Volume 7, Issue 3
published September 2012
Contents | |
Research articles |
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Collin H. Johnson, Judith E. Winston and Robert M. Woollacott
Western Atlantic introduction and persistence of the marine bryozoan Tricellaria inopinata
(pp 295-303)
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Most species of bryozoans have short-lived larvae with limited dispersal potential, yet many of these species possess global distributions.
In this study, we report the first occurrence from the western Atlantic Ocean of the widely distributed arborescent bryozoan Tricellaria inopinata
d’Hondt and Occhipinti-Ambrogi, 1985. This species was collected in Eel Pond, Woods Hole, Massachusetts, in September 2010. At that time, T. inopinata
colonies had already formed dense conspecific aggregations at some collection sites, despite the presence of several other arborescent bryozoans.
Sites were monitored throughout 2011 to track the success of this introduction, and to assess the reproductive timing of T. inopinata in Eel Pond.
To determine the likelihood of T. inopinata persisting in Eel Pond and competing with previously established bryozoans, rates of metamorphic initiation,
metamorphic completion, and overall offspring survivability were compared to one of the other dominant arborescent species. Finally, we provide taxonomic
details to aid in identifying these animals, consider the potential mode of transport, and discuss the potential ecological implications resulting from this introduction.
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Kirsty F. Smith, Joshua Thia, Chrissen E. C. Gemmill, S. Craig Cary and Andrew E. Fidler
Barcoding of the cytochrome oxidase I (COI) indicates a recent introduction of Ciona savignyi into New Zealand and
provides a rapid method for Ciona species discrimination
(pp 305-313)
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Mitochondrial cytochrome oxidase I (COI) gene sequencing (DNA barcoding) of Ciona specimens from New Zealand (NZ)
led to the first record of the solitary ascidian Ciona savignyi in the Southern Hemisphere. We sought to quantify
C. savignyi COI genetic diversity around the NZ archipelago and to compare this with diversity within C. savignyi’s
native range in the north-west Pacific. Ciona savignyi specimens were collected from two NZ sites and from three sites around Japan.
COI sequences (595 bp) were amplified and measures of genetic diversity were calculated. Based on differences between their COI sequences
we developed a PCR-based assay to distinguish C. savignyi from the morphologically similar C. intestinalis.
A total of 12 C. savignyi COI haplotypes were recovered from the 76 samples. Of the four haplotypes observed in NZ,
two were unique. From the 10 haplotypes observed in the Japan samples, eight were unique. The C. savignyi populations
in Japan were found to contain higher haplotype diversity when compared with those in NZ. The NZ samples contained only a small
subset of the haplotype variation of the Japan samples, however, NZ samples did harbor two haplotypes not observed in the Japan samples.
A PCR-based assay developed from the COI sequences was able to reliably discriminate the two Ciona species. The low COI genetic
diversity within the two NZ C. savignyi populations sampled is consistent with a founder effect associated loss of genetic diversity.
The robust PCR-based assay for distinguishing C. savignyi and C. intestinalis may find application in ecological and taxonomic
studies and can be applied to both archival materials and live animals.
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Melisa C. Wong and Bénédikte Vercaemer
Effects of invasive colonial tunicates and a native sponge on the growth, survival, and light attenuation of eelgrass (Zostera marina)
(pp 315-326)
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We examined the effects of invasive colonial tunicates (golden star, Botryllus schlosseri; violet Botrylloides violaceus),
and the native breadcrumb sponge (Halichondria panicea) on the growth, survival, and light attenuation of eelgrass (Zostera marina).
Eelgrass shoot growth and survival were higher for unfouled shoots than for fouled shoots, and dependent on fouling species identity.
Growth was lowest for shoots with violet tunicate fouling, and survival was lowest for shoots with sponge fouling. A large proportion (0.20-0.38)
of fouled shoots marked for growth measurements were not found during retrieval compared to unfouled plants (0.08), suggesting that fouling led
to premature breaking away of shoots and blades. Transmission of incident photosynthetically active radiation (PAR) through fouled blades decreased
exponentially with increasing biomass of most fouling species. Relatively low biomass (1-1.5 dry mg cm-2 of blade) of the fouling organisms reduced
light transmission by up to 98 % compared to unfouled blades. The proportion of incident PAR attenuated by the sponge and orange and burgundy morphs
of the violet tunicate increased hyperbolically across their biomass, and reached a plateau at ~0.5 dry mg cm-2 of blade. The golden star tunicate
and cream morph of the violet tunicate attenuated incident PAR linearly across their biomass. For the range of biomass examined, all fouling species
attenuated 65-95 % of incident PAR prior to it reaching the blade. The reduction in light transmission was likely the causal mechanism underlying
reduced growth of fouled shoots. Fouling of eelgrass by the invasive colonial tunicates and the native sponge will have numerous ecological consequences,
including reduced productivity and coverage of eelgrass beds.
