Volume 9, Issue 2 (2014)
published June 2014
Contents | |
Research articles |
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Bruce R. Ellender and Olaf L.F. Weyl
A review of current knowledge, risk and ecological impacts associated with non-native freshwater fish introductions in South Africa
(pp 117-132)
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The introduction and spread of non-native species is one of the least reversible human-induced global changes. In South Africa, non-native
fish introductions have occurred over the last two and a half centuries. Resultant invasions have been cited as a primary threat to imperilled
South African fishes and other aquatic fauna. Addressing a problem of this magnitude requires an organised approach. The aim of this paper is
to summarise the current knowledge, risk and ecological impacts associated with non-native freshwater fish introductions in South Africa.
A total of 55 fishes have been introduced into novel environments in South Africa. Of these, 27 were alien and 28 were extralimital introductions.
Only 11 introduced species failed to establish and of the 44 species that have established, 37% are considered fully invasive. Introductions for
angling were responsible for the highest proportion (55%) of fully invasive species with the remainder linked to inter-basin water transfers (15%),
bio-control (15%), ornamental fish trade (10%) and aquaculture (5%). There was a general paucity of published literature on the introduction,
establishment and spread of non-native fishes, and recent research has largely focused on impacts on native biota. While documented impacts
spanned multiple levels of biological organisation, most papers focused on individual and population level impacts. Large taxonomic biases
were also observed, and invasive impacts were estimated for less than 50% of fully invasive fishes. There is also an extensive knowledge gap
on the impacts of associated parasites and diseases introduced with non-native fishes. These knowledge gaps constrain effective management
of non-native fishes in South Africa and research at all invasion stages (introduction, establishment, spread and impact) is necessary
to guide conservation practitioners and managers with information to manage current invasions and curb future introductions.
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Ana Luísa Nunes, Stelios Katsanevakis, Argyro Zenetos and Ana Cristina Cardoso
Gateways to alien invasions in the European seas
(pp 133-144)
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The spatial pattern of initial introductions of marine alien species in the European Seas (including the entire Mediterranean) was investigated.
Marked geographic patterns depending on the pathway of introduction were revealed, with specific countries acting as gateways to alien invasions.
France and Italy were the countries mostly responsible for introductions by aquaculture, while Lessepsian species were first reported (as anticipated)
in the countries of the Levantine Sea, especially Israel. Shipping was the most important pathway of introduction, with a widely dispersed geographic
pattern of initial introductions, especially near large ports. Certain taxonomic groups were mostly introduced by specific pathways, and hence
the taxonomic identity of the introduced alien species in each region was greatly dependent on the dominant maritime activities/interventions
and the related pathways of introduction. Our data can be very useful for informing and supporting national policy and management decisions
necessary to prevent future introductions of marine alien species.
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Anastasija Zaiko, Dan Minchin and Sergej Olenin
"The day after tomorrow": anatomy of an ‘r’ strategist aquatic invasion
(pp 145-155)
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Invasive alien species, following an arrival, undergo different colonization stages. The full pattern of an invasion is seldom tracked
as many studies on invasive processes only take place over a few years. In this study the invasion of the zebra mussel, Dreissena polymorpha
(Pallas, 1771), was followed for more than a ten-year period. It developed an expansion stage with peak abundance (outbreak) four to six years
following arrival. Thereafter the population entered an accommodation stage at a lower level of abundance and biomass. This pattern was repeated
for two separate lakes on the Shannon River in Ireland. In concert with the biomass at each invasion stage there were changes to the transparency
and chlorophyll a levels of lake water. Based on the results of the current study, revision of the terminology of invasion stages is suggested.
Providing some additional insight into the invasion process, it can be accorded with existing frameworks and bioinvasion impact assessment approaches.
The sequence of invasion stages with corresponding direct (semi-quantitative) and indirect (qualitative) features as well as examples of empirical
evidence is presented in this account.
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Joëlle Gérard, Natacha Brion and Ludwig Triest
Effect of water column phosphorus reduction on competitive outcome and traits of Ludwigia grandiflora and L. peploides, invasive species in Europe
(pp 157-166)
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The invasion of alien macrophytes in aquatic ecosystems has caused serious ecological and economic impacts. Their introduction
often leads to competition with natives and already established invasive species. Competition among invasive species is assumed
to be greater than among native and invasive species, especially for plants with similar growth form and position in the water column.
Many freshwater bodies are eutrophicated due to high phosphorus inputs, which have led to a competitive advantage for invasive macrophytes.
A decrease in water column phosphorus load might lead to a change in competitive performance and reveal apparent variation in those traits
promoting invasiveness. We investigated the effect of a water column phosphorus reduction on the growth, competitive outcome, traits
and nutrient uptake of two related invasive Ludwigia species, L. grandiflora and L. peploides. We performed indoor
competition experiments in eutrophic and mesotrophic conditions following a complete additive design. L. grandiflora always was
the better competitor in both trophic conditions and had higher trait values compared to L. peploides. Both species relative growth
rates (RGR) and trait values were affected by a P reduction, especially the number of branches and stem length. Although both species
prefer higher water column phosphorus loadings, they can also colonize habitats of lower mesotrophic phosphorus concentrations.
