Forty years of experiments on aquatic invasive species: are study biases limiting our understanding of impacts?
Mads S. Thomsen
Julian D. Olden
James E. Byers
John F. Bruno
Brian R. Silliman
David R. Schiel
- Invasions by non-native species are a threat to biodiversity because invaders can impact native populations, communities and entire ecosystems. To manage this threat, it is necessary to have a strong mechanistic understanding of how non-native species affect local species and communities. We reviewed 259 published papers (1972–2012) that described field experiments quantifying the impact of aquatic nonnative species, to examine whether various types of study biases are limiting this understanding. Our review revealed that invasion impacts had been experimentally quantified for 101 aquatic non-native species, in all major freshwater and marine habitats, on all continents except Antarctica and for most higher taxonomic groupings. Over one-quarter (26%) of studies included tests for impacts on local biodiversity. However, despite this extensive research effort, certain taxa, habitats and regions remain poorly studied. For example, of the over one hundred species examined in previous studies, only one was a marine fish and only six were herbivores. Furthermore, over half (53%) of the studies were from the USA and two-thirds (66%) were from experiments conducted in temperate latitudes. By contrast, only 3% of studies were from Africa and <2% from high latitudes. We also found that one-fifth (20%) of studies were conducted in estuaries, but only 1% from coral reefs. Finally, we note that the standard procedure of pooling or not reporting non-significant treatments and responses is likely to limit future synthetic advancement by biasing meta-analysis and severely limiting our ability to identify non-native species with none or negligible ecological impacts. In conclusion, a future focus on poorly-studied taxa, habitats and regions, and enhanced reporting of results, should improve our understanding and management of impacts associated with aquatic non-native species.
"Das Ergebnis waren tränenreiche Gedichte"
Antoine Vumilia Muhindo
The Global Garlic Mustard Field Survey (GGMFS): challenges and opportunities of a unique, large-scale collaboration for invasion biology
Robert I. Colautti
Steven J. Franks
Ruth A. Hufbauer
Peter M. Kotanen
James E. Byers
- To understand what makes some species successful invaders, it is critical to quantify performance differences between native and introduced regions, and among populations occupying a broad range of environmental conditions within each region. However, these data are not available even for the world’s most notorious invasive species. Here we introduce the Global Garlic Mustard Field Survey, a coordinated distributed field survey to collect performance data and germplasm from a single invasive species: garlic mustard (Alliaria petiolata) across its entire distribution using minimal resources. We chose this species for its ecological impacts, prominence in ecological studies of invasion success, simple life history, and several genetic and life history attributes that make it amenable to experimental study. We developed a standardised field survey protocol to estimate population size (area) and density, age structure, plant size and fecundity, as well as damage by herbivores and pathogens in each population, and to collect representative seed samples. Across four years and with contributions from 164 academic and non-academic participants from 16 countries in North America and Europe thus far, we have collected 45,788 measurements and counts of 137,811 plants from 383 populations and seeds from over 5,000 plants. All field data and seed resources will be curated for release to the scientific community. Our goal is to establish A. petiolata as a model species for plant invasion biology and to encourage large collaborative studies of other invasive species.
