Debunking paradigms in estuarine fish species richness

Abstract

The comparison of species complements within and between habitats and geographical areas is a fundamental aspect of ecological assessments. However, many influences resulting from variability in sampling and data analysis often hinder the ability to determine important patterns in community structure. The study is based on the hypothesis that using a standard sampling method, an asymptote in the rarefaction curve represents the total (gear-specific) species complement likely to be encountered for the geographical area. Accordingly, an asymptotic species richness estimator was used to predict the full complement of species present within each estuary that could be caught using seine netting. The rarefaction curves and species richness estimator enable the interrogation of two underlying paradigms of ecological species richness: the species-energy relationship and the species-area relationship. This analysis reveals distinct groups which show a significant relationship with latitude and size, although the size effect has a smaller influence. In particular, the species-latitude relationship paradigm holds true in this study while the species-area relationship paradigm only applies when latitude is considered concomitantly. Marine species in particular appear to account for the increased fish species number at lower latitudes. The underlying influence of latitude and estuary size suggests that any managerial tool that explores anthropogenic impacts (such as those used in the European Water Framework Directive) should include these aspects. It is concluded that the analysis gives environmental managers an objective cost-beneficial method of identifying when and where further sampling does not give further information for management.

Biodiversity assessment across a dynamic riverine system: A comparison of eDNA metabarcoding versus traditional fish surveying methods

“…However, any future studies should increase the volume of water filtered, as this is likely to increase the probability of detecting less abundant species. The detection of estuarine fish species richness using traditional methods is known to be problematic (Waugh et al, 2018) and although it has great potential, eDNA needs to be optimized for estuarine environments. Data derived from eDNA have only recently begun to be used in existing bioassessment programs with encouraging results (Bagley et al, 2019; Pont et al, 2019) although it is also proposed that current assessments of ecological quality could be adapted to eDNA frameworks (Hering et al, 2018; Ruppert et al, 2019).…”

Community dynamics of estuarine forage fishes are associated with a latitudinal basal resource regime

“…Apalachicola Bay and Cedar Key are located in the confluence between temperate and subtropical ecoregions. This may allow for higher taxonomic diversity through a mixture of species (Waugh et al, 2019), as temperate residents comingle with seasonally ephemeral subtropical taxa during warmer months. Indeed, seven of the 50 taxa were found only in either Apalachicola Bay or Cedar Key, while only one taxon was found exclusively in Tampa Bay or Charlotte Harbor.…”

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

“…When sample sizes are not uniform among sites or over time, SR obs values need to be corrected for SC before valid comparisons can be made. However, such methods have so far only rarely been used for coastal and estuarine fish assemblages (Waugh et al, 2019).…”