DOI: 10.5061/dryad.37pvmcvr1
title: Dynamics-based characterisation and classification of biodiversity indicators

description: Various biodiversity indicators, such as species richness, total
 abundance, and species diversity indices, have been developed to capture
 the state of ecological communities over space and time. As biodiversity
 is a multifaceted concept, it is important to understand the dimension of
 biodiversity reflected by each indicator for successful conservation and
 management. Here we utilised the responsiveness of biodiversity
 indicators’ dynamics to environmental changes (i.e. environmental
 responsiveness) as a signature of the dimension of biodiversity. We
 present a method for characterising and classifying biodiversity
 indicators according to environmental responsiveness and apply the
 methodology to monitoring data for a marine fish community under
 intermittent anthropogenic warm water discharge. Our analysis showed that
 ten biodiversity indicators can be classified into three super-groups
 based on the dimension of biodiversity that is reflected. Group I (species
 richness and community mean of centre of distribution latitude (cCOD))
 showed the greatest robustness to temperature changes; Group II (species
 diversity and total abundance) showed an abrupt change in the middle of
 the monitoring period, presumably due to a change in temperature; Group
 III (species evenness) exhibited the highest sensitivity to environmental
 changes, including temperature. These results had several ecological
 implications. First, the responsiveness of species diversity and species
 evenness to temperature changes might be related to changes in the species
 abundance distribution. Second, the similar environmental responsiveness
 of species richness and cCOD implies that fish migration from lower
 latitudes is a major driver of species compositional changes. The study
 methodology may be useful in selecting appropriate indicators for
 efficient biodiversity monitoring.
description: A long-term monitoring dataset for a marine fish
 community on the coast of Uchiura Bay (35 °32' N, 135 °30' E)
 was used. The monitoring area was located 2 km from the discharge outlet
 of the Takahama Nuclear Power Plant (NPP). The Takahama NPP started
 operation in 1974 and was shut down for two periods: 4 years from February
 2012 to January 2016, and
 14 months from March 2016 to May 2017 (Kansai Electric Power Group
 2021). During operation,
 Takahama NPP drains a
 maximum thermal discharge of 238
 m<sup>3</sup>s<sup>-1</sup>, which is 7 °C higher
 than the water temperature in the natural environment
 (Kokaji
 1995). As a result, the
 temperature increase in the survey area due to the NPP operation is
 approximately 2 °C (Masuda
 2020).  Abundance data for each fish species were
 obtained by direct visual underwater surveys, covering an area of
 approximately 1200 m<sup>2</sup> (2 m wide by 600 m long).
 These surveys were conducted once a month from January 18,
 2012, to April 26,
 2019. The fish
 identification procedure followed that described by Nakabo et al. (2013). The survey method was previously described by Masuda (2020). Data were obtained at 88 time-points over 7
 years. A total of 95 fish species were recorded during the survey
 periods (Figure 1:
 Examples of fish species observed in the survey). Using
 time-series data, ten
 biodiversity indicators were calculated for each survey, including species
 richness (i.e., number of species), relative abundance of species, and
 differences in fish taxonomy and geographic
 distribution.
description: One of the
 R packages used for the regularised S-map analysis is available on GitHub
 (https://github.com/somanyfrogs/density_dependent_study/tree/main/rpkg).