Abstract
We present a 2.5-year-long sediment trap record of dinoflagellate cyst production in the Cariaco Basin, off Venezuela (southern Caribbean Sea). The site lies under the influence of wind-driven, seasonal upwelling which promotes high levels of primary productivity during boreal winter and spring. Changes in dinoflagellate cyst production is documented between November 1996 and May 1999 at ∼14-day intervals and interpreted in the context of in situ observations of physico-chemical and biological parameters measured at the mooring site. Dinoflagellate cyst assemblages are diverse (57 taxa) and dominated by cyst taxa of heterotrophic affinity, primarily Brigantedinium spp. (51% of the total trap assemblage). Average cyst fluxes to the trap are high (17.1×103 cystsm-2 day-1/ and show great seasonal and interannual variability. On seasonal timescales, dinoflagellate cyst production responds closely to variations in upwelling strength, with increases in cyst fluxes of several protoperidinioid taxa observed during active upwelling intervals, predominantly Brigantedinium spp. Cyst taxa produced by autotrophic dinoflagellates, in particular Bitectatodinium spongium, also respond positively to upwelling. Several "spiny brown" cysts contribute substantially to the assemblages, including Echinidinium delicatum (9.7 %) and Echinidinium granulatum (7.3 %), and show a closer affinity to weaker upwelling conditions. The strong El Niño event of 1997/98 appears to have negatively impacted cyst production in the basin with a 1-year lag, and may have contributed to the unusually high fluxes of cysts type "Cp" (possibly the cysts of the toxic dinoflagellate Cochlodinium polykrikoides sensu Li et al., 2015), with cyst type Cp fluxes up to 11.8×103 cystsm-2 day-1 observed during the weak upwelling event of February-May 1999. Possible trophic interactions between dinoflagellates and other major planktonic groups are also investigated by comparing the timing and magnitude of cyst production with proxies for phytoplanktonic communities (from photopigment data) and micro-to macrozooplankton abundance indicators (from palynological data) at the site. This work provides new, detailed insights into the ecology of cystproducing dinoflagellates and will allow for more detailed interpretations of fossil assemblages extracted from sedimentary records in the basin and elsewhere.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2325-2348 |
| Number of pages | 24 |
| Journal | Biogeosciences |
| Volume | 15 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 19 2018 |
| Externally published | Yes |
Bibliographical note
Funding Information:This work was funded by a Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship (PDF) and an Advanced Support Program for Innovative Research Excellence (ASPIRE I - Track IIb) from the U. of South Carolina to Manuel Bringué, and an NSERC Discovery grant to Vera Pospelova. The CARIACO sediment trapping program was supported by the National Science Foundation (NSF; grants OCE 9401537, OCE 9729697, and OCE 1258991). The authors wish to thank Claudia Benitez-Nelson (University of South Carolina) for providing mixed layer depth data and for helpful discussions on the hydrology of the basin. Kenneth Mertens (IFREMER - Concarneau) is kindly thanked for his help in dinoflagellate cyst identification. The crew of the R/V Hermano Gines is also gratefully acknowledged for all operations at sea. The authors are grateful to Barrie Dale (University of Oslo), Sofia Ribeiro (Geological Survey of Denmark and Greenland), and the anonymous reviewer for their helpful and constructive comments that helped improve the manuscript. NRCan Contribution number: 20180015.
Funding Information:
Acknowledgements. This work was funded by a Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship (PDF) and an Advanced Support Program for Innovative Research Excellence (ASPIRE I – Track IIb) from the U. of South Carolina to Manuel Bringué, and an NSERC Discovery grant to Vera Pospelova. The CARIACO sediment trapping program was supported by the National Science Foundation (NSF; grants OCE 9401537, OCE 9729697, and OCE 1258991). The authors wish to thank Claudia Benitez-Nelson (University of South Carolina) for providing mixed layer depth data and for helpful discussions on the hydrology of the basin. Kenneth Mertens (IFRE-MER – Concarneau) is kindly thanked for his help in dinoflagellate cyst identification. The crew of the R/V Hermano Gines is also gratefully acknowledged for all operations at sea. The authors are grateful to Barrie Dale (University of Oslo), Sofia Ribeiro (Geological Survey of Denmark and Greenland), and the anonymous reviewer for their helpful and constructive comments that helped improve the manuscript. NRCan Contribution number: 20180015.
Publisher Copyright:
© Author(s) 2018.
