WP2-Task 2.1�Global ecological impacts of

con- vs. heteropecific salmonid invasions �

Mathieu  Buoro  &  Julien  Cucherousset  

Toulouse  2015  

Context: Salmonids as invasive species

•  Introduction outside of their native range and into areas containing native salmonids species

Toulouse  2015  

I N T RO D U C T I O N S , S T O C K I N G , E C O L O G Y A N D E VO L U T I O N 1909

Fig. 1. Inter-country stocking of Salvelinus fontinalis from 1868 to 1990. Each arrow extends from the sourcecountry to the destination country [the arrow heads to the east of South Africa are directed to the CrozetIslands ( ) and Kerguelen Islands ( )]. The years associated with each stocking event are identified inTable I. Data were collated from Froese & Pauly (2013).

has unintentionally yielded novel research and research opportunities in areas unrelatedto the primary causes and consequences of introductions and stocking. These unantic-ipated insights are directly related to a key condition for the persistence and naturalreproduction of an introduced or stocked population in the wild: evolutionary changeby the colonizing population in response to novel, local selection pressures.

Natural environmental change over the millennia has produced countless opportuni-ties for species to disperse into and persist in habitats where they previously did notexist. Isostatic, post-glacial rebound provides a common and striking example of howshifts in the physical landscape can facilitate fish movement by connecting previouslydisjunct bodies of water (Smith & Bermingham, 2005; Griffiths, 2006). Introductionand stocking programmes have facilitated similar sorts of colonization opportunitiesacross considerably greater geographical scales and much shorter time periods (Fig. 1and Table I). This study provides an opportunity to consider introductions and stock-ing from a perspective not typically ascribed to these practices, as a research vehiclefor enhancing knowledge of the ecology and evolution of fishes, and potentially as ameans of informing current and future conservation-based, re-introduction and stock-ing programmes.

LOCAL ADAPTATION AND RATE OF EVOLUTION

Somewhat paradoxically, both stocking and introductions have provided some of thestrongest evidence for the phenomenon that they are often feared to corrupt: local adap-tation. Some of this evidence comes from studies that compare metrics of the fitnessof stocked individuals with wild members of the same species inhabiting the same

© 2014 The Fisheries Society of the British Isles, Journal of Fish Biology 2014, 85, 1907–1926

Inter-country stocking of Salvelinus fontinalis from 1868 to 1990 (from Hutchings 2014)

Cucherousset & Olden 2011 Fisheries

The ecological impacts on-native Salmonids have been well studied……

But… No studies have quantitatively assessed the scientific knowledge on the ecological impacts of non-native salmonids

Context: Salmonids as invasive species

Toulouse  2015  

•  Global ecological impacts of salmonid invasions •  Determining which introductions (intraspecific vs

interspecific) have the strongest ecological impacts:  –  intraspecific invasions had stronger impacts at lower

levels (individual & population) of biological organization?

–  interspecific invasions had stronger impacts at higher levels (community & ecosystem) of biological organization?

Context: Objectives

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•  Literature review and meta-analysis of the ecological impacts

•  Across levels of

biological organization

Cucherousset & Olden 2011 Fisheries

Toulouse  2015  

Material & Method: A global meta-analysis

Follow the procedure used in the recently published meta-analysis:

Material & Method: A global meta-analysis

Toulouse  2015  

Literature search procedure:

-  ISI Web of Science: peer-reviewed papers and studies referenced within the articles obtained from this search

-  Review the references cited section of each article Only manipulative experimental studies : -  To avoid other confounding effects on the response of organisms -  Manipulation: ex situ (laboratory, outdoor mesocosms) or in situ (sections/

caging)

Only studies that compared organisms exposed to nonnative Salmonids (treatment) to organisms without nonnative Salmonids (control) -  Species under consideration: only those investigated in SalmoInvade

(Salmo, Oncorhynchus, Salvelinus) Toulouse  2015  

Material & Method: A global meta-analysis

Search terms (keywords combinations):

Organisms Topic Manipulation Effects salmonid* invasi* experiment* impact* trout* invader manipulat* Effect* salmon* alien control consequence* char exotic treatment Interarction* salmo nativ* /nonnative laboratory Affect* salvelinus Introduc* channel* Comparison* oncorhynchus Nonindigenous /

indigenous

Channel/ River* /stream*/lake

Change*

Stocked / stocking /hatchery-reared

Tank / mesocosm*

modif*

naturaliz* /Domesticated*

Removal / eradication /suppression

influence

Toulouse  2015  

Material & Method: A global meta-analysis

3908 records identified through the database (WOK)

and reference searching (from 1987 to 2014)

3908 records screened 3582 records deemed

not suitable based on evaluation of abstract

326 full-text articles assessed for eligibility records

screened

59 studies included in quantitative synthesis

> 1047 essays (~8.4/study)

