Alpine fishes

Keywords Alpine diatoms, Alpine fishes, mental indicator. Glacier retreat... 

Kock, G., R. Hofer, and S. Wograth. 1995a. Accumulation of trace metals (Cd, Pb, Cu, Zn) in Arctic char (Salvelinus alpinus) from oligotrophic Alpine lakes relation to alkalinity. Canad. Jour. Fish. Aquat. Sci. 52 2367-2376. 

After the Chernobyl accident, radiocesium isotopes were also elevated in trees and lichens bordering an alpine lake in Scandinavia and in lake sediments, invertebrates, and fishes (Table 32.18). Radiocesium levels in muscle of resident brown trout (Salmo trutta) remained elevated for at least 2 years (Brittain etal. 1991). People consuming food near this alpine lake derived about 90% of their effective dose equivalent from the consumption of freshwater fish, reindeer meat, and milk. The average effective dose equivalent of this group during the next 50 years is estimated at 6 to 9 mSv with a changed diet and 8 to 12 mSv without any dietary changes (Brittain et al. 1991). 

In alpine regions, especially in maritime climates, snow depths may be considerable. This insulates the stream environment from subzero temperatures. River ice is an important environmental component of alpine rivers and has resulted in adaptive mechanisms among the fauna [50, 51]. Despite these adaptations, winter conditions inevitably cause high mortality to stream invertebrates and fish, especially in reaches with unstable snow and ice cover and thereby susceptible to formation of frazil and anchor ice. The lack of winter ice cover in lake outflows and groundwater-fed reaches provides a favourable environment for primary producers and those benthic invertebrates utilising primary production [52]. 

The goal of this chapter is to summarize the composition and community patterns of algae (with special consideration to benthic diatoms), zoobenthos, and fish that occur in Alpine freshwaters. The data presented are a synthesis of published research and represent the current state of knowledge on the different groups. The chapter closes with a general perspective on the biodiversity of alpine freshwaters. 

Alpine waters are sensitive ecosystems with unique features and resources. Extreme environmental conditions (altitude, gradient, low nutrients, duration of snow cover) shape special habitats that are only suitable for highly-adapted fishes. Only cold stenothermic species can inhabit Alpine waters. During spawning and the period of egg development, water temperature is low and can reach 0°C. Therefore, only a few of the native fishes were able to colonize and inhabit Alpine waters. In the last decades, non-native cold water resistant fish appeared in many Alpine waters. Nonnative species have inhabited alpine lakes since the late 19th century Salvelinus namaycush were stocked in 1886 in small alpine lakes in the Swiss Alps [92]) and started to reproduce in many lakes. Over the last decades in many Alpine streams, non-native, cold stenothermic species have established self-reproducing populations and appear well-adapted to the harsh environmental conditions. 

Fig. 3 Alpine brown trout from the River Vorderrhein, Switzerland. The brown trout is the most important fish species in the alpine region and is stocked in many streams for recreational fishery and trout conservation and population management...

Fishes in Alpine floodplains are limited to cold stenothermic species such as the brown trout, and many alpine lakes are currently stocked to sustain the fishery. Water abstraction and flow regulation severely constrain the management of the fishery in Alpine waters today. The effects of climate change on the fishery are difficult to predict but could facilitate the upward migration of more cool water fishes in the future. The implications of these new fishes on aquatic food webs are not certain but could be substantial. 

The presence of some parasites, like Diphyllibotrium, in fishes favours the contamination especially when are used not cooked such sushi or marinated fishes infected with larval plerocercoids. The diffnsion is mainly in the freshwaters and in Europe especially in Switzerland and in Italian, French Alpine lake region. 

While the role of carotenoid photoprotection seems well justified in copepods, it is more obscure in the cladocera [16,41]. Sub-Arctic alpine copepods (Hetero-cope) were found to have ten times more carotenoids than sympatric populations of cladocerans, and even low-land transparent copepods have higher carotenoid levels than highly light-exposed Daphnia [41]. Carotenoids are also widespread in fish, notably anadromous salmonids, yet the role of carotenoids in photoprotection in these species is not settled. 

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