Invasive Freshwater Research Articles

Volatility in the effective size of a freshwater gastropod population.

Despite the utility of gastropod models for the study of evolutionary processes of great generality and importance, their effective population size has rarely been estimated in the field. Here, we report allele frequency variance at three allozyme‐encoding loci monitored over 7 years in a population of the invasive freshwater pulmonate snail Physa acuta (Draparnaud 1805), estimating effective population size with both single‐sample and two‐sample approaches. Estimated N e declined from effectively infinite in 2009 to approximately 40–50 in 2012 and then rose back to infinity in 2015, corresponding to a striking fluctuation in the apparent census size of the population. Such volatility in N e may reflect cryptic population subdivision.

Transformation of detritus by a European native and two invasive alien freshwater decapods

Invasive alien species have the potential to alter biodiversity and ecosystem processes. In freshwaters, detritus decomposition is a major ecosystem service but it remains uncertain whether invasive alien decapods process detritus differently to natives. This study examined leaf litter processing, and cascading effects on biofilms, by the European native white clawed crayfish (Austropotamobius pallipes) compared to two invasive alien decapod species: the American signal crayfish (Pacifastacus leniusculus) and the Chinese mitten crab (Eriocheir sinensis). Invasive alien decapods were responsible for higher leaf litter decomposition than the native. In comparison with native crayfish, invasive alien crab and crayfish showed higher rates of litter consumption, increased production of smaller leaf fragments, fine particulate organic matter (FPOM) and dissolved organic carbon. Nutrients (ammonia and soluble reactive phosphorous) derived from excretion (measured separately in the absence of biofilms) varied among decapod species, being lower for P. leniusculus. However, nutrient concentrations did not vary among species in the detritivory experiments with biofilm, implying nutrients were utilised for biofilm production and respiration as no differences in biomass were evident among decapod treatments. These results show invasive alien decapods have the potential to increase the magnitude of detrital processing to FPOM in rivers, but indirect impacts on primary producers due to nutrient release are uncertain based on this experimental context.

Water transparency affects the survival of the medusa stage of the invasive freshwater jellyfish Craspedacusta sowerbii

Craspedacusta sowerbii is a global invader of inland waters, but little is known on what environmental factors control its colonization success. We hypothesized that water transparency and thus, exposure to UV radiation are relevant for the colonization success of this relatively transparent invasive hydroid. Here we used field and laboratory experiments to assess the effect of natural solar radiation and artificial UV radiation on the medusa stage of C. sowerbii across natural and simulated water transparency gradients in three Chilean Patagonian lakes. Short-term exposure of the jellyfish to artificial UV radiation under low Dissolved Organic Carbon (DOC) treatments induced mortality and caused sublethal effects such as swimming anomalies and production of reactive oxygen species. Outdoor exposure of jellyfish to full solar radiation in the most transparent water (Lake Ranco; DOC = 0.6 mg l−1) resulted in almost complete mortality. However, higher DOC contents provided partial or almost complete protection against the adverse impact of UV radiation. Overall, our findings provide evidence of the role of underwater light conditions in the underlying mechanisms that may favor the invasion of this gelatinous alien species in inland waters. The results imply that under the current “brownification” of lakes, an increase in water color might provide more favorable conditions for the invasion process of this hydroid.

Parasites of invasive freshwater fishes and the factors affecting their richness

AbstractFreshwater environments are threatened by nonnative species introductions, often involving fishes. Parasites and pathogens introduced with fishes have the potential to infect native taxa an...

Euryhalinity of Ponto-Caspian invaders in their native and introduced regions

In the past several decades, Ponto-Caspian species have established in freshwater and brackish habitats of the North and Baltic Sea and Great Lakes-St. Lawrence River region in much higher numbers than expected based on introduction effort (i.e. shipping frequency) and environmental conditions between these regions. Several studies have suggested that Ponto-Caspian taxa are euryhaline and might be able to adapt rapidly to changing salinity conditions, and therefore may be more successful colonizers than species from other regions. To determine the realized niche in the native and introduced habitats of Ponto-Caspian invaders and to assess whether they have expanded their salinity tolerance during the invasion process, we conducted a literature search to assess the salinity ranges of 55 Ponto-Caspian species in their native and introduced ranges. Our results confirmed that the majority of those species occupied a wide range of salinity in their native and introduced habitats. Approximately 50% of species were reported from both freshwater and brackish habitats (0–18 PSU) in their native region, occupying a salinity range of at least 10 PSU difference. In general, the number of species tended to decline as salinity increased in both native and introduced habitats. More than 90% of Ponto-Caspian invaders occupied freshwater (< 0–0.5 PSU) habitats, while 18% did not occur above 18 PSU. Overall, 46% of species were reported from a narrower salinity range in their introduced compared to their native region. Consequently, our study revealed significantly broader salinity ranges in native compared to introduced habitats. As our results suggest that the majority of Ponto-Caspian invaders occupy freshwater and brackish habitats in their native region, the recent numerous invasions of freshwater and brackish areas by these species should not be a surprise. Therefore, managers and policy makers should take into account that the majority of Ponto-Caspian invaders originate from fresh water or low salinities and develop new regulations to prevent future invasions from the Ponto-Caspian region, as well as from areas highly invaded by Ponto-Caspian taxa such as Northern Europe.

