Caulerpa brachypus

Invasion History

First Non-native North American Tidal Record: 2001
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 2001

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General Invasion History:

Caulerpa brachypus was described by Harvey from Japan in 1860. This alga has a wide native distribution in the Indo-Pacific, including the Philippines (Meinesz and Calumpong 1982), New Guinea ( Coppejeans and Meinesz 1988), Fiji (South and de Ramon n'Yeurt 1993), Mozambique, Madagascar, and Somalia (Guiry and Guiry 2022). In 1966, this alga was collected off Brazil (Lat 05 05 °S, Long 34 57 °W), as var. "brasiliana" (Joly et al. 1974).  Caulerpa brachypus as collected in 1975 and 1976 on the Florida Middle Ground, a reef about 130 km off the west coast of Florida, and  roughly 20 m deep. In 1999, C. brachypus was collected off Palm Beach County, Florida (US National Museum of Natural History 2022). In 2001, C. brachypus occurred on the Florida Atlantic Coast from Jupiter to Boynton Beach (Lapointe et al. 2005; Lapointe et al. 2006).  Likely vectors include aquarium releases, ballast water, or hull fouling (Glardon 2006). It has rapidly expanded its range in the Indian River Lagoon, possibly responding to eutrophication from fertilizers and sewage. In 2003, it was found near the historic House of Refuge in Martin County in the Indian River Lagoon, and in 2004 in the Fort Pierce Inlet (US National Museum of Natural History 2022). However, the expansion of C. brachypus in the Indian River Lagoon may be limited by high light penetration (Brian LaPointe, personal communication).

North American Invasion History:

Invasion History on the East Coast:

Caulerpa brachypus was collected in 1975 and 1976 on the Florida Middle Ground, a reef about 130 km off the west coast of Florida, and roughly 20 m deep. In 1999, C. brachypus was collected off Palm Beach County, Florida (US National Museum of Natural History 2022). It has rapidly expanded its range in the Indian River Lagoon, possibly responding to eutrophication from fertilizers and sewage. In 2001, C. brachypus occurred on the Florida Atlantic Coast from Jupiter to Boynton Beach (Lapointe et al. 2005; Lapointe et al. 2006). In 2003, it was collected in the Indian River Lagoon (IRL), near the historic House of Refuge in Martin County (Harbor Branch Oceanographic Institution 2003; Wentley 2003). In 2004, it was collected in the Fort Pierce Inlet (US National Museum of Natural History 2022). 'Initial concerns that the alga would gain a foothold and quickly spread through the IRL have been partially allayed with the finding that it is largely intolerant of the high-light conditions characteristic of the shallow IRL system' (Brian LaPointe, personal communication).

Invasion History on the Gulf Coast:

Caulerpa brachypus was collected in 1975 and 1976 on the Florida Middle Ground, a reef about 130 km off the west coast of Florida, and roughly 20 m deep (US National Museum of Natural History 2022). However, we have no recent records from the Gulf.

Invasion History Elsewhere in the World:

Caulerpa brachypus was collected off Brazil in 1966 as C. b. var. "brasiliana" (Joly et al. 1974). It is apparently established in the Caribbean and was collected in Saint Barthelemy in 1987, in the US Virgin Islands in 1995, and in Guadeloupe and Martinique (Global Biodiversity Information (GBI) Facility 2022; Guiry and Guiry 2022; US National Museum of Natural History 2022). In 2023, this alga was found to be established on Great Barrier Island, off the North Island of New Zealand (Scott 2023; New Zealand Ministry of Primary Industries 2023).

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Description

Caulerpa brachypus is a green alga which consists of blade-like fronds branching from a creeping stolon. The fronds have a short stipe, and oval to tongue-shaped 'leaves', lined with small triangular outgrowths (Coppejans and Meinesz 1988). The plants form dense mats, spreading across the substrate. They are coenocytic, meaning that chloroplasts can move through the whole thallus, making it the equivalent of a cell with multiple nuclei (Bold and Wynne 1978).

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Taxonomy

Ecology

General:

Caulerpa brachypus is a marine green alga which consists of blade-like fronds branching from a creeping stolon, and can form dense mats on a variety of substrates (Coppejans and Meinesz 1988). It is widespread in tropical and subtropical climates (Guiry and Guiry 2022). In experiments, it grew and survived at 25-35 PSU, but died at 20 PSU (Iralandi et al, 2005). Caulerpa brachypus grows on reef areas in association with corals, gorgonian, sponges, and other sessile invertebrates. Caulerpa spp. are normally rare on healthy coral reefs, and blooms are associated with inputs of nitrogen in phosphorus.  For C. brachypus in Florida, stable isotope analysis indicated that most of the inputs come through groundwater from heavy development in southern Florida (LaPointe and Bedford 2010). Off the coast of southeast Florida, C. brachypus grows best at depths of 25–47 m, under low-light conditions (50–200 mmol photons; LaPointe and Bedford 2010). In the Indian River Lagoon, high light levels have limited penetration.  However, increasing turbidity could change that (Smithsonian Marine Station at Fort Pierce 2022).  Caulerpa brachypus in Florida seems to be resistant to grazing, although it has relatively low levels of the defensive compound caulerpenyne (Smithsonian Marine Station at Fort Pierce 2022).

Trophic Status:

Primary Producer

PrimProd

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Habitats

General Habitat	Grass Bed	None
General Habitat	Rocky	None
General Habitat	Coral reef	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

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Life History

Sexual reproduction is uncommon in the genus Caulerpa. However, reproduction by fragmentation is very frequent in Caulerpa brachypus, while sexual reproduction is rare. It was not observed, but considered a a possible factor in the invasion (Lapointe and Bedford 2010).

