The coastal zone of the Humboldt Current system is one of the world´s most productive aquatic ecosystems. Although some studies have been oriented towards understanding the relationship between climate, environmental factors, and productivity, oceanographic processes related to key species dynamics are not fully understood. With respect to human resources there is an enormous lack in knowledge of the life history and ecology of many coastal benthic and pelagic species despite their enormous importance for artisanal fishery. Freshwater impact is also important in the coastal zone. Especially the transport of water and sediments to the coastal system determines the boundary condition of the nearshore region. The activities within this workpackage focus on the following issues:

1. Collection, archiving, dissemination, and analysis of existing data on pelagic-benthic processes in the coastal zone of the Humboldt Current system.

2. Realisation of process-oriented studies on pelago-benthic coupling complementary to ongoing time series work on the eastern South Pacific continental shelf.

3. Collection of existing information and field studies on the ecology of coastal fish and pelagic larvae of benthic key species caught by artisanal fisheries.

4. Quantification of the terrestrial hydrological cycle and estimation of the mass transport (freshwater surface runoff and related sediments) to the nearshore marine system via the river network.

In this work package, CENSOR will assess seasonal and interannual changes in the Humboldt Current system and their influence on the distribution, community structure, population dynamics, and production of coastal benthic and pelagic species, and on fluxes of to the sea floor. In this way, processes which influence the abundance and production of key species can be understood. This approach includes hydrographical studies, studies of the abundance, composition, and biomass of pelagic communities, of particle fluxes, bacterial production, and sedimentological studies. Special attention is directed to the ecology of species relevant to artisanal fishery.

We will contribute with information on the distribution and development of life-history stages of benthic and fish larvae identified in the laboratory by workpackage 3 and provide a detailed description of their physical and biological environment. Results of trophodynamic studies workpackage 1 will be used in models of workpackage 4.

Our results will help to identify mechanisms that mediate the climate signal to the ecosystem, to complete and better understand observations from existing time series, and plan efficient time series work in the future.

For the general description of the environmental and biological conditions we will build on ongoing time series work and use the existing grid of stations, which will be covered seasonally. Sampling frequency will increase in case of sudden climatic events such as EN. To obtain time series data of particle flux and currents, arrays of different sediment traps and a benthic lander, all equipped with current meters, will be moored from days to years, depending on water depth. As an innovative approach to resolve mesoscale physical and biological processes (thermoclines, fronts, oxygen minimal zone (OMZ)) quasi-synoptically, high resolution transects will complete each time-series survey using an undulating towfish.

Contact

Workpackage Leader: Ruben Escribano