Peacock Emily E.

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Last Name
Peacock
First Name
Emily E.
ORCID
0000-0003-0194-7282

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2010 - 2016 7
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  • Preprint
    Mesoscale variability in intact and ghost colonies of Phaeocystis antarctica in the Ross Sea : distribution and abundance
    ( 2016-05) Smith, Walker O. ; McGillicuddy, Dennis J. ; Olson, Elise M. B. ; Kosnyrev, Valery ; Peacock, Emily E. ; Sosik, Heidi M.
    Phaeocystis, a genus with a cosmopolitan distribution and a polymorphic life cycle, was observed during summer in the Ross Sea, Antarctica, where large blooms of this haptophyte regularly occur. The mesoscale vertical and horizontal distributions of colonies of P. antarctica were assessed using a towed Video Plankton Recorder (VPR). The mean size of colonies was 1.20 mm, and mean abundances within the three VPR surveys were 4.86, 1.96, and 11.5 mL-1. In addition to the typical spherical, transparent colonies, the VPR quantified an optically dissimilar form of colony that had a distinctive translucent appearance. It also measured the abundance of collapsed colonies, similar to those observed previously from cultures and mesocosms, which we called “ghost colonies”. The translucent colonial form had a different distribution than the more common colonial form, and at times was more abundant. Relative to intact colonies, the ghost colonies occurred less frequently, with mean abundances in the three surveys being 0.01, 0.08, and 0.0004 mL-1. Ghost colonies generally were found below the euphotic zone, where they often were in greater abundance than intact colonies. However, the relationship of ghost colonies to intact P. antarctica colonies was not direct or consistent, suggesting that the formation of ghost colonies from living colonies and their appearance within the water column were not tightly coupled. Given their relative scarcity and low carbon content, it is unlikely that ghost colonies contribute substantially to vertical flux; however, it is possible that we did not sample periods of major flux events, and as a result minimized the importance of ghost colonies to vertical flux. They do, however, represent a poorly documented feature of polar haptophyte life cycles.
  • Dataset
    2014 labeled IFCB images
    ( 2014) Sosik, Heidi M. ; Peacock, Emily E. ; Brownlee, Emily F.
  • Dataset
    2011 labeled IFCB images
    ( 2011) Sosik, Heidi M. ; Peacock, Emily E. ; Brownlee, Emily F.
  • Dataset
    2013 labeled IFCB images
    ( 2013) Sosik, Heidi M. ; Peacock, Emily E. ; Brownlee, Emily F.
  • Dataset
    2010 labeled IFCB images
    ( 2010) Sosik, Heidi M. ; Peacock, Emily E. ; Brownlee, Emily F.
  • Dataset
    2012 labeled IFCB images
    ( 2012) Sosik, Heidi M. ; Peacock, Emily E. ; Brownlee, Emily F.
  • Article
    Parasitic infection of the diatom Guinardia delicatula, a recurrent and ecologically important phenomenon on the New England Shelf
    (Inter-Research, 2014-04-29) Peacock, Emily E. ; Olson, Robert J. ; Sosik, Heidi M.
    Plankton images collected by Imaging FlowCytobot from 2006 to 2013 at the Martha’s Vineyard Coastal Observatory (Massachusetts, USA) were used to identify and quantify the occurrence of the diatom Guinardia delicatula and of a parasite that seems specific to this host. We observed infection with morphological stages that appear similar to the parasite Cryothecomonas aestivalis. Our results show that events during which infection rates exceed 10% are recurrent on the New England Shelf and suggest that the parasites are an important source of host mortality. We document a significant negative relationship between bloom magnitude and parasite infection rate, supporting the hypothesis that the parasites play a major role in controlling blooms. While G. delicatula is observed during all seasons, the infecting stages of the parasite are abundant only when water temperature is above 4°C. The anomalously warm water and small G. delicatula bloom during the winter of 2012 provided evidence that parasites can be active through winter if temperatures remain relatively high. As climate change continues, winter periods of water below 4°C may shorten or disappear in this region, suggesting that parasite effects on species such as G. delicatula may increase, with immediate impacts on their population dynamics.