The ShearStress importance on the spatial distribution pattern of the invader Limnoperna fortunei in the Upper Paraná River Basin. - An assessment based on the Spatial Distribution Models

Abstract

The introduction of the golden mussel, Limnoperna fortunei (Dunker, 1857) in South America was related to the discharge of ballast water, with its first record in 1991 in the La Plata River estuary. Since then, the species is spreading throughout the continent, with several economic and ecological negative consequences. Aim: To model, in the headwaters of Parana River, the spatial distribution of L. fortunei and to understand the determinants of the current pattern of species distribution and the risk of invasion of areas not yet colonized. Methods: The ecological niche of L. fortunei was modeled using the algorithm MAXENT (Maximum Entropy Method) combined with records of occurrence of the bivalve, limnological data and the shear force measured by the index Hack (SL). The evaluation of the performance of different models was based on AUC (Area Under the Curve).The analysis of each variable's contribution to the responses of the models was made based on the Jackknife test, available in the Maxent program. The models were validated with real absence data collected between 2006 and 2007. Based on the limnological characterization of the area and on outputs of the models, this analysis sought to understand the contributing aspects to the current and potential spatial distribution and to verify the risk of invasion of environments not yet colonized by the species. Results/Conclusion: The limnological characterization showed that the ecological requirements for the species as, pH, calcium, oxygen and chlorophyll a, were appropriate in both the connected stretches, invaded and noninvaded. Turbidity showed significant spatial differences which proved to be higher in environments with higher levels of Hack (SL), i.e. higher energy fluvial. In addition, the algorithm showed the importance of hydrodynamical aspects expressed by Hack index (SL) to the spatial distribution of species, since the models with the best performances were those that considered the Hack index (SL) as one of the environmental layers of the mussel's niche. All models indicated a high risk of invasion into the reservoir of São Simão. Keywords: invasive species, biological invasions, niche modeling, Maxent, ecological requirements.

High‐resolution ecological niche modelling of threatened freshwater mussels in east Texas, USA

“…The modelling approach used here has rarely been used to model unionids in North America, where other modelling approaches have been favoured (but see Lois et al , for a similar approach in Europe). Typical methods for modelling mussel occurrences require localized, within‐stream habitat measurements integrated over a small stream segment (Allen & Vaughn, ; Atkinson et al , ; Campos et al , ; Gangloff & Feminella, ; Weber & Schwartz, ), which limits the spatial extent, or modelling the habitat suitability of entire catchments, which limits the resolution (Atkinson et al , ; Cao et al , ; Mynsberge et al , ; Weber & Schwartz, ). The method employed in this paper has a relatively high resolution and can encompass a very large spatial extent.…”

“…Shown are (a) threatened mussel species beds overall, (b) P. amphichaenus, (c) F. askewi, and (d) L. satura. The predictions are specific to the spatial extent of Figure 1 Typical methods for modelling mussel occurrences require localized, within-stream habitat measurements integrated over a small stream segment (Allen & Vaughn, 2010;Atkinson et al, 2012;Campos et al, 2016;Gangloff & Feminella, 2007;Weber & Schwartz, 2011), which limits the spatial extent, or modelling the habitat suitability of entire catchments, which limits the resolution ( can encompass a very large spatial extent. If environmental layers are available, the only fieldwork that is needed is to sample river systems for mussels of interest and record their locations with a global positioning system; such environmental layers are available online that encompass much of the USA.…”

“…Traditional methods for predicting unionid occurrences and abundances within a stream involve complex hydraulic models that compute several instream flow and limnological variables (Allen & Vaughn, 2010;Atkinson, Julian, & Vaughn, 2012;Campos, Peifer, & Castro, 2016;Gangloff & Feminella, 2007). These measurements, however, are difficult to obtain at a large spatial scale, constraining these approaches to smaller geographic extents (Haag, 2012).…”

Effect of temperature on behavior, glycogen content, and mortality in Limnoperna fortunei (Dunker, 1857) (Bivalvia: Mytilidae)

“…Water pH is another vital parameter for aquatic animals. The tolerance range of L. fortunei lies between pH 6.0 and 9.0 Campos et al, 2016). Moreover, pH increases also induce unionized ammonia formation.…”

“…Temperature increases also decrease the concentrations of dissolved gases in the water, and oxygen concentrations thus decrease at high temperatures. The ideal concentration of oxygen is above 5.0 mg L -1 (Campos et al, 2016), and we kept the concentration above this value during the trials. Water pH is another vital parameter for aquatic animals.…”