Transport of larval fish in the Amazon

Abstract

In the Amazon near Manaus, larvae of Characiformes, Clupeiformes, Tetraodontiformes, Pleuronectiformes, Gymnotiformes, Belonidae and Sciaenidae were sampled in the river during most of the year, except in June and July, when the water level was at its maximum. Characiformes, Tetraodontiformes and Siluriformes were found in the ichthyoplankton mostly during the rising waters, but Clupeiformes and Sciaenidae drifted in the river almost all year around. Egg abundance was extremely low, suggesting that they do not drift or have a very short residence time. Two types of larval drift seemed to occur: a rising water drift and a lowering water drift. Characiformes, Tetraodontiformes and some Clupeiformes drifted mostly during the rising waters and were more abundant near the banks. Their strategy seemed to be a passive dispersion towards the floodplain with the flood pulse. The high densities near the banks optimized their chances of reaching a floodplain inlet. The groups that drifted during the lowering waters showed an alternative strategy. They were flushed from the floodplain lakes and may have stayed in the main river channel for a few months before returning to the floodplain. Predation in the lakes during the period when water level decline was probably the force behind this drift.

Reproduction, feeding and migration patterns of Prochilodus nigricans (Characiformes: Prochilodontidae) in northeastern Ecuador

“…, respectively (AraujoLima, Oliveira, 1998). We observed similar or higher current speeds in the Napo basin (Tab.…”

“…The latter two authors, however, did not report body mass or length of fishes examined. After spawning, eggs and larvae apparently drift downstream several hundreds of kilometers to floodplains where food is abundant and chance of survival may be higher (Araujo-Lima, Oliveira, 1998). Reproduction is highly seasonal and, as in the Aquarico River, it takes place during rising waters just before the flood period (Ruffino, Issac, 1995).…”

“…Also, there are various studies on the movement of eggs, larvae and juvenile characin fishes in Neotropical river basins (e.g., Flecker et al, 1991;Araujo-Lima, 1994;Pavlov et al, 1995;Araujo-Lima, Oliveira, 1998;AraujoLima et al, 2001;Barthem et al, 2014). Fish movements in tropical freshwater rivers are principally affected by flood pulse dynamics (e.g., Junk et al, 1989).…”

“…This suggests that most of the passive drifting would occur in the larval stage. These tiny larvae (< 10 mm) can drift about 15 days before dying of starvation (Araujo-Lima, 1994: Araujo-Lima, Oliveira, 1998AraujoLima, Ruffino, 2004). Based on the above information, we hypothesized that eggs of P. nigricans should travel about 58 km in the midstream or 23 km near the bank before hatching.…”

Spatial and temporal distribution of ichthyoplankton in the upper Uruguay river, Brazil

“…There are two forms of fish migration in the Uruguay river basin, one in which the fish remain in the mainstream and another in which the fish enter tributary rivers (Zaniboni-Filho and Schulz, 2003). By studying the distribution of fish eggs and larvae, we can provide evidence on spawning time and natural breeding areas, which present valuable information for the protection of fish populations and the management of fishery resources, especially in relation to successful recruitment (Araújo- Lima and Oliveira, 1998;Bialetzki et al, 2004;Lima and Araújo-Lima, 2004). The Upper Uruguay river is characterized by flowing stretches separated by geographical features, such as rapids, waterfalls and gorges (Zaniboni-Filho and Schulz, 2003).…”