Balanus trigonus

Invasion History

First Non-native North American Tidal Record: 1885
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1885

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General Invasion History:

Balanus trigonus was described using specimens from the Pacific (Indonesia, Colombia, Peru, Australia, and New Zealand) (Darwin 1854). This species appears to have a broad native distribution in the Pacific and Indian Oceans, including Australia and Japan, southern California (north to Monterey Bay), Peru, the Red Sea, and the southern tip of Africa. It may be introduced to New Zealand where it has a limited range (Cranfield et al. 1998), although it was reported from there by Darwin (1854).

Balanus trigonus is introduced in the Atlantic Basin (Carlton et al. 2011), where it was first recorded in Brazil in 1867. It is found on both sides of the Atlantic and throughout the Mediterranean. In the Western Atlantic, it occurs from North Carolina to Argentina, and in the Eastern Atlantic it is known from the Azores to South Africa. It seems to have colonized the warmer, more saline parts of the Atlantic long before reaching the East and Gulf coasts of the United States (US). It was found on a ship returning from the West Indies in 1877 (Pilsbry, 1916; US National Museum of Natural History 2012). This barnacle generally prefers subtidal habitats in warm-temperate to tropical waters (Werner 1967; Utinomi 1970; Southward 1975; Laguna 1985).

North American Invasion History:

Invasion History on the East Coast:

In U.S. waters, Balanus trigonus was found on the hull of ships arriving at Cape Cod in 1877 and 1879 (Zullo 1992; USNM 51541 and 21550, U.S. National Museum of Natural History 2012), but it was not found until 1961 on the Atlantic coast, in Biscayne Bay, Florida (Moore and McPherson 1963). In 1963 it was collected near Cape Lookout, North Carolina, at, or near, the northern limit of its range (Ross et al. 1964). This barnacle is now widespread from Florida to North Carolina (Werner 1967; Zullo and Lang 1978; Williams et al. 1984; Crickenberger and Sotka 2009).

Invasion History on the Gulf Coast:

In 1885, Balanus trigonus was collected off the Florida Coast in the Gulf of Mexico (Henry pers. comm., cited by Werner 1967). Currently its known range in the Gulf is from the southern tip of Florida, through Louisiana and Texas (Gittings 1985) to Tamaulipas, Mexico (Celis et al. 2007). Most records are from clear, high-salinity waters, including offshore oil platforms (Gittings et al. 1986). Carlton et al. (2011) correct and expand the chronology of Atlantic collections reported by Werner (1967) and Zullo (1992), and provide a detailed discussion of its history in the Western Atlantic. 

Invasion History Elsewhere in the World:

Balanus trigonus was first recorded in the Atlantic from Florianopolis, Brazil in 1864 (Carlton et al., 2011). It now ranges from North Carolina (35° N) and the Azores (38° N) south to Rio Grande do Sul, Brazil (27° S) and False Bay, South Africa (34° S) (Zullo 1992; US National Museum of Natural History 2012). In the Eastern Atlantic, it was first found on the West African Coast, Madeira, and the Azores between 1887 and 1909 (Zullo 1992). In the Mediterranean, as far as we are aware, the earliest dated record is from Sicily in 1927 (Zullo 1992). One empty specimen of B. trigonus was found on a buoy in Belgian waters in 1997-1998 (Kerckhof and Cattrijsse 2001).

While B. trigonus is native to Korea and southern Japan (Utinomi 1970; Kim 1992), it appears to be sporadically introduced by shipping to the northern Sea of Japan, where it has not become established (Zvyagintsev 2003). It has been listed as introduced to New Zealand (1960, Cranfield et al. 1998). Cranfield et al. (1998) give the first date of occurrence as 1960, and do not mention Darwin’s New Zealand specimens, or other early collections (Darwin 1854; Jennings 1917, cited by Foster 1967). Its distribution is limited to the region around Auckland (Foster 1967). Dromgoole and Foster (1983) considered it a species of 'uncertain native status'.

