Re-evaluating Primary Biotic Resource Use for Marine Biomass Production: A New Calculation Framework

Area of Science:

• Marine ecology
• Ecosystem modeling
• Biomass assessment

Background:

• Environmental impacts of biomass harvesting are often quantified using specific primary production required (SPPR).
• Existing methods often simplify complex marine food webs, potentially underestimating the true production demands.
• Understanding these demands is crucial for sustainable resource management and ecological impact assessment.

Purpose of the Study:

• To introduce a novel calculation framework for SPPR that explicitly incorporates full food web complexity.
• To compare SPPR estimates derived from the new framework with those from simplified food web approaches.
• To demonstrate the framework's utility in assessing ecological uncertainty and its application in different marine ecosystems.

Main Methods:

• Development of a new calculation framework for SPPR that integrates detailed food web dynamics.
• Application of the framework to the Icelandic marine ecosystem to estimate SPPR for toothed whales.
• Coupling the framework with food web modeling to explore the impact of ecological uncertainty, such as varying degrees of heterotrophy.
• Comparative analysis of SPPR estimates against traditional food chain theory and simplified food web models.

Main Results:

• The new framework yields SPPR estimates 2.8 times higher for toothed whales in Iceland compared to simplified models.
• Incorporating full food web complexity significantly increases SPPR values, with estimates 3.9 to 5.0 times higher than those based on food chain theory for herring and capelin, respectively.
• Model simulations show a two-fold increase in SPPR estimates in the Barents Sea with a 100% increase in flagellate heterotrophy.
• The framework highlights the sensitivity of SPPR estimates to ecological data and processes.

Conclusions:

• A comprehensive food web approach is essential for accurate SPPR quantification, revealing significantly higher biomass production requirements than previously estimated.
• The developed framework provides a robust method for assessing ecological uncertainty in SPPR calculations.
• Findings underscore the need to consider full food web interactions for realistic environmental impact assessments of biomass harvesting.
• The SPPR estimates are specific to the modeled time period and food web structure and should not be used for inferring changes due to external alterations.