ISOZOO

Isotopes of Zooplankton to measure climate and human impacts on pelagic food webs

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 Obiettivo del progetto (Objective)

'In all pelagic marine food-webs, zooplankton are the critical link between the phytoplankton primary producers and higher trophic levels, including fish. On-going changes observed for zooplankton communities in the Mediterranean and other oceans around the world therefore have serious implications for food-web productivity, and their continued provision of ecosystem services (e.g., food security). Current gaps in our knowledge of how the zooplankton component of the food-web functions, limit our ability to sustainably manage our marine resources. The ISOZOO program is designed to make a significant contribution to our understanding of zooplankton food-web processes, and how climate change and anthropogenic impacts affect these. Facilitated by IIF mobility, this overarching goal will be achieved by a multi and interdisciplinary approach, combining stable isotope ecology, ocean biochemistry, physical and biological oceanography, and ecosystem modelling. Working with a set of collaborators at the LOPB in Marseille, we will define Phyto-Zooplankton relationships across a range of nutrient conditions, and estimate the impact of these relationships on zooplankton food-chain length and transfer efficiencies. Established relationships between zooplankton and phytoplankton-nutrients will be used to: 1. develop an Index of zooplankton food-web status that can be applied to monitor food-web response to changing ocean conditions (physics & nutrients) and, 2. parameterise the Eco3M bio-physical model for the Gulf of Lion, to simulate/predict the impacts of climate change and anthropogenic forcing on ecosystem function. Together objectives 1 and 2 should allow for better informed management of marine resources given future variability. Through collaboration beyond the time frame of this project we aim to develop world-wide application of the Food-Web Index (1) and model parameters (2) through networks of international collaborators for climate change monitoring and research.'

Introduzione (Teaser)

Researchers used a multidisciplinary approach to measure the effects of climate change and human activity on food webs in the ocean.

Descrizione progetto (Article)

Plankton are marine-dwelling microscopic plants (phytoplankton) and animals (zooplankton) that form an essential part of pelagic food webs. At the bottom of the food chain, phytoplankton are primary producers that convert sunlight into carbohydrates. Since zooplankton eat phytoplankton and themselves are eaten by higher organisms like fish, they play a critical role in linking food webs.

The EU-funded 'Isotopes of zooplankton to measure climate and human impacts on pelagic food webs' (ISOZOO) project analysed environmental conditions affecting phyto-zooplankton food web structures.

To simulate the effect of future nutrient-deficient oceans, researchers sampled and characterised food web structures in oceans spanning nutrient-rich to nutrient-poor environments. Using data from the Mediterranean Sea and South Pacific, North Pacific and South Atlantic Oceans, researchers confirmed that food chains were longer in nutrient-poor than in nutrient-rich regions.

Since energy is lost with each step in the food chain, food-chain length has a profound effect on top-end predators. Nutrient-rich conditions supporting large, highly productive phytoplankton species require fewer trophic levels and result in increased animal and fish biomass.

Conversely, in nutrient-poor regions low primary productivity from smaller phytoplankton leads to increased food-chain length, energy loss at each step and decreased top-level predator biomass.

ISOZOO will use established zooplankton-phytoplankton nutrient relationships to develop a zooplankton food web index to monitor climate-induced changes in ocean conditions. Ultimately, they hope their data will be incorporated into ecosystem models to enhance ocean food web management amid predicted changes in oceanic nutrient conditions.