Fiel notes of two hunters for Nehalennia speciosa in boggy Vasyugan Plain, West Siberia
Oleg E. Kosterin
- In July 2005, Rafal Bernard requested Oleg Kosterin to collect some samples of Nehalennia speciosa from West Siberia for a DNA analysis. Oleg replied that so far he had only seen one individual of this species 25 years ago, but asked in which habitats it should be sought for exactly. Rafal sent him a draft of his paper (Bernard & Wildermuth, 2005) devoted to this subject. Having read it, Oleg came to the conclusion that this habitat (shallow water with Sphagnum and Carex limosa or C. lasiocarpa) might occupy the largest area in the world just in the boggy West Siberian Plain. Personal consultation with the geobotanist Dr. Nikolai Lashchinskii confirmed this notion. Then an almost automatic supposition followed that this area may serve as the main reservoir of N. speciosa, considered a local and endangered species in Western and Central Europe. At the same time, the existing records of N. speciosa from West Siberia were remarkably scarce. It was known from the Khanty-Mansi Autonomous Region (basins of the Tura and Konda Rivers), a small number of records from North Altai and adjacent areas north of it, a record from the steppe zone of Novosibirsk Province (Karasuk), a record in the basin of the Tuba River (Krasnoyarskii Krai), and a dubious old record from Omsk (see the map in Belyshev (1973) and a review in Bernard & Wildermuth (2005)). There was no record from the boggy Irtysh-Ob’ interfluve, where we would expect the species to flourish. This could be explained by the lack of attention by odonatologists to that interesting area. In these circumstances, the project of a special expedition(-s) was put forward, aimed to check the presence, pattern of distribution, abundance and habitat preferences of N. speciosa in these areas. For a decisive expedition we chose the Vasyugan Bog, the largest bog in the world, more precisely its north-eastern margin where we could find a good base in Plotnikovo village, Bakchar District, Tomsk Province.
Untangling some taxonomic riddles on damselfly genera (Zygoptera) from the neotropical region
Natalia von Ellenrieder
Rosser W. Garrison
- Examination of type material deposited in the IRSNB (Royal Belgian Institute of Natural Sciences, Brussels, Belgium) and in the BMNH (British Museum of Natural History, London, Great Britain) allowed us to solve taxonomic riddles regarding several damselfly (Zygoptera) genera from the neotropical region. We provide notes on the status of several types, and introduce the following new synonymies: Argia huallaga Fraser, 1946 = A. adamsi Calvert, 1902; Argia makoka Fraser, 1946 = A. kokama Fraser, 1946; Argia mollusca Fraser, 1946 = A. collata Selys, 1865; Argia trifoliata Fraser, 1946 = A. variegata Förster, 1914; Argia umbriaca Fraser, 1946 = A. indicatrix Calvert, 1902; Amphiagrion amphion Selys, 1876 = Ischnura verticalis (Say, 1840); a new combination: Oxyagrion cardinalis Fraser, 1946 to Leptobasis cardinalis (Fraser, 1946); and three lectotype designations (for Acanthagrion gracile race? lancea Selys, 1876, Acanthagrion trimaculatum Selys, 1876, and Leptagrion flammeum Selys, 1876).
Corduliochlora gen. nov. from the Balkans (Odonata: Corduliidae)
- The adult morphology of the recently established species Somatochlora borisi Marinov, 2001 is outlined. The species has a unique combination of features, especially when compared to representatives of the two closest European genera, Cordulia Leach, 1815 and Somatochlora Selys, 1871 but also compared to other Holarctic genera and species within the Corduliinae (sensu Garrison et al. 2006). The extent of these morphological differences suggests that the species can not be assigned to any of the extant genera, and therefore the new genus Corduliochlora is being established.
Colonization of Brazil by the cattle egret (Bubulcus ibis) revealed by mitochondrial DNA
Sílvia Nassif Del Lama
- The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θs) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample.
The Zygoptera of Viti Levu and Vanua Levu, the two larger islands in the Fiji archipelago
Hans Van Gossum
- In 2005 we started a study of the ecology and evolutionary history of damselflies of the genus Nesobasis, endemic to Fiji. In addition we made account of the species of Zygoptera present at our study sites, and made notes on the Anisoptera. In general, the odonate fauna of the Fiji archipelago is poorly studied. Here, we provide an historical overview of the knowledge on this fauna and give details of the species we encountered in August - September 2005. We made observations and collected voucher specimens for 2 species of the genus Ischnura, 2 of the genus Agriocnemis, 1 of the genus Austrolestes, 7 of the genus Melanesobasis and 25 of the genus Nesobasis. For Melanesobasis we also made account of an additional subspecies. Further, we discovered 2 species of damselfly new to science, 1 on Viti Levu and 1 on Vanua Levu, both belonging to the genus Nesobasis. Our results indicate that further exploration within the Fiji archipelago will be rewarding and that more species new to science are to be discovered. We hope our work will spur further interest in the Pacific, which will be essential if we are to conserve the unique community of damselflies encountered in this region.
