AUTHOR=Del Solar Alonso , Romagnoni Giovanni , Kluger Lotta C. , Céspedes Carlos M. Salazar , Wolff Matthias 

TITLE=Comparative Food Web Analysis of Two Peruvian Bay Systems Along a Latitudinal Gradient: Resource Use and the Environmental Envelope

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.829424

DOI=10.3389/fmars.2022.829424

ISSN=2296-7745

ABSTRACT=The coast of Peru lies within the tropics under the influence of the cold, nutrient-rich waters of the Humboldt Current and the interannual onslaught of El Niño phenomenon. The Peruvian upwelling system is exceptionally productive and has many unique ecosystems at different scales along the coast. We aimed to understand the differences between two shallow coastal systems: Sechura Bay in the north (at the convergence of Humboldt and tropical waters) and Independencia Bay in the central-south (under typical upwelling conditions); comparing their biodiversity, trophic dynamics, community energetics, resource use and underlying abiotic conditions. Over the past two decades, Sechura has shown a warming trend, while Independencia has maintained its cold water conditions. Chlorophyll concentrations have risen significantly in both systems, though higher values in Sechura suggest increasing local pressures. Trophic models of La Niña 07/08 period revealed that both systems are bottom-up driven with high biomass and production at the lower trophic levels. Benthic and demersal assemblages proliferate under average conditions of elevated temperatures and great primary production, even with reduced oxygen levels. Productivity was similar in both systems, with differences in the structure and size of their energy flows. More cycling was done in Independencia, where phytoplankton-based food chains played an essential role in the overall dynamic. In contrast, the detritus food chain appears to be crucial for energy flow in Sechura. Differences in biota and flow structure relate to the systems’ environmental conditions, i.e., more diverse warm-water species in the north and mostly invertebrates adapted to high-circulating cold water in the central-south. Catches in both systems were dominated by the diving fisheries and comprised mostly scallops (bottom-cultured), snails and fish in Sechura, and mussels, clams, crabs and fish in Independencia. Overall, system indicators suggest that Sechura is a comparatively less developed system. Independencia shall likely maintain its general highly-productive system features, possibly increasing its resilience over the following years, whereas Sechura will continue to be more frequently disturbed by El Niño and ongoing human-driven activities, reducing its overall stability and functionality. In the context of climate change, acknowledging these differences is essential for future adaptive management regimes.