Planktonic ecological networks support quantification of changes in ecosystem health and functioning

Area of Science:

• Marine ecology
• Ecosystem dynamics
• Food web analysis

Background:

• Plankton communities form the base of marine food webs.
• Physicochemical changes significantly impact plankton, making them indicators of ecosystem health.
• The Venice Lagoon's ecosystem health is influenced by various factors, including sediment resuspension.

Purpose of the Study:

• To compare the planktonic food webs of Palude della Rosa in the Venice Lagoon during July 2005 and 2007.
• To assess the impact of environmental stressors, such as sediment resuspension, on the lagoon's ecosystem.
• To evaluate the role of plankton communities in monitoring ecosystem health and resilience.

Main Methods:

• Utilized a novel Monte Carlo random sampling approach to generate 1000 food web models for each year.
• Analyzed consumption flows, focusing on key zooplankton groups like Strombididae, Evadne spp., and Podon spp.
• Quantified functional nodes (FNs) and overall system indicators to compare food web structures and dynamics.

Main Results:

• Consumption flows involving specific zooplankton were key differentiators between the 2005 and 2007 food webs.
• Despite differences in functional nodes, overall system indicators remained similar between the two years.
• Sediment resuspension was identified as a major stressor, increasing turbidity and inhibiting primary producers, while benthic FNs primarily drove water column production.

Conclusions:

• Plankton communities are effective indicators for assessing the health of marine ecosystems like the Venice Lagoon.
• The Venice Lagoon ecosystem exhibited increased resilience at the expense of efficiency due to sediment resuspension stress.
• Understanding plankton dynamics is crucial for managing and monitoring estuarine environments.