Tampa Bay Nekton Index

Overview

The Tampa Bay Nekton Index (TBNI) is a multimetric assessment method that quantifies the ecological health of the nekton community (fish and selected invertebrates) in Tampa Bay. The TBNI uses catch data from the Florida Fish and Wildlife Conservation Commission (FWC) Fish and Wildlife Research Institute’s (FWRI) Fisheries-Independent Monitoring (FIM) program. The index uses FIM data to calculate five metrics that are sensitive to stressor gradients and provide unique information about Nekton community response to environmental conditions. The metrics include:

  • NumTaxa: Species richness
  • BenthicTaxa: Species richness for benthic taxa
  • TaxaSelect: Number of “selected” species (i.e., commercially and/or recreationally important)
  • NumGuilds: Number of trophic guilds
  • Shannon: Shannon Diversity (H)

Raw metrics are first calculated from the observed data and then scaled to a standard score from 0 – 10. The final TBNI score is the summed average of the scores ranging from 0 – 100. The final TBNI scores are binned into assessment categories that serve as management guidelines each year for activities to support environmental resources of the Bay: Stay the Course, Caution, and On Alert.

Scores over time for the Tampa Bay Nekton Index. Scores are shown as annual averages for major bay segments (Old Tampa Bay, Hillsborough Bay, Middle Tampa Bay, Lower Tampa Bay).

The TBNI dashboard provides an interface to view and download results for all locations in Tampa Bay where index scores have been calculated.

The TBNI interactive dashboard

The tbeptools R package includes several functions to import data required for the index, analyze the data to calculate metrics and index scores, and plot the results to view trends over time. A detailed vignette is available on the tbeptools website that provides an overview of how to use the functions to calculate TBNI metrics and scores.