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Description

Balanus trigonus is a small to medium-size barnacle, ranging from conical to nearly-cylindrical in shape and reaching up to 25 mm in diameter. Its shell is composed of six overlapping plates, which are folded with wide longitudinal spaces (radii) which narrow at the top, and with transverse striations around a roughly triangular central opening (orifice). The shell has narrow white longitudinal ribs, and is colored or mottled with colored or mottled with purplish pink. . Inside the orifice are two large valves covering the appendages of the animal. Each valve is composed of two parts, the scutum and the tergum. The scutum is distinguished by one to six longitudinal rows of pits. Balanus trigonus can be distinguished by the scutum, which has one to six longitudinal rows of pits (Darwin 1854). The tergum is externally smooth and flat, with 'scarcely a trace of a longitudinal furrow' (Darwin 1854). The spur of the tergum is broad, being one-third to one-half of the width (Darwin 1854; Pilsbry 1916; Foster 1967; Werner 1967). Larval stages are illustrated by Barker (1976) and Lang (1979).

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Taxonomy

Ecology

General:

Balanus trigonus prefers saline (26-40 ppt), subtidal habitats in warm-temperate, subtropical and tropical seas (Werner 1967). This species, like many other barnacles, is hermaphroditic, but is capable of cross-fertilization. The fertilized eggs are brooded in the mantle cavity, sometimes for several months, and are released as nauplius larvae with three pairs of appendages (Barnes 1983). Balanus trigonus in culture produced broods of 1,000 to 35,000 eggs, averaging ~13,000 eggs (El-Komy and Kajihara 1991)..The nauplii feed in the plankton and go through five successive molts, spending at least 4 -11 days in the water column before molting into a non-feeding cypris stage, covered with a pair of chitinous shells (Barker 1976). Cyprids swim, investigating suitable surfaces and then settle, secreting a shell, and molting into the first juvenile barnacle stage (Barnes 1983). Juvenile and adult barnacles are filter feeders, sweeping the water with their long bristled appendages, and gathering phytoplankton, zooplankton, and detritus (Barnes 1983). Balanus trigonus grows on a wide range of hard surfaces, including mangroves, rocks, oysters, crabs, pilings, docks and ship hulls (Werner 1967; Zullo 1992).

Food:

Phytoplankton, zooplankton

Trophic Status:

Suspension Feeder

SusFed

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Habitats

General Habitat	Rocky	None
General Habitat	Marinas & Docks	None
General Habitat	Mangroves	None
General Habitat	Oyster Reef	None
General Habitat	Coarse Woody Debris	None
General Habitat	Vessel Hull	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None

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Tolerances and Life History Parameters

Maximum Temperature (ºC)	37	50% of adults survived 20 h in water at 37ºC.(Ritz and Foster 1968)
Minimum Salinity (‰)	22	Lowest tested (Thiyagarajan et al. 2003)
Maximum Salinity (‰)	40	Typical Red Sea salinity.
Minimum Reproductive Temperature	18	Lowest tested (Thiyagarajan et al. 2003).
Maximum Reproductive Temperature	28	Highest tested (Thiyagarajan et al. 2003).
Minimum Reproductive Salinity	22	Lowest Tested(Thiyagarajan et al. 2003).
Maximum Reproductive Salinity	40	Typical Red Sea salinity.
Minimum Duration	4.5	28 C (Thiyagarajan et al. 2003).
Maximum Duration	15	20 C, Barker 1976
Minimum Width (mm)	25	Maximum adult size (Darwin 1854)
Broad Temperature Range	None	Warm temperate-Tropical
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

Economic Impacts 

Shipping- We have not found specific reports of economic impacts for Balanus trigonus in North American waters. However, it is common in subtropical waters, frequently reported from ship hulls, and contributes to barnacle fouling of ships and harbor structures (Utinomi 1970; Moore et al. 1974; Zullo 1992).

Ecological Impacts

Fouling communities including B. trigonus were studied in North Carolina, off Cape Lookout. This barnacle was the most common species on fouling plates, together with the octocoral, Titanideum frauenfeldii. However, there was no evidence of spatial competition, since much space remained unoccupied. Balanus trigonus suffered considerable mortality from sea urchin (Arbacia punctulata) predation and sediment scour (Williams et al. 1984). These studies did not indicate unique impacts resulting from this barnacle’s invasion. However, B. trigonus is a potential competitor with other fouling organisms in suitable habitats.

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