Volume 8, Issue 2 (2013)
published June 2013
Contents | |
Research articles |
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Mareike Hammann, Björn Buchholz, Rolf Karez and Florian Weinberger
Direct and indirect effects of Gracilaria vermiculophylla on native Fucus vesiculosus
(pp 121-132)
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The perennial red macroalga Gracilaria vermiculophylla (Ohmi) Papenfuss has recently been introduced to the Baltic Sea and is a potential competitor to Fucus vesiculosus,
the most common native perennial alga in large parts of the Baltic Sea. Gracilaria might interfere with Fucus through direct competition for resources. In addition,
Gracilaria is a favoured refuge for mesograzers, which prefer to feed on Fucus. Mesocosm-experiments were conducted over one year in the Kiel Fjord in order to test
the direct and indirect effects of Gracilaria on Fucus. Fucus was incubated with Gracilaria at three different densities and grazers in high or low abundances.
High densities of Gracilaria inhibited the growth of Fucus adults and also reduced the half-life-time of Fucus germlings. Associated grazers also had a negative effect
on Fucus adults. Our results suggest that Gracilaria is able to influence Fucus in the Baltic Sea through direct competition for resources and by exposing it to higher
grazer pressure.
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Mads S. Thomsen, Peter A. Stæhr, Lars Nejrup and David R. Schiel
Effects of the invasive macroalgae Gracilaria vermiculophylla on two co-occurring foundation species and associated invertebrates
(pp 133-145)
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Non-native foundation species occasionally invade habitats occupied by native foundation species. Little is known, however, about reciprocal effects of native
and non-native foundation species and cascading effects on organisms that depend on foundation species. In a 3-factorial field experiment, we tested for:
(1) reciprocal effects between the invasive red alga Gracilaria vermiculophylla and two native co-occurring foundation species, the mussel
Mytilus edulis and the seagrass Zostera marina; and (2) effects on mobile macro-invertebrates associated with the three foundation species.
We found a negative effect of G. vermiculophylla on the above-ground biomass of Z. marina and a positive effect of M. edulis on Z. marina
below-ground biomass, but no other significant effects between the three foundation species. Both M. edulis and G. vermiculophylla had positive effects
on invertebrate richness and diversity, but Gracilaria also had positive effects on densities of most invertebrate taxa. Additional correlation analyses showed
that the abundance of invertebrates increased with the biomass of G. vermiculophylla, indicating density-mediated habitat cascades in invaded seagrass beds.
The strong facilitation by G. vermiculophylla could be related to its complex morphology that creates a 3D mosaic of structures and interstitial spaces
for different sizes of invertebrates to occupy. Although these results are constrained by the experimental design (one month duration, small plot size, embedded
in seagrass meadow, relatively low invader density, invader physically attached with pegs) we suggest that our findings are typical when an invader is structurally
complex and mainly occurs in localized patches.
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Alpa P. Wintzer, Mariah H. Meek and Peter B. Moyle
Abundance, size, and diel feeding ecology of Blackfordia virginica (Mayer, 1910), a non-native hydrozoan in the lower Napa and Petaluma Rivers, California (USA)
(pp 147-156)
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Blackfordia virginica (Mayer, 1910) is a small hydrozoan that has invaded estuaries around the world. In the lower Napa and Petaluma rivers, located within the San Francisco Estuary,
B. virginica populations followed a classic pulsed bloom event. Medusae monthly bell diameter measurements showed an initial increasing trend with a wide range of sizes, followed
by a decreasing average size and narrower size range towards bloom culmination. Biomass was generally greatest in June. Medusae were pelagic feeders, consuming both invertebrates and fish larvae.
Copepod nauplii were by far most numerous prey in the guts, followed by cyclopoid copepods and mysids. Further studies of B. virginica are needed to understand its potential impacts
on estuarine ecosystems, which may be great where it is abundant.
