Special Issue: Marine Invasive Species
Published in December 2019
This special issue of Management of Biological Invasions includes applied papers presented at the
2018 International Invasive Sea Squirt Conference
held at Woods Hole, Massachusetts, USA, May 2-4, 2018, and at the
10th International Conference on Marine Bioinvasions
held in Puerto Madryn, Argentina, October 16–18, 2018.
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Editorial
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P. Joana Dias, Mary R. Carman and Stephan G. Bullard
All for one and one for all: research from the 6th International Invasive Sea Squirt Conference and the 10th International Conference on Marine Bioinvasions (pp 597–601) |
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Research articles
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Mary R. Carman, Philip D. Colarusso, Hilary A. Neckles, Paul Bologna, Scott Caines, John D.P. Davidson,
N. Tay Evans, Sophia E. Fox, David W. Grunden, Sarah Hoffman, Kevin C.K. Ma, Kyle Matheson, Cynthia H. McKenzie, Eric P. Nelson, Holly Plaisted,
Emily Reddington, Stephen Schott and Melisa C. Wong
Biogeographical patterns of tunicates utilizing eelgrass as substrate in the western North Atlantic between 39º and 47º north latitude
(New Jersey to Newfoundland) (pp 602–616) |
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Colonization of eelgrass (Zostera marina L.) by tunicates can lead to reduced plant growth and survival. Several of the tunicate species that are found
on eelgrass in the northwest Atlantic are highly aggressive colonizers, and range expansions are predicted in association with climate-change induced increases
in seawater temperature. In 2017, we surveyed tunicates within eelgrass meadows at 33 sites from New Jersey to Newfoundland. Eight tunicate species were identified
colonizing eelgrass, of which four were non-native and one was cryptogenic. The most common species (Botrylloides violaceus and Botryllus schlosseri)
occurred from New York to Atlantic Canada. Tunicate faunas attached to eelgrass were less diverse north of Cape Cod, Massachusetts. Artificial substrates
in the vicinity of the eelgrass meadows generally supported more tunicate species than did the eelgrass, but fewer species co-occurred in northern sites than
southern sites. The latitudinal gradient in tunicate diversity corresponded to gradients of summertime sea surface temperature and traditional biogeographical
zones in the northwest Atlantic, where Cape Cod represents a transition between cold-water and warm-water invertebrate faunas. Tunicate density in the eelgrass
meadows was low, ranging generally from 1–25% cover of eelgrass shoots, suggesting that space availability does not currently limit tunicate colonization of eelgrass.
This survey, along with our 2013 survey, provide a baseline for identifying future changes in tunicate distribution and abundance in northwest Atlantic eelgrass
meadows.
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Yingqi Zhang, Linda Deegan and Mary R. Carman
Invasive tunicate (Ascidiacea) metabolic and filtration rates in comparison to native tunicate and bivalve species (pp 617–625) |
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Several invasive species of tunicates (Ascidiacea) have become cosmopolitan and widely distributed in coastal areas worldwide over the past few decades.
These non-indigenous tunicates have consequently caused fouling problems in aquaculture and marine harbors. The goal of our project was to enrich
the understanding of how invasive tunicates interact with other organisms in the ecosystem. Two species of invasive tunicates (Didemnum vexillum
and Botrylloides violaceus) and one species of native tunicate (Aplidium glabrum) were evaluated for their metabolic rates. The filtration
rates for native blue mussels (Mytilus edulis) and invasive tunicates (Diplosoma listerianum) were determined. D. vexillum regenerated
NH4+ at a faster rate than A. glabrum and B. violaceus. Both tunicates and blue mussels were feeding on phytoplankton
as their major food source, although the size of particles utilized by different organisms was not examined in this study. Invasive tunicates were strongly
competing with mussels to filter feed, but were not inhibiting mussel’s filtration rate.
