Reproductive patterns of mussel Perumytilus purpuratus (Bivalvia: Mytilidae), along the Chilean coast: Effects caused by climate change?

Reproductive cycles were studied in seven natural populations of the intertidal bivalve Perumytilus purpuratus, distributed in a latitudinal gradient of ~2400 km along the Chilean Pacific coast (20-40°S). The results, both qualitative (gametogenic stages) and quantitative (GSI and GVF), over a period of 24 months, showed that these populations presented asynchrony in the reproductive cycle. Semi-annual cycles in Iquique (20°S), Antofagasta (23°S) and Montemar (32°S), and annual cycles in Caleta Bolfin (23°S), Taltal (25°S), Tumbes (36°S) and Pucatrihue (40°S) (2010-2012) were found. The results indicate that latitude does not have an effect on the development stage, but it does on the spawning date. However, there is a relationship between the reproductive cycles and temperature fluctuations. In addition, there was a significant negative linear correlation between gonadosomatic index and sea surface temperature in the populations studied. The decrease in temperature reduces the rate of development stages and, therefore, increases the reproductive cycles from semi-annual to annual, as evidenced in bivalve samples from Taltal, along a semi-decadal period (2007-2012). From these results, we discuss the likely biological and ecosystem consequences in connection to the effects of climate change in the South Pacific.