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Michiel J.J.M. Verhofstad, Bart M.C. Grutters, Gerard van der Velde and Rob S.E.W. Leuven
Effects of water depth on survival, condition and stable isotope values of three invasive dreissenid species in a deep freshwater lake
(pp 157-169)
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To examine the effects of depth on the performance of the freshwater dreissenid species Dreissena polymorpha and D. rostriformis bugensis,
and the brackish water dreissenid, Mytilopsis leucophaeata, a controlled experiment lasting four months was conducted in a manmade freshwater lake
in the Netherlands. The three species used in the experiment were collected from other water bodies in the Netherlands. Cages containing each species
in separate compartments were placed at water depths of 2, 5, 10 and 17 m from November 2009 until February 2010. Samples of individuals were retrieved
at the start and at approximately four-week incubation intervals, for determination of overall survival, condition and soft tissue carbon and nitrogen
stable isotope ratios. In contrast to the Dreissena species, survival of M. leucophaeata decreased strongly over time at each depth.
Mortality increased with increasing depth and was greatest at 17 m. Survival of D. polymorpha at 17 m was much greater than that of D. rostriformis bugensis.
The condition of all species after 3.5 weeks did not differ significantly from that at the start. Surviving M. leucophaeata showed a significantly reduced condition
at all depths after 16 weeks. Both Dreissena species showed an improved condition at depths of 2, 5 and 10 m after 16 weeks, the greatest improvement being found at 2 m.
After 16 weeks at 17 m, both Dreissena species had the lowest condition index. Stable isotope ratios of soft tissue for both Dreissena species showed a shift
in δ15N within 3.5 weeks. The δ15N values of mussels held at 2-10 m fell. Those held at 17 m had values similar to that initially recorded, possibly indicative of very limited
food intake at that depth or a diet similar to that at their location of origin. After 16 weeks, δ13C values became more negative than those at the start, in particular at 2 m.
The stable isotope ratios of soft tissue of M. leucophaeata did not change at any depth throughout the experiment, possibly indicating lack of feeding in the freshwater lake.
Changes in stable isotope values for both Dreissena species were reduced at 17 m. Mortality of D. polymorpha was lower at 17 m compared to the other two dreissenid
species which indicated greater tolerance of habitat conditions a this deeper depth.
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Christopher A. Pearl, Michael J. Adams and Brome McCreary
Habitat and co-occurrence of native and invasive crayfish in the Pacific Northwest, USA
(pp 171-184)
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Biological invasions can have dramatic effects on freshwater ecosystems and introduced crayfish can be particularly impacting.
We document crayfish distribution in three large hydrographic basins (Rogue, Umpqua, Willamette/Columbia) in the Pacific Northwest USA.
We used occupancy analyses to investigate habitat relationships and evidence for displacement of native Pacifastacus leniusculus (Dana, 1852) by two invaders.
We found invasive Procambarus clarkii (Girard, 1852), in 51 of 283 sites and in all three hydrographic basins. We found invasive Orconectes n. neglectus
(Faxon, 1885) at 68% of sites in the Rogue basin and provide first documentation of their broad distribution in the Umpqua basin. We found P. clarkii in both lentic
and lotic habitats, and it was positively associated with manmade sites. P. leniusculus was positively associated with lotic habitats and negatively related to manmade sites.
In the Rogue and Umpqua basins, O. n. neglectus and P. leniusculus were similar in their habitat associations. We did not find a negative relationship in site
occupancy between O. n. neglectus and P. leniusculus. Our data suggest that P. clarkii has potential to locally displace P. leniusculus.
There is still time for preventive measures to limit the spread of the invasive crayfish in this region.
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Cock van Oosterhout, Ryan S. Mohammed, Raquel Xavier, Jessica F. Stephenson, Gabrielle A. Archard, Fran A. Hockley, Sarah E. Perkins and Joanne Cable
Invasive freshwater snails provide resource for native marine hermit crabs
(pp 185-191)
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Invasive species can have significant direct and indirect impacts on native biota. Here, we conducted a survey of two invasive freshwater snail species
(Melanoides tuberculata and Tarebia granifera) in Tobago and assessed the effects on shell use by native marine hermit crab populations
(Clibanarius tricolor and C. vittatus). Abundant in freshwater, numbers of empty shells at the mouth of a river in Charlotteville (Northeast Tobago)
increased from 75 to 800 m-2 after heavy rains in the wet-season of June 2012. Subsequent sampling of a nearby rocky shore revealed that the freshwater shells
were occupied by 70.2% of hermit crabs. Mimicking a flood event, the experimental planting of marked alien freshwater shells showed that 20.3% of hermit
crabs exchanged their marine shell for a freshwater shell. Similarly, a laboratory shell-choice experiment showed that C. tricolor hermit crabs changed
shells repeatedly, and that 22.2% occupied a freshwater shell rather than a marine shell. Overall, due to the numeric abundance of freshwater shells and
the compulsive shell changing behaviour of Clibanarius spp., the ongoing invasion of freshwater gastropods in the Caribbean may change the shell use
patterns and population dynamics of the native hermit crabs.
