Initial spread of the invasive green alga Caulerpa verticillata over coral reef communities in the Gulf of California

Abstract

Initial spread of the invasive green alga Caulerpa verticillata over coral reef communities in the Gulf of California Caulerpa verticillata J. Agardh 1847 (Bryopsidales, Caulerpaceae) is an invasive and aggressive algal species that quickly spreads by extensive blooms and overgrows coral colonies until the corals are completely covered (Lapointe and Bedford 2010). Like other species in this genus, this alga has the potential to impact ecosystem diversity and function of coral reefs (Fernández and Cortés 2005; Kružić et al. 2008). In the tropical Eastern Pacific, this species has been reported only in Panama at 8°N and in the Mexican Pacific at 19°N (Mateo-Cid and Mendoza-González 1991; Pérez-Justavino et al. 2010). Little is known about the spread of this alga. In January 2010, C. verticillata (Fig. 1a) was recorded for the first time covering a few square meters in rocky areas at 2 m depth at Esterito (24°10¢36.46 †N, 110°18¢21.16 †W) and La Concha (24°12¢4.72 †N, 110°18¢2.24 †W), in the southwestern part of the Gulf of California. One year later, diver and aerial surveys revealed that the alga had increased its coverage at the same two locations~200,700 and~11,000 m 2 , respectively. In November 2011, the alga was found at Palmira (24°11¢18.52 †N, 110°18¢12.00 †W), cov-ering~30,000 m 2 at 0.5-7 m depth and growing on a coral reef community (Fig. 1b). Algal growth occurred between branches of Pocillopora damicornis (Fig. 1c) and over P. damicornis and Porites panamensis colonies (Fig. 1d,e). Surveys of 12 sites (from 24.04°N to 24.74°N) between 2010 and 2012 indicated that C. verticillata so far remains limited to the three sites above. This is the first report of C. verticillata overgrowing coral reef communities in the Gulf of California. This finding emphasizes that regular reef monitoring will be necessary to evaluate the effects of this algal invasion on coral populations in this region.

Experimental evidence of the synergistic effects of warming and invasive algae on a temperate reef-builder coral

“…Scleractinian reef-builders have been critically impacted by warming in tropical 11 12 and temperate seas 5 13 14 15 . In addition, they increasingly interact with invasive species, especially algae 6 16 17 18 . The responses of scleractinian corals to warming and the invasion of algal species have been reported separately.…”

Caulerpa chemnitzia in Darwin threatening Galapagos coral reefs

“…By July of 2014, algae cover had increased to 22.6% and coral cover was only 1.6 times that of algae cover. From October 2014, a strong ENSO event lasted a year and a half, with SST anomalies reaching +2.6°C [ 16 ]. Algae cover continued to increase to 29.6% by March 2016, but at a slower rate.…”

“…Also, coral cover increased. Towards the end of 2017 and early 2018, a La Niña caused a maximum negative anomaly of 1.0°C across the tropical Pacific [ 16 ]. Nevertheless, consistently higher yearly average temperatures have been maintained since 2014 ( S1 Fig ).…”

“…This can even occur in their native ranges [13]. Their ability to monopolize space and alter food webs makes macroalgae particularly damaging marine invaders [12][13][14][15][16].…”

Morphological and molecular clarification of the enigmaticCaulerpa floridanaW.R. Taylor (Chlorophyta, Bryopsidales) from the Dry Tortugas, Florida

“…the non-pinnate species C. racemosa (Forsskål) J. Agardh sensu lato including the variety cylindracea spreading in the Mediterranean Sea (e.g. Klein & Verlaque, 2008) (now C. cylindracea Sonder, fide Belton et al, 2014) and C. verticillata J. Agardh in Florida (Lapointe et al, 2005) and the Gulf of California, Mexico (Pérez-Estrada et al, 2013), and pinnate, feather-like species that may be easily confused with C. taxifolia: C. ashmeadii, C. cupressoides (H. West) C. Agardh, C. mexicana Sonder ex Kützing, C. scalpelliformis (Turner) C. Agardh and C. sertularioides (S.G. Gmelin) M. Howe. In an informative pamphlet prepared by Merkel & Associates, Inc., illustrating the above taxa and entitled 'A guide to the nine species of Caulerpa banned in California' (available at www.…”