Volume 10, Issue 3 (2015)
published June 2015
Contents | |
Research articles |
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John D.D. Bishop, Christine A. Wood, Anna L.E. Yunnie and Carly A. Griffiths
Unheralded arrivals: non-native sessile invertebrates in marinas on the English coast
(pp 249-264)
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Between 2005 and 2012, 61 marinas and harbours around the English coast were surveyed to record the occurrence of non-native species (NNS)
of sessile invertebrates. From these surveys, geographic distributions are described for eight species of ascidians, six bryozoans and five
other species. A mean of 6.7 sessile invertebrate NNS per site (range 0–13 species) was recorded. At the 43 sites on the English Channel coast,
the mean was 7.8 NNS per site, and all of the ten English sites that had ≥ 10 NNS were in the western or central region of the Channel coast.
Ten sites on the Channel coast surveyed in 2004 were re-visited at least once in 2009 or 2010, and the mean number of sessile invertebrate NNS
had increased from 6.0 to 7.6 species per site. Combining data from all visits in 2005–2012 for the sites surveyed in 2004, the mean number
of NNS recorded per site rose to 9.2. Very rapid rates of spread along the English coast and beyond are inferred for the erect bryozoan
Tricellaria inopinata d’Hondt & Occhipinti Ambrogi, 1985 and the ascidian Corella eumyota Traustedt, 1882. At least five recently
arrived species that were limited to a small number of sites in 2012 are expected to increase markedly in geographic range and prevalence:
the ascidians Asterocarpa humilis (Heller, 1878), Botrylloides diegensis Ritter and Forsyth, 1917, and Didemnum vexillum Kott, 2002;
and the bryozoans Schizoporella japonica Ortmann, 1890 and Watersipora subatra (Ortmann, 1890). Rapid assessment surveys of marinas
and similar sites proved to be an effective means of documenting the arrival and spread of NNS over a relatively wide geographic range and
of distinguishing different rates of progression.
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Julieta Muñoz, Mike Page, Justin I. McDonald and Samantha D. Bridgwood
Aspects of the growth and reproductive ecology of the introduced ascidian Didemnum perlucidum (Monniot, 1983) in Western Australia
(pp 265-274)
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In 2010, the colonial ascidian Didemnum perlucidum (Monniot, 1983) was first recorded in Western Australia and is now widespread across the state.
This species is classified as a target biosecurity species by the Department of Fisheries, Government of Western Australia. However, limited information
on the biology of this ascidian is available for Australian waters. The aim of this study was to gather baseline information on the temporal variation in growth,
survival, and reproduction of D. perlucidum. The mean average colony area was significantly higher in summer (29.7 cm2) decreasing towards winter (3.3 cm2).
Colonies produced larvae year round with maximum production (1109.0 larvae cm-2) and highest recruitment (0.90 settlers cm-2) in summer. Larva density was positively
correlated to salinity (r = 0.965) and chlorophyll a concentration (r = 0.958) in the water column. From a management point of view, the decrease in colony size,
larvae production, and recruitment of D. perlucidum during winter could offer the best opportunity for the control or eradication of this ascidian at specific locations
in the state.
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Jonne Kotta, Ilmar Kotta, Andreas Bick, Ralf Bastrop and Risto Väinölä
Modelling habitat range and seasonality of a new, non-indigenous polychaete Laonome sp. (Sabellida, Sabellidae) in Pärnu Bay, the north-eastern Baltic Sea
(pp 275-285)
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An as-yet-undescribed, non-indigenous polychaete species was found at very high densities in the eastern part of the Baltic Sea in Estonia in 2012.
The species belongs to the sabellid genus Laonome Malmgren, 1866, but it could not be assigned to any of the previously described species.
