Grunden David W.

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David W.

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  • Article
    Species–specific crab predation on the hydrozoan clinging jellyfish Gonionemus sp. (Cnidaria, Hydrozoa), subsequent crab mortality, and possible ecological consequences
    (PeerJ, 2017-10-26) Carman, Mary R. ; Grunden, David W. ; Govindarajan, Annette F.
    Here we report a unique trophic interaction between the cryptogenic and sometimes highly toxic hydrozoan clinging jellyfish Gonionemus sp. and the spider crab Libinia dubia. We assessed species–specific predation on the Gonionemus medusae by crabs found in eelgrass meadows in Massachusetts, USA. The native spider crab species L. dubia consumed Gonionemus medusae, often enthusiastically, but the invasive green crab Carcinus maenus avoided consumption in all trials. One out of two blue crabs (Callinectes sapidus) also consumed Gonionemus, but this species was too rare in our study system to evaluate further. Libinia crabs could consume up to 30 jellyfish, which was the maximum jellyfish density treatment in our experiments, over a 24-hour period. Gonionemus consumption was associated with Libinia mortality. Spider crab mortality increased with Gonionemus consumption, and 100% of spider crabs tested died within 24 h of consuming jellyfish in our maximum jellyfish density containers. As the numbers of Gonionemus medusae used in our experiments likely underestimate the number of medusae that could be encountered by spider crabs over a 24-hour period in the field, we expect that Gonionemus may be having a negative effect on natural Libinia populations. Furthermore, given that Libinia overlaps in habitat and resource use with Carcinus, which avoids Gonionemus consumption, Carcinus populations could be indirectly benefiting from this unusual crab–jellyfish trophic relationship.
  • Preprint
    An initial assessment of native and invasive tunicates in shellfish aquaculture of the North American east coast
    ( 2009-11-23) Carman, Mary R. ; Morris, James A. ; Karney, R. C. ; Grunden, David W.
    The objective of the study was to assess the distribution of native and invasive tunicates in the fouling community of shellfish aquaculture gear along the U.S. east coast of the Atlantic. Since the 1980s, several species of invasive tunicates have spread throughout the coastal waters of the North American east coast and have become dominant fouling organisms on docks, boat hulls, mooring lines, and in shellfish aquaculture. Invasive and native tunicates negatively impact shellfish aquaculture through increased maintenance costs and reduced shellfish growth. While the presence of alien tunicates has been well documented at piers, harbors, and marinas, there are few published reports of invasive tunicate impacts to aquaculture. We surveyed shellfish aquaculture operations at Martha’s Vineyard, Massachusetts and shellfish aquaculturists in other areas along the North American east coast and report high levels of fouling caused by seven invasive, three native, and two cryptogenic species of tunicates. All study sites were fouled by one or more tunicate species. Biofouling control treatments varied among aquaculture sites and were effective in removing tunicates. Invasive and native tunicates should be considered when assessing the economic impacts of fouling organisms to the aquaculture industry.
  • Article
    Coldwater reattachment of colonial tunicate Didemnum vexillum fragments to natural (eelgrass) and artificial (plastic) substrates in New England
    (Regional Euro-Asian Biological Invasions Centre (REABIC), 2014-03) Carman, Mary R. ; Grunden, David W. ; Ewart, Danielle
    The colonial tunicate Didemnum vexillum Kott, 2002, was introduced to New England in the 1980s and by 2000 it was widespread. This highly invasive species spreads by larval release and fragmentation. We tested the ability of D. vexillum fragments to reattach to natural (eelgrass Zostera marina (Linnaeus, 1753)) and artificial (plastic container) substrates during late fall and early winter. On average, 77% of D. vexillum fragments reattached to eelgrass and plastic in water temperatures between 6 and 10°C. Eelgrass appeared to facilitate D. vexillum reattachment success in early winter but this tendency should be further investigated.
  • Article
    A preliminary assessment of crab predation on epifaunal fouling organisms attached to eelgrass at Martha's Vineyard, Massachusetts, USA
    (Regional Euro-Asian Biological Invasions Centre, 2019-10-28) Carman, Mary R. ; Grunden, David W.
    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.
  • Article
    Biogeographical patterns of tunicates utilizing eelgrass as substrate in the western North Atlantic between 39 degrees and 47 degrees north latitude (New Jersey to Newfoundland)
    (Regional Euro-Asian Biological Invasions Centre, 2019-10-30) Carman, Mary R. ; Colarusso, Philip D. ; Neckles, Hilary A. ; Bologna, Paul ; Caines, Scott ; Davidson, John D.P. ; Evans, N. Tay ; Fox, Sophia E. ; Grunden, David W. ; Hoffman, Sarah ; Ma, Kevin C.K. ; Matheson, Kyle ; McKenzie, Cynthia H. ; Nelson, Eric P. ; Plaisted, Holly ; Reddington, Emily ; Schott, Stephen ; Wong, Melisa C.
    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.