Meta-analysis of Ecopath models reveals secondary productivity patterns across the Gulf of Mexico

The Gulf of Mexico large marine ecosystem (LME) is ecologically and economically important, yet faces numerous anthropogenic stressors. Common metrics driving ecosystem assessment and management, particularly at the LME scale, include fisheries harvest and primary productivity. However, neither is adequate in revealing a complete picture of ecosystem health. Secondary production is an important functional component of marine ecosystems. Yet, inherent difficulties in measuring higher productivity limit its use as an ecosystem indicator. The goals of this study were to: 1) use existing ecosystem models to estimate secondary production within the Gulf of Mexico, 2) identify productivity hotspots based on spatial patterns of secondary productivity across the Gulf LME, 3) compare trophic structure, function, efficiency, and productivity among ecosystem types within the Gulf, and 4) determine effectiveness of primary productivity as an indicator of secondary productivity. A meta-analysis of 18 Ecopath models describing Gulf of Mexico subsystems was conducted. Representative systems included temperate estuaries, tropical lagoons, continental shelves, and coral reefs. Annual secondary production ranged from 128 tonnes (t) wet weight (ww) km−2 in Tampamachoco Lagoon to 15 466 t ww km−2 in the Florida Keys. Spatial patterns of secondary productivity across the Gulf of Mexico LME demonstrate higher values in coastal regions, especially coral reefs. Secondary production is largely supported by benthic food webs across all ecosystems. Benthic food webs are also more efficient with regards to transfer of production than pelagic food webs. No significant relationships between primary and secondary production were observed via linear regression for any ecosystem type, indicating that primary production is not a strong indicator of secondary production. Comparative analyses of ecosystems across the Gulf of Mexico, such as the one presented here, identify critical areas at the LME scale, and support ecosystem-based management initiatives.