Description
This species lacks a medusa, sexual reproduction takes place and planula larvae are produced in the gonophores (Calder 1971).
Synonymy - G. franciscana (Torrey 1902) may be probably synonymous with G. cerulea, which was described earlier by Clarke (1882) as Calyptospadix cerulea. The chief morphological difference between the species is the number of eggs, only 1 in G. franciscana, 'several' to' many' (~5-10 shown in drawings, Calder 1971; Clarke 1882). G. cerulea is restricted to polyhaline and euhaline salinities (Calder 1972), while G. franciscana is euryhaline. 'As for Garveia cerulea (Clarke's Calyptospadix cerulea), I am now pretty convinced that it is the same as G. franciscana (Calder 1997).
Genetic and rearing studies are needed to determine the relationship between the two forms. It is possible that the two forms are ecotypes. If they are conspecific, G. cerulea might be the correct name because of seniority, but new taxonomic rules may permit the more widely used name G. franciscana to prevail (Calder 1971; Calder 1997).
Potentially Misidentified Species - The male colonies lack a theca and can be confused with Cordylophora caspia (Vervoort 1964).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Cnidaria | Hydrozoa | Anthomedusae | Bougainvilliidae | Garveia |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1946 | Established | Stable | Introduced | Regular Resident | Unknown-Marine | Unknown-Marine | Shipping(Fouling Community) |
History of Spread
Garveia franciscana (Rope Grass Hydroid) was first described from San Francisco Bay (as Bimeria franciscana; Torrey 1902) but its highly disjunct world distribution [Black-Azov Seas, India, Australia, San Francisco Bay, Atlantic-Gulf of Mexico (Delaware Bay to Brazil), Europe, West Africa] (Deevey 1950; Partaly 1979; Vervoort 1964) strongly suggests that it is introduced over much of its range. Carlton (1979) suggested an Indo-Pacific origin, but Calder (1997) speculates that G. franciscana may have originated from the 'Sarmatic' region (Caspian-Black Sea), as several other widespread invading hydrozoans and other spp. have. Garveia spp. were not reported from the Black Sea by Naumov (1969), and G. franciscana appear to have invaded the Sea of Azov around 1960 (Simkina 1963). The oldest verified European record seems to be from the Netherlands in 1922 (Vervoort 1964). (Dutch and Russian records were first reported under the name 'Perigonimus megas', and confusion with Cordylophora caspia may have delayed recognition of this species.) The first Mediterranean record, from the lagoon of Venice, was found in 1978 (Morri 1980).
A source of uncertainty regarding G. franciscana's invasion in the Northwest Atlantic is the presence of the very closely related G. cerulea, which differs from G. franciscana principally in having multiple eggs, and may be conspecific. In this account, we shall treat them as separate species, Garveia cerulea was first described from Fort Wool, Hampton VA in 1882 (Clarke 1882). In Chesapeake Bay it appears to be confined to polyhaline waters [e.g. Norfolk Navy Base (Calder and Brehemer 1967), lower James R., Calder 1971; mouth of the Potomac, Fraser 1944]. Its range on the Atlantic coast is from Chesapeake Bay to the Miramichi estuary, New Brunswick (collected 1918, Fraser 1944). Garveia cerulea is usually considered as a native northwest Atlantic form, but G. cerulea appeared to be a recent arrival at Woods Hole MA: 'Dr. Hargitt believes that this species has but recently established itself in the region' (Sumner et al. 1913).
Atlantic Coast Records of G. franciscana are summarized below:
Gulf of Mexico (LA, TX)- G. franciscana was present by 1944, and abundant by 1950 (Crowell and Darnell 1950; Deevey 1950; Fraser 1944).
Chesapeake Bay - G. franciscana was reported by Frey (1946) as Bimeria tunicata, and was abundant by 1967 (Cory 1967).
Delaware Bay - G. franciscana was present by 1968, and had an apparent range expansion (or fluctuation) between 1968 and 1971 (Maurer and Watling 1972).
