Delta Invasive Species

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Invasive Animal Species in the Delta

Click the caption of each photo for more information about the species.

  • A brown-colored Chinese mitten crab (Eriocheir sinensi). Photo by CDFW.
    Chinese mitten crab – Eriocheir sinensi (Photo by CDFW)
  • Many tan-colored New Zealand mudsnails (Potamopyrgus antipodarum) shown with a dime for size reference. Photo by U.S. Geological Survey.
    New Zealand mudsnails – Potamopyrgus antipodarum (Photo by U.S. Geological Survey)
  • A northern watersnake (Nerodia sipedon) with brown and tan stripes in the grass next to a rock. Photo by Patrick Coin.
    Northern watersnake (Nerodia sipedon) (Photo by Patrick Coin)
  • A nutria (Myocastor coypus) animal with brown fur, white whiskers and orange teeth. Photo by CDFW.
    Nutria – Myocastor coypus (Photo by CDFW)
  • Five dark brown/tan-striped and five light brown/tan-striped Quagga Mussels (Dreissena rostriformis bugensis) shown next to a dime in a person's hand for size reference. Photo by CDFW.
    Quagga Mussels (Dreissena rostriformis bugensis) (Photo by CDFW)
  • A southern watersnake (Nerodia fasciata) with tan, brown, and red-striped skin in the grass. Photo by CDFW.
    Southern watersnake – Nerodia fasciata (Photo by CDFW)
  • Three Zebra mussels (Dreissena polymorpha) with brown and tan-color stripes.
    Zebra mussels (Dreissena polymorpha)

Invasive Plant Species in the Delta

Click the caption of each photo for more information about the species.

  • The white flower and green leaves of an alligatorweed (Alternathera philoxeroides) plant. Photo by National Plant Data Center, Baton Rouge, LA.
    Alligatorweed – Alternathera philoxeroides (Photo by National Plant Data Center, Baton Rouge, LA)
  • A section of the Brazilian egeria (Egeria densa) plant. Photo by Lara Gudmundsdottir.
    Brazilian egeria – Egeria densa (Photo by Lara Gudmundsdottir)
  • Brown, fluffy seedheads and green leaves of the nonnative common reed (Phragmites australis subsp. australis) plant. Photo by Erlend Bjortvedt.
    Common reed – Phragmites australis subsp. australis (Photo by Erlend Bjortvedt)
  • Curlyleaf pondweed (Potamogeton crispis) plants in the water. Photo by Christian Fischer.
    Curlyleaf pondweed – Potamogeton crispis (Photo by Christian Fischer)
  • Eurasian watermilfoil (Myriophyllum spicatum) in the water. Photo by Fungus Guy.
    Eurasian watermilfoil – Myriophyllum spicatum (Photo by Fungus Guy)
  • Giant reed (Arundo donax) plants growing in the Sacramento-San Joaquin Delta.
    Giant reed (Arundo donax)
  • White flowers and green leaves of the perennial pepperweed (Lepidium latifolium) plant. Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.
    Perennial pepperweed – Lepidium latifolium (Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org)
  • Purple loosestrife (Lythrum salicaria) plants with purple flowers and green leaves. Photo by Liz West.
    Purple loosestrife – Lythrum salicaria (Photo by Liz West)
  • South American spongeplant (Limnobium laevigatum) in the water. Photo by Cardex.
    South American spongeplant – Limnobium laevigatum (Photo by Cardex)
  • Purple water hyacinth (Eichhornia crassipes) flowers with yellow and blue markings and green leaves growing in the water. Photo by Wouter Hagens.
    Water hyacinth – Eichhornia crassipes (Photo by Wouter Hagens)
  • The flower and leaves of a water primrose plant (Ludwigia spp.). Photo by Bouba.
    Water primrose – Ludwigia spp. (Photo by Bouba)