To date, the species has established a stable population after surviving a notably cold winter (2012/2013). To study the local distribution and abundance
of the species, a spatial grid with some stations repeated seasonally and interannually was sampled in a quantitative manner. Based of the survey data and
available environmental data, the variables that contributed significantly to explaining variation in the abundance of the polychaete were determined using
the Boosted Regression Trees modelling approach. Molecular barcodes to characterize the identity of the species were also established. The abundance of
Laonome sp. exhibited strong seasonal variation, peaking between July and November. Besides seasonality, the quantity of decomposed microalgae in
the sediment and wave exposure best explained the variation in abundance. Laonome sp. is now well-established in the Baltic Sea and locally reached
high densities in low salinity areas. This non-indigenous polychaete may potentially modify sediment morphology and chemistry and disrupt the natural infaunal
communities. Laonome sp. could displace or even completely eliminate some species currently present in the study area and beyond if it spreads; however,
it could also facilitate currently-present species through the provision of alternative substrate and/or food. Given its persistence and high abundance in Pärnu Bay,
colonization of other low-salinity areas of the Baltic Sea can be expected.
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Jonathan Marescaux, Pieter Boets, Julien Lorquet, Rose Sablon, Karine Van Doninck and Jean-Nicolas Beisel
Sympatric Dreissena species in the Meuse River: towards a dominance shift from zebra to quagga mussels
(pp 287-298)
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The rapid spread of the quagga mussel, Dreissena rostriformis, in Western Europe is of particular concern since the species
is known to have serious ecological and economic impacts, similar to those of the well-established zebra mussel, Dreissena polymorpha.
This study aimed (1) to provide an update on the quagga mussel distribution in several Belgian inland waterways, and (2) to check if a shift
in dominance between Dreissena species is occurring. Using density measurements and artificial substrate samplers, we compared population
dynamics for both species at different time-points based on size-frequency distribution. Our results show that quagga mussels are spreading
rapidly throughout Belgium via a number of possible invasion fronts based around large rivers and canals. The quagga mussel became the dominant
dreissenid species in both the Meuse River and a number of Belgian canals. In just three years, quagga mussel’s relative abundance increased
from 2.9% (±2.9) to 52.6% (±43.1) of the total dreissenid population in the Meuse River. The most rapid increase in abundance has occurred
in the Albert Canal, where quagga mussels achieved a mean relative abundance of 80% two years after the first observation. In the Meuse River,
the quagga mussel displays a faster growth rate and/or earlier reproduction than the zebra mussel. We discuss different mechanisms that could
explain the quagga mussel’s apparent competitive advantage over the zebra mussel.
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Enrique González-Ortegón, Philip Sargent, Gerhard Pohle and Andres Martinez-Lage
The Baltic prawn Palaemon adspersus Rathke, 1837 (Decapoda, Caridea, Palaemonidae): first record, possible establishment, and illustrated key of the subfamily Palaemoninae in northwest Atlantic waters
(pp 299-312)
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This study documents the introduction of the European Baltic prawn, Palaemon adspersus Rathke, 1837 to the coastal waters of northeastern North America,
specifically the west coast of Newfoundland and the Magdalen Islands in the Gulf of St. Lawrence, Canada. Species identification was verified using morphological
and genetic criteria. In September 2011, the first specimens of P. adspersus were collected in Gulf of St. Lawrence waters near Stephenville Crossing,
Newfoundland, Canada. In 2012, additional P. adspersus specimens were collected in this area and at St. Andrew’s, located further south in western Newfoundland
and in 2013 several egg-bearing females were collected further north in York Harbour. Accidental transport by ballast water of ships seems the likely vector for transport
of Baltic prawn to the Gulf of St. Lawrence from Northern Europe or the Caspian Sea. It is possible that this shrimp has a wider presence in Atlantic Canadian waters but,
due to its close resemblance to native shrimp species, it may have been previously misidentified, as occurred with specimens collected from the Magdalen Islands. We further
expect that other species of the genus Palaemon, including P. elegans Rathke, 1837 from the Baltic Sea or northeastern United States, and P. macrodactylus
Rathbun, 1902 from the northeastern United States, may invade the Gulf of St. Lawrence. We provide an illustrated key for the identification of these exotic Palaemon
species and to differentiate them from native members of the subfamily Palaemoninae.