Chesapeake Records:
James, York, and Rappahannock Rivers - G. franciscana was not separated from G. cerulea until late in Calder's survey, but given G. franciscana's tolerance for low salinities, this appears to have been the dominant form in meso- and oligohaline waters. It was very abundant in 1965-68 (Calder 1971) and both abundant and unusually large after Hurricane 'Agnes' floods in 1972 (Andrew 1973). Crabbers claimed this species had been absent from the Rappahannock before the floods (Andrews 1973), but Calder found it earlier. At Surry Nuclear Power Plant in the James River, G. franciscana was the biomass dominant on fouling plates in 1991-1992. It occurred on fouling plates from the mouth of the river, to just north of Hog Island (Thompson 1993).
Potomac River - G. franciscana was reported from Lower Cedar Point as 'Bimeria tunicata (=G. franciscana) (only one specimen obtained) (Frey 1946). It is regularly occurring at the Morgantown (VA) power plant (mesohaline) (Lippson et al. 1979; Patrick 1994), and was collected in oligohaline waters (Pfitzenmeyer 1976).
Patuxent River - G. franciscana was abundant on fouling panels in the lower estuary, Benedict to Solomons, in 1963-64 (Cory 1967; Nauman and Cory 1969).
Middle Bay - G. franciscana was abundant on fouling panels at Calvert Cliffs Nuclear Power Plant; 1970-1980 (Abbe 1987). Although this species is found in areas of oligo-mesohaline salinity in the lower Bay, and elsewhere, it was not found in fouling panel studies of the upper Bay. However, in the summer of 1997, large colonies were found in a trawl in the Rhode River, Edgewater MD (Ruiz et al. unpublished).
History References - Abbe 1987; Andrews 1973; Calder 1971; Calder 1972; Clarke 1882; Cory 1967; Cory and Nauman 1969; Fraser 1944; Frey 1946; Lippson et al. 1979; Maurer and Watling 1972; Morri 1980; Nauman and Cory 1969; Naumov 1969; Pfitzenmeyer 1976; Simkina 1963; Ruiz et al. unpublished data; Sumner et al. 1913; Thompson 1993; Vervoort 1964
Invasion Comments
Native Region, Invasion Status - 'If I had to hazard a guess, my wild guess would be that like many other brackish water hydroid species with widespread distributions, it originated in the Sarmatic Sea area [Black-Caspian-Aral sea region]. That is pure unadulterated speculation, though. I would feel reasonably safe in claming that it is quite likely an introduction to the Chesapeake.' (Calder 1997).
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 0.0 | 37.5 | 9.0 | 34.0 |
| Salinity (‰) | 1.0 | 35.0 | 5.0 | 25.0 |
| Oxygen | ||||
| pH | ||||
| Salinity Range | oligo-poly |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | ||
| Typical Adult Size (mm) | 70.0 | 70.0 |
| Maximum Adult Size (mm) | 300.0 | 300.0 |
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Garveia franciscana is a major fouling organism in the Chesapeake Bay region.
Industry- The organism with the highest quantified cost to power plants in the Chesapeake Bay is G. franciscana, which is a major fouler of power plants along mesohaline waters of Chesapeake Bay (Cory 1967; Virginia Power 1992) and elsewhere in the world (Simkina 1963). At two power plants Chesapeake Bay, Chalk Point (Patuxent River) and Morgantown (Potomac River), the cost of biocides to control fouling dominated by G. franciscana was $95,000 to $180,000 per year in 1995-97 (Krueger 1997). At the Surry Nuclear Power Plant on the lower James River, the weight of the hydroids caused breakdowns of the traveling screens which remove debris. Aggregates of hydroids blocked water flow in the main condensers, in the circulating water systems used for cooling during routine operation, and in the service water systems, which would be used in shutdown after an accident. 'Almost daily' cleaning was required during warm weather to keep water flowing through the service system. In 1992, the projected cost of “doing nothing” about the biofouling problem, except routine cleaning and repairs was $37.5 million projected over the plant’s remaining license period (to the year 2013), or $3.4 million per year. The operators of the plant instead undertook an extensive reconstruction of the cooling and screen, which was intended to reduce fouling problems, with a projected cost of $23.6, or $2.1 million per year (Virginia Power 1992).
