Veligers of the invasive bivalveLimnoperna fortuneiin the diet of indigenous fish larvae in a eutrophic subtropical reservoir

Abstract

Larval fish development depends largely on their ability to capture and ingest food items, and on food availability. In this context, invasive species, eutrophication and river impoundments have complex impacts on fish larvae. Using samples collected in 2005-2009 in the Salto Grande reservoir (Argentina-Uruguay), periodically affected by cyanobacterial blooms, we studied the impact of the larvae of the exotic bivalve Limnoperna fortunei (Dunker, 1857) (Bivalvia) on larval fish diets. Compared with other nearby waterbodies, the abundance of fish larvae was scarcer in the reservoir, especially during algal bloom periods. Only 20% of the larval fish with gut contents fed on L. fortunei veligers. Seven fish taxa (of a total of 12) consumed veligers of L. fortunei, but only two showed a preference for this prey. Taxonomic changes in the larval fish assemblages due to the river's impoundment, and temporal uncoupling between veliger densities (affected by the toxigenic effects of Microcystis spp.) and ichthyoplankton could account for the comparatively low trophic importance of the invasive bivalve's veligers. These results reflect the complexity of interactions brought about when the same invasive species invades different environments, underscoring that the impacts involved depend as much on the invader, as on the regional and ecological settings of the area invaded.

Impact of a hydroelectric power plant on migratory fishes in the Uruguay River

“…T A B L E 1 Percentages of the taxonomic groups found in each sampling station The long temporal scale of our study (2009-2016) allowed to detect the direct impact of Salto Grande on the species of ichthyoplankton. Previous shorter studies (1-2 years) conducted in this reservoir also reported similar changes in the specific composition of both ichthyoplankton (Paolucci, 2002;Paolucci, Leites, Cataldo, & Boltovskoy, 2017), and adult fishes (Quirós & Boveri, 1999). Freshwater secondary fish species (mainly L. grossidens) predominated in the stations located inside the reservoir and closer to the dam, while most fishes found in the headwater of the reservoir corresponded to river migratory species (e.g., P. lineatus, Pseudoplatistomas spp.,…”

“…In the reservoir of Salto Grande, cyanobacterial blooms were reported to have a negative impact on the feeding of fish larvae (Paolucci et al, 2017; Paolucci & Thuesen, 2015), probably affecting their abundance and composition in our study. Our data underline the dependency of fish reproduction on water input into the reservoir.…”

“…Our data underline the dependency of fish reproduction on water input into the reservoir. A relationship between reproductive activities and reservoir water level has also been reported for other species, such as the invasive golden mussel Limnoperna fortunei in Salto Grande (Boltovskoy et al, 2013), where it represents an important feeding resource for adult and larval fish species (Cataldo, 2015;Paolucci et al, 2017;Paolucci, Cataldo, Fuentes, & Boltovskoy, 2007;Sylvester, Boltovskoy, & Cataldo, 2007).…”

Metabolic response to increasing environmental temperature in the invasive mussel Limnoperna fortunei

“…The low caloric values of adult L. fortunei could have negative impacts on the diet of several native predators (Cataldo 2015;González-Bergonzoni et al 2020), if this new food item is less energetically valuable compared with native ones. This is the opposite of the recorded impact of L. fortunei veligers in larval fish diets of several fish species (Paolucci et al 2010;Paolucci & Thuesen 2015;Paolucci et al 2015;Paolucci et al 2017).…”

Ventajas y límites de la variabilidad morfofisiológica para el establecimiento, la colonización y la expansión del bivalvo invasor Limnoperna fortunei en Sudamérica

“…Un factor biológico mencionado como potencialmente capaz de limitar la abundancia y/o distribución de esta especie es la presencia de depredadores, en particular peces (Paolucci, et al, 2007;Sylvester, et al, 2007;Nakano, et al, 2010;González-Bergonzoni, et al, 2020). Se han registrado alrededor de 50 especies de peces, tanto larvas como juveniles y adultos (Cataldo, 2015;Paolucci y Thuesen, 2015;González-Bergonzoni, et al, 2020), incluso en algunos casos consumiendo de manera preferencial (Paolucci, et al, 2010;Paolucci, et al, 2017). Sin embargo, el efecto en los casos más extremos parece ser una disminución de la abundancia de L. fortunei que no resulta suficiente para impedir su avance o, más aún, producir su erradicación.…”