Reproduction of two loricariid species in a confined river and implications for environmental impacts of dams

Abstract

Fish reproduction in floodplain rivers is often linked to flow regime and with the inundation of floodplain habitats. However, in confined rivers, where floodplains are absent, the relation between reproduction and flow can in comparison be expected to be distinct. In this study, we describe the reproductive life-history of Hemiancistrus fuliginosus and Hypostomus isbrueckeri in a confined river and discuss its differences relative to floodplain loricariids and also the implications for effects of dam construction and flow regulation. We found the reproductive peak of both species occurred during lowering waters, just after maximum river flow, in contrast to floodplain species that tend to spawn during rising waters. The studied species presented attributes of equilibrium life-history strategy, which are related to predictable river flow variation. Because both species spawned during low river flow, which is historically predictable in summer, we suggest that their reproduction may be severely disrupted, depending on how flow regime is affected by dam operation. These results have implications for assessing and mitigating the impacts of river damming on fish populations in confined rivers, and we point to ecologically driven flow management and conservation of free-flowing rivers as mitigation and conservation alternatives.

Insights into Environmental Drivers on the Reproductive Cycle of Diopatra neapolitana (Polychaeta: Onuphidae)

“…On the other hand, the rise in water temperature in August 2020 after the end of the July upwelling event was followed by an increase in the proportion of individuals with oocytes in September and October 2020. However, once again this increase did not occur immediately after the rise in water temperature, but with a month’s delay, which may be due to a “lag” effect, since the consequences of environmental changes on the biology of an individual are not immediate but need some time to manifest themselves [ 49 , 50 ].…”

Do Local Environmental Factors and Lunar Cycle Influence Timing and Synchrony of Oviposition of a Turtle with Strict Nocturnal Nesting?

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