210 Po and 210 Pb trophic transfer within the phytoplankton–zooplankton–anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea)

Abstract

The transfer of (210)Po and (210)Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of (210)Po and (210)Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes.

Patterns of trace metal bioaccumulation and trophic transfer in a phytoplankton-zooplankton-small pelagic fish marine food web

“…Our study enabled the characterization of trace metal burdens in seawater, plankton and two major small pelagic fish species from the GoL in the NW Mediterranean Sea. A consistent and original database was obtained on trace metal contamination in the study area, including its short, small pelagic fish food web, hence reinforcing available data on radionuclides and rare earth elements (Strady et al, 2015a(Strady et al, , 2015b. This geographical area is of major economic and ecological importance and has been widely investigated in recent years, in particular in the aim of understanding the potential drivers of change observed in the small pelagic fish community (e.g.…”

“…Various zooplankton habitats exist in the GoL, characterized by different biological and physical variables: species composition, size structure, depth, salinity, wind and currents (Espinasse et al, 2014a). Differences in zooplankton and pelagic fish isotopic signatures and radionuclide contamination have already been observed in the eastern and the western areas of the GoL (Espinasse et al, 2014b;Strady et al, 2015a). Phytoplankton and zooplankton communities display conspicuous seasonal variations in composition and structure, efle ed e respective carbon and nitrogen isotopic signatures Bă u e l , 2013; E e e l , 2014, 2014bH mel -Vivien et al, 2008).…”

“…1). As described in previous publications related to this study (Strady et al, 2015a(Strady et al, , 2015bTiano et al, 2014), the sampling strategy was adapted to the compartment and size of the sampled organisms. A chlorophyll a (Chl-e file (measured continuously) was obtained at e m l e u CTD be fi ed with flu me e .…”

“…Recent data on trace metal concentrations in plankton in the Mediterranean Sea are also relatively scarce (however, see Battuello et al, 2016;Rossi and Jamet, 2008;Strady et al, 2015aStrady et al, , 2015b for recent data reported in the northwestern Mediterranean Sea) in comparison to the numerous Mediterranean Sea studies conducted in the 1980s (see in Roméo et al, 1992). Different plankton species are known to show significant variations in terms of metal bioaccumulation (Battuello et al, 2017;Bhattacharya et al, 2014;Levy et al, 2008).…”

Effects of Pollution on Marine Organisms

“…Radionuclides. Strady et al (2015) measured the transfer of 210 Polonium in a food web consisting of phytoplankton, zooplankton and fish. Different size classes of fish food were measured in the spring and winter months.…”