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Mary R. Carman and David W. Grunden
A preliminary assessment of crab predation on epifaunal fouling organisms attached to eelgrass at Martha’s Vineyard, Massachusetts, USA (pp 626–640) |
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Eelgrass (Zostera marina) is an ecologically valuable seagrass which is exposed to a wide range of stressors and has declined worldwide. The proliferation of epifaunal
fouling organisms such as the sponge Halichondria panicea, colonial tunicate Botryllus schlosseri, and solitary tunicate Molgula manhattensis represents
additional stress for eelgrass. Predation of this epifauna that would otherwise cause harm to eelgrass, will likely reduce their impact. On Martha’s Vineyard, an island
in the Northwest Atlantic off southern Massachusetts, USA, green crabs Carcinus maenas and spider crabs Libinia dubia were examined as potential predators
of sponges and tunicates attached to eelgrass. Crabs were somewhat starved for one week and then, in the lab, put in enclosures with three eelgrass shoots and tunicate/sponge
epifauna. Consumption of prey items and crab survival were measured at one and 24 hours. After one hour, C. meanas did not consume any prey, while predation
by L. dubia did occur. After 24 hours, C. meanas had still not consumed any tunicates or sponges, while L. dubia consumed eelgrass with H. panicea
(100%); B. schlosseri (40% completely, 40% partially, and 20% unconsumed); and M. manhattensis (60% completely, 20% partially, and 20% unconsumed). High densities
of M. manhattensis often occurs on eelgrass at Martha’s Vineyard (up to 6,700 per m²), thus we sought to determine a M. manhattensis consumption rate
for L. dubia in the lab. A single L. dubia can consume at least 30 M. manhattensis in a 24-hour period. Because of the recent declines in eelgrass acreage,
understanding the ecological mechanisms that minimize impacts to eelgrass can be advantageous to both the individual pant and the meadow. Natural predation by L. dubia
in eelgrass meadows heavily fouled by tunicates and sponges is an important ecosystem function that may contribute to controlling the epifauna, and thus maintaining healthy
eelgrass and eelgrass habitat. However, the extent to which crabs control eelgrass epifauna in the field is unknown. Our results were determined in a laboratory setting and
further work should be done to confirm that similar results will be found in the field.
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Kristin L. Osborne and Helen C. Poynton
Copper pollution enhances the competitive advantage of invasive ascidians (pp 641–656) |
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Invasive species dominate and often outcompete native species in marine harbors. The abundance of introductions due to shipping activity combined with artificial
substrates and poor water quality helps to facilitate invasion success in these areas. Colonial ascidians, in particular, have broad environmental tolerances that allow
them to invade novel ecosystems including urban harbors. While the effects of invasive species and poor water quality on native species have been explored, the relative
influence and how these pressures may interact to degrade biodiversity is not well characterized. The purpose of this study was therefore to understand the role
of interspecific competition and pollution on the native Aplidium glabrum and the invasive Botrylloides violaceus. Colony surface area has been previously
identified as a sensitive toxicity endpoint and was measured weekly to assess impacts both separately and together at 0, 1, 10, 20, and 40 μg/L copper concentrations.
A. glabrum was significantly impacted at 1 μg/L in the presence of interspecific competition and at 10 μg/L with no competition; however, the copper EC50
revealed increased sensitivity in the presence of B. violaceus (11.3 μg/L versus 6.9 μg/L while in competition). Conversely, significant impacts to B. violaceus
growth did not occur until much higher copper concentrations with an EC50 of 37.1 μg/L while alone and 31.7 μg/L when in competition. Interspecific competition was
found to significantly impact A. glabrum surface area growth at 1, 10, and 40 μg/L, while there was no significant effect on B. violaceus at any
of the concentrations tested. Finally, an interaction effect was found between copper pollution and competition status only for A. glabrum. The results of this study support
the hypothesis that invasive species are more tolerant of pollution while also revealing the interactive effects of pollution exposure and interspecific competition.
