Evaluating detectability of freshwater fish assemblages in tropical streams: Is hand-seining sufficient?

Deacon, Amy E.; Mahabir, Rajindra; Inderlall, Devan; Ramnarine, Indar W.; Magurran, Anne E.

doi:10.1007/s10641-017-0610-5

Cited by 11 publications

(12 citation statements)

References 37 publications

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“…However, in no case did we detect a significant correlation between overall species richness and either biomass or numerical abundance across the 16 sites (see Appendix). This shows that richness cannot necessarily be used as a surrogate for risk, in this system at least, given its spatial scale and the gamma diversity involved ( Deacon et al 2017 ).…”

Section: Discussionmentioning

confidence: 99%

“…All fish were identified to species, and weighed individually to the nearest gram, with the exception of guppies, which were too small to be weighed in the field, and were instead noted as mature female, mature male, or juvenile (typical weights were then used to estimate biomass for this species). On occasions where fish were seen but not caught, length was estimated and an appropriate length–weight curve consulted to give an estimate of biomass (see Deacon et al 2017 for more details).…”

Section: Methodsmentioning

confidence: 99%

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Gradients in predation risk in a tropical river system

2018

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The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has provided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask: 1) Is there evidence for a gradient in predation risk? 2) Does the ranking of sites (by risk) change with the definition of the predator community (in terms of species composition and abundance currency), and 3) Are site rankings consistent over time? We find compelling evidence that sites lie along a continuum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study suggests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Gradients in predation risk in a tropical river system

2018

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“…The same 50-m stretches of stream were revisited each session. Fish were exhaustively sampled (35, 36) using a seine net followed by electrofishing (37). The species of all individuals were identified and counted.…”

Section: Methodsmentioning

confidence: 99%

Divergent biodiversity change within ecosystems

Magurran

Deacon

Moyes

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The Earth's ecosystems are under unprecedented pressure, yet the nature of contemporary biodiversity change is not well understood. Growing evidence that community size is regulated highlights the need for improved understanding of community dynamics. As stability in community size could be underpinned by marked temporal turnover, a key question is the extent to which changes in both biodiversity dimensions (temporal α- and temporal β-diversity) covary within and among the assemblages that comprise natural communities. Here, we draw on a multiassemblage dataset (encompassing vertebrates, invertebrates, and unicellular plants) from a tropical freshwater ecosystem and employ a cyclic shift randomization to assess whether any directional change in temporal α-diversity and temporal β-diversity exceeds baseline levels. In the majority of cases, α-diversity remains stable over the 5-y time frame of our analysis, with little evidence for systematic change at the community level. In contrast, temporal β-diversity changes are more prevalent, and the two diversity dimensions are decoupled at both the within- and among-assemblage level. Consequently, a pressing research challenge is to establish how turnover supports regulation and when elevated temporal β-diversity jeopardizes community integrity.

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“…The primary predators of guppies in the Northern Range are the pike cichlid, Crenicichla frenata and the wolf fish, Hoplias malabaricus [28]. A survey of these predators was conducted using hand seining (64 mm mesh) followed by electrofishing [29]. On capture, all the individuals were identified, counted and weighed on a portable balance, and finally released unharmed.…”

Section: (A) Assessment Of Temporal Heterogeneity In Predator Biomassmentioning

confidence: 99%

Individual variation in reproductive behaviour is linked to temporal heterogeneity in predation risk

et al. 2018

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Variation in predation risk is a major driver of ecological and evolutionary change, and, in turn, of geographical variation in behaviour. While predation risk is rarely constant in natural populations, the extent to which variation in predation risk shapes individual behaviour in wild populations remains unclear. Here, we investigated individual differences in reproductive behaviour in 16 Trinidadian guppy populations and related it to the observed variation in predator biomass each population experienced. Our results show that high heterogeneity in predator biomass is linked to individual behavioural diversification. Increased within-population heterogeneity in predator biomass is also associated with behavioural polymorphism. Some individuals adjust the frequency of consensual mating behaviour in response to differences in sex ratio context, while others display constantly at elevated frequencies. This pattern is analogous to a 'live fast, die young' pace-of-life syndrome. Notably, both high and low mean differences in predator biomass led to a homogenization of individual frequency of consensual mating displays. Overall, our results demonstrate that individual behavioural variation is associated with heterogeneity in predator biomass, but not necessarily with changes in mean values of predator biomass. We suggest that heterogeneity in predator biomass is an informative predictor of adaptive responses to changes in biotic conditions.

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Evaluating detectability of freshwater fish assemblages in tropical streams: Is hand-seining sufficient?

Cited by 11 publications

References 37 publications

Gradients in predation risk in a tropical river system

Gradients in predation risk in a tropical river system

Divergent biodiversity change within ecosystems

Individual variation in reproductive behaviour is linked to temporal heterogeneity in predation risk

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