Interannual variability in temporal patterns of Chlorophyll–a and their potential influence on the supply of mussel larvae to inner waters in northern Patagonia (41–44°S)

• We report a dramatic drop in larvae of M. chilensis in Northern Patagonia.
• Drop in larvae co-occurred with a break in the seasonal cycle of chlorophyll-a.
• Lagged correlations suggest a seasonal coupling between larvae and chlorophyll-a.
• We discuss the role of regional SST patterns on chlorophyll-a variability.

Environmental forcing of biophysical processes can have deep influences on patterns of supply of planktonic larvae to benthic communities in coastal marine ecosystems. We investigated the role of environmental forcing following a recent interannual decrease in larval supply in the Inner Sea of Chiloé (41–45°S) using direct observations and environmental time series over the period 2003–2014. To examine the temporal structure of larval supply and potential associations with environmental forcing (approximated using satellite chlorophyll-a and sea surface temperature), we used wavelet analysis and lagged correlations to test the hypothesis of an association between larval availability and changes in the seasonal cycle of chlorophyll-a concentration, sea surface temperature, and relevant climate variability (Pacific Decadal Oscillation, El Niño-Southern Oscillation and Southern Annular Mode). Our results indicate that a weakening in the annual cycle of chlorophyll-a concentration and abnormally cold sea surface temperature during 2009–2010 can be related to the observed disruption in larval supply to the Inner Sea of Chiloé starting during the 2010–2011 season. The potential influence of climate variability is further discussed as the spatial extent and temporal persistence observed suggest that other ecological processes might have also been affected, and consequently, we suggest a link to transient large-scale climatic forcing.