Pilferer, murderer of innocents or prey? The potential impact of killer shrimp (Dikerogammarus villosus) on crayfish

Abstract Freshwater ecosystems worldwide are facing the establishment of non-native species, which, in certain cases, exhibit invasive characteristics. The impacts of invaders on native communities are often detrimental, yet, the number and spread of non-native invasive species is increasing. This is resulting in novel and often unexpected combinations of non-native and native species in natural communities. While the impact of invaders on native species is increasingly well-documented, the interactions of non-native invaders with other non-native invaders are less studied. We assessed the potential of an invasive amphipod, the killer shrimp Dikerogammarus villosus (Sowinsky, 1894), to cope with other established invaders in European waters: North American crayfish of the Astacidae family—represented by signal crayfish Pacifastacus leniusculus (Dana, 1852), and the Cambaridae family—represented by marbled crayfish Procambarus virginalis Lyko, 2017. The main goal of this study was to investigate if killer shrimp, besides their role as prey of crayfish, can significantly influence their stocks by predating upon their eggs, hatchlings and free-moving early juveniles. Our results confirmed that killer shrimp can predate on crayfish eggs and hatchlings even directly from females abdomens where they are incubated and protected. As marbled crayfish have smaller and thinner egg shells as well as smaller juveniles than signal crayfish, they were more predated upon by killer shrimp than were signal crayfish. These results confirmed that the invasive killer shrimp can feed on different developmental stages of larger freshwater crustaceans and possibly other aquatic organisms.

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Crayfish plague affects juvenile survival and adult behaviour of invasive signal crayfish

Parasitology ◽

10.1017/s0031182020000165 ◽

2020 ◽

Vol 147 (6) ◽

pp. 706-714 ◽

Cited By ~ 1

Author(s):

John Rhidian Thomas ◽

Chloe V. Robinson ◽

Agata Mrugała ◽

Amy R. Ellison ◽

Emily Matthews ◽

...

Keyword(s):

North American ◽

Native Species ◽

North American Species ◽

Juvenile Survival ◽

Signal Crayfish ◽

Aphanomyces Astaci ◽

The North ◽

High Infection ◽

Oomycete Pathogen ◽

The Impact

AbstractThe spread of invasive, non-native species is a key threat to biodiversity. Parasites can play a significant role by influencing their invasive host's survival or behaviour, which can subsequently alter invasion dynamics. The North American signal crayfish (Pacifastacus leniusculus) is a known carrier of Aphanomyces astaci, an oomycete pathogen that is the causative agent of crayfish plague and fatal to European crayfish species, whereas North American species are considered to be largely resistant. There is some evidence, however, that North American species, can also succumb to crayfish plague, though how A. astaci affects such ‘reservoir hosts’ is rarely considered. Here, we tested the impact of A. astaci infection on signal crayfish, by assessing juvenile survival and adult behaviour following exposure to A. astaci zoospores. Juvenile signal crayfish suffered high mortality 4-weeks post-hatching, but not as older juveniles. Furthermore, adult signal crayfish with high-infection levels displayed altered behaviours, being less likely to leave the water, explore terrestrial areas and exhibit escape responses. Overall, we reveal that A. astaci infection affects signal crayfish to a much greater extent than previously considered, which may not only have direct consequences for invasions, but could substantially affect commercially harvested signal crayfish stocks worldwide.

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Divergent temperature-specific metabolic and feeding rates of native and invasive crayfish

Biological Invasions ◽

10.1007/s10530-021-02687-1 ◽

2021 ◽

Author(s):

T. J. Ruokonen ◽

J. Karjalainen

Keyword(s):

Native Species ◽

Ecological Impacts ◽

Metabolic Rates ◽

Feeding Rates ◽

Cold Temperatures ◽

Signal Crayfish ◽

Climatic Scenarios ◽

Invasive Crayfish ◽

Noble Crayfish ◽

The Impact

AbstractTemperature is one of the most important factors governing the activity of ectothermic species, and it plays an important but less studied role in the manifestation of invasive species impacts. In this study, we investigated temperature-specific feeding and metabolic rates of invasive and native crayfish, and evaluated how temperature regulates their ecological impacts at present and in future according to different climatic scenarios by bioenergetics modelling. We conducted a series of maximum food consumption experiments and measured the metabolic rates of cold-adapted native noble crayfish (Astacus astacus) and invasive signal crayfish (Pacifastacus leniusculus) originally from a warmer environment over a temperature gradient resembling natural temperatures in Finland. The maximum feeding rates and routine metabolic rates (RMR) of native noble crayfish were significantly higher at low temperatures (< 10 °C than the rates of invasive signal crayfish. The RMRs of the species crossed at 18 °C, and the RMRs of signal crayfish were higher at temperatures above 18 °C. These findings indicate that the invader’s thermal niche has remained stable, and the potential impacts per capita are lower at suboptimal cold temperatures than for the native species. Our bioenergetics modelling showed that the direct annual predation impact of noble and signal crayfish seem similar, although the seasonal dynamics of the predation differs considerably between species. Our results highlight that the temperature-specific metabolic and feeding rates of species need to be taken into account in the impact assessment instead of simple generalisations of the direction or magnitude of impacts.