Wrack burial reduces germination and establishment of the invasive cordgrass Spartina densiflora
Ahmed M. Abbas
Alfredo E. Rubio-Casal
Alfonso de Cires
Javier J. Nieva
Jesús M. Castillo
- Germination and emergence of halophytes may decrease significantly by seed burial in dead plant material, or wrack, which is common and abundant in tidal marshes. The effects of plant debris (wrack) burial on seed germination and seedling establishment of Spartina densiflora, an invasive cordgrass, were studied under greenhouse conditions and compared with field observations. Five wrack burial depths were applied: control without wrack, 1 cm (1235 ± 92 g DW wrack m-2), 2 cm (3266 ± 13 g DW m-2), 4 cm (4213 ± 277 g DW m-2), and 8 cm (6138 ± 227 g DW m-2). Sediment pH, electrical conductivity, redox potential and temperature were recorded. Quiescence increased with wrack load up to ~20% at 8 cm deep. Germination decreased with wrack load from 96% to 14%, which could be related with anoxic conditions under the debris since sediment redox potential was as low as -83 ± 7 mV at 8 cm. Germination percentage increased and quiescent and dormant percentages decreased at higher daily sediment temperatures and with higher daily temperature fluctuations, conditions that were recorded without or under low loads of wrack. Spartina densiflora did not show primary dormancy, but its seeds entered into a non-deep physiological dormancy below 1 cm deep in plant debris. The establishment of S. densiflora seedlings was also greatly reduced by wrack burial since only 6 seedlings (11 ± 5 % of germinated seeds) emerged above plant debris from 1 cm and all seedlings died from deeper than 1 cm. S. densiflora seedling development was also reduced by wrack burial. The inverse relationship between germination and emergence of S. densiflora with wrack burial recorded in our study is useful to predict its invasion dynamics and to plan the management of invaded marshes.
Annotated bibliography of the odonatological papers of Ukraine
Lyudmila A Khrokalo
- The ecological and faunistic research of Odonata in Ukraine has been based on three main pillars. The first are investigations of species composition, habitat preferences, trophic connections, parasites and predators, behaviour patterns, and morphological and physiological peculiarities of dragonflies by expert-odonatologists. The second pillar is the collection and identification of adults for the survey of animals from different regions, especially rare and endangered species for the Red Lists and Red Data Book. Thirdly, there is the study of Odonata larvae as components of freshwater ecosystems, particularly as food of fish.
Some present Ukrainian regions belonged to Poland, Hungary, Slovakia and Romania before 1939-1945. Odonatological investigations were held up during the Second World War and the 12 years of post-war rebuilding.
The first data on Ukrainian Odonata were published in the second part of the 19th century (Belke, 1859, 1866). Since then, several Ukrainian, Russian, Polish, Hungarian and Romanian scientists have made great contributions to the investigation of the odonate fauna and ecology. One of the most famous odonatologists, J. Dziêdzielewicz, worked in the western Ukraine from the end of the 19th to the early 20th century. At the same time G. Artobolevs’ky investigated the northern and central parts of Ukraine and the Crimea peninsula. A. Brauner and A. Bartenev carried out research in the southern Ukraine and Crimea.
R. Pavlyuk continued research in the western region of Ukraine. He carried out faunistic, ecological and parasitological investigations. A. Oliger studied faunistic and ecological aspects of dragonflies in the easternmost part of the Ukraine (Donets’k region). Recently, S. Gorb published many papers devoted to the functional morphology of dragonflies. He also provided a study of the species composition and ecological peculiarities of Odonata in northern Ukraine and a catalogue of the Ukrainian species. Today, several odonatologists are actively involved in odonatological research in Ukraine. N. Mathuskina works on the functional morphology of the ovipositor and dragonfly behaviour, L. Khrokalo on faunistics and ecology in the northeastern Ukraine and on aspects of nature conservation, O. Dyatlova on the faunistics in the southwest of the country and some aspects of morphology and behaviour. A. Martynov studies the faunistics in the eastern part of Ukraine.