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).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic

Realized:
Research in the Great Lakes and Europe indicates that C. caspia has complex relationships with dreissenids. Competition for space (i.e. suitable substrate for colonization) may occur between zebra mussels (Dreissena polymorpha) and C. caspia (Folino, 2000; Walton, 1996). However, these species have been known to colonize one another; juvenile zebra mussels may use C. caspia as a substrate (Moreteau and Khalanski, 1994), while C. caspia may settle on dreissenids (Darling and Folino-Rorem, 2009; Folino, 2000). An initial survey completed in Chicago harbors found 55% of quagga mussels to be colonized by C. caspia (Berg and Folino-Rorem, 2009). In addition, zebra and quagga mussel larvae appear to constitute a large portion of C. caspia diet (Berg and Folino-Rorem, 2009).

Potential:
Studies have suggested that C. caspia may contribute to the restructuring of benthic and pelagic freshwater communities (Folino 2000). For example, research found that as compared to uncolonized control substrates, the successful inoculation of a substrate with C. caspia resulted in a shift in relative abundance of other invertebrates (Ruiz et al. 1999).

Smith et al. (2002) described C. caspia as a benthic colonial predator that preys upon chironomids and other larval insects. Where the hydroid is sufficiently dense, this could locally reduce the preferred prey of certain fishes. Following a study in Chicago harbors, researchers concluded that while the current impact of C. caspia on fish food availability is likely limited, it has the possibility of becoming significant in combination with the growth of D. bugensis populations.

Current research on the socio-economic impact of Cordylophora caspia in the Great Lakes is inadequate to support proper assessment.

Realized:
C. caspia clogged intake tunnels and blocked filters and condenser tube sheets at a power plant in Morris, IL; however, these colonies were eradicated by exposing them to temperatures > 37.7 C for > 1 hour (Folino, 2000)

Potential:
Cordylophora has had degrading effects on cement and mortar at Brazilian power plants (Berg and Folino-Rorem 2009, Folino 2000, Portella and Joukoski 2009).

There is little or no evidence to support that Cordylophora caspia has significant beneficial effects in the Great Lakes.

Potential:
C. caspia has been found to consume settling zebra mussel veligers, but this predation is unlikely to control the well-established Dreissena populations found in the Great Lakes.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Control of Cordylophora caspia will likely focus on its potential role as a biofouling agent. Cordylophora spp. has been documented colonizing the inner walls of power plants in Europe and the United States (Folino 2000), primarily causing blockages in nozzles and tailpipes of rapid gravity filter beds (RGFs) (Mant et al. 2011).  The menont life-stage of Cordylophora caspia often found in hydroelectric intakes, is both drought and temperature resistant which may prove an obstacle to control.  (Gutierre 2011).  

Biological
In estuarine, brackish habitats such as San Francisco Bay on the Pacific and the North American Atlantic coast, nudibranchs such as Tenellia adspersa feed on Cordylophora caspia and other hydroids (Mills and Sommer 1995). However, unlike hydroids, nudibranchs are exclusively sea-dwelling invertebrates (Anderson 1995), and thus are only a source of biological control in brackish areas where the macroinvertebrates’ habitats intersect.

Physical
Thermal treatments of >37°C have been proven effective in eradicating colonies of Cordylophora spp. sampled from the walls of power plant intakes (Folino 2000), but are not efficient in water treatment facilities where there is no residual heat energy available (Mant et al. 2011).

Chemical
Gutierre (2011) found that Cordylophora caspia is completely eradicated at pH levels of below 4.0 or above 10.0, with increasing survival rates in between, and suggested maintaining pH levels at 10.0 for 6 hours or more by injection of NaOH to reduce and eliminate colonies. Chlorine treatments negatively affect Cordylophora growth, but treatments as high as 5 mg/L for periods of 105 minutes have been unsuccessful in completely eradicating colonies (Mant et al. 2011). Furthermore, chlorine use is highly regulated at water treatment facilities where Cordylophora most frequently cause problems. Hydroids are sensitive to vanadium leeching from slag stones used in riverbank reinforcement, and are sensitive to heavy metals in general, especially mercury, copper, cadmium, and arsenic, though it is unlikely that these will be useful in control (Ringelband and Karbe 1996).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Cordylophora caspia is preyed upon by an introduced nudibranch (Tenellia adspersa) (Mills and Sommer 1995).

Cordylophora caspia is thought to be taxonomically synonymous with C. lacustris by many scientific researchers (Folino 2000 and references).