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Diversity and biomass of native macrophytes are negatively related to dominance of an invasive Poaceae in Brazilian sub-tropical streams

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x2013000200011 ◽

2013 ◽

Vol 25 (2) ◽

pp. 202-209 ◽

Cited By ~ 9

Author(s):

Luiz Felipe Gonçalves Fernandes ◽

Mariana Carolina Teixeira ◽

Sidinei Magela Thomaz

Keyword(s):

Native Species ◽

Biotic Resistance ◽

Aquatic Macrophyte ◽

Shannon Index ◽

Freshwater Ecosystems ◽

Freshwater Biodiversity ◽

Native Communities ◽

Environmental Perturbations ◽

Mechanical Removal ◽

Successful Invader

Besides exacerbated exploitation, pollution, flow alteration and habitats degradation, freshwater biodiversity is also threatened by biological invasions. This paper addresses how native aquatic macrophyte communities are affected by the non-native species Urochloa arrecta, a current successful invader in Brazilian freshwater systems. We compared the native macrophytes colonizing patches dominated and non-dominated by this invader species. We surveyed eight streams in Northwest Paraná State (Brazil). In each stream, we recorded native macrophytes' richness and biomass in sites where U. arrecta was dominant and in sites where it was not dominant or absent. No native species were found in seven, out of the eight investigated sites where U. arrecta was dominant. Thus, we found higher native species richness, Shannon index and native biomass values in sites without dominance of U. arrecta than in sites dominated by this invader. Although difficult to conclude about causes of such differences, we infer that the elevated biomass production by this grass might be the primary reason for alterations in invaded environments and for the consequent impacts on macrophytes' native communities. However, biotic resistance offered by native richer sites could be an alternative explanation for our results. To mitigate potential impacts and to prevent future environmental perturbations, we propose mechanical removal of the invasive species and maintenance or restoration of riparian vegetation, for freshwater ecosystems have vital importance for the maintenance of ecological services and biodiversity and should be preserved.

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Cucumispora dikerogammari n. gen. (Fungi: Microsporidia) infecting the invasive amphipod Dikerogammarus villosus: a potential emerging disease in European rivers

Parasitology ◽

10.1017/s0031182009991119 ◽

2009 ◽

Vol 137 (2) ◽

pp. 191-204 ◽

Cited By ~ 32

Author(s):

M. O. OVCHARENKO ◽

K. BACELA ◽

T. WILKINSON ◽

J. E. IRONSIDE ◽

T. RIGAUD ◽

...

Keyword(s):

Western Europe ◽

Developmental Stages ◽

Anterior Part ◽

Polar Filament ◽

Taxonomic Status ◽

Molecular Data ◽

Spore Wall ◽

Complete Sequence ◽

Dikerogammarus Villosus ◽

Invasive Amphipod

SUMMARYDikerogammarus villosus is an invasive amphipod that recently colonized the main rivers of Central and Western Europe. Two frequent microsporidian parasites were previously detected in this species, but their taxonomic status was unclear. Here we present ultrastructural and molecular data indicating that these two parasites are in fact a single microsporidian species. This parasite shares numerous characteristics of Nosema spp. It forms elongate spores (cucumiform), developing in direct contact with host cell cytoplasm; all developmental stages are diplokaryotic and the life cycle is monomorphic with disporoblastic sporogony. Initially this parasite was described as Nosema dikerogammariOvcharenko and Kurandina 1987. However, phylogenetic analysis based on the complete sequence of SSU rDNA places the parasite outside the genus Nosema and it is therefore ascribed to a new genus Cucumispora. The key features characteristic to this genus are: presence of a very well-developed, umbrella-shape anchoring disk covering the anterior part of polaroplast; arrangement of isofilar polar filament into 6–8 coils convoluted with different angles, voluminous diplokaryon, thin spore wall and relatively small posterior vacuole containing posterosome. The parasite infects most host tissues but mainly muscles. It showed high rates of horizontal trophic transmission and lower rates of vertical transmission.

