A real-time PCR assay to estimate invertebrate and fish predation on anchovy eggs in the Bay of Biscay
KAUST DepartmentRed Sea Research Center (RSRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Marine Science Program
Plankton ecology Research Group
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AbstractIn order to investigate the role of predation on eggs and larvae in the recruitment of anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus), sprat (Sprattus sprattus) and 52 macrozooplankton taxa were assayed for anchovy remains in the gut during the 2010 spawning season using a molecular method. This real-time PCR based assay was capable of detecting 0.005. ng of anchovy DNA (roughly 1/100 of a single egg assay) in a reliable way and allowed detecting predation events up to 6. h after ingestion by small zooplankton taxa. A total of 1069 macrozooplankton individuals, 237 sardines and 213 sprats were tested. Both fish species and 32 macrozooplankton taxa showed remains of anchovy DNA within their stomach contents. The two main findings are (1) that the previously neglected macrozooplankton impact in anchovy eggs/larvae mortality is in the same order of magnitude of that due to planktivorous fishes and that, (2) the predation pressure was notably different in the two main spawning centers of Bay of Biscay anchovy. While relatively low mortality rates were recorded at the shelf-break spawning center, a higher predation pressure from both fish and macrozooplankton was exerted at the shelf one.
SponsorsWe are grateful to the crews of the RV 'Investigador' and RV 'Emma Bardan' and the BIOMAN 2010 campaign onboard scientists and analysts for their support during sampling. SGIker technical and human support (UPV/EHU) is gratefully acknowledged. The authors are indebted to J. Illera and D. Prieto (UPV/EHU) for their technical assistance and to J. Langa (UPV/EHU) for his help on the statistical analyses of fish results. Thanks are due to U. Laconcha (AZTI Tecnalia and UPV/EHU) for collecting and preserving fish specimens for predation assessment, I. Zarraonaindia (UPV/EHU), MA Pardo and E. Jimenez (AZTI Tecnalia) and P. Borsa (IRD, France) for providing European anchovy samples for assay design and validation and, S. Milligan (CEFAS, UK) and C. Fox (SAMS, UK) for providing clupeid samples for assay testing purposes. This research was financially supported by the projects ECOGENBAY (MICINN CTM2009-13570-C02-02), funded by the Ministry of Science and Research of the Government of Spain, and BIOMAN, funded by the Department of Economic Development and Competitiveness of the Basque Government and by the European Commission.
JournalProgress in Oceanography