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Ayako Yashiki Yamakawa and Hideyuki Imai
Hybridization between Meretrix lusoria and the alien congeneric species M. petechialis in Japan as demonstrated using DNA markers
(pp 327-336)
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Meretrix lusoria supports an important shellfish fishery distributed around Japan and the southern coast of Korea.
The species is considered to be either local extinct or endangered in Japan and in response to a decrease in availability in Japan,
M. petechialis, a closely related species, has recently been imported from China and the Korean Peninsula. M. petechialis
is currently defined as an “alien species” in Japan, has been released into habitats where the local species M. lusoria occurs.
We conducted a survey and detected natural hybrids between M. lusoria and M. petechialis. Nineteen Meretrix spp.
population samples were collected in Japan, China, and Korea from 2004 to 2006 (15 samples from Japan, two from China, and two from South Korea).
Polymerase chain reaction-restriction fragment length polymorphisms in the cytochrome c oxidase subunit I region after HincII digestion and
amplification of the nuclear gene ANT enabled identification of the two species. The exotic M. petechialis was found in Yoshinogawa and Kanonji,
where periodically, large numbers of M. petechialis seedlings have been released. Combined results of RFLP and ANT individual genotypes suggest
the existence of at least one hybrid individual and two putative hybrids between the Japanese local species M. lusoria and the continental
alien species M. petechialis found in Chichibugahama and Kanonji. This is the first record demonstrating the existence of the alien species
M. petechialis and of hybrids co-occurring with local M. lusoria in a natural habitat. Our results show that the alien species
M. petechialis is currently relatively rare in Japan. If however, M. petechialis populations expand in the wild, they could replace
the local M. lusoria and cause genetic disturbance via hybridization, as observed at one site (Kanonji, Kagawa Pref.). To conserve
the endangered local M. lusoria resource, immediate controls of the release of M. petechialis will be necessary to prevent this
species spreading and hybridizing with the native M. lusoria population. |
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Michal Grabowski, Tomasz Rewicz, Karolina Bacela-Spychalska, Alicja Konopacka, Tomasz Mamos and Krzysztof Jazdzewski
Cryptic invasion of Baltic lowlands by freshwater amphipod of Pontic origin
(pp 337-346)
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Gammarus varsoviensis is morphologically close to G. lacustris, with which it is often misidentified.
Geographic range of G. varsoviensis includes Germany, Poland, Lithuania, Latvia, Belarus and Ukraine.
Such a distribution pattern led us to the assumption that the species might have originated in the Black Sea drainage area.
From there, as early as the nineteenth century, it could possibly have migrated to the Baltic basin through the Pripyat-Bug canal.
Thus, the goals of this study are: (1) to indicate the level of genetic divergence of G. varsoviensis from the morphologically
closest species – G. lacustris and (2) to investigate the possibility of the Pontic origin of G. varsoviensis and its
range expansion across the Black Sea/Baltic Sea watershed to Central Europe through the artificial canal network. Altogether 128 partial
16S rDNA sequences of Gammarus varsoviensis from 19 localities were gained. They were analysed in conjunction with a sequence of
G. lacustris obtained in this study from the Dnieper system and sequences of G. lacustris, G. pulex and
G. fossarum available in GenBank in order to estimate the relationships among the species. GenBank accession numbers
for all the haplotypes defined within this study are: G. varsoviensis – from JN641868 to JN641875; G. lacustris – JN641876.
The genetic distance within and between the species was calculated, as well as phylogenetic relationships among haplotypes, which were
inferred with Neighbor-Joining method. The haplotype relationships were analysed with the Minimum Spanning Network. Also mismatch
distribution of the haplotypes were tested under sudden expansion model and sequence deviations from selective neutrality.
