Effects of inter-annual temperature variability, including ENSO and post-ENSO events, on reproductive traits in the tunicate Pyura praeputialis

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.

SUBJECT EDITOR:

• Manuela Truebano

KEYWORDS:

• Circular statistic
• condition index
• ENSO
• gonadosomatic index
• long-term study
• thermal anomalies
• tunicate

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

Additional information

Funding

This work was supported by a Chilean Presidential Chair in Science to Juan Carlos Castilla, Fund for Research Centers in Prioritary Areas (FONDAP) and The National Fund for Scientific and Technological Development (FONDECYT) [grant No 1501-0001]. Grant funding from Minera Escondida Limitada (MEL) to Juan Carlos Castilla, via the Pontificia Universidad Católica de Chile, for basic studies on the Pyura praeputialis populations of the Bay of Antofagasta are acknowledged. Ricardo Guiñez acknowledges financial support from Universidad de Antofagasta [grant No CODEI-31-2010]. During the writing of the present study Patricio H Manríquez was under the tenure of the The National Fund for Scientific and Technological Development (FONDECYT) [grant No 1130839] and of the grant ‘Climate driven Changes in the Habitat Suitability of Marine Organisms’ [grant CLIMAR, ELAC2015/ T01-0495, 2017–2020] funded by the Network of the European Union, Latin America and the Caribbean Countries on Joint Innovation and Research Activities.