**Author details**

age fish is difficult to predict. Third, they may turn to more hunting to supply their protein needs, leading to other negative impacts on the ecosystem. In particular, the hunting of cai‐ man could lead to impacts on biodiversity as the controlling predators are eliminated from the ecosystem. This would be in addition to the impacts of reductions in intermediate level aquatic predators such as peacock bass (*Cichla* spp.) which would suffer from the negative

Worse impacts could potentially occur if the rural populations increased their participation in other extractive activities, including agriculture, timbering and non-timber forest prod‐ ucts. Although the collection of non-timber forest products, such as fruit and fibers is likely to be have a relatively benign direct impact, areas of the forest that were previously not the subject of economic activity could become the subject of economic activity. The heavy pres‐ ence of people in these previously unharvested areas could lead to impacts on fisheries and wildlife, interfering with the ability of these areas to serve as a reserve for repopulating de‐

Increased participation in timbering and agriculture will lead to deforestation, which has a negative impact on the biodiversity of the forest. Moreover, it will have a negative impact on the aquatic systems. If communities are successful in developing markets for these extrac‐ tive products, it could lead to a reverse migration of people from urban areas back to the

Both the direct effects of global climate change and the indirect effects associated with the reaction to global climate change will have negative impacts on the social welfare of both urban and rural populations. It is likely that a feedback cycle could develop where the reac‐ tion to degradation is more degradation, dramatically reducing both social welfare and eco‐

Climate changes and dams are likely to represent the most important threats to freshwater fish around the world. The effects of climate change on the ecosystem will include altera‐ tions of the timing, distribution and form of precipitation, as well as the timing of the flood pulse, and the intensity and frequency of floods and droughts. The impacts of these changes on the fish fauna and fisheries are, at that moment, unpredictable at both the species and ecosystem level. Actually, the degree of uncertainty and the low level of knowledge about the biology of the most of Amazonia fish species, make it hard to determine the current im‐ pacts of climate changes for each species and for the ecosystem as a whole, and even harder to predict future impacts. In addition to regional impacts, it will be very difficult to predict the impacts of dams for each fish species from the Amazon basin. As we discussed earlier, dams block fish migration, which could be very critical for many freshwater fish species that

One pertinent question is what we can do to minimize the impacts of global climate changes and dams. Actually, we need to identify clearly the possible strategies to avoid human con‐

impacts of global climate change.

190 New Advances and Contributions to Fish Biology

forest, leading to an increasing cycle of degradation.

need to do migrations to complete their life cycles.

pleted areas.

system function.

**6. Conclusions**

Carlos Edwar de Carvalho Freitas1,3\*, Alexandre A. F. Rivas1,3, Caroline Pereira Campos2 , Igor Sant'Ana1 , James Randall Kahn1,3, Maria Angélica de Almeida Correa1 and Michel Fabiano Catarino2

\*Address all correspondence to: cefreitas@ufam.edu.br


3 Washington and Lee University, Manaus, Amazonas, Brazil
