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Vast reef-like accumulation of the hydrocoral Errina antarctica (Cnidaria, Hydrozoa) wiped out in Central Patagonia
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Fig. 1 Errina antarctica in shallow water of Chilean Patagonia (scale bar 10 cm)
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The hydrocoral Errina antarctica is described around southern South America (south of 50 S; Fig. 1) and along the Scotia Arc down to 771 m (Cairns 1983). In Chile, we found E. antarctica
in diving depths as far north as 43 25S. It has been identified as key structural species creating important habitats for a multitude of organisms (Haussermann and Forsterra 2007; Fig. 1b, d),
but the colonies are slow growing and easily damaged (Miller et al. 2004). In 2006, we discovered impressive reef-like accumulations of large colonies of E. antarctica on slopes below 10 m
and on the bottom of Copihue Channel in the Madre de Dios archipelago (50 S) (Haussermann and Forsterra 2007; Fig. 1a).
In April 2013 at exactly the same spot, we only found Errina rubble accumulated in dips on the bottom of the approx. 250 m long, 50 m wide and 2040 m deep channel (Fig. 1c), and
only a hand full of small recruits scattered over the area. Estimating from the level of erosion and age of epibionts on the fragments, all colonies had died more than 2 yrs ago. Local seafood
divers observed colonies in the Copihue Channel with dark filamentous overgrowth in 2009 or 2010. This may refer to hydrozoan overgrowth (typical for dead stylasterid colonies in this
area), which could indicate that the corals were already dead by then but physically undamaged. Subsequently they must have eroded quickly which may have been enhanced by strong
overgrowth, by the considerable currents in this channel and by boring organisms that are abundant in this limestone dominated area. At a study site 3.5 km south-east, we found large healthy
colonies and no indication of enhanced mortality (Fig. 1b, d). The cause of the mortality in this case is still completely unknown and subject of a planned study. The finding underlines the
vulnerability of Patagonian hydrocorals and the need for efficient protection.
Cairns SD (1983) Antarctic and Subantarctic Stylasterina (Coelenterata: Hydrozoa). Biol Antarct Seas XIII 38:61164
Haussermann V, Forsterra G (2007) Extraordinary abundance of hydrocorals (Cnidaria, Hydrozoa, Stylasteridae) in shallow water of the Patagonian fjord region. Polar Biol 30:487492
Miller KJ, Mundy CN, Chadderton L (2004) Ecological and genetic evidence of the vulnerability of shallow-water populations of the stylasterid hydrocoral Errina novaezelandiae in New
Zealands fiords. Aquat Conserv Mar Freshw Ecosys 14:7594
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