Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem

Abstract

Event Abstract Back to Event Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem A. Miguel P. Santos1, 2* 1 Portuguese Institute of Ocean and Atmosphere (IPMA), Portugal 2 Center of Marine Sciences (CCMAR), Portugal The Canary Current Upwelling Ecosystem is one of the four major upwelling regions of the Eastern Boundary Currents (EBC) of the global ocean (Fig. 1). These EBC systems are highly productivity and host large population of small pelagic fish (e.g., sardines and anchovies; SPF), which sustain important fisheries (e.g., the “anchoveta” fishery off Peru is the world’s largest). The collapses of these SPF fisheries have enormous negative economic and social effects on the fishing nations that border these EBC (Aristegui et al, 2009; Checkley et al., 2009). In order to avoid the negative effects (e.g., food availability and settlement conditions) of Ekman offshore transport due to coastal upwelling the marine organisms that inhabit these regions developed mechanisms to assure inshore transport and/or larval retention. In this review several examples of these mechanisms will be presented from phytoplankton to fish. Relatively high offshore Chlorophyll-a concentrations were detected during a winter (February 2000) upwelling event off NW Iberia (Fig. 2). The response of the surface waters to this event was strongly affected by two distinct local features observed during wintertime in the region: the Western Iberia Buoyant Plume (WIBP) and the Iberian Poleward Current (IPC).The WIBP provided conditions for the development of a shallow Ekman layer nearly coincident with the stratified upper meters (Ribeiro et al., 2005). This surface stratification was an important factor in assuring the stability needed for phytoplankton growth, as well as in establishing a vertical retention mechanism for fish larvae and a suitable environment (food availability) for their survival. The observed transport, .induced by the joint effect of wind-driven dynamics and the IPC, comprised a westward advection and stretching of the plume, with little entrainment with the offshore deep mixed layer waters, and a northward displacement of sardine larvae (Fig. 3) (Santos et al., 2004). In conclusion, the IPC and the WIBP introduce important fluctuations in the transport patterns of the region, these conditions provided retention and convergence mechanisms that influenced the distribution of phyto- (Ribeiro et al., 2005) and ichthyoplankton (Garrido et al., 2009) in the area and modulate the impact of winter upwelling events in the survival of larval fish (Fig. 4) (Chicharo et al., 2003; Santos et al., 2004; 2006). In the Portuguese continental shelf decapod larvae are retained on the continental shelf along 3 meridional bands parallel to the coast (Fig. 5), independent of larval phase duration or taxonomic group but closely related to their parental populations: inner shelf species larvae are distributed close to the shore (maximum of larval abundances along the 30 m isobath), shelf species are distributed along the continental shelf (maximum of larval abundances in middle shelf) and finally slope species are distributed close to the shelf break (along the 200 m isobath). This distribution pattern (i.e. in bands) results from the relationship between larval behaviour (e.g., vertical migration) and local oceanographic processes (dos Santos et al., 2008; Peliz et al., 2007). Ontogenetic vertical migration behaviour is evident for almost all the taxa, in which the older stages (last zoeal stages, decapodids and megalopae) were usually found in deeper strata of the water column (Fig. 6) (Bartilotti et al., 2014). Upogebia pusilla and U. deltaura are two common congeners ghost shrimps species occurring in European estuarine and shelf areas, respectively. Their planktonic larval phase lasts around 3 weeks and consists of 4 zoeal stages and a decapodid that must settle in the benthos before recruiting to adult populations. Inhabiting different habitats of the same geographic area and exposed to similar oceanographic conditions these species developed different dispersal/retention mechanisms (e.g., emission points, vertical distribution and ocean circulation) to return to the estuaries or for the suitable settlement substrates where adult populations occur (Fig. 