L. peploides was able to store more P in its tissue compared to L. grandiflora, thereby possibly outcompeting L. grandiflora
in even lower P concentrations. Our results show a water column P reduction to lower branch numbers, stem length and biomass, which could reduce
mat formation and allow for more effective control of both species.
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Elvire Antajan, Thomas Bastian, Thomas Raud, Jean-Michel Brylinski, Stefan Hoffman, Gérard Breton, Vincent Cornille, Alice Delegrange and Dorothée Vincent
The invasive ctenophore Mnemiopsis leidyi A. Agassiz, 1865 along the English Channel and the North Sea French coasts: another introduction pathway in northern European waters?
(pp 167-173)
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The presence of Mnemiopsis leidyi A. Agassiz, 1865 along the French coasts of the Eastern English Channel and the North Sea (EEC-NS)
was established via morphological observation and molecular evidence. The earliest records were from surveys carried out in autumn 2005
in Le Havre harbour (Bay of Seine, EEC) and coincided with the historical introduction of the species in other Northern European waters.
Since 2009, the species has also been frequently observed along the French coast of the North Sea. Results indicate M. leidyi has established
a self-sustaining population in the Bay of Seine, which may act as a source population for northern European harbours via commercial shipping.
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Tilde Groslier, Helle Toft Christensen, Jens Davids, Per Dolmer, Ingrid Elmedal, Mark Wejlemann Holm and Benni W. Hansen
Status of the Pacific Oyster Crassostrea gigas (Thunberg, 1793) in the western Limfjord, Denmark – Five years of population development
(pp 175-182)
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The Pacific oyster, Crassostrea gigas, was introduced into the Netherlands in 1964 for aquaculture purposes and has since spread extensively
in Northern European waters. Eight locations in the western part of the Limfjord, Denmark, first sampled in 2006 were revisited in 2011, to determine
how the population of C. gigas has changed. Densities were lower at all but two locations. No differences in average shell lengths or condition
indices were detected. No changes in the number or distribution of shell size classes were observed. These similarities suggest there is a single population
that has not expanded in terms of geographic distribution. While reproduction does occur, conditions for population growth appear to be suboptimal.
The species has become established in western Limfjord but abundance is low and densities are much lower than those considered harmful to the ecosystem.
At present, the C. gigas population is not a cause for concern in the Limfjord ecosystem.
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Irene Guarneri, Oana Paula Popa, Laura Gola, Lyudmila Kamburska, Rosaria Lauceri, Manuel Lopes-Lima, Luis Ovidiu Popa and Nicoletta Riccardi
A morphometric and genetic comparison of Sinanodonta woodiana (Lea, 1834) populations: does shape really matter?
(pp 183-194)
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Sinanodonta woodiana (Lea, 1834) is an invasive species which has spread rapidly across Europe over the last few decades.
Although it is already well established throughout Italy (both in lakes and in rivers), during a regular monitoring of the mussel
communities in Northern Italy, this species was found for the first time in the fluvial natural reserve of Ghiaia Grande (Po River basin).
The strong differences in shell shape between these specimens and those from Lake Maggiore prompted a genetic comparison based on DNA barcoding
analyses to establish whether specimens from both sites belong to the same species. Our results confirm that the wide shell plasticity may help
to explain the role of environmental factors in driving shells’ morphology. Additionally, it may also induce S. woodiana misidentification
with the native Anodonta sp. This fact may have strong negative implications for freshwater conservation if on one hand, the native species
distribution is falsely over represented; or on the other hand, if the invasive species has a much wider distribution than predicted.
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Ian C. Duggan, Martin W. Neale, Karen V. Robinson, Piet Verburg and Nathan T.N. Watson
Skistodiaptomus pallidus (Copepoda: Diaptomidae) establishment in New Zealand natural lakes, and its effects on zooplankton community composition
(pp 195-202)
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The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations
recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment
on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in late-2008, coincident with releases of domestically
cultured grass carp (Ctenopharyngodon idella). Although not present in any of our samples prior to August 2008, S. pallidus was found
in all samples collected in the subsequent five years. ANOSIM indicated zooplankton community composition significantly differed between samples
collected before and after S. pallidus invasion, whether the invader was included in the analysis or not. Zooplankton species affected most
greatly were the copepods Calamoecia lucasi and Mesocyclops sp., which decreased in their relative importance, and the cladocerans
Bosmina meridionalis and Daphnia galeata, which increased. Rotifer species were relatively unaffected. As the length of grass carp
released were >6.5 cm, direct predatory effects by this species on the zooplankton community are unlikely. Associated reductions in macrophyte
biomass could explain increases in the relative abundances of planktonic cladocerans (B. meridionalis and D. galeata). However,
the effect of macrophyte reduction by grass carp on zooplankton communities is considered to be limited elsewhere, while the reduced macrophyte
biomass cannot explain the decrease in relative abundance of the native planktonic calanoid copepod C. lucasi. Competition between
C. lucasi and S. pallidus is the most compelling explanation for the reduction in importance of the native calanoid copepod species.