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Jessica M. Webster, Paul F. Clark and David Morritt
Laboratory based feeding behaviour of the Chinese mitten crab, Eriocheir sinensis (Crustacea: Decapoda: Brachyura: Varunidae): fish egg consumption (De Haan, 1835)
(pp 313-326)
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Dispersal of Eriocheir sinensis from its native habitat is a worldwide concern. As one of the most invasive species known, this crab causes significant
disruption to foreign ecosystems. In particular, populations in the United Kingdom (UK) are increasing in number and E. sinensis has been reported from
many river catchments. The ecological implications of this invasion are not fully understood. One aspect of concern lies in the potential for mitten crabs
to predate fish eggs which, if realistic, could contribute to the decline of riverine populations. In this study, 100 mitten crabs from the River Thames
were used in experimental feeding trials to 1) investigate foraging ability on a variety of fish eggs and 2) establish whether crab size affected foraging potential.
Eggs ranged from 1–6 millimetres (mm) in diameter from one of four species of marine and freshwater fish; zebrafish, lumpfish, Pacific salmon and trout. Predation
by crabs varied with egg type; crabs were capable of foraging 1mm zebrafish eggs, but the majority consumed eggs 2–6mm in diameter. The most attractive eggs were
apparently lumpfish, where the median proportion consumed was 100%. Crab size did not appear to govern foraging potential, though variation was observed in the size
range of juvenile crabs consuming the different eggs with the largest, salmon, being consumed by crabs of the broadest size range. E. sinensis does have
the potential to predate on a range of fish eggs, and the results are used to infer the risk presented to specific groups of UK fish stocks.
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Nicolas Spilmont, Moâna Gothland and Laurent Seuront
Exogenous control of the feeding activity in the invasive Asian shore crab Hemigrapsus sanguineus (De Haan, 1835)
(pp 327-332)
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The Asian shore crab Hemigrapsus sanguineus (De Haan, 1835) is an invasive decapod along the coast of the English Channel
and the North Sea where it is displacing the indigenous European green crab Carcinus maenas. Although behavioural traits
have been identified as a critical component of invasion success, they remain poorly studied in H. sanguineus. Hence,
the present study quantitatively assessed the feeding activity of H. sanguineus in the laboratory under different light
and starvation conditions. Non-starved H. sanguineus exhibited an exogenous day-night rhythm driven by a photophobic behaviour.
Starved individuals lacked the photophobic behaviour, which may allow H. sanguineus to spend more time foraging than species
characterised by true endogenous rhythms. Altogether, the foraging behaviours reported in this work highlight the behavioural flexibility
and adaptive nature of this species, which may confer to H. sanguineus a competitive advantage in intertidal environments.
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Pamela J. Schofield, Dane H. Huge, Troy C. Rezek, Daniel H. Slone and James A. Morris Jr.
Survival and growth of invasive Indo-Pacific lionfish at low salinities
(pp 333-337)
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Invasive Indo-Pacific lionfish [Pterois volitans (Linnaeus, 1758) and P. miles (Bennett, 1828)] are now established throughout
the Western North Atlantic. Several studies have documented negative effects of lionfish on marine fauna including significant changes to reef
fish community composition. Established populations of lionfish have been documented in several estuaries, and there is concern that the species
may invade other low-salinity environments where they could potentially affect native fauna. To gain a better understanding of their low-salinity
tolerance, we exposed lionfish to four salinities [5, 10, 20 and 34 (control)]. No lionfish mortality was observed at salinities of 34, 20 or 10,
but all fish died at salinity = 5 within 12 days. Lionfish survived for at least a month at a salinity of 10 and an average of about a week at 5.