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Monitoring of alien aquatic plants in the inland waters of Sicily (Italy)

Webbia ◽

10.36253/jopt-8414 ◽

2020 ◽

Vol 75 (1) ◽

pp. 77-83

Author(s):

Angelo Troia ◽

Vincenzo Ilardi ◽

Elisabetta Oddo

Keyword(s):

Native Species ◽

Aquatic Plant ◽

Freshwater Ecosystems ◽

Leaf Mass Per Area ◽

Inland Waters ◽

Emergent Macrophytes ◽

Relative Growth ◽

Efficient Management ◽

Mediterranean Island ◽

The Impact

Updated and reliable data on the presence and distribution of alien aquatic plant species in Sicily are lacking, and there is a need to fill this gap for a proper and efficient management of freshwater ecosystems and biodiversity. This paper reviews the available knowledge about alien aquatic vascular plants in the inland waters of Sicily (Italy). The aim is to provide an updated checklist, as a first step in the study of the impact of those plants on the native species and ecosystems of this Mediterranean island. The paper focuses on the strictly aquatic species (hydrophytes), excluding emergent macrophytes. Four species were listed, all of them free-floating and with American origin. Most of them occur within protected areas, and their introduction in the island appears to be anthropogenic. A set of functional traits of the alien species, such as relative growth rate, leaf mass per area, nitrogen and carbon content, were screened. These traits are useful for assessing the species invasive potential compared to native ones.

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Variation in Diet Patterns of the Invasive Top Predator Sander lucioperca (Linnaeus, 1758) across Portuguese Basins

Water ◽

10.3390/w13152053 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2053

Author(s):

Diogo Ribeiro ◽

Christos Gkenas ◽

João Gago ◽

Filipe Ribeiro

Keyword(s):

Native Species ◽

Freshwater Ecosystems ◽

Top Predator ◽

Sander Lucioperca ◽

Diet Patterns ◽

Diet Specialization ◽

Size Dependent ◽

Important Prey ◽

Potential Impact ◽

The Impact

The introduction of non-native species is recognized as a major threat to biodiversity, particularly in freshwater ecosystems. Pikeperch Sander lucioperca, is a recent invader to Portugal, primarily providing commercial and angling interest. The aim of this work was to study the diet of this top predator across Portuguese basins and to evaluate its potential impact on recipient ecosystems. In total, 256 pikeperch stomachs from seven basins were examined, of which 88 (n = 34%) were empty. Pikeperch diet was dominated by R. rutilus, M. salmoides and Diptera in northern populations, while A. alburnus, P. clarkii and Atyidae were important prey in more humid highlands. Variation in diet was most strongly linked to latitude and ontogeny, with both size classes showing signs of cannibalism. The population niche breadth remained low and was accompanied by higher individual diet specialization, particularly in northern populations. Pikeperch dietary patterns denoted an opportunistic ability to use locally abundant prey in each ecosystem, and was size dependent, with larger individuals becoming more piscivores, causing a higher impact in the lotic systems. This first perspective about the pikeperch diet presents a very broad view of the feeding traits of this non-native predator across Portugal, being very important to deepen our knowledge about the impact of these introduced piscivores.

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Rotifers in Heated Konin Lakes—A Review of Long-Term Observations

Water ◽

10.3390/w12061660 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1660

Author(s):

Jolanta Ejsmont-Karabin ◽

Andrzej Hutorowicz ◽

Andrzej Kapusta ◽

Konrad Stawecki ◽

Jacek Tunowski ◽

...

Keyword(s):

Alien Species ◽

Aquatic Organisms ◽

Species Structure ◽

Native Communities ◽

Archival Material ◽

Power Stations ◽

The Impact ◽

Natural Laboratory ◽

Rotifer Communities

The Konin lakes, heated by power stations and invaded by alien organisms, are a natural laboratory in which we can study the impact of climate change on the native communities of aquatic organisms. The aim of our study was to assess the impact of water heating and the occupation of the littoral zone of the lake by invasive species Vallisneria spiralis on changes in the species structure of rotifer communities of plankton, epiphyton and psammon. The archival material was used from the years: 1970–1975, 1978 and 1983, and compared with the results of studies conducted in Licheń and Ślesin Lakes in the years 2010–2011 and 2017–2018. It has been shown that the heating of waters of the studied lakes, combined with the shortening of their retention time, as well as the invasions of alien species, have caused significant changes in the taxonomic and trophic structure of plankton rotifers. In inhabiting Vallisneria bed epiphytic rotifer communities, the share of alien species did not increase, but relatively high densities of uncommon sessile species still persist. Psammon communities in the lakes are dominated by monogonont species relatively common in this habitat in nonheated lakes, but they are nearly devoid of bdelloids, which are abundant in psammon of Masurian lakes.

