Differential accumulation of metals in the lacustrine and fluvial Alpine bullheads (Cottus poecilopus) and recovery of fish from metal contamination after a flash flood.

The spatiotemporal distribution and transport of mercury, zinc, molybdenum, rubidium, and strontium from alpine terrestrial ecosystems to alpine lake and mountain stream populations of Cottus poecilopus were investigated. Metals were measured for 66 wild fish collected from different lakes and Javorinka stream across. Mercury was measured in the pectoral fins, other elements in the skull. Bullheads contained more metals in the alpine lakes than in the mountain stream. In particular, mercury and zinc concentrations in lake bullheads were 6 and 2.5 times higher, respectively, than those of stream-dwelling fish. New data were generated on metal bioaccumulation in fish of understudied West Carpathian alpine lake environments. In July 2018, a major flood occurred in the area of the Javorinka. Already then, the mercury content in bullheads increased significantly. Bioaccumulation of mercury in fish occurred very quickly after the flood and was also significant in the following 2019. Then, the concentrations of mercury quickly decreased up to 70% in 2021-2022. Average concentrations of molybdenum and rubidium in bullheads in the stream rapidly declined in the year following the flood disturbance, but within less than 2 years, the metal levels stabilized at about the same level as in 2017 prior the flood. Strontium concentrations in fish dropped rapidly immediately after the flood, increased in the following years, and dropped again after 4 years, suggesting that many more factors are influencing strontium bioaccumulation in fish that are comparable in magnitude to the flood. The most serious warning seems to be the absence of biogenic zinc. The average concentration in the Alpine bullheads population in the stream has declined by 70% in less than 5 years and is steadily declining. An important result of this study is the demonstration that disturbance by a single factor (heavy rainfall and flooding) has a clear and timely effect on average metal concentrations in the fish population.

Different accumulation of some elements in the fry and adults of alpine bullheads (Cottus poecilopus).

Skulls of alpine bullhead sampled from the Javorinka stream in the Tatra Mountains, West Carpathians, were analyzed to determine concentrations of S, Cl, K, Ca, P, Rb, Zn, Mn, Mb, Fe, Ti, Sn, Co, Ni, Cu, As, Se, Pb, Sb, Ba, Hg, Cr, Ag, and Cd. The stage of development is the most influential factor determining element concentrations in the sampled bullhead, as fry were more polluted than adult fish. The different diets consumed by fry and adult bullhead plays a key role in the accumulation of chemical elements in their bodies. Young bullheads live in small natural embankments containing higher levels of a mixture of sedimentary minerals and microorganisms than in running water. Thus, newly hatched bullheads may serve as excellent indicators of water quality in mountain creeks or streams, as they can indicate the higher pollution of water or prey in their habitats (small bays with sandy bottoms) when compared to the preferred habitat of adult individuals.

Ecotoxicology of alpine streams in the West Carpathians-Alpine Bullhead (Cottus poecilopus) and high mountain flash flood effects.

Flash floods represent a serious threat to wildlife, water biota, and human life in pre-alpine regions, particularly in recent historical memory. The alpine bullhead is an established bioindicator of water quality in mountain streams, which can be adversely affected by an increased propensity for flash flooding. The aim of this study was to examine the effect of flash flooding on the variation of chemical elements found in the skull of alpine bullheads, with a focus on inter-annual effects. Their bone tissue reflects an increased concentration of K and Cl and a decreased concentration of biogenic Cr, Zn, and Mo, absorbed mainly through the gills, for up to 2 years following a flood. During autumn, following a summer flash flood, the amount of Mn and Fe present in skull tissues of fish was found to have increased, tapering off again over the following year. These metals are predominantly ingested by bullheads while feeding. The lack of specific types of biogenic concentration in the water may be critical to the definition of presence/absence patterns, as populations were shown to decline 2 to 3 years post-flood. Pre-alpine streams are particularly susceptible to this type of flooding. The decreases in biogenic elements and increase of K and Cl exhibited in bullhead tissues indicate that a negative ecological footprint due to flash floods can still be observed several years following the event.

Occurrence and vertical distribution of Ca, Cl, Cr, Fe, Mn, Mo, K, Rb, Sr, S, Sn, and Zn in the skull bones of alpine bullhead (Cottus poecilopus) in the West Carpathians.

The aim of this study was to examine the contents of calcium, chlorine, chromium, iron, manganese, molybdenum, potassium, rubidium, strontium, sulfur, tin, and zinc in the bones of the alpine bullhead (Cottus poecilopus) related to its vertical distribution in the mountain river Javorinka. This river is located on the northern side of the High Tatras, the West Carpathians. Sampling took place during 2017, 2018, and 2019. One hundred three individuals of bullheads were collected. Only deceased individuals were selected for sampling; there was no deliberate harm to any sampled individuals. Weight, body length, and head length and width were measured. The amounts of Ca, Rb, and Mo were significantly dependent on the altitude and the fish size. At higher altitudes, there are smaller fish that colonize more inaccessible waters with smaller habitat flow options and these smaller fish contain relatively more Ca, Rb, and Mo in their skulls than large fish. The presence of Mn, Sr, and Zn was related to the altitude. Concentrations of Zn and Sr increase with altitude in the alpine bullhead skulls. The amounts of S, Cl, K, Cr, Sn, and Mo did not differ among fish living at different elevations.