitoring studies. The health integrity of fish from streams in forest areas further reinforces the importance of maintaining preservation areas in basins under intensive land use.

摘要 本研究以双带丽脂鲤（Astyanax bifasciatus）的鳃与肝脏作为组织学生物标志物（histological biomarkers），对不同土地利用类型沿线溪流开展生物监测（biomonitoring）评估。研究人员采用电捕鱼法（electrofishing），在伊瓜苏河下游流域的6条溪流中采集了该鱼类样本。本研究旨在探究不同土地利用类型沿线溪流中，鱼类鳃与肝脏的组织病理学改变（histopathological alterations）的存在情况及病变程度与流域环境变量（environmental variables）之间的相关性。森林溪流中的鱼类样本仅出现极低频率的组织病理学改变，提示其器官功能处于正常状态。农村与城市溪流中的鱼类则呈现出更高频率的组织病理学改变：农村溪流鱼类的鳃与肝脏仅表现为轻度至中度损伤，而城市溪流鱼类的肝脏则出现中度至重度损伤。受干扰溪流中观测到的鳃组织病变（鳃片动脉瘤，lamellar aneurysm）与肝脏组织病变（血管充血，vascular congestion），其发生频率与严重程度均显著更高。本研究可有效区分不同土地利用类型沿线的溪流，表明此类组织病理学改变可作为生物监测研究的有效生物标志物。森林区域溪流中鱼类的健康完整性，进一步印证了在土地利用强度较高的流域中保留保护区域的重要性。