One aliquot of each collected sample was cryopreserved in dilutors as proposed by (Carolsfeld et al., 2003) for
rheophilic fish.
For example,
rheophilic suspension feeders such as crinoids adopt feeding postures by stiffening the ligaments of arm joints for hours (LaBarbera, 1982), and starfish keep their special feeding postures by stiffening the body-wall dermis for hours while attached to clams (Eylers, 1976).
Kottelat (1997: 57) writes that "Balon (1974, 1995) discussed the origin of domesticated carps and concluded that the European ones originated from a
rheophilic stock from the Danube.
Both mullet species are classified as
rheophilic: fast-flowing waters stimulate them to swim up river, and their fusiform body shape enables them to swim against strong currents, sometimes jumping over small falls and obstacles while reaching higher reaches of river.
On the other hand, there was a negative impact on the
rheophilic genera.
Like all
rheophilic fish species, the piabanha needs hormone treatment to trigger and increase the release of gametes in captivity.
Therefore, we recommend that IBAMA should change this normative because our results indicated that the closed season for this species is between February 1 and May 31; however, the closed season of other species with
rheophilic habits present at this hydrographic basin should be reviewed.
The matrinxa Brycon amazonicus (Spix & Agassiz, 1829) is a
rheophilic species native to the Amazon basin, which has great potential as a fish farming region, both in semi-intensive and intensive systems (Zaniboni-Filho et al., 2006).
In general,
rheophilic species with physical and behavioral adaptations to survive in high flow environments were more common and restricted to R1 and species typical of lentic environments were predominant in R2.
To assess differences between the LZ and RZ, we applied the Mann-Whitney test (Zar, 2009) on the medians of 1) the abundance, richness, diversity, and evenness and 2) the abundance of selected species (most abundant, migratory,
rheophilic) in each site.
Most species are
rheophilic and migratory, but some have specific habitat affinities, such as the pirapitinga Brycon nattereri Gunter, 1864.