Effects of water level fluctuations and substratum drying on the survival and behaviour of the invasive freshwater snail Physa acuta Draparnaud, 1805

Pulmonate snails live in nearshore zones of waterbodies, experiencing water level fluctuations. In the present study we investigated the resistance of Physa acuta to desiccation and its behavioural responses (horizontal migrations and burrowing) to drying. Determining the adaptations of P. acuta to extreme ranges of environmental factors may be crucial for understanding its invasiveness. Survival in gradually drying sand was determined as LT50 and LT90 (i.e. the time until death of 50 and 90% of individuals respectively). Horizontal migration was studied at shorter and longer distances (24 and 48cm), with gradual or sudden (longer distance only) dewatering. Burrowing was studied during a gradual decrease in water level. Snails were highly resistant to drying as the LT50 and LT90 values on the exposed substratum were 8 and 11 days respectively. In addition, snails exhibited horizontal migrations at shorter distances during gradual dewatering. Migration was less pronounced at the longer distance. After a sudden dewatering, snail movement was limited, suggesting that the snails stayed passive rather than risked a migration over the exposed substratum. Snails never burrowed in sediments in response to dewatering. Resistance to drying and ability to migrate enables P. acuta to survive in harsh environments and can contribute to its invasiveness.

Predatory behaviour of an invasive amphipod in response to varying conspecific densities under higher-order predation risk

Behavioural responses of invasive animals to biotic interactions can inform predictions of their consumptive impacts; however, such biotic contexts are often overlooked. Here, we assessed the interacting effect of conspecific and higher-order predation risk on the per capita consumption and behaviours of the invasive freshwater amphipod Gammarus pulex, using field microcosm and video-recorded lab experiments in Northern Ireland. Gammarus pulex exhibited higher per capita consumption in the presence of conspecifics, owing to reduced handling time of prey, regardless of fish presence and despite reduced swimming time and increased time spent physically interacting with each other. Consumption was lower in the presence of fish in the field, and handling time decreased with greater amphipod densities in the presence of fish cue in the lab. Our results show that impacts of G. pulex are independently influenced by conspecifics and predation risk, whereas handling time revealed an interacting effect of conspecific density and predation risk. Further assessments of the responses of invasive animals to biotic interactions could help explain variability in their impacts at local spatial scales.

A long-term study (1949–2015) of the aftermaths of the deliberate experimental introduction of an invasive freshwater amphipod (Crustacea) to a small Island

The ability to track changing distributions and long-term inter actions between native and introduced species provides insights into forecasting impacts of invaders. We used data from deliberate field introduction experiments of a freshwater Gammarus amphipod (Crustacea) to the rivers of a small British island, The Isle of Man. The deliberate introductions commenced in 1949 and re-sampling occurred in the ‘60s, ‘70s ‘80s, ‘90s, 200 5 and finally in 2015. The findings generally confirmed the failure of introductions of Gammarus pulex into sites previously dominated by the native Gammarus duebeni celticus even with high propagule pressure in terms of numbers of individual invaders released and repeated introductions. Despite this, the island-wide 2015 survey revealed that G. d. celticus occurred in fewer sites and G. pulex in more sites than a decade earlier, indicating at this island-wide scale, the displacement of G. pulex by G. d. celticus seems to be continuing. In addition, one of the introduction sites, Arbory Stream which contained G. d. celticus from 1951–2005 contained only G. pulex in 2015, showing that even after six decades, assumptions cannot be made as to the limits of invader range expansion. Multivariate analysis of physico-chemical data from the 2015 island-wide sur vey revealed water quality as a crucial environmental gradient that influences the distributions of the native and invader species, with the former in higher organic water quality sites than sites with the invader or where invader and native co-occurred. The North American amp hipod Crangonyx pseudogracilis had expanded its range since 2005, including invading low biological water quality sites previously devoid of both Gammarus spp.. Pollution from historic metal mining is implicated as a potential major factor excluding amphipods. This deliberate ecological experiment, through long-term monitoring, continues to provide insights into the factors determining the distributions of natives and invaders.

