Trans-Atlantic rafting by the brooding reef coral Favia fragum on man-made flotsam

Abstract

Specimens of the brooding reef coral Favia fragum were found on man-made flotsam stranded on the North Sea shore of the Netherlands. Based on the associated epifauna originating from the southeast USA, we estimate that the corals must have crossed the Atlantic Ocean, transported by the Gulf Stream and the North Atlantic Drift. The size of the corals suggests that they might have had enough time to cross the Atlantic alive and that they already reached the age of possible self-fertilization before they entered waters that were too cold to survive. The temperature requirements and the presently known geographic range of F. fragum are compared with Atlantic summer and winter isotherms and oceanic currents in order to project a hypothetical northernmost range boundary. With increasing pollution, man-made flotsam may become a progressively more common substrate for reef corals that depend on rafting for long-distance dis persal. Eventually, with warming seawater, floating debris may cause tropical marine species to expand their distribution ranges towards higher latitudes.KEY WORDS: Distribution range · Epifauna · Life history · Long-distance dispersal · Ocean currents · Temperature tolerance 445: 209-218, 2012 (Uneputty & Evans 1997, Willoughby et al. 1997, Derraik 2002, Thiel et al. 2003, Taffs & Cullen 2005, Gregory 2009, Ryan et al. 2009). Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerThe growth in man-made flotsam also causes an increase of buoyant substrate for benthic organisms, which has become most evident in areas where it used to be rare (Barnes 2002, Aliani & Molcard 2003. Fouling organisms are able to reach remote coastlines as long as their growing weight does not negatively affect the buoyancy of their substrate. Eventually, long-lasting flotsam can become responsible for the introduction of exotic species (Winston 1982, Winston et al. 1997, Barnes & Fraser 2003, Barnes & Milner 2005. When these exotic species appear to colonize new areas and become harmful to allochtonous species, it is important to know their origin and natural environment for their control.Recently, several specimens of the brooding amphiAtlantic reef coral Favia fragum (Esper, 1793), together with other fouling animals, were discovered on a gas cylinder that was beached on Texel, the Netherlands, (Fig. 1). Although the corals were dead, they were large enough to tell that they must have survived for a long time. So far, it has only been hypothesised that the wide distribution range of brooding organisms, and F. fragum in particular, may be caused by long-distance dispersal through rafting (Highsmith 1985, Goodbody-Gringley et al. 2010. Based on the species composition of the epifauna of the cylinder, the course of oceanic currents, the size and growth form of the corals, and information on the biogeography and life history of F. fragum, we reconstruct a scenario in order to explain how these reef corals were able to reach the temperate coastline of the Netherlands. MAT...

Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

“…However, there is increasing evidence that the duration of pelagic stages is not directly correlated with dispersal potential (Johannesson 1988;Strathmann et al 2002). This is supported by the fact that many brooding species have wider geographic distributions showing even more genetic connectivity on large scales than congeners with a planktonic larval stage (Highsmith 1985;Ó Foighil et al 2001;Nunes et al 2011;Hoeksema et al 2012;Xavier et al 2012). Passive dispersal through rafting and floating can greatly enhance natural dispersal in the marine environment and is supposed to be the main process leading to long-distance dispersal of these brooding marine invertebrates (Johannesson 1988;Locke and Corey 1989;Thiel and Gutow 2005b;Goodbody-Gringley et al 2010).…”

“…Dispersal by rafting is considered as an important means of maintaining population connectivity on both small and large spatial scales: marine organisms that use rafting for dispersing can maintain large and relatively homogeneous populations with little or no genetic subdivision (Fraser et al 2011;Hoeksema et al 2012;Xavier et al 2012). However, some studies have shown that rafting facilitates dispersal, but does not necessarily maintain genetic connectivity among distant populations (Waters and Roy 2004;Baratti et al 2005;Waters 2011).…”

“…Rawson et al 2003;Torres-Pratts et al 2009;Hoeksema et al 2012;Xavier et al 2012), the studies only focussing on caprellid amphipods have been carried out on a facultative rafter species (see Ashton 2006;Boos 2009). Therefore, the importance of rafting in the dispersal of an obligate rafter caprellid species has not been investigated.…”

First record of the Central Indo-Pacific reef coral Oulastrea crispata in the Mediterranean Sea

“…O. crispata corals can settle on various artificial shallow-water substrates (Lam, 2000b(Lam, , 2003. Therefore, they may also be able to attach themselves to metal substrates, as demonstrated by the amphi-Atlantic reef coral Favia fragum (Esper, 1793) (Hoeksema et al, 2012). The Indo-Pacific coral species Tubastraea micranthus (Ehrenberg, 1834), was first observed on an oil rig in the Gulf of Mexico, western Atlantic (Sammarco et al, 2010).…”

Correlation between pelagic larval duration and realised dispersal: long-distance genetic connectivity between northern New Zealand and the Kermadec Islands archipelago

“…Long-distance dispersal, environmental tolerance and phenotypic plasticity Long-distance dispersal may be achieved in different ways, including rafting on natural or man-made objects (Fraser et al 2011;Hoeksema et al 2012). Whilst there is presently no evidence for rafting as mechanism of dispersal for N. melanotragus, it cannot be discounted for post-metamorphic stages.…”