Skistodiaptomus pallidus appears to have undergone a “boom-and-bust” cycle in Lake Kereta, increasing in relative abundance in the first three
years following establishment, before declining in importance.
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Anne Schrimpf, Thomas Schmidt and Ralf Schulz
Invasive Chinese mitten crab (Eriocheir sinensis) transmits crayfish plague pathogen (Aphanomyces astaci)
(pp 203-209)
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The Chinese mitten crab (Eriocheir sinensis) is a vector of the fatal crayfish plague pathogen (Aphanomyces astaci).
Both species are listed among the world´s 100 worst invasive species. From its origin in China the Chinese mitten crab was introduced to Europe,
presumably via ballast water from ships. A. astaci originated in North America and is assumed to have been firstly introduced to Europe
through human-mediated transportation of live specimens of North American freshwater crayfish species. While the North American crayfish species
are resistant to the pathogen, it causes a fatal disease to native European crayfish species. It was generally assumed that the crayfish plague
could only infect freshwater crayfish species. Until recently, the Chinese mitten crab had not been recognised as a host of the pathogen.
And no study has yet been carried out to investigate if they also serve as a vector. In this study, transmission experiments are carried out
in combination with subsequent species-specific molecular analysis. The results establish that the Chinese mitten crab carry the crayfish plague
pathogen and can transmit it to the European noble crayfish (Astacus astacus). The implications of these findings are ecologically alarming,
considering the high invasive potential and the catadromous life cycle of Chinese mitten crabs, facilitating the widespread distribution of the pathogen.
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Allison S. Quan, Katherine M. Pease, Jesse W. Breinholt and Robert K. Wayne
Origins of the invasive red swamp crayfish (Procambarus clarkii) in the Santa Monica Mountains
(pp 211-219)
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Although native to the southeastern United States, the red swamp crayfish (Procambarus clarkii) has become established worldwide
through accidental and intentional actions by humans. In the Santa Monica Mountains of southern California, the presence of the omnivorous
crayfish is associated with the absence or reduced abundance of native amphibians. The original source of P. clarkii in southern
California is unknown; however genetic analysis can be used to determine sources of invasion. We sequenced 16S rRNA subunit and cytochrome
oxidase I (COI) mitochondrial genes to trace the origins of P. clarkii in the Santa Monica Mountains. The resulting haplotype network
of the combined COI and 16S rRNA subunit genes showed 19 distinct haplotypes and suggested multiple introductions of crayfish to the Santa
Monica Mountains from possible source locations in Texas, Florida and Louisiana. Identifying original sources and mechanisms of introduction
can slow and prevent further expansion of P. clarkii.
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Koh Hasegawa, Nobuo Ishiyama and Hideyuki Kawai
Replacement of nonnative rainbow trout by nonnative brown trout in the Chitose River system, Hokkaido, northern Japan
(pp 221-226)
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In this study, evidence for interspecific interaction was provided by comparing distribution patterns of nonnative rainbow trout
Onchorhynchus mykiss and brown trout Salmo trutta between the past and present in the Chitose River system, Hokkaido, northern Japan.
O. mykiss was first introduced in 1920 in the Chitose River system and has since successfully established a population. Subsequently, another
nonnative salmonid species, S. trutta have expanded the Chitose River system since the early 1980s. At present, S. trutta have replaced
O. mykiss in the majority of the Chitose River, although O. mykiss have persisted in areas above migration barriers that prevent
S. trutta expansion. In conclusion, the results of this study highlight the role of interspecific interactions between sympatric nonnative
species on the establishment and persistence of populations of nonnative species.
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Carlos Toledo-Hernández, Ximena Vélez-Zuazo, Claudia Patricia Ruiz-Diaz, Ana Rita Patricio, Pascal Mège, Melissa Navarro, Alberto Miguel Sabat, Ricardo Betancur-R and Riccardo Papa
Population ecology and genetics of the invasive lionfish in Puerto Rico
(pp 227-237)
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The lionfish (Pterois volitans), has become an abundant alien species along the southeast coast of the United States of America
and in Caribbean coastal waters. Although, they represent a major concern in conservation, no studies have yet assessed their population
ecology and genetic structure simultaneously. We collected 227 lionfish from 24 sites around Puerto Rico to investigate, the length distribution,
length-weight relationships, relative condition factor, and mitochondrial DNA (mtDNA) genetic diversity. The total length distribution ranged between
37 and 349 mm with a single peak between 130 and 149 mm. Our analysis indicated isometric growth for mature individuals and a positive allometric growth
for immature lionfishes. These results suggest a different allocation of resources, most likely reproduction for mature individuals and somatic growth
for the immature lionfish. The relative condition factor (KN) was similar for immature and mature individuals. Genetic analyses indicated that
P. volitans is the only lionfish species present in Puerto Rico, and that its origin was likely dispersal from the epicenter of introduction
off the coast of Florida. Interestingly, only four of the nine mtDNA haplotypes identified in the Atlantic were observed in the Puerto Rican population.
A fine-scale population genetic analysis suggested a significantly different population structure between the west and south coasts. Finally, our data
suggests a second founder effect, but with a reduction of haplotype diversity.
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