Invasive freshwater shrimp, Palaemon sinensis (Sollaud, 1911) found in Tama River, Kanagawa, and identified by morphological characteristics and DNA barcoding

Invasive freshwater shrimp, <i>Palaemon sinensis </i>(Sollaud, 1911) found in Tama River, Kanagawa, and identified by morphological characteristics and DNA barcoding

Enhanced fecundity and parasite release in the first amphipod invader on the Iberian Peninsula

Crangonyx pseudogracilis is a North American amphipod recently detected in Portugal and it is the first invasive freshwater amphipod detected in the Iberian Peninsula. The aim of this study was to assess the population structure and its invasion range in this area, but also to assess its pathogen profile and its origin through genetic analyses. Crangonyx pseudogracilis was only found in the lowlands of the Tagus River basin, a restricted area of the three sampled river basins (Tagus, Guadiana and Sado). Only one mitochondrial DNA (mtDNA) gene cytochrome oxidase subunit 1 (COI) haplotype, identical to the one already detected in Europe and in the Lake Charles, USA, was identified. The obtained data show that the studied populations are well-established, have a high female fecundity and a reproduction period extended throughout the year. No parasites were detected in the 236 dissected specimens. The dissimilarity of parasites prevalence to other European invasive populations opens the possibility of a direct introduction from North America but it also does not exclude the possibility of a secondary introduction from another European country.

Resistance to dehydration and positive hygrotaxis in the invasive red swamp crayfish Procambarus clarkii

The red swamp crayfish Procambarus clarkii is the most cosmopolitan invasive freshwater crayfish species in the world. High tolerance to a wide range of environmental conditions, among which its great ability to survive drought conditions, and the economic importance are the main factors of its spreading success. The present study tests for the first time the survival of this species to different relative humidity (RH) conditions (plastic boxes with humidity controlling salt solutions at 30%, 50%, 70%, 100% RH) and its ability to orient in humidity gradients (dual-choice chambers 50–78% RH, 60–75% RH). P. clarkii shows a great ability to survive out of water, positively related to the RH conditions, surviving more than two days at very low humidity (30% RH) and more than one month at 100% RH. In addition the crayfish showed a positive hygrotaxis spending most of their time in the area of the choice chambers with a higher RH. The results of the present investigation are particularly relevant considering that one of the major challenges to predict and control biological invasion lies in understanding which biological and ecological features might favor the colonization of alien invasive species in new areas.

Recreational angling as a vector of freshwater invasions in Central Italy: perceptions and prevalence of illegal fish restocking

Italian freshwater ecosystems were strongly affected by biological invasions during the last few decades. Recreational angling contributed to this, through the widespread use of invasive alien species for fish restocking. To date, no research is available about the psychological and structural determinants of deliberate fish restocking in Italy. This work aims to fill this research gap, through structured questionnaires administered to a sample of recreational anglers (n = 276) in the Arno river basin (Central Italy). A predictive model for fish restocking, based on a quasi-binomial logistic regression, was fit and multi-model inference was drawn, to highlight the most significant predictors. Respondents, who expected that most anglers practiced restocking and who believed restocking could create closer fishing spots, were more prone to illegally restock fish. Our findings indicate that expectations about illegal fish restocking might exist among specialized segments of anglers. Targeted communication campaigns must be enforced as soon as possible to change them. Furthermore, fish restocking is supposed to reduce the travel costs for angling: future research about this is needed to model invasion hotspots.

Predation risk affects growth and reproduction of an invasive snail and its lethal effect depends on prey size.

The behavior of invasive species under predation risk has been studied extensively, but their growth and reproductive responses have rarely been investigated. We conducted experiments with juveniles and adults of the invasive freshwater snail Pomacea canaliculata, and we observed changes in growth and reproduction in response to predation risk from a caged predator (Trachemys scripta elegans). P. canaliculata produced eggs earlier in the presence of predators and injured conspecifics compared with the control group (no risk), although the total number of egg masses laid by per female was exceeded by that of the controls after 15 days. Egg hatching success noticeably decreased under predation risk, and the incubation period was significantly prolonged; however, the oviposition height of the snails was not affected. A lethal effect of predation risk was detected in juvenile snails but not in adults. The growth of juvenile P. canaliculata was inhibited under predation risk, probably due to a reduction in food intake. Adult females exhibited a greater reduction in growth under predation risk than males, which likely resulted in part from the high reproductive investment of females in egg laying. These results indicate that P. canaliculata snails under predation risk face a trade-off between predator avoidance and growth and reproduction, where the lethal effect of predation risk is linked to the size of the prey.