One major consequence of the invasion of exotic fouling organisms is the increased use of biocides and antifouling coatings in power plants and industrial water systems. These chemicals are toxic substances used to kill microbial and invertebrate organisms on surfaces exposed to natural waters. Among coatings used in power plants are copper oxide paints, organotin compounds, as well as nontoxic coatings that inhibit attachment of organisms (Virginia Power 1992). The most common biocide is chlorine, but a variety of mixtures and compounds are used. Since traces of the toxic compounds are discharged with used cooling waters, they are a major pollution concern, leading to the testing of less toxic alternatives (Maryland Power Plant Research Program 1998). At the Surry Nuclear Power Plant, several biocides in addition to chlorine were tested against G. franciscana, including ammonium hydroxide, hydrogen peroxide, sodium bromide-hypochlorite mixture, a surfactant mixture (“ClamTrol”), and chemically induced anoxia. However, at doses allowed by their U.S. EPA permit, these were ineffective (Virginia Power 1992).
Fisheries- Fouling by Garveia franciscana has been a major problem on fishing gear, including crab pots and oyster trays (Andrews 1973).
Habitat Change- Garveia francsicana probably benefits commerical and sport fisheries by providing habitat for juvenile and bait fishes, shrimps, crabs, and other motile organsisms (Thompson 1993).
References- Andrews 1973; Cory 1967; Krueger 1997; McLean 1972; Simkina 1963; Thompson 1993; Virginia Power 1992
Economic Impacts Outside of Chesapeake Bay
Garveia franciscana (Rope Grass hydroid) is probably an important fouling organism through much of its range. However, the only specific mentions of its economic importance, outside of Chesapeake Bay which we have found, have been its recognition as a major fouling organism in power plants in the Sea of Azov (Simkina 1963), and as important fisheries habitat in Lake Ponchartrain LA (Crowell and Darnell 1955).
References- Crowell and Darnell 1955; Simkina 1963
Ecological Impacts on Chesapeake Native Species
Although Garveia franciscana (Rope Grass Hydroid) is an abundant and sometimes dominant part of the fouling community in parts of Chesapeake Bay, its ecological impacts are largely unknown. If G. francisicana and G. cerulea are separate species, and exotic and native, respectively, interactions are likely. However, the taxonomy of the species is unresolved, and the releative distribution and interactions of the forms is unknown.
Competition - Garveia franciscana and Victorella pavida overgrew most other organisms on fouling panels at Calvert Cliffs MD in summer (Abbe 1987).
Habitat Change - Growths of Garveia franciscana provide cover for numerous amphipods, mud crabs, and other organisms in the Patuxent River (Cory 1967) and James River (Thompson 1993).
Food - Garveia franciscana is fed on by nudibranchs, particularly Tenellia sp. (Abbe 1987;Cory 1967; Thompson 1993).
References - Abbe 1987; Cory 1967; Thompson 1993
Ecological Impacts on Other Chesapeake Non-Native Species
Impacts of Garveia franciscana on introduced species have not been studied, but are likely given its abundance in the fouling community.
Competition - Garveia franciscana overlaps spatially with Cordylophora caspia, although C. caspia ranges into lower salinities (Calder 1971; Cory 1967; Thompson 1993). It also co-occurs with Victorella pavida (cryptogenic). Victorella pavida and G. franciscana settle at the same time at Calvert Cliffs, but G. franciscana persists longer in summer (Abbe 1987).
References - Abbe 1987; Calder 1971; Cory 1967; Thompson 1993
References
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