ABSTRACT
Reproduction in tunicates is considered to be particularly vulnerable to changes in seawater temperature. In the present study we investigated the effects of sea surface temperature and temperature anomalies on reproductive traits of the non-native sessile tunicate Pyura praeputialis. Reproductive traits of this species were investigated over the course of 67 months, based on samples collected at two localities (eastern and western shorelines) of the Bay of Antofagasta. The study period included years with different oceanic and atmospheric conditions: a warm event, El Niño (June 1997 to July 1998); a cold event, La Niña (August 1998 to December 2000); and post-La Niña (January 2000 to December 2002). We compared two common indices (condition and gonadosomatic) and histological sections to evaluate the maximum reproduction index of this introduced species that dominates a large part of the rocky intertidal habitat in the Bay of Antofagasta. We found sexually mature individuals all year-round and a decrease in both reproductive indices matching the reduction in the sea surface temperature during the austral autumn and winter months. The results suggest that gonad development in this species is sensitive to sea surface temperature and thermal anomalies. We conclude that future thermal anomalies or projected global average sea surface warming associated with climate change might have no negative consequences on these reproductive traits of P. praeputialis. This suggests this species is ecologically resilient and that the ecosystem services that this species provides for other invertebrate and algal species will be maintained.
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Acknowledgements
Much appreciation goes to Verónica Ortiz for improving the quality of the histological pictures. We gratefully acknowledge the Servicio Hidrográfico y Oceanográfico de la Armada de Chile (SHOA) for supplying the 41-year time data series of sea surface temperature (1962–2003) requested through their website. Dr Richard Strathmann is acknowledged for valuable comments made on an early version of the manuscript. Two anonymous referees provided very helpful improvements to the final version of the manuscript. Much appreciation goes to Miles Abadilla for improving the English.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Patricio H. Manriquez https://orcid.org/0000-0001-6586-764X
Ricardo Guiñez http://orcid.org/0000-0003-3658-7360
Alberto Olivares http://orcid.org/0000-0003-3949-5955