DNA Barcoding of the Banded Mystery Snail, Viviparus georgianus in the Adirondacks with Quantification of Parasitic Infection in the Species

The banded mystery snail, Viviparus georgianus (Lea, 1834) is an invasive freshwater mollusc of the northeastern United States, where it has become the dominant fauna in many lakes and rivers of upstate New York (NY). Despite a series of comprehensive taxonomic studies carried out in the early 1990s on molluscs in the region, this species was never genetically confirmed in NY. In addition, its invasive potential had never approached that of the notorious zebra and quagga mussels. In this study, we report a new population of V. georgianus from the Adirondacks (northern NY) and genetically confirm its identity for the first time using Bayesian analysis. Based on field observations, we also investigated trematode infection in 200 snails and quantify their prevalence and intensity over four months in the summer of 2016 (May–August). Our results found that V. georgianus serves as the intermediate host of an echinostomatid trematode species with an overall prevalence of 66.7% (N=177). We discuss the implications of these results within the context of the snail's invasive status in NY and provide a framework for future research on the species.

Effects of food concentration on the reproductive capacity of the invasive freshwater calanoid copepod Arctodiaptomus dorsalis (Marsh, 1907) in the Philippines

Effects of food concentration on the reproductive capacity of the invasive freshwater calanoid copepod Arctodiaptomus dorsalis (Marsh, 1907) in the Philippines

Escape Burrowing of Modern Freshwater Bivalves as a Paradigm for Escape Behavior in the Devonian Bivalve Archanodon catskillensis

Many freshwater bivalves restore themselves to the sediment water interface after burial by upward escape burrowing. We studied the escape burrowing capacity of two modern unionoids, Elliptio complanata and Pyganodon cataracta and the invasive freshwater venerid Corbicula fluminea, in a controlled laboratory setting varying sediment grain size and burial depth. We found that the relatively streamlined E. complanata is a better escape burrower than the more obese P. cataracta. E. complanata is more likely to escape burial in both fine and coarse sand, and at faster rates than P. cataracta. However, successful escape from 10 cm burial, especially in fine sand, is unlikely for both unionoids. The comparatively small and obese C. fluminea outperforms both unionoids in terms of escape probability and escape time, especially when body size is taken into consideration. C. fluminea can escape burial depths many times its own size, while the two unionoids rarely escape from burial equivalent to the length of their shells. E. complanata, and particularly P. cataracta, are morphological paradigms for the extinct Devonian unionoid bivalve Archanodon catskillensis, common in riverine facies of the Devonian Catskill Delta Complex of the eastern United States. Our observations suggest that the escape burrowing capability of A. catskillensis was no better than that of P. cataracta. Archanodon catskillensis was likely unable to escape burial of more than a few centimeters of anastrophically deposited sediment. The long (up to 1 meter), vertical burrows that are associated with A. catskillensis, and interpreted to be its escape burrows, represent a response to episodic, small-scale sedimentation events due to patterns of repetitive hydrologic or weather-related phenomena. They are not a response to a single anastrophic event involving the influx of massive volumes of sediment.

Characteristics of matrix of the invasive freshwater Ectoprocta species Pectinatella magnifica

Abstract(Leidy, 1851) (phylum Ectoprocta) is an invasive species that is spread in many areas of the world. Its significant attribute is the production of large colonies formed by a specific gelatinous matrix which is usually occupied by microorganisms such as bacteria, algae, and cyanobacteria. This work compares the matrix characteristics of

A Preliminary Study on the Distribution Pattern, Feeding Behavior and Invasiveness of the Exotic Fish, Chitala ornata (Clown Knife Fish) in the Sub Water Ways of Attanagalu Oya