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Andrey N. Reshetnikov
Spatio-temporal dynamics of the expansion of rotan Perccottus glenii from West-Ukrainian centre of distribution and consequences for European freshwater ecosystems
(pp 193-206)
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The invasive fish rotan or Amur sleeper, Perccottus glenii (Perciformes, Odontobutidae), arrived in Western Ukraine during the stocking of commercial cyprinid fish in the 1960s.
Three periods were identified in its expansion. Period I: during the first two decades post-arrival, the fish was restricted to the upper section of a local river basin. Period II:
rotan penetrated the adjacent river basins and over the following two decades, it rapidly self-distributed over huge distances, using rivers as long-distance, one-way natural corridors
(natural conveyors). This expansion resulted in the invasion of many European river systems including the Danube, Dniester, western part of the Dnieper basin, Southern Bug (all belonging
to Black Sea basin), and the Vistula (Baltic Sea basin). During colonization, rotan was found in Lviv, Zakarpatie, Volynskaya, Povno, Ivano-Frankovsk, Chernovtsy and Khmelnitskiy provinces
of Western Ukraine, as well as in territories of south-western Belarus, Poland, Slovakia, Hungary, Serbia, Bulgaria, Romania, Croatia, and Moldova. This invader demonstrated comparatively
rapid expansion from riverheads to downstream river mouths, but slower or negligible expansion upstream in tributaries. This example of the West-Ukrainian centre of distribution demonstrates
the significance of upper parts of river basins for rapid distribution of this species, as well as the important function of rivers in crossing country borders. Period III relates to the period
from approx. 2005 to the present day. During this period, perceived to be the longest in terms of colonization, its invaded range extends to tributaries and isolated water bodies filling gaps
in areas between already colonized main rivers. Rotan did not reach high densities in the main river channels or deep, well-oxygenated lakes because of the presence of native fish predators.
However, this alien species did form numerous dense populations in shallow lentic water bodies. The expansion of rotan may lead to adverse economic impacts upon European aquaculture farms,
as well as predictable, ecological consequences for populations of some native European aquatic animals including invertebrates, fish and amphibians. Rotan has the potential to also influence
adjacent terrestrial ecosystems. A review of rotan and native species interactions is presented.
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Melissa A. Gibbs, Benjamin N. Kurth and Corey D. Bridges
Age and growth of the loricariid catfish Pterygoplichthys disjunctivus in Volusia Blue Spring, Florida
(pp 207-218)
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Little is known of age and growth patterns in loricariid armored catfish living either in their native or invasive ranges. For this first study of age and growth patterns
in a loricariid invasive to the US, we collected 185 lapillar otoliths from vermiculated sailfin catfish, Pterygoplichthys disjunctivus, in Volusia Blue Spring,
Florida and used them for age determination. Age estimates were generated and compared with reproductive, standard length (SL), and body mass data collected over a seven year period.
Otolith band-pair counts yielded high precision age estimates (Average Percent Error = 4.3, Coefficient of Variation = 5.8, Precision = 3.36), which indicated the oldest catfish
were no more than 5.25 years old. Standard length-frequency analysis and a linear growth model both supported a growth rate of approximately 10 cm/year. The von Bertalanffy Growth
model did not provide a better fit, and was therefore discarded. Since none of the 185 otoliths was estimated to be from catfish older than 5.25 years, and none of the 5,800 fish
caught in the past ten years was longer than 51.5 cm SL, it appears that P. disjunctivus in this Florida spring and river environment grows rapidly for about five years,
but the cohort dies out due to high natural mortality rates.