Fish started the experiment at an average mass of 127.9 g, which increased at a rate of 0.55 g per day while they were alive, regardless of salinity
treatment. Our research indicated lionfish can survive salinities down to 5 for short periods and thus may penetrate and persist in a variety
of estuarine habitats. Further study is needed on effects of salinity levels on early life stages (eggs, larvae).
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David A. Schumann, W. Wyatt Hoback and Keith D. Koupal
Complex interactions between native and invasive species: investigating the differential displacement of two topminnows native to Nebraska
(pp 339-346)
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The establishment of nonnative species and subsequent replacement of native species is among the greatest threats to freshwater biodiversity worldwide.
However, little is known of the effects that invasive species have on individual species and specific mechanisms by which species displacement occurs.
The expansion of western mosquitofish Gambusia affinis beyond its native range has commonly been thought to cause shifts in species assemblages
throughout the United States. Although plains topminnow Fundulus sciadicus populations have declined as the range of western mosquitofish
in Nebraska has expanded, long-term co-existence of mosquitofish with the closely related northern plains killifish Fundulus kansae has been
observed within the same systems. To investigate the potential mechanisms by which differential displacement of the native topminnow species may have occurred,
biotic interactions and spatial distribution of both conspecific and heterospecific groups of plains topminnow, plains killifish, and western mosquitofish were
quantified in microcosms for three life stages (larval, juvenile, and adult). Interactions between adult western mosquitofish and the native species were complex
and dependent upon life stage, but collectively suggested that populations of both plains topminnow and plains killifish are vulnerable to mosquitofish establishment.
Detrimental effects towards fundulid species were primarily mediated through predation of larvae and aggressive interactions directed towards juvenile life stages
which caused significant mortality. In addition, simultaneous alterations of behavior, as quantified by activity patterns and microhabitat use, were apparent
in both native species in response to western mosquitofish presence. Because similar impacts of western mosquitofish were observed for plains killifish and plains
topminnow, the persistence of plains killifish in areas occupied by western mosquitofish may be linked to species attributes not assessed in the current analysis.
Subtle differences in microhabitat selection between the topminnow species and adult western mosquitofish could potentially explain observed differential
displacement in the environment. These results have augmented our understanding of the impacts that western mosquitofish has on the at-risk plains topminnow,
and have further elucidated the potential mechanisms for impact via competitive interactions.
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Steven A. Pothoven and Tomas O. Höök
Feeding ecology of invasive age-0 white perch and native white bass after two decades of co-existence in Saginaw Bay, Lake Huron
(pp 347-357)
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The diets and energy content of sympatric populations of invasive age-0 white perch Morone americana and native age-0 white bass Morone chrysops
were evaluated in Saginaw Bay, Lake Huron following >20 years of coexistence. Fish were collected during July-November in 2009 and 2010 to assess seasonal and
interannual patterns of diet composition, diet similarity, feeding strategy and energy density for the two species. The diet composition by weight of age-0 white
bass was dominated by various zooplankton taxa, fish, or emergent insects, depending on the month and year. Although fish occasionally comprised a large fraction
of the diet biomass, they were eaten by <24% of white bass each month. The diet composition of age-0 white perch shifted from one dominated by chironomids and
other benthic macroinvertebrates in 2009 to one largely consisting of Daphnia spp. in 2010. There was more overlap in standardized diet assemblages in 2010
than in 2009 due to the increased importance of Daphnia spp. in white perch diets in 2010. Contrary to expectations, complete separation of diets was not
a requirement that enabled the long-term coexistence of invasive white perch and native white bass in Saginaw Bay. Both age-0 white bass and white perch had a mixed
feeding strategy with varying degrees of specialization and generalization on different prey. The inter-annual variation in prey, i.e., higher densities of zooplankton
in 2009 and chironomids in 2010, is directly opposite of the pattern observed in white perch diets, i.e., diets dominated by chironomids in 2009 and zooplankton in 2010.
Energy density increased from July into autumn/fall for both species suggesting that food limitation was not severe.
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