Increasing threat from the introduced invasive species has been identified as one of the major risk factors for the extinction of freshwater fishes. There are number of identified freshwater alien species which have become invasive within Sri Lankan natural waters. However, there is a dearth of information regarding many of these alien invasive species. Therefore, this research project focused on elucidation of distribution pattern, food and feeding habitats and invasiveness of Chitala ornata, an alien invasive freshwater fish species in potentially new site of infestation in the Attanagalu oya and its tributaries over a period of three months as a preliminary study. Key objectives of the study were, to find out the present distribution of C. ornata in Attanagalu Oya and its tributaries, to evaluate the food and feeding habits of C. ornata through gut analysis and to find out the presence of other invasive/introduced species in the area. Over the study peroid, 50 individuals of C. ornata ranging from 21cm to >80cm were collected using hook and line fishing gear and captured fish were deep-frozen immediately after capturing to avoid the deterioration of the food items within the fish gut. Fish gut analyses have been carried out under laboratory conditions. Morphological measures, frequency of occurrence and Index of fullness were calculated. The results indicated that C. ornata has established in the Attanagalu oya basin in areas such as Ekala and Kotugoda. Gut content analysis indicated that C. ornata feeds on significant number of native fish species. Five major prey fish species, consisting 58 Hirikanaya (Labeo dussumeri), 35 Rathu waral katu kuriya (Puntius kelumi), 23 Iri ankutta (Mystuss vittatus), 13 Walapoththa (Ompok bimaculatus) and 16 Illeya (Megalops cyprinoides) were found to make up the diet of 28 adults and 05 juveniles of C. ornata. The average Index of fullness was 378.19. Frequencies of occurrence are 0.606, 0.485, 0.424, 0.121 and 0.242 respectively for L.dussumeri, P. kelumi, M. vittatus, O. bimaculatus and M. cyprinoides. Out of these five species P. kelumi is listed as an endangered endemic species. Other than fishes, one shrimp species, molluscs and fish eggs were also recorded as their food items. Further, other exotic species such as Tank cleaner (Pterygoplichthys spp.) and giant gourami (Osphronemus goramy) were also recorded in the Attanagalu oya. It was concluded that immediate steps should be taken to manage this potentially harmful Alien invasive species in the Attanagalu Oya basin. Keywords: Invasive, Exotic, Fresh water, Chitala, Attanagalu oya

Winery wastewater treatment by integrating Fenton's process with biofiltration by Corbicula fluminea

AbstractBACKGROUNDCorbicula fluminea is an invasive freshwater clam with strong environmental and economic impact. Management of this pest should include its application, thus biofiltration by C. fluminea was successfully tested for the treatment of winery wastewater. Fenton's process was used in order to reduce the initial effluent toxicity.RESULTSClam mortality was observed to significantly decrease when exposed to Fenton‐treated samples compared with untreated wastewater. Although COD depletion by oxidation was strongly affected by the reactant concentration applied, the toxicity of the output effluent did not change markedly even when higher iron and hydrogen peroxide loads were used. Biofiltration led to COD abatements near 100% both when applied to raw and Fenton‐treated effluents. However, for the raw effluent significant COD removal occurred only after an initial period where the organic load remained unchanged.CONCLUSIONIt seems advisable to integrate biofiltration with Fenton's peroxidation as a pre‐treatment. The results discussed here support the integration of C. fluminea in wastewater treatment as a potential contribution to pest management. © 2017 Society of Chemical Industry

Size-selective predation by all-male prawns: implications for sustainable biocontrol of snail invasions

All-male populations of the freshwater prawn Macrobrachium rosenbergii were recently produced by a novel temporal RNA interference (RNAi)-based biotechnology for aquaculture purposes. This biotechnology opens the way to the wide use of all-male prawn populations as sustainable biocontrol agents against invading populations of freshwater snails, for which there is currently no environmentally friendly solution. Among the most damaging of the invasive freshwater snail species are the apple snails (Pomacea spp.), which inflict major damage on natural ecosystems and rice fields. The proposed use of all-male prawn populations as environmentally friendly biocontrol agents against invasive freshwater snails has several advantages: efficient predation by the prawns over a wide range of freshwater snails, the ready availability of the prawns, and the monosex non-reproductive nature of the biocontrol agents. Since the aquatic predators are strongly size selective, we quantified the predation rate as a function of body size of both predator and prey (M. rosenbergii and P. caniculata). Medium-sized and large prawns (~10–30 g) efficiently preyed small and medium-sized snails (up to 15 mm), while small prawns (up to 4 g) immediately and completely eradicated snail hatchlings. Medium-sized prawns (~22 g) exterminated a significant fraction of snail biomass within 24 h (up to 58% of their body mass) after being introduced into a tank of snails. A typical ‘climbing-to-the surface’ anti-predator behavior of the snails was recorded. The potential of all-male prawns as efficient biocontrol agents over hatchling and adult apple snails as part of an integrated pest management program is discussed. Our experiments set the stage for evaluating the ecological and economic implications of this generic solution for a wide variety of habitats.