Combining ex situ and in situ methods to improve water quality testing for the conservation of aquatic species

Abstract

1.Determining whether water quality is suitable is an important part of managing aquatic species for conservation, although it is often challenging to achieve. Past approaches have largely consisted of tests exposing individuals to artificial solutions, or field studies that examine the effect of a subset of water quality parameters on the distribution or abundance of a species.2. Owing to the complex nature of water chemistry in natural systems, which is difficult to replicate using laboratory studies or to capture entirely with correlational field studies, these types of study may not be suitable for determining accurately whether or not water quality at a particular site is suitable for a target species. In situations where conservation outcomes rely heavily on achieving this, an alternative approach is therefore needed.3. Embryos of the threatened green and golden bell frog Litoria aurea were placed in water collected from ponds that were used by this species for breeding and ponds where breeding was not detected at Sydney Olympic Park, Australia. After 19 days, the tadpoles were placed in enclosures in the same breeding and non-breeding ponds, and monitored until they metamorphosed.4. There was no difference in tadpole survival, time to metamorphosis or body condition between the two treatments, indicating that poor water quality was not a cause of low pond occupancy by tadpoles at the site and resources should be directed towards investigating other potential causes.5. We suggest that this method of an ex situ followed by an in situ exposure study is an effective approach to eliminating or confirming poor water quality as a cause of population declines and reduced occupancy, for species that are aquatic for at least part of their life cycle. Other applications include establishing that artificially created habitat provides suitable water chemistry, or identifying a potential location for a reintroduction project.

In situ works on ecotoxicology in amphibians: current state of the art

“…Summary of the main works presented in this research, summarizing the species studied, the location of the study, which pesticides were found, and the effects identified by the respective researchers. The environments used for the in situ experiments involved environments intended for general agricultural cultivation (Orton & Routledge 2011;Sparling et al, 2014), fruit orchards (Rosenbaum et al, 2012), rice cultivation (Attademo et al, 2014), soybean (Agostini et al, 2020;Dyck et al, 2021), maize and sorghum (Dyck et al, 2021), in addition to industrial use areas (Pollard et al, 2016) and water bodies with controlled spraying of pesticides (Thompson et al, 2004;Wojtaszek et al, 2005;Edge et al, 2014).…”

“…Among the main methodologies used to assess the effects of pesticides present in the environment, the survival and growth of tadpoles stand out (Thompson et al, 2004;Wojtaszek et al, 2005;Orton & Routledge, 2011;Edge et al 2014;Attademo et al, 2014;Sparling et al, 2014;Pollard et al, 2016;Agostini et al 2020;Dyck et al, 2021). In addition to these analyses, hatch success (Dyck et al, 2021), changes in mobility (Wojtaszek et al 2005;Agostini et al 2020), malformations (Thompson et al 2004), cytometry (Thompson et al, 2004), cell morphology (Attademo et al 2014) and biochemical markers such as carboxylase (Rosenbaum et al, 2012), cholinesterase (Attademo et al, 2014;Thompson et al, 2004), glutathione (Rosenbaum et al, 2012), and glutathione-Stransferase (Rosenbaum et al, 2012;Attademo et al, 2014) activities.…”

Experimental quantification of multiple point‐source pollution effects on juvenile freshwater mussels in a stream exposure gradient

“…This may also be applicable for other mussel species with broad potential uses in freshwater mussel action plans, information campaigns and stream biotope conservation. Future studies should focus on long‐term exposure to assess the full impact of contamination (Belamy et al, 2020), and ex situ and in situ exposure can be combined to improve water quality testing for the conservation of aquatic species (ASTM, 2013a; Patnode et al, 2015; Pollard et al, 2017; Wagner et al, 2018). Caged experiments could be performed simultaneously with bivalve surveys (Nobles & Zhang, 2015; Patnode et al, 2015) to compare field‐deployed mussel results with wild populations.…”

“…In situ exposure with subsequent evaluation of species performance is often used in conservation biology (Armstead & Yeager, 2007 and references therein) and provides valuable information on the environmental quality and site suitability for endangered species (Haag, 2012;Pollard et al, 2017), including FPM (Buddensiek, 1995;Gum, Lange & Geist, 2011;Bílý et al, 2018).…”

“…In situ exposure with subsequent evaluation of species performance is often used in conservation biology (Armstead & Yeager, 2007 and references therein) and provides valuable information on the environmental quality and site suitability for endangered species (Haag, 2012; Pollard et al, 2017), including FPM (Buddensiek, 1995; Gum, Lange & Geist, 2011; Bílý et al, 2018). Recent studies have confirmed the applicability of these bioindication methods for freshwater mussels at various spatial scales (Bartsch et al, 2017; Černá et al, 2018; Bílý et al, 2021), and several authors (Haag, 2012; Ferreira‐Rodríguez et al, 2019; Haag et al, 2019) recommend using field exposures to investigate the multiple‐stress effects in natural settings.…”