Salinity tolerance of diapausing eggs of freshwater zooplankton

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73091/1/j.1365-2427.2004.01185.x.pd

Impact assessment of the introduction of Cichla kelberi in a large Neotropical reservoir and its lateral lagoons (Upper Paraná River Basin, Brazil)

Abstract This study aimed to understand how the introduction of Cichla kelberi in Rosana Reservoir (Paranapanema River) affected the native ichthyofauna. Data on the structure of the small fish fauna assemblage were obtained before and after the introduction of this carnivorous species. Samplings were carried out in February and September of 2004, previously to the register of Cichla kelberi in the reservoir, and after its introduction, November of 2004, January, March, May and August of 2005, February and June of 2006, February and July of 2007, February and October of 2008 and February of 2009. A total of 4,693 fish, belonging to 43 different species was sampled between 2004 and 2009. The order Characiformes was the most abundant, followed by Perciformes and Siluriformes. Comparative analyses, before and after the introduction, could not demonstrate significant changes in composition, richness, abundance, biomass, mean length and diversity of fish. Aquatic insects were the main feeding item of C. kelberi, followed by tetragonopterinae fish. Cannibalism was recorded during the whole study period. The results showed that Cichla cannot deeply affect the ichthyofauna assemblages of a large Neotropical reservoir, at least in a short or medium term period after its introduction. The results also allowed concluding that the introduction of C. kelberi in the reservoir is in the phase 3. In this phase, the specie can survive and reproduce in the new environment; however it is not totally established and disseminated. The reasons for the fact that Cichla is still not dominant in Rosana Reservoir could be related to feeding competition, high rate of cannibalism and the presence of large amount of aquatic macrophytes (refuge zones). In spite of the results, the continuous monitoring of the role of non-native species on the local fish fauna is absolutely necessary because the impacts caused by colonization of this undesirable species can be magnified by complex processes, usually correlated with other environmental disturb, especially the negative effects of damming

Does saltwater flushing reduce viability of diapausing eggs in ship ballast sediment?

Flushing of ballast tanks with seawater has been proposed to reduce the risk of invasion associated with residual ballast in \u27no ballast on board\u27 ships. The efficacy of this procedure, however, has not been determined. Using diapausing eggs isolated from ballast sediments - as well as from Lake Erie sediment - this study investigated the impact of salinity (0, 8 and 35‰) and temperature (10, 20 and 30°C) on the cumulative abundance and species richness of hatched zooplankton taxa. The rate and amount of hatching varied dramatically between sediments and across salinity-temperature regimes. Although exposure to saline water inhibited emergence of freshwater taxa during the exposure phase of all trials, mixed results were evident after diapausing eggs were returned to freshwater. The efficacy of salinity as a ballast treatment method was temperature dependent, although the direction of the effect was case-specific. Exposure of eggs to saline water was less effective at 10 and 30°C than at 20°C. Although flushing ballast tanks with open ocean water is expected to significantly reduce the number of active invertebrates living in residual ballast water (a potentially larger source of invaders), our results indicate that the most effective treatment conditions for reduction of diapausing egg viability is 8‰ salinity at 20°C. © 2006 Blackwell Publishing Ltd

Invasions Toolkit :Current Methods for Tracking the Spread and Impact of Invasive Species

International audienceBiological invasions exert multiple pervasive effects on ecosystems, potentially disrupting species interactions and global ecological processes. Our ability to successfully predict and manage the ecosystem-level impacts of biological invasions is strongly dependent on our capacity to empirically characterize complex biological interactions and their spatiotemporal dynamics. In this chapter, we argue that the comprehensive integration of multiple complementary tools within the explicit context of ecological networks is essential for providing mechanistic insight into invasion processes and their impact across organizational levels. We provide an overview of traditional (stable isotopes, populations genetics) and emerging (metabarcoding, citizen science) techniques and methods, and their practical implementation in the context of biological invasions. We also present several currently available models and machine-learning approaches that could be used for predicting novel or undocumented interactions, thus allowing a more robust and cost-effective forecast of network and ecosystem stability. Finally, we discuss the importance of methodological advancements on the emergence of scientific and societal challenges for investigating local and global species histories with several skill sets

Biological invasions concepts to understand and predict a global threat

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