Uncommon southwest swells trigger sea urchin disease outbreaks
in Eastern Atlantic archipelagos
José Carlos Hernández1*, Carlos
Sangil1 and Jacob Lorenzo-Morales2
1Departamento de Biología Animal, Edafología y
Geología. Facultad de Ciencias. 456-38200, Universidad de La Laguna.
Tenerife, Canary Islands, Spain.
2Instituto de Enfermedades Tropicales y Salud Pública
de Canarias. 456-38200, Universidad de La Laguna. Tenerife, Canary
Islands, Spain.
ABSTRACT : Recurrent sea urchin mass mortality has recently
affected eastern Atlantic populations of the barren-forming sea urchinDiadema africanum . This new episode of die-off affords the
opportunity to determine common meteorological and oceanographic
conditions that may promote disease outbreaks. The population dynamics
of this sea urchin species are well known—urchin barrens have
persisted for many decades along most of the coastlines off the
archipelagos of Madeira, Selvages and the Canary Islands, where they
limit macroalgae biomass growth. However, this new and explosive
mortality event decimated the sea urchin population by 93% on Tenerife
and La Palma Islands. Two severe episodes of southwestern rough sea that
lead to winter storms, in February 2010 (Xynthia) and February 2018
(Emma), preceded both mass mortality events. The autumn and winter
months of those years were anomalous and characterized by swells with an
average wave height above 2 m that hit the south and southwest sides of
the islands. The amoeba Paramoeba brachiphila was the only
pathogen isolated this time from the moribund and dead sea urchins,
suggesting that the amoeba was the primary cause of the mortality. This
new sea urchin die-off event supports the “killer-storm” hypothesis
that has been already described for western Atlantic coasts. These
anomalous southwest storms during winters generate pronounced underwater
sediment movement and large-scale vertical mixing, detected in local
tide gauge, which may promote paramoebiasis. This study presents
valuable insights about climate-mediated changes in disease frequency
and its impacts on the future of coastal marine ecosystems in the
Atlantic.
KEY WORDS: Winter storms, sea urchins, pathogenic amoebae,Paramoeba brachiphila , Diadema africanum , mass mortality,
Eastern Atlantic.
Running Head: Storms trigger sea urchin die-off
*Corresponding author: jocarher@ull.es