Neighbor-Joining analysis revealed that G. varsoviensis and G. lacustris haplotypes formed separate well defined clades.
Mean genetic diversity between the two species was ca. 15× higher than the intraspecific distance and similar to the value obtained for
G. fossarum/G. pulex species pair. Therefore, G. varsoviensis can be definitely considered as a distinct species from
G. lacustris. Among 128 sequences obtained from G. varsoviensis, 8 haplotypes were identified and grouped into two clades:
one found only in the lower Dnieper (two haplotypes) and the second one encompassing the rest of haplotypes observed in the upper Dnieper
and Baltic Sea basin. Only one haplotype was found in the Baltic Sea drainage area. A mismatch distribution curve as well as selective
neutrality tests demonstrated sudden expansion model. Our findings suggest that G. varsoviensis is an alien gammarid that originated
in the Pontic area. Its expansion in Central Europe apparently started soon after the opening of the artificial waterways joining the Black
and the Baltic Sea drainage basins.
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Bruno Sampaio Sant’Anna, Timóteo Tadashi Watanabe, Alexander Turra and Fernando José Zara
Relative abundance and population biology of the non-indigenous crab Charybdis hellerii (Crustacea: Brachyura: Portunidae)
in a southwestern Atlantic estuary-bay complex
(pp 347-356)
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Invasive species are potential threats to biodiversity, especially if they become established and outnumber native species.
In this study, a population of the non-indigenous crab Charybdis hellerii was analyzed in an estuary-bay complex on the southeastern Brazilian coast,
with respect to its abundance relative to sympatric native brachyuran species, as well as the size structure, sexual maturity, sex ratio, frequency of mutilation,
reproductive period, and development of the reproductive system. Crabs were sampled monthly both in the intertidal zone of rocky shores and on sublittoral soft-bottom.
Nine species were recorded on the rocky shores, where C. hellerii was the second most abundant species; only three individuals of C. hellerii
were collected in the sublittoral samples. This population of C. hellerii showed a unimodal size structure composed mainly of mature individuals;
males were larger than females, and the sex ratio was skewed toward males (3.1:1). About 46.9% of the individuals (75 of 160 crabs) had mutilated or regenerating
appendages, more frequent in males (56.8%) than in females (28.2%), which may reflect both inter- and intraspecific agonistic interactions. A continuous reproductive
pattern is suggested for this population, although ovigerous females occurred unevenly during the year, with 58.82% of them being collected in winter.
There was evidence of multiple spawning, since the ovigerous females with an initial egg mass showed mature ovaries as well as seminal receptacles filled with sperm.
C. hellerii is well established in the estuary-bay complex, but is concentrated in intertidal and shallow subtidal rocky shores, where it may compete with
and replace other species such as the portunid Cronius ruber. This study also highlights the importance of systematic monitoring studies to evaluate the effects
of the introduction of non-indigenous species on ecologically similar natives. |
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Andrew D. Nunn and Ian G. Cowx
Diel and seasonal variations in the population dynamics of Hemimysis anomala, a non-indigenous mysid: implications for surveillance and management
(pp 357-365)
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This study investigated diel and seasonal variations in the population dynamics of Hemimysis anomala, a non-indigenous mysid originating
from the Ponto-Caspian region. There were strong diel variations in the abundance (catch-per-unit-effort; CPUE) of H. anomala, with CPUE
being low during the day but increasing by up to an order of magnitude at night. Abundance also varied seasonally, with CPUE increasing from mid-May
to a peak in late June/early July, followed by a crash in mid-July. However, the seasonal variations in abundance were apparent only in nocturnal surveys,
with CPUE during the day being low throughout the study. There were also seasonal variations in population structure (life stages, length distributions,
sex ratios, reproductive state, fecundity). The nocturnal behaviour of H. anomala renders it difficult to assess its geographical distribution or population
dynamics using only diurnal surveys or inappropriate sampling methods, which could underestimate the size, structure, reproductive potential and sustainability
of non-indigenous populations of this invasive species. Surveillance programmes for H. anomala should therefore be conducted at night, at intervals
throughout the year and targeting likely habitats using site-specific methods of proven effectiveness.