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Norio Onikura, Takuya Miyake, Jun Nakajima, Shinji Fukuda, Tomonori Kawamato and Koichi Kawamura
Predicting potential hybridization between native and non-native Rhodeus ocellatus subspecies: the implications for conservation of a pure native population in northern Kyushu, Japan
(pp 219-229)
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Hybridization between native and non-native fishes is a serious global problem. Thus, there is a need to develop monitoring methods for predicting potential hybridization
to evaluate the risk of genetic introgression and to identify important areas for conservation of pure native populations. Here, we developed a prediction model
for intersubspecific hybridization, based on distribution and genetic data. We selected Rhodeus ocellatus kurumeus and R. ocellatus ocellatus
as the native and non-native subspecies, respectively. First, we developed generalized linear models (GLMs) for the species habitat requirements by using presence/absence
data and environmental variables. The best-fit models showed river length gave conflicting effects for the two subspecies. Next, we developed a GLM using the ratio of non-native
haplotypes in mitochondrial DNA as an objective variable, with the predicted probabilities of the occurrence of each fish and spatial information as explanatory variables.
The best-fit model selected the distance from the center of native distribution and the non-native habitat requirement as key factors. Our findings indicate that hybridization
occurs highly and/or initially near the margin of native distribution where non-native habitat requirements are available. Our model could identify sites in native habitats
with very low potential risk for genetic invasion as important areas for conservation of pure native populations.
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Anastasia Fedorenkova, J. Arie Vonk, Anton M. Breure, A. Jan Hendriks and Rob S.E.W. Leuven
Tolerance of native and non-native fish species to chemical stress: a case study for the River Rhine
(pp 231-241)
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Freshwater ecosystems can be impacted by invasive species. Non-native species can become invasive due to their high tolerance to environmental stressors (e.g., pollution and habitat modifications).
Yet, tolerance of native and non-native fish species exposed simultaneously to multiple chemical stressors has not been investigated. To quantify tolerance of native and non-native fish species
in the Delta Rhine to 21 chemical stressors we derived Species Sensitivity Distributions (SSDs). Differences in tolerance between the two species groups to these stressors were not statistically
significant. Based on annual maximum water concentrations of nine chemical stressors in the Delta Rhine the highest contribution to the overall Potentially Affected Fraction (PAF) of both species
groups was noted for ammonium, followed by azinphos-methyl, copper, and zinc. PAFs of both groups for metals and ammonium showed a significant linear decrease over the period 1978–2010. Deriving
a PAF for each species group was a useful tool for identifying stressors with a relatively highest impact on species of concern and can be applied to water pollution control. Species traits such
as tolerance to chemical stress cannot explain the invasiveness of some fish species. For management of freshwater ecosystems potentially affected by non-native species, attention should be given
also to temperature, hydrological regimes, and habitat quality.
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Short communication |
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Macarena Marambio, Ignacio Franco, Jennifer E. Purcell, Antonio Canepa, Elena Guerrero and Verónica Fuentes
Aggregations of the invasive ctenophore Mnemiopsis leidyi in a hypersaline environment, the Mar Menor lagoon (NW Mediterranean)
(pp 243-248)
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The ctenophore Mnemiopsis leidyi, a species native to estuaries and coastal regions of the western Atlantic Ocean, was first introduced into the Black Sea in the early 1980s,
where it negatively affected zooplankton biodiversity and biomass, and commercial fisheries. This invasive ctenophore was first reported along the Spanish Mediterranean coast in 2009.
In 2012, new blooms of this species were reported in the hypersaline and largest coastal lagoon of the Western Mediterranean basin, the Mar Menor lagoon, Spain. Sampling in the lagoon
during summer 2012 showed an average abundance of 23.4 ctenophores 100 m-3, in early August, declining to 8.2 ctenophores 100 m-3 by early September. The population contained only adults
(total length 19 to 79 mm), which increased in size through the summer. Generalized additive models suggested M. leidyi abundance was significantly related to temperature,
but not to salinity or depth. The Mar Menor lagoon is an anthropogenically-disturbed habitat that may favour this species. Blooms of M. leidyi in the Mar Menor lagoon
are of great concern given its negative impacts in previously invaded habitats.
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Last update: 26 June 2013
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(c) 2013 Regional Euro-Asian Biological Invasions Centre (REABIC)
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