Cordylophora caspia

Invasion History

First Non-native Panama (Pacific) Tidal Record: 1944
First Non-native Panama (Caribbean) Tidal Record: 1925

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Panama Invasion History:

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Invasion history elsewhere in the world:

In Europe, Cordylophora caspia was probably first introduced in the late 17th century through canals linking the waterways of the Baltic and Black Seas (Olenin 2002). It spread rapidly, and was widespread in inland waters and estuaries in northern Europe, from Finland to the British Isles by the late 19th century (Allman 1872; Arndt 1984; Jensen and Knudsen 2005; Wolff 2005). More recently, C. caspia spread north to Bergen and Stavanger, Norway (by 1985, Hopkins 2002) and south to the Guadalquivir River, Spain (by 2001, Escot et al. 2003, cited by Garcia-Berthou et al. 2007), the Po River delta, Italy (Morri and Bianchi 1983), and other Mediterranean lagoons. It is widespread in the major freshwater rivers of Europe, including the Rhine (Vervoort 1964; Roos 1979), the Elbe (Nehring 2006), Weser, Oder, and Danube basins (Bij de Vaate et al. 2002).

In Central America, C. caspia was first collected on the Caribbean side of the Panama Canal in the Gatun Locks in 1925 (Hildebrand 1939; Fraser 1944; USNM 43378, U.S. National Museum of Natural History 2007). Subsequently, it was collected on the Pacific side in the Pedro Miguel Locks in 1975 (Arndt 1984, Cohen 2006; USNHM 89237, U.S. National Museum of Natural History 2007). Specimens have also been collected from Gamboa, Panama, on Gatun Lake, and they belonged to the widespread freshwater genotype 1A (Folino-Rorem et al. 2009). In South America, it is known from the coast and freshwaters of Brazil (Arndt 1984; Grohmann 2008; Farrapeira et al. 2011), Uruguay, Argentina (Grohmann 2008), and from Chilean fjords (in 2006, Galea 2007, Folino-Rorem et al. 2009).

Cordylophora caspia has been introduced to freshwater lakes and brackish estuaries in New Zealand (1st record 1885, Cranfield et al. 1998), Australia (1st Record 1922, Briggs 1931, Hewitt, personal communication), Iraq (Shatt-al-Arab estuary) and Shanghai, China (Arndt 1984).

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Description

Cordylophora caspia grows in erect, branching colonies, growing from a single stem, arising from stolons attached to the substrate. Sometimes one colony will grow on top of another. The shoots branch regularly or irregularly. Frequently, there is one main stem and shorter side branches. Annulations (rings) are present near the base of the stems and branches. A colony may have 40 or more hydranths. The hydranths are spindle-shaped when relaxed, ovoid when contracted, about 1-2 mm high, with a conical or bullet-shaped hypostome. There are scattered (usually 14-16, sometimes up to 27) tentacles. The gonophores are oval, arising from the stem or branches, and contain 7-16 eggs. Hydranths are white or pale pink and the stems are yellowish-brown. Stems are typically 30-45 mm in size, but may reach 150 mm or more (Calder 1971; Schuchert 2004; Calder 2010).

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Taxonomy

Ecology

General:

Cordylophora caspia is a sessile hydrozoan which lacks a planktonic medusa stage. Colonies grow on a solid substrates, with polyps arising from a creeping stolon. The polyps form bushy structures, with many hydranths, whose tentacles capture zooplankton. The polyps produce gonophores, which produce either eggs or sperm. Colonies are diecious (single-sexed). Female gonophores produce multiple eggs, typically 7-16, which are brooded and fertilized by sperm from the water column. The eggs develop into ciliated non-feeding planula larvae (Schuchert 2004). These larvae probably spend less than a day in the water before settlement (Sommer 1992).