267 full-text articles excluded because of

values could not be extracted (no control) or field work

Toulouse  2015  

Material & Method: A global meta-analysis

Study selection and data extraction (following Twardochleb et al. 2013)

Toulouse  2015  

Material & Method: A global meta-analysis

See database

Gene$c  

Individual  

Popula$on  

Community  

Ecosystem  

Toulouse  2015  

Classification of response measured to trait classes:

Introgression  

Growth  Size  Aggressiveness  …  

Energy    Primary  producBon  

Biomass  Species  richness  

Density  Movement  Survival  

Results: Literature research

Direct fitness (survival) Indirect fitness (Growth) Demography (density) Physiology Foraging Displacement Behavior Diversity Habitat use

•  Cohen's d (or Standardized Mean Difference, SMD) as the metric of effect size for ecological responses

•  An effect size of 0.2 to 0.3 might be a "small" effect,

around 0.5 a "medium" effect and 0.8 to infinity, a "large" effect

Material & Method: Data analysis

Toulouse  2015  

Treatment mT mean ST standard deviation

Control mC mean SC standard deviation d  

•  Negative values of SMD indicate a negative effect of nonnative salmonid on the measured response variable (e.g., biomass or abundance) compared to controls of native salmonid.

•  SMD method does not correct for differences in the direction of the scale.

•  We multiplied the mean values from one set of studies by –1 to ensure that all the scales point in the same direction (e.g. aggressiveness, primary production, hormones)

•  We also controlled for phylogenetic relationships (using distance calculated from Macqueen & Johnston, 2014)

Material & Method: Data analysis

Toulouse  2015  

•  R package: meta & metafor •  Weighted analysis •  Fixed / random effects •  Meta-regression

Material & Method: Data analysis

Toulouse  2015  

Results: Distribution of publications

Toulouse  2015  

>  60  %  of  studies  are  located  in  North  America  >  30  %  of  studies  are  located  in  US  only  

World  map  about  here  

Results: Geographical distribution of publications

Toulouse  2015  

>  80%  

Results: Distribution of publications

Toulouse  2015  

Salmo trutta   Oncorhynchus mykiss

Salvelinus fontinalis

Oncorhynchus tshawytscha

Oncorhynchus kisutch

Salmo salar  

Results: Intra vs. Interspecific effects sizes

Intraspecific  

Interspecific  

No significant difference

p-value = 0.34

Overall impact  

Toulouse  2015  

No impact  

Results: Effects sizes across levels of organization

Toulouse  2015  

Results: Effects sizes across levels of organization

No significant differences between levels of

organization

Overall impact  

Toulouse  2015  

No impact  

Results: Effects sizes across salmonid genus

Non native species

Toulouse  2015  

Results: Effects sizes across salmonid genus

Toulouse  2015  

No clear significant differences (p-value = 0.054)

Overall impact  

Results: Effects sizes across salmonid genus

Toulouse  2015  

Test for subgroup differences: p-value=0.036

Test for subgroup differences: p-value=0.91

Test for subgroup differences: p-value=0.21

Results: Effects sizes across salmonid genus

Toulouse  2015  

Test for subgroup differences: p-value=0.17

Test for subgroup differences: p-value=0.23

Test for subgroup differences: p-value=0.26

Results: Effects sizes across taxonomy

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Results: Effects sizes across taxonomy

Toulouse  2015  

Overall impact  

Results: Effects sizes across response measured

Toulouse  2015  

Results: Effects sizes across responses measured Overall impact  

Toulouse  2015  

Results: Effects sizes across experimental venues

Toulouse  2015  

Overall impact  

No significant differences P-value > 0.61

Results: Bias

Toulouse  2015  

Linear regression test of funnel plot asymmetry Asymmetry in funnel plot (p-value = 0.0002)

Meta-analyses can be influenced by the publication bias associated a tendency of journals to publish studies showing significant results "fail-safe number” Number of studies combined: k=389 (with 32 added essays) SMD 95%-CI -0.1886 [-0.2769; -0.1004] p-value < 0.0001

•  No  significant  difference  of  impact  between  intra  vs.  interspecific  

•  Should  we  consider  interspecific  only  for  publicaHon?    BUT…  •  Less  studies  extracted  for  intraspecific:  –  Inappropriate  terms?  

•  Few  studies  at  higher  levels  of  organizaHon  –  Gap  idenHfied!  (Ims  experiment  2015)  

•  Impacts  variables  #  Traits  measured    

Conclusion

Toulouse  2015  

•  “OpHmize”  database  – ContacHng  authors  – UpdaHng  (arHcle  published  in  2015)  – Dealin  with  “0s”  

•  PublicaHon  

Next steps

Toulouse  2015