Daniel Cataldo

Filtration rates of the invasive pest bivalve Limnoperna fortunei as a function of size and temperature

Clearance rates of Limnoperna fortunei (Bivalvia) were investigated in laboratory experiments using monocultures of the alga Chlorella vulgaris. Experimental conditions included two mollusc sizes (15 and 23 mm), and three water temperatures (15, 20 and 25 °C) covering the normal seasonal range in the lower Paraná river and Río de la Plata estuary. Filtration rates obtained were, for the larger mussels: 9.9, 13.1 and 17.7 ml mg tissue dry weight−1 h−1 at 15, 20 and 25 °C, respectively; and for the smaller ones: 17.7, 20.8 and 29.5 ml mg−1 h−1. Differences between sizes and between temperatures (except 15 vs. 20 °C) were statistically significant. In absolute terms larger animals have higher clearance rates, but as a function of body mass smaller individuals feed more actively. Within the range of experimental values used, filtration rates were positively associated with water temperature. These clearance rates (125–350 ml individual−1 h−1) are among the highest reported for suspension feeding bivalves, including the invasive species Dreissena polymorpha, D. bugensis and Corbicula fluminea. High filtration rates, associated with the very high densities of this mollusc in the Paraná watershed (up to over 200,000 ind m−2) suggest that its environmental impact may be swiftly changing ecological conditions in the areas colonized.

Population dynamics of Limnoperna fortunei, an invasive fouling mollusc, in the lower Paraná River (Argentina)

Settling and growth of the Asian freshwater mussel Limnoperna fortunei on experimental PVC frames in the Parana de las Palmas river, ca 130 km north of Buenos Aires was monitored at monthly intervals in 1998. Frames were deployed in January. In February and March colonization reached 3800044000 mussels m-*, with early juveniles ( 2 mm) mussels. In September through December densities grew steadily again, with early juveniles (< 2 mm) accounting for over 95% of the mussels recorded. During their first month, animals born in January grew to ca 34 mm in length; in March they reached 7-8 mm, and by mid April 11-12 mm. In late April through July the growth rate decreased to < 2 mm per month, and in August it stopped almost completely, resuming again in late September. During the first year animals born in January reached 20mm in length; by the end of the second year the estimated length was 30mm, with a maximum theoretical length of 35mm being reached after 3 years. The data agree with the reported population dynamics of L. fortunei in Hong Kong in that both populations are characterized by extended reproduction periods lasting ca 9 months, and that the spring onset of breeding is triggered by a rise in temperature above approximately 16-17°C. On the other hand, in the Parana river reproduction was found to be continuous between September and March, and the period of lowest yearly temperatures was characterized by a very strong breeding decline, whereas for the Chinese populations 2-3 yearly spatfalls and breeding pulses roughly coinciding with the lowest and highest water temperatures were described.

Population dynamics of Corbicula fluminea (Bivalvia) in the Paraná River Delta (Argentina)

Benthic individuals and drifting planktonic juveniles of Corbicula fluminea were sampled in the Lower Delta of the Paraná River (Argentina) at monthly intervals between October 1995 and October 1996. Densities of settled clams above 1 mm, around 300–1000 ind. m-2, varied little throughout the year. Below 1 mm benthic juveniles, on the other hand, showed a single conspicuous abundance peak in October-November (up to 1722 ind. m-2), and were practically absent during the rest of the year (overall annual mean: 1070 ± 797 ind. m-2). Drifting juveniles showed one major peak in December 1995 (160 ind. m-3), and a minor one at the end of March (24 ind. m-3). Length-frequency analyses of the monthly field data clearly indicate a highly structured population with a single well defined reproduction period centered on October–November. Population parameters derived from the seasonally oscillating version of von Bertalanffys growth formula were as follows: maximum shell length: 32 mm (maximum observed shell length: 33 mm); growth constant: 0.65; growth seasonality (i.e., span of summer-to-winter growth-rate difference): 0.7; winter point (i.e., time of the year when growth is minimum): 0.5 (June–July); estimated size range for one year-old individuals: 15.3–22.4 mm; for two years: 23.5–27 mm, and three years: 27.5–29.3 mm. Comparison with previous data confirm the influence of water temperature on the clams reproduction and growth and furnish additional evidence suggesting that food availability may be as important for recruitment as thermic regimes. Contrasts between traits of the population analyzed herein with those described previously from a nearby (ca. 10 km) site more influenced by industrial pollution point at the influence of water quality on Corbiculas recruitment and growth.