Planulae of C. caspia settle and grow on a wide range of substrates, including shells, rock, wood, and vegetation. This hydroid has been found on a number of plants, including submerged plants (Ceratophyllum demersum- Coontail; Nitella sp.; Potamogeton sp.- Pondweeds; Elodea sp.- Waterweed; Vallisneria americana- Wild Celery), stalks of floating plants (Nymphaea odorata- White Water Lily), and roots and stems of emergents (Alternanthera philoxeroides- Alligatorweed; Phragmites australis - Common Reed) (Clarke 1878; Poirrier and Denoux 1973; Calder 1978; Roos 1979). It has also been reported from shells of living freshwater (native Unionidae, introduced Dreissena spp.- Zebra and Quagga Mussels) and brackish-water mussels (Mytilopsis leucophaeta- Dark False Mussel) (Calder 1978; Curry et al. 1981; Walton 1996). It has also been found on man-made substrates including old automobiles and nylon ropes (Roos 1979), buoys and ships (Woods Hole Oceanographic Institution 1952), and doubtless many others.

Cordylophora caspia grows in a vast range of aquatic environments, varying in salinity, temperature, currents, oxygen, etc. Survival tolerances vary greatly among populations as a result of both genetics and acclimation (Arndt 1984; Kinne 1956). Experimental limits were 24⁰C for C. caspia from Germany (Kinne 1956) and 30+⁰C for animals collected near Woods Hole, Massachusetts (Fulton 1962). Optimal temperatures for asexual growth appeared to be 11-18⁰C for German populations (Kinne 1956), 18-26⁰C for MA populations (Fulton 1962), 16-25⁰C for San Francisco estuary populations (Meek et al. 2012), and 23-30⁰C for colonies from Iraq (Arndt 1984). At least one genetic lineage of C. caspia (1A) ranges from Europe (UK and Germany) to the tropics (Panama) (Folino-Rorem et al. 2009). This hydroid is known to grow abundantly in fresh and brackish waters, and can tolerate exposure to full seawater (Kinne 1958; Mace and Mackie 1970; Arndt 1984). Tolerance to seawater may vary genetically. One lineage in Folino-Rorem et al.'s (2009) study was restricted to fresh water (lineage 1A), one to brackish water (2), and one inhabited both (1B). Cordylophora caspia is also tolerant of hypoxia, and had optimal growth at 40% of saturation (Fulton 1962). In the San Francisco estuary, it was associated with middle levels of oxygen concentration, low salinity, and low transparency (Wintzer et al. 2011a). This hydroid can respond to unfavorable conditions by regressing into a dormant state, consisting of bodies of tissue (menonts) in the stolons and stems, which serve as a diapause stage (Kinne 1956; Roos 1979; Jormalainen et al. 1994). In regions with milder climates, such as San Francisco Bay (Wintzer et al. 2011a) and South Carolina (Calder 1992) the hydroid is active all year, with extended polyps. In more severe climates, such as the Netherlands and Finland, hydroids may be dormant in winter (Roos 1979; Jormalainen et al. 1994) and sometimes also during periods of high predation in mid-summer (Jormalainen et al. 1994).

Food:

Zooplankton; Small epibenthos

Consumers:

Tenellia adspersa; amphipods, fishes

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Vessel Hull	None
General Habitat	Swamp	None
General Habitat	Salt-brackish marsh	None
General Habitat	Oyster Reef	None
General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Grass Bed	None
General Habitat	Canals	None
General Habitat	Rocky	None
General Habitat	Marinas & Docks	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Nontidal Freshwater	None
General Habitat	Coarse Woody Debris	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Salinity Range	Mesohaline	5-18 PSU
Salinity Range	Polyhaline	18-30 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	0	Based on geographic range
Maximum Temperature (ºC)	30	Experimental upper limits were 24 C for C. caspia from Germany (Kinne 1956) and 30+ C for animals collected near Woods Hole MA (Fulton 1962)
Minimum Salinity (‰)	0	This hydroid grows and reproduces in freshwater.
Maximum Salinity (‰)	35	Upper salinity ranges are based on experimental survival. The upper limit for sexual reproduction was 27 ppt ( Kinne 1958). Field salinity ranges are generally much lower (Arndt 1984; Lippson et al. 1979; Poirrier and Denoux 1973; Ruiz et al. unpublished data).
Minimum pH	6.2	Field data from TX (McClung and Davis 1983) and LA (Poirrier and Denoux 1973). Optimal growth in experiments occurred at 6.8-8.6, but no growth occurred at 5.1 (Fulton 1962).
Maximum pH	8.6	None
Minimum Duration	0.5	Sommer 1992
Maximum Duration	1	Sommer 1992
Maximum Height (mm)	150	Stems are typically 30 45 mm, but may reach 150 mm or more (Calder 1971; Schuchert 2004; Calder 2010)
Broad Temperature Range	None	Cold-temperate-Tropical
Broad Salinity Range	None	Fresh-Polyhaline

