Ecology: Cordylophora caspia is a colonial hydroid that lives in freshwater and brackish habitats. Colonies are composed of three types of chitin tubes: stolons, uprights, and branches (Seyer et al., 2017). C. caspia can reproduce sexually or asexually via fragmentation (Pucherelli et al., 2016). During sexual reproduction, ova are retained in female gonophores. Male gonophores release sperm that fertilize the eggs in female gonophores. Female gonophores then release planula larvae to find suitable substrate; these larvae grow into new colonies of C. caspia (Seyer et al., 2017; Pucherelli et al., 2016). Unlike other cnidarians, C. caspia does not have a medusoid stage (Pucherelli et al., 2016). C. caspia colonies can respond to adverse conditions by producing a resting stage called a menont that remains sheltered within the hydrocaulus; these menonts can regenerate colonies when favorable conditions return (Seyer et al., 2017).
C. caspia has relatively broad environmental tolerances. They can survive temperatures ranging from 8 to 30 degrees celsius and salinity as high as 40 ppt (Seyer et al., 2017). Colonies of C. caspia grow on hard substrates such as rock surfaces, shells, wood, and submerged infrastructure (Pucherelli et al., 2016).
This species is considered a benthic predator, capturing prey using nematocysts: their diet includes small crustaceans, worms, insect larvae, watermites and other zooplankton and benthic invertebrates (Pucherelli et al., 2016). Their diet puts them in competition with many species of larval, juvenile, and benthivorous fish (Seyer et al., 2017). They also compete with other benthic species for substrate; however, their filamentous structure may also provide substrate for chironomids, caddisflies and Dreissena spp. veligers (Folino-Rorem, 2015).
Impact of Introduction: Smith et al. (2002) described C. caspia as a 'benthic colonial predator' that preys upon chironomids and other larval insects. This may result in less prey availability for fish. The ecological impacts of C. caspia, however, have not yet been thoroughly studied. Uncolonized substrate introduced to C. caspia and subsequently colonizied had different realtive abundances of other invertebrates as compared to substrates not colonized by C. caspia (Ruiz et al. 1999). Other studies have suggested that C. caspia may contribute to a restructuring of benthic and pelagic freshwater communities (Folino 2000).
Competition for space, i.e. suitable substrate for colonization, may occur between zebra mussel (Dreissena polymorpha) and C. caspia (Walton 1996, Folino 2000). Cordylophora caspia also typically eats zebra and quagga mussel larvae.
There is a negative economic impact associated with the biofouling caused by Cordylophora caspia (Folino 2000).
References: (click for full references)
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