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Migration of Non-Native Predator Asp (Leuciscus aspius) from a Reservoir Poses a Potential Threat to Native Species in Tributaries

Water ◽

10.3390/w11061306 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1306 ◽

Cited By ~ 2

Author(s):

Nikola Pfauserová ◽

Ondřej Slavík ◽

Pavel Horký ◽

Jitka Kolářová ◽

Tomáš Randák

Keyword(s):

Native Species ◽

Freshwater Ecosystems ◽

Upstream Migration ◽

Dam Construction ◽

Movement Activity ◽

Potential Threat ◽

The Status ◽

River Fragmentation ◽

The Impact

The introduction of non-native species and human-altered habitats are currently the main threats to freshwater ecosystems. Due to predation and competition, biological invaders can cause extinctions and imperil the status of native species, and this phenomenon is enhanced by habitat alteration, for example, dam construction. In addition to river fragmentation caused by dam construction, the impact of non-native species migrating from reservoirs on native assemblages in their tributaries should be considered from a long-term perspective. The present study focused on asp (Leuciscus aspius), an artificially introduced piscivorous cyprinid that became established in the Lipno Reservoir (Czech Republic). Asp regularly occur in a tributary, the Vltava River, where twenty-five individuals were captured, radio-tagged, and tracked for five consecutive years. Asp occurrence in the tributary was highest during spring due to the upstream migration of spawning fish, and this was interconnected with a movement activity peak in March when the temperature reached 6 °C. The fish migrated a maximum distance of 31 km, and the probability of asp occurrence in the tributary was sex-dependent, with more females than males. Some individuals occupied the Vltava River not only for spawning but remained until the temperatures dropped below 10 °C. This study shows how non-native predators use reservoirs for wintering but feed and spawn in tributaries.

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Developing Effective Dispositions for Teaching Music

The Oxford Handbook of Preservice Music Teacher Education in the United States ◽

10.1093/oxfordhb/9780190671402.013.15 ◽

2019 ◽

pp. 321-344

Author(s):

Michael Raiber

Keyword(s):

Music Education ◽

Teacher Educators ◽

Systematic Approach ◽

Music Teachers ◽

Developmental Stages ◽

Music Teacher ◽

Teacher Dispositions ◽

Teacher Concerns ◽

Teaching Music ◽

The Impact

The impact of teacher dispositions on the professional development of preservice music teachers (PMTs) has been substantiated. This chapter describes an approach to dispositional development within the structure of an introduction to music education course. A teacher concerns model is used to organize this systematic approach through three developmental stages that include self-concerns, teaching task concerns, and student learning concerns. A series of 11 critical questions are presented for use in guiding PMTs’ dispositional development through these developmental stages. Activities to engage PMTs in the exploration of each of these questions are detailed for use by music teacher educators desiring to engage PMTs in dispositional development.

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Exogenous application of growth stimulators improves the condition of maize exposed to soil drought

Acta Physiologiae Plantarum ◽

10.1007/s11738-021-03232-2 ◽

2021 ◽

Vol 43 (4) ◽

Author(s):

Agnieszka Ostrowska ◽

Maciej T. Grzesiak ◽

Tomasz Hura

Keyword(s):

Plant Growth ◽

Developmental Stages ◽

Aminolevulinic Acid ◽

Stem Elongation ◽

Development Stage ◽

Photochemical Activity ◽

Soil Drought ◽

Beneficial Effects ◽

Induced Changes ◽

The Impact

AbstractSoil drought is a major problem in plant cultivation. This is particularly true for thermophilic plants, such as maize, which grow in areas often affected by precipitation shortage. The problem may be alleviated using plant growth and development stimulators. Therefore, the aim of the study was to analyze the effects of 5-aminolevulinic acid (5-ALA), zearalenone (ZEN), triacontanol (TRIA) and silicon (Si) on water management and photosynthetic activity of maize under soil drought. The experiments covered three developmental stages: three leaves, stem elongation and heading. The impact of these substances applied during drought stress depended on the plant development stage. 5-ALA affected chlorophyll levels, gas exchange and photochemical activity of PSII. Similar effects were observed for ZEN, which additionally induced stem elongation and limited dehydration. Beneficial effects of TRIA were visible at the stage of three leaves and involved leaf hydration and plant growth. A silicon preparation applied at the same developmental stage triggered similar effects and additionally induced changes in chlorophyll levels. All the stimulators significantly affected transpiration intensity at the heading stage.

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