The effects of the invasive mussel, Limnoperna fortunei, on associated fauna in South American freshwaters: importance of physical structure and food supply.

We examined the importance of the introduced Asian golden mussel (Limnoperna fortunei) in structuring invertebrate communities in South American rresnwaters. An experiment using artificial substrata (i.e., concrete tiles with either a layer of living mussels, a layer of intact empty shells that mimicked living mussels, or blank tiles) showed that, when considered in bulk, invertebrates (density and biomass) are enhanced significantly in the presence of live mussels (as compared with shells only and blank tiles). On a taxon-by-taxon basis, however, significantly higher densities and biomass on live mussel tiles than on blank and/or shells-only tiles were found only for Oligochaeta, which would especially benefit from the feces and pseudofeces produced by the living mussel beds. At the end of the experiment, the amount of accumulated sediment on the tiles differed greatly among treatments, with values up to three times higher on shells-only tiles than on live-mussel and blank tiles. Dead mussels act as a sediment trap, whereas the activity of live mussels helps keep the tiles less clogged with sediments. On the other hand, proportions of organic matter were two times higher in the presence of live mussels than in the other two treatments. Although the physical structure created by mussel shells plays a significant role, we conclude that the activity of living mussels is of major importance for controlling invertebrate numbers, biomass and diversity.

Biochemical responses of the golden mussel Limnoperna fortunei under dietary glyphosate exposure

The aim of this study was to analyze the biochemical alterations in the golden mussel Limnoperna fortunei under dietary glyphosate exposure. Mussels were fed during 4 weeks with the green algae Scenedesmus vacuolatus previously exposed to a commercial formulation of glyphosate (6 mg L-1 active principle) with the addition of alkyl aryl polyglycol ether surfactant. After 1, 7, 14, 21 and 28 days of dietary exposure, glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), acetylcholinesterase (AChE), carboxylesterases (CES) and alkaline phosphatase (ALP) activities, glutathione (GSH) content and damage to lipids and proteins levels were analyzed. A significant increase (72%) in the GST activity and a significant decrease (26%) in the CES activity in the mussels fed on glyphosate exposed algae for 28 days were observed. The ALP activity was significantly increased at 21 and 28 days of dietary exposure (48% and 72%, respectively). GSH content and CAT, SOD and AchE activities did not show any differences between the exposed and non exposed bivalves. No oxidative damage to lipids and proteins, measured as TBARS and carbonyl content respectively, was observed in response to glyphosate dietary exposure. The decrease in the CES activity and the increases in GST and ALP activities observed in L. fortunei indicate that dietary exposure to glyphosate provokes metabolic alterations, related with detoxification mechanisms.

Effect of glyphosate acid on biochemical markers of periphyton exposed in outdoor mesocosms in the presence and absence of the mussel Limnoperna fortunei

Glyphosate is currently the most widely used herbicide in agricultural production. It generally enters aquatic ecosystems through surface water runoff and aerial drift. We evaluated the effect of glyphosate acid on biochemical parameters of periphyton exposed to concentrations of 1, 3, and 6 mg/L in outdoor mesocosms in the presence and absence of the mussel Limnoperna fortunei. Periphyton ash-free dry weight, chlorophyll a content, carotene/chlorophyll a ratio, lipid peroxidation levels, and superoxide dismutase and catalase activities were determined at days 0, 1, 7, 14, and 26 of the experimental period. Ash-free dry weight was similar between control and glyphosate-treated periphyton in the absence of L. fortunei. The latter had significantly lower carotene to chlorophyll a ratios and enzyme activities, and higher lipid peroxidation levels and chlorophyll a content than the former. These results show an adverse effect of glyphosate on the metabolism of periphyton community organisms, possibly inducing oxidative stress. On the contrary, no differences were observed in any of these variables between control and glyphosate-treated periphyton in the presence of L. fortunei. Mussels probably attenuated the herbicide effects by contributing to glyphosate dissipation. The results also demonstrate that biochemical markers provide useful information that may warn of herbicide impact on periphyton communities. Environ Toxicol Chem 2017;36:1775-1784.