POSTER SESSION 1
15:30–17:30, Monday, September 14
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1213 | POSTER 125
RELATIONSHIPS BETWEEN PHYTOPLANKTON BIOMASS, SIZE DISTRIBUTION, AND YELLOWFIN TUNA PRESENCE USING SENTINEL 3/OLCI AND FISHERIES DATA IN THE EASTERN TROPICAL PACIFIC
This study aims to better define the link between primary producers and top oceanic predators. These represent opposite levels of the trophic chain, and models are usually required to establish relationships between them. Since primary producers can be estimated from remote sensing, their biomass can be retrieved at large scale and in near real time. Primary producers are commonly approximated using chlorophyll concentration, but they can also be separated into functional types, which may be more appropriate for linking with top predators, since bigger phytoplankton, are presumably the main drivers of productivity for such trophic levels.
Primary producer biomass was estimated using satellite-derived chlorophyll concentration, and size composition was studied by adapting the method developed by Kostadinov (2009), based on the backscattering spectral slope. Model parameters were optimized for Sentinel-3/OLCI data, and a neural network was trained to replicate the physical model’s results. The training strategy was constrained to preserve gradients, since oceanic fronts are supposed to be important drivers of fish habitats.
Generalized additive models were used to compare the influence of sea surface temperature, phytoplankton biomass, and size distribution, and their gradients. The results suggest that absolute values of chlorophyll and sea surface temperature may be more significant indicators of fish presence than their respective gradients, as evidenced by lower p-values (<0.005). Furthermore, the analysis shows an optimal 20-day lag between phytoplankton bloom and yellowfin tuna in the Eastern Tropical Pacific, which is shorter but still consistent with the ecological timescales usually used for trophic transfer.
Lea Schamberger, Collecte Localisation Satellites, [email protected]
Camille Keisser, Collecte Localisation Satellites, Ramonville-St-Agne, France, [email protected]
Vincent Laborde, Collecte Localisation Satellites, Ramonville-St-Agne, France, [email protected]
Jihwan Kim, Collecte Localisation Satellites, Ramonville-St-Agne, France, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