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Marjorie Couton, Thierry Comtet, Sabrina Le Cam, Erwan Corre and Frédérique Viard
Metabarcoding on planktonic larval stages: an efficient approach for detecting and investigating life cycle dynamics of benthic aliens (pp 657–689) |
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High-throughput sequencing (HTS) technologies offer new promise to support surveillance programs targeting marine non-indigenous species (NIS). Metabarcoding
might surpass traditional monitoring methods, for example through its ability to detect rare species, a key feature in early detection of NIS. Another interest of this
approach is the identification of organisms difficult to identify based on morphology only (e.g., early developmental stages), making it relevant in the context of
management programs. Because many marine benthic NIS have a biphasic benthopelagic life cycle, targeting their pelagic larval stages in zooplankton may allow
early detection and assessment of their establishment and potential spread. We illustrate this approach with an analysis of bulk-DNA retrieved from a time-series
of zooplankton samples collected over 22 months in one bay in Brittany (France). Using HTS of amplicons obtained with two markers (COI and 18S) and a metabarcoding approach,
12 NIS were identified and their temporal larval dynamics were monitored. Importantly, we chose to focus on a closed list of species, from four metazoan classes encompassing
52 NIS reported within the study area or nearby seas, with molecular references available or obtained locally for 42 of them. The use of a custom-designed database allowed
the detection of three NIS otherwise not detected when using public databases. Interestingly, NIS known to have a short-lived larval stage were detected (e.g., the bryozoan
Bugula neritina or the tunicate Corella eumyota). For two molluscs Ruditapes philippinarum and Crepidula fornicata, metabarcoding results were
compared to those obtained using traditional methods (i.e., barcoding of individual larvae and morphology, respectively) to show the reliability of the approach in detecting
and assessing the extent of their reproductive periods. Our results also revealed that the Pacific oyster Crassostrea gigas, a notorious invasive species, failed
to reproduce in the study bay, showing that metabarcoding on larval stages also provides information regarding the establishment success (or failure) of NIS. While metabarcoding
has its limitations and biases, this study demonstrates its effectiveness for surveillance of targeted NIS, notably to support management strategies like the European
Marine Strategy Framework Directive (MSFD).
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Shaun Cunningham, Laurel Teirney, Jennie Brunton, Rebecca McLeod, Richard Bowman, Derek Richards,
Richard Kinsey and Fleur Matthews
Mitigating the threat of invasive marine species to Fiordland: New Zealand’s first pathway management plan (pp 690–708) |
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Multiple human-mediated pathways in the marine environment provide ample opportunities for new and potentially harmful species to spread into high-value natural areas.
Often, these areas are remote and reactive measures to an invasion prove to be difficult, therefore a more precautionary and proactive approach is necessary. The Fiordland
Marine Area (FMA) is largely unmodified and has a unique and productive underwater environment. Following an amendment in 2012 to the Biosecurity Act 1993 the Fiordland
Marine Guardians and an inter-agency government group worked to develop and implement the Fiordland Marine Regional Pathway Management Plan (FMPP), whose overarching objective
is to prevent the introduction and spread of invasive marine species to the FMA. The plan involves three key elements to manage invasive species vectors: (1) that vessel owners
and operators hold a current Clean Vessel Pass for their vessel; (2) that the vessel meets clean vessel standards including hull biofouling, gear biofouling and residual
seawater requirements; and (3) that owners and operators maintain and can present records on the steps taken to meet the clean vessel standards. The plan was made operative
in 2017, and to date, uptake has generally been positive with only a small number of compliance issues. The adoption of this plan is largely due to an integrated iwi,
community and agency management approach which has encouraged engagement and participation from the Fiordland stakeholders. The ongoing success of this programme will rely
on the commitment from the partnering central and local government agencies to improve and refine the plan, and on a general elevation in the importance of marine biosecurity
management nationwide. Ideally, the plan will significantly reduce the risk of further marine bioinvasions within the FMA.
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