7). These species are good models for other coastal invertebrates that reproduce in summer and have short larval development (Pires et al., 2013). Cephalopod planktonic paralarvae of the neritic species occur during a considerably extended period of the year with two or three abundance peaks within the highly productive upwelling system of the western Portuguese coast and contrasting with the Gulf of Cadiz area. There is an apparent relationship of loliginid and Octopus vulgaris paralarvae with upwelling dynamics. The eventual advection from the shelf during upwelling events is probably prevented by their diel migration behaviour (Fig. 8). The summer inshore counter-current is suggested to advect L. vulgaris paralarvae from the warm summer spawning grounds on the northern Gulf of Cadiz to the western upwelled waters around Cape S. Vicente. O. vulgaris paralarvae are located on the outer-shelf during the upwelling season and near the shore during autumn, possibly following the Ekman dynamics of cross-shelf transport (Moreno et al., 2009). Satellite-derived sea-surface temperature (SST) data revealed a sudden change in the intensity of the coastal outcrop regime in the Canary Current Upwelling System between the 1980s and 1990s, contrasting with the quasi-decadal oscillations of the SST anomaly in the open ocean over the same period. The outcrop indices and the SST gradient showed that this sudden change occurred earlier (~ 1992) in the northern part of the EACC (off the Iberian Peninsula) and a few years later (~ 1995) off the coast of NW Africa. Changes in the productivity of several small pelagic fish species observed for the same period suggest that there was a response of the ecosystem to these changes (Fig. 9) (Santos et al., 2005). The European sardine (Sardina pilchardus) is the most important small pelagic fishery of the Western Iberia Upwelling Ecosystem (WIUE). Recently, recruitment of this species has declined and this can be, at least partially, explained by changing environmental conditions. Simulation studies using using a Regional Ocean Modeling System climatology (1989–2008) coupled to the Lagrangian transport model, Ichthyop, showed that there is a weak, continuous alongshore transport between release areas, though a large proportion of simulated ichthyoplankton transport north to the Cantabrian coast (up to 27%). We also show low level transport into Morocco (up to 1%) and the Mediterranean (up to 8%) (Fig. 10). The high proportion of local retention and low but consistent alongshore transport supports the idea of a series of metapopulations along this coast and to explain how these small pelagic fish have adapted their reproductive strategies in a coastal upwelling system to ensure coastal retention and recruitment success (Santos et al., 2018). The optimal temperature for larval sardine development varies between 13 and 17 °C and survival outside these boundaries is reduced, particularly during the first weeks of life (Garrido et al., 2016). At the same time, larvae depend of large food concentrations to be able to survive (Caldeira et al., 2014). Thus, low larval survival linked with sub-optimal temperature and low food availability may result in low recruitment strength. In general, high recruitment years are associated with high food availability (Chla) and low temperature (SST), but this is recruitment area-specific. High recruitment years are mostly related to high food availability, particularly during the last quarter of the previous year. In Western Iberia and in the Gulf of Cadiz, high recruitment years were also associated to lower SST, whereas in the Bay of Biscay, where SST during the winter was generally below the optimal range ≈11–12 °C for sardine larval development, higher recruitment is associated with high SST (Garrido et al., 2017). Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Acknowledgements These studies are funded by FCT through projects MODELA (PTDC/MAR/098643/2008), SURVIVAL (PRAXIS/P/CTE/11282/1998), PO-SPACC (FCT PRAXIS/CTE/11281/98), Pro-Recruit (POCTI/1999/BSE/36663), IMPROVE (PTDC/MAR/110796/2009), MedEx (MARIN-ERA/MAR/0002/2008), UID/Multi/04326/2016 and ID/Multi/04326/2019. European funds are received for projects SIGAP (EC-FEDER 22-05-01-FDR-00013), SAFI (FP7-Grant agreement n° 607155) and the EUR-OCEANS network of excellence (Contract No. 511106). References Bartilotti, C., A. dos Santos, M. Castro, A. Peliz, A.M.P. Santos (2014). Decapod larval retention within distributional bands in a coastal upwelling ecosystem. Marine Ecology Progress Series, 507: 233–247. Caldeira, C., A.M.P. Santos, P. Ré, M.A. Peck, E. Saiz, S. Garrido (2014). Effects of prey concentration on ingestion rates of European sardine (Sardina pilchardus) larvae in the laboratory. Marine Ecology Progress Series, 517: 217-228. Checkley, D., J. Alheit, Y. Oozeki, C. Roy, Eds. (2009). Climate Changers and Small Pelagic Fish. Cambridge University Press, 372 p. Chícharo, M.A., E. Esteves, A.M.P. Santos, A. dos Santos, A. Peliz, P. Ré (2003). Are sardine larvae caught off northern Portugal in winter starving? An approach examining nutritional conditions. Marine Ecology Progress Series, 257: 303-309. dos Santos, A., A. M. P. Santos, D. V. P. Conway, C. Bartilotti, P. Lourenço, H. Queiroga (2008). Diel vertical migration of decapod larvae in the Portuguese coastal upwelling ecosystem: implications for offshore transport. Marine Ecology Progress Series, 359: 171-183. Garrido S., A. Cristóvão, C. Caldeira, R. Ben-Hamadou, N. Baylina, H. Batista, E. Saiz, M.A. Peck, P. Ré, A.M.P. Santos (2016). Effect of temperature on the growth, survival and foraging behaviour of Sardina pilchardus larvae. Marine Ecology Progress Series, 559: 131-145. Garrido, S., A.M.P. Santos, A. dos Santos, P. Ré (2009). Spatial distribution and vertical migrations of fish larvae communities off Northwestern Iberia sampled with LHPR and Bongo nets. Estuarine, Coastal and Shelf Science, 84: 463-475. Garrido, S., A. Silva, V. Marques, I. Figueiredo, P. Bryère, A. Mangin, A.M.P. Santos (2017). Temperature and food-mediated variability of European Atlantic sardine recruitment. Progress in Oceanography, 159, 267-275. Moreno; A., A. dos Santos, U. Piatkowski, A.M.P. Santos, H. Cabral (2009). Distribution of cephalopod paralarvae in relation to the regional oceanography of the western Iberia. Journal of Plankton Research, 31: 73-91. Peliz, A., Marchesiello, P., Dubert, J., Roy, P., Almeida, M., H. Queiroga (2007). A study of crab larvae dispersal on the Western Iberian Shelf: Physical processes. Journal of Marine Systems, 68(1-2): 215-236. Pires, R.F.T., M. Pan, A.M.P. Santos, A. Peliz, D. Boutov, A. dos Santos (2013). Modelling the variation in larval dispersal of estuarine and coastal ghost shrimp: Upogebia congeners in the Gulf of Cadiz. Marine Ecology Progress Series, 492: 153-168. Ribeiro A.C., A. Peliz, A.M.P. Santos (2005). A study of the response of chl-a biomass to a winter upwelling event off western Iberia using SeaWiFS and in situ data. Journal of Marine Systems, 53: 87-107. Santos, A. M. P., A. Kazmin, A. Peliz (2005). Decadal changes in the Canary upwelling system as revealed by satellite observations, and their impact in the productivity. Journal of Marine Research 63(2): 359-379. Santos, A. M. P., A. Peliz, J. Dubert, P.B. Oliveira, M.M. Angélico, P. Ré (2004). Impact of a Winter Upwelling Event on the Distribution and Transport of Sardine Eggs and Larvae Off Western Iberia: A Retention Mechanism. Continental Shelf Research, 24: 149-165. Santos, A. M. P., P. Ré, A. dos Santos, A. Peliz (2006). Vertical distribution of the European sardine (Sardina pilchardus) larvae and its implications for their survival. Journal of Plankton Research, 28(5): 523-532. Keywords: Coastal upwelling, Phyto- and zooplankton, Cephalopod paralarvae, ichthyoplankton, Sardine (Sardina pilchardus), small pelagic fish, transport, retention, Dispersal, Connectivity (B) Conference: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019. Presentation Type: Keynote talk Topic: Keynote lecture Citation: Santos AP (2019). Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem. Front. Mar. Sci. Conference Abstract: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) . doi: 10.3389/conf.fmars.2019.08.00006 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Aug 2019; Published Online: 27 Sep 2019. * Correspondence: Mx. A. Miguel P Santos, Portuguese Institute of Ocean and Atmosphere (IPMA), Lisbon, Portugal, amsantos@ipma.pt Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers A. Miguel P Santos Google A. Miguel P Santos Google Scholar A. Miguel P Santos PubMed A. 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