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Gretchen L. Grammer, William T. Slack, Mark S. Peterson and Mark A. Dugo
Nile tilapia Oreochromis niloticus (Linnaeus, 1758) establishment in temperate Mississippi, USA: multi-year survival confirmed by otolith ages
(pp 367-376)
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Tolerance and adaptability to changing environmental parameters have made Nile tilapia Oreochromis niloticus (Linnaeus, 1758)
a hardy and desirable aquaculture species. These traits have also enabled this fish to become a highly successful invasive species
into temperate and subtropical aquatic environments. Otolith-based ages of Nile tilapia (41.3 – 400.0 mm TL, 1.34 – 1,293 g WW, n = 259)
collected from a power plant cooling reservoir and the Pascagoula River proper indicated that feral populations overwintered reaching
ages up to 4+ years old in coastal Mississippi, USA; these data confirm their establishment. A survey of mean daily winter (December – February)
water temperatures from 2004 – 2010 in this region showed minimum lethal temperatures of < 10°C to occur nearly 11% of the time attesting
to the adaptability of the Nile tilapia as an invasive species. One annulus (opaque zone) per year was being deposited from
April to August based on marginal increment analysis along with sulcal groove length-age estimation of the young-of-the-year Nile tilapia.
Additionally, life history metrics measured for this temperate population of Nile tilapia were nearly identical to those reported from
African environments, indicating they are flourishing in this non-native habitat.
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Helen M. Poulos, Barry Chernoff, Pam L. Fuller and David Butman
Mapping the potential distribution of the invasive red shiner, Cyprinella lutrensis (Teleostei: Cyprinidae) across waterways of the conterminous United States
(pp 377-385)
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Predicting the future spread of non-native aquatic species continues to be a high priority for natural resource managers striving to maintain biodiversity
and ecosystem function. Modeling the potential distributions of alien aquatic species through spatially explicit mapping is an increasingly important tool
for risk assessment and prediction. Habitat modeling also facilitates the identification of key environmental variables influencing species distributions.
We modeled the potential distribution of an aggressive invasive minnow, the red shiner (Cyprinella lutrensis), in waterways of the conterminous
United States using maximum entropy (Maxent). We used inventory records from the USGS Nonindigenous Aquatic Species Database, native records for
C. lutrensis from museum collections, and a geographic information system of 20 raster climatic and environmental variables to produce a map
of potential red shiner habitat. Summer climatic variables were the most important environmental predictors of C. lutrensis distribution,
which was consistent with the high temperature tolerance of this species. Results from this study provide insights into the locations and environmental
conditions in the US that are susceptible to red shiner invasion.
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Nicole Cliff and Marnie L. Campbell
Perception as a tool to inform aquatic biosecurity risk assessments
(pp 387-404)
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We set out to explore whether the inclusion of perceptions into risk assessment might be a key to unlocking
the human factor in the vectoring of aquatic non-indigenous species. To this end, we developed a risk assessment
model that used people’s perception of concern and stated behavioural intentions to measure consequence.
We trialled this risk model using a test scenario of the non-indigenous species Didymosphenia geminata
(a freshwater diatom) being introduced to Tasmania, Australia: a location where it is currently not present.
Likelihood was determined by calculating the probability of Didymosphenia entering the test region
based on exposure to D. geminata (travel history of arriving air passengers and the passenger’s
participation in freshwater recreational activities) and mitigation activities (whether their recreational
equipment had been washed). The likelihood of a Didymosphenia incursion into Tasmania was determined to be rare.
Consequence was determined by targeting three recreational user groups that participate in activities related
to the movement of this species in other countries: trout anglers, hikers, and kayakers. Consequence was measured
as respondent’s level of concern and stated behavioural intentions if the respondent was confronted with an incursion
of Didymosphenia. The consequence of a Didymosphenia incursion ranged from moderate to catastrophic.
Thus, the total derived risk was determined to be low-medium. The use of perception to inform the consequence
component of the risk assessment proved useful as individuals behaviours are often attributable to the introduction
of species, and thus are an important consideration for risk management and education. At a local level these outcomes
provide direction to biosecurity of unregulated pathways. At a global level, this risk assessment is a useful tool
to assess the potential vectoring of a non-indigenous aquatic species, and potential human actions that might
impede the management of a non-indigenous species once it crosses a border.
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Matthew W. Johnston and Samuel J. Purkis
Invasionsoft: A web-enabled tool for invasive species colonization predictions
(pp 405-417)
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Predicting and averting the spread of invasive species is a core focus of resource managers in all ecosystems.