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Tolerances and Life History Parameters

Minimum Salinity (‰)	25	experimental, Irlandi et al. 2007
Maximum Salinity (‰)	35	Highest tested , Irlandi et al. 2007
Broad Temperature Range	None	Subtropical-Tropical
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

Like other invasive Caulerpa species, Caulerpa brachypus can form dense mats and spread quickly and overgrow other native seaweeds, seagrasses, and fauna, reducing biodiversity. On the coast of northern Palm Beach County, blooms of Caulerpa brachypus were overgrowing sponges, corals, soft corals, and native algae (Caulerpa verticllatata, C. racemosa), forming dense mats. The rhizoids could also intercept nutrients which would support upright, frondose algae (LaPointe et al. 2005; Lapointe and Bedford 2010). A recent bloom in New Zealand is being monitored for local spread and impacts (https://www.mpi.govt.nz/biosecurity/exotic-pests-and-diseases-in-new-zealand/pests-and-diseases-under-response/exotic-caulerpa-seaweeds-at-great-barrier-great-mercury-islands-and-bay-of-islands-te-rawhiti-inlet/).

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Regional Impacts

CAR-I	Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida		Ecological Impact	Competition
On the coast of northern Palm Beach County, Florida, from Boynton Beach to Jupiter, blooms of Caulerpa brachypus were overgrowing  sponges, corals, soft corals, and native algae (Cauilerpa verticllatata, C. racemosa), forming dense mats. Stable isotope analysis suggests that submarine groundwater discharge, absorbed through C. brachypus' rhizoids, is the major source of nutrients for these blooms. The rhizoids could also intercept nutrients which would support upright, frondose algae (LaPointe et al. 2005; Lapointe and Bedford 2010).
CAR-I	Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida		Ecological Impact	Habitat Change
The dense, continuous mats formed by Caulerpa brachypus  cover sponges and corals, and displace taller frondose algae (LaPointe and Bedford 2010), probably erasing refuge habitats for small invertebrates and fishes.
S196	_CDA_S196 (Cape Canaveral)		Ecological Impact	Competition
On the coast of northern Palm Beach County, Florida, from Boynton Beach to Jupiter, blooms of Caulerpa brachypus were overgrowing  sponges, corals, soft corals, and native algae (Cauilerpa verticllatata, C. racemosa), forming dense mats.  Stable isotope analysis suggests that submarine groundwater discharge, absorbed through C. brachypus' rhizoids,  is the major source of nutrients for these blooms. The rhizoids could also intercept nutrients which would support upright, frondose algae (LaPointe et al. 2005; Lapointe and Bedford 2010).
S196	_CDA_S196 (Cape Canaveral)		Ecological Impact	Habitat Change
The dense, continuous mats formed by Caulerpa brachypus cover sponges and corals, and displace taller frondose algae (LaPointe and Bedford 2010), probably erasing refuge habitats for small invertebrates and fishes.
FL	Florida		Ecological Impact	Competition
On the coast of northern Palm Beach County, Florida, from Boynton Beach to Jupiter, blooms of Caulerpa brachypus were overgrowing  sponges, corals, soft corals, and native algae (Cauilerpa verticllatata, C. racemosa), forming dense mats.  Stable isotope analysis suggests that submarine groundwater discharge, absorbed through C. brachypus' rhizoids,  is the major source of nutrients for these blooms. The rhizoids could also intercept nutrients which would support upright, frondose algae (LaPointe et al. 2005; Lapointe and Bedford 2010).
FL	Florida		Ecological Impact	Habitat Change
The dense, continuous mats formed by Caulerpa brachypus cover sponges and corals, and displace taller frondose algae (LaPointe and Bedford 2010), probably erasing refuge habitats for small invertebrates and fishes.

References

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Guiry, M. D.; Guiry, G. M. 2004-2023 AlgaeBase. National University of Ireland Galway--http://algaebase.org



Harbor Branch Oceanographic Institution 2003 Coral smothering 'Green Tide' seaweed spreading on Florida reefs.. Web Page: http://www.sciencedaily.com/print.htm



Irlandi, Elisabeth; Zsiros, Jaime; Orcutt, Carrie; McKay, Alison (2007) Morphometric changes and tolerance to low salinity for the green alga Caulerpa brachypus and potential consequences for its establishment in the Indian River Lagoon FL., Florida Scientist 70(4): 405-414

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Lapointe, Brian E.; Barile, Peter J.; Littler, Mark M.; Littler, Diane S. (2005) Macroalgal blooms on southeast Florida coral reefs 2. Cross-shelf discrimination of nitrogen sources indicates widespread assimilation of sewage nitrogen., Harmful Algae 4: 1106-1122

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doi:10.1016/j.hal.2009.06.001

Lapointe, Brian E.; Bedford, Bradley J.; Baumberger, Rex. (2006) Hurricanes Frances and Jeanne remove blooms of the invasive green alga Caulerpa brachypus forma parvifolia (Harvey) Cribb from coral reefs off northern Palm Beach County, Florida., Estuaries and Coasts 29(6A): 966-971

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Riddle, Amanda 2001 Scientists study invasive algae choking reefs off South Florida.. Web Page: http://cfapps.naplenews.com/sendlink/printthis.cfm



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Wentley, Suzanne (3/4/2004) Killer exotic algae skulks in Martin County waters., Fort Pierce Tribune <missing volume>: <missing location>

Zaleski, Susan Frisch; Murray, Steven N. (2006) Taxonomic diversity and geographic distributions of aquarium-traded species of Caulerpa (Chlorophyta: Caulerpaceae) in southern California, USA., Marine Ecological Progress Series 314: 97-108

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