General Impacts

Economic impacts 

Cordylophora caspia has been reported from the cooling water systems of power plants in Illinois (Folino 2000), Brazil (Grohmann 2009), Finland (Vuorinen et al. 1984), Luxembourg (Massard and Geimer 1990), and the Ukraine (Simkina 1963). Fouling by C. caspia has required the shutdown of generators for cleaning and the use of toxic chemicals such as chlorine to prevent fouling (Folino 2000; Grohmann 2008). Other impacts are possible. It occurs in fouling on boats, ships, and buoys (Woods Hole Oceanographic Institution 1952), but is not widely reported as a ship fouling problem.

Ecological impacts

Cordylophora caspia is now a significant biomass component of the fouling community in the fresh-mesohaline regions of many estuaries around the world. It is also the only erect compound hydroid occurring in inland freshwater lakes (Pennak 1978; Hutchinson 1993). However, information on the ecological impact of its invasion is scarce, and mostly anecdotal, although some experimental studies have been conducted in Chesapeake Bay (see Von Holle and Ruiz 1997; Von Holle unpublished data).

Competition - Cordylophora caspia is a potential competitor for space in fouling communities. In field experiments on fouling plates (Key Bridge, Patapsco River, Maryland), where laboratory-grown colonies of C. caspia were added, abundances of the bryozoan Victorella pavida (cryptogenic), the entoproct Loxosomatoides laevis (introduced), and the protozoans Metafolliculina sp., and Stentor sp. were reduced (Von Holle and Ruiz 1997; Von Holle unpublished data).

Food/Prey - Cordylophora caspia is an important food for nudibranchs, which include many specialized predators of hydroids. Cordylophora caspia is apparently eaten by the nudibranch Tenellia adspersa, cryptogenic on the East Coast of North America, but widely introduced elsewhere (Gaulin et al. 1986; Chester 1996). Despite its nematocysts, C. caspia is also eaten by some generalized predators, such as amphipods (Roos 1979). Extensive feeding by the introduced amphipod Gammarus tigrinus (native in Chesapeake Bay) on C.caspia was reported in Dutch freshwaters by Roos (1979). In the San Francisco Bay estuary, C.caspia comprised 18-23% of the diet of the introduced Shimofuri goby (Tridentiger bifasciatus) (Matern and Brown 2005).

Predation -Although colonies of Cordylophora caspia in many bodies of water represent a substantial biomass of predators on zooplankton and mobile epibenthos (Bibbins 1892; Arndt 1984; Roos 1979), their role as predators has rarely been studied quantitatively. However, C. caspia predates on settling Zebra Mussel (Dreissena polymorpha) veligers, selecting smaller veligers, even as their filaments increase overall rates of settlement (Folino-Rorem and Stoeckel 2006).

Habitat Change - Cordylophora caspia colonies are dense and bushy, and constitute a substantial structural alteration to surfaces of wood, plants, rocks, etc., which may provide some protection from predators and currents (Roos 1979). In field experiments, the addition of laboratory-grown colonies of C. caspia resulted in increased abundances of Amphibalanus improvisus, Alitta succinea, and corophiid amphipods on fouling plates (Von Holle and Ruiz 1997; Von Holle unpublished data). In the Great Lakes basin, colonies of C. caspia provide substrate for settlement of larval Zebra Mussels (Dreissena polymorpha) (Folino-Rorem et al. 2006). This hydroid has been recorded as a fouling organism on living native freshwater bivalves (Amblema plicata, Potamilus purpuratus) in Louisiana (Curry et al. 1981), Zebra Mussels in the Great Lakes region (Folino-Rorem et al. 2006), and Zebra Mussels and Dark False Mussels (Mytilopsis leucophaeta) in the Hudson River (Walton 1996). However, impacts of C. caspia on these bivalves were not reported. 

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