Patterns of invasion are difficult to forecast, compounded by a lack of user-friendly species distribution model (SDM)
tools to help managers focus control efforts. This paper presents a web-based cellular automata hybrid modeling tool
developed to study the invasion pattern of lionfish (Pterois volitans/miles) in the western Atlantic and is
a natural extension our previous lionfish study. Our goal is to make publically available this hybrid SDM tool
and demonstrate both a test case (P. volitans/miles) and a use case (Caulerpa taxifolia). The software
derived from the model, titled Invasionsoft, is unique in its ability to examine multiple default or user-defined parameters,
their relation to invasion patterns, and is presented in a rich web browser-based GUI with integrated results viewer.
The beta version is not species-specific and includes a default parameter set that is tailored to the marine habitat.
Invasionsoft is provided as copyright protected freeware at http://www.invasionsoft.com.
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Short communications |
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Rosana Moreira da Rocha, Laura Pioli Kremer and Karin Hoch Fehlauer-Ale
Lack of COI variation for Clavelina oblonga (Tunicata, Ascidiacea) in Brazil: Evidence for its human-mediated transportation?
(pp 419-424)
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Recent studies indicate that ascidians are efficiently dispersed by human transport. We have chosen the mitochondrial gene
cytochrome c oxidase subunit I (COI) to address whether Clavelina oblonga is an introduced species in the Brazilian coast.
Colonies of C. oblonga were sampled in different localities along Atlantic coasts of USA, Panama, and Brazil. The sequencing
of 92 colonies resulted in three haplotypes for the species, two unique to Florida and the other shared by exemplars collected in Brazil
and Panama; the latter haplotype is identical to the published sequence of Azores. Our evidence, including the absence of C. oblonga
in the country’s northern tropical waters, its association with artificial habitats and lack of COI variation suggest that the species has
been introduced in the southeastern and southern Brazilian coasts. Previous records (85 years old) suggest that it could be a relatively
long-term introduction. |
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Alexandra Temnykh and Shuhei Nishida
New record of the planktonic copepod Oithona davisae Ferrari and Orsi in the Black Sea with notes on the identity of “Oithona brevicornis”
(pp 425-431)
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Specimens of small (< 1 mm) cyclopoid copepods of the genus Oithona were collected from Sevastopol Bay
and an offshore area of the Black Sea. On the basis of a combination of characteristics such as those in the maxillule
and the genital double-somite, the specimens were identified as O. davisae Ferrari and Orsi, 1984. The identity
of “O. brevicornis” that was reported in the Black Sea and the possible origin of O. davisae in the Black Sea are discussed.
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Åsa Strand, Elisa Blanda, Torjan Bodvin, Jens K. Davids, Lasse Fast Jensen, Tore Hejl Holm-Hansen, Anders Jelmert,
Susanne Lindegarth, Stein Mortensen, Frithjof E. Moy, Pernille Nielsen, Pia Norling, Carlo Nyberg, Helle Torp Christensen, Bent Vismann,
Mark Wejlemann Holm, Benni Winding Hansen and Per Dolmer
Impact of an icy winter on the Pacific oyster (Crassostrea gigas Thunberg, 1793) populations in Scandinavia
(pp 433-440)
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The Pacific oyster (Crassostrea gigas) is an invasive species that has dispersed into Scandinavia during the last few decades.
The objective of this study was to evaluate the effects of extreme winter conditions on the mortality of the Pacific oyster in Scandinavia.
The study was done by compiling mortality data from independent surveys in Denmark, Sweden and Norway. Winter mortality of the oysters increased
with latitude, which can be explained by the colder climate experienced at higher latitudes. Mortality was also found to be affected by site
specific conditions such as water depth at the sampling sites of oyster populations. Despite the severe winter conditions of 2009/2010 causing
high mortality, the Pacific oyster still exists in large numbers in Scandinavia. The present investigation indicates that extreme winter conditions
may result in a temporary reduction of the density of the Pacific oyster, but that the species can be expected to continue its invasion of Scandinavian
coastal areas.
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Book review |
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Gerard van der Velde
Book Review: De Nederlandse rivierkreeften (Astacoidea & Parastacoidea)
(pp 441-442)
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