McGill University
Ph.D. candidate
Supervisor: Andrew Hendry
Start: 2005-09-01
End: 2012-08-31
Personal page

Project

Ecological impacts of invasive trout in Patagonian lakes
Earth is undergoing an acute anthropogenic biodiversity crisis, and invasive species are a primary cause. Understanding the ecological impacts of two of the most disruptive cosmopolitan freshwater fish invaders, brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss), is a priority to develop conservation guidelines and learn about the functioning of natural ecosystems. The impacts of these salmonids native to the northern hemisphere are especially worrisome in cold-temperate freshwaters of the Southern Hemisphere, where they are now popular as sport fish. This region is the realm of the Galaxiidae, a family of freshwater and diadromous fishes considered amongst the most seriously threatened fishes known. The decline of galaxiids has been linked to trout invasions but data is often qualitative and ambiguous. Furthermore, little is known about the extent to which native ecosystems have been transformed, especially in lakes. My goal is to remedy some of these deficiencies by investigating Patagonian lakes. In order to isolate the impacts of trout on a single galaxiid species I chose an especially fish-depauperated study system – 25 lakes with only galaxiids and/or trout. Results of fishing catch-per-unit-effort data showed a strong negative association between the density of trout and the density of the most widespread Patagonia-endemic galaxiid, Galaxias platei. Furthermore, I ruled out alternative natural and anthropogenic confounding effects, and identified a critical natural constraint to salmonid invasion success which is widely applicable. Given the strong population-level impacts on the native fish, I examined the possibility of food web disruptions by focusing on isotopic (δ15C and δ13N) ontogenetic niche shifts. I looked at the reciprocal effects of the native and the invasive fish density on each other, a perspective rarely studied. I found strong effects whereby the galaxiid lost, at high trout density, its ability to enhance its trophic position during ontogeny, while trout achieved a high trophic position only at high G. platei density. Finally, by studying zooplankton along the galaxiid-trout density countergradient, I could demonstrate both a negative, strong top-down control on zooplankton elicited solely by G. platei, and a positive, strong top-down control elicited by the cascading effects of trout. My dissertation delivers overdue evidence of the detrimental effects of invasive trout on Patagonian galaxiids, contributes to the understanding of salmonid invasion ecology, and provides several mechanistic hypotheses and new perspectives on the pervasive nature of the ecological impacts of invasive fish predators. Based on my results, I advocate the management strategy of culling trout from overpopulated lakes to simultaneously protect native fish and enhance a lucrative sport fishery for large trout, and encourage the active protection of rare relicts of unspoiled native biodiversity.

Keywords

invasive species, ecology, Paleolimnology, salmonidae, galaxidae, trophic interactions, trophic niche shift, cascading effects , Galaxias platei, Salmo trutta, Oncorhynchus mykiss, Chile, invasiveness

Publications

1- MATING BEHAVIOR AND FERTILIZATION SUCCESS OF THREE ONTOGENETIC STAGES OF MALE ROCK SHRIMP RHYNCHOCINETES TYPUS (DECAPODA: CARIDEA)
Correa, Cristián, Juan A. Baeza, Enrique Dupré, Ivan A. Hinojosa, Martin Thiel
2000 Journal of Crustacean Biology

2- MALE DOMINANCE HIERARCHY AND MATING TACTICS IN THE ROCK SHRIMP RHYNCHOCINETES TYPUS (DECAPODA: CARIDEA)
Correa, Cristián, Juan A. Baeza, Ivan A. Hinojosa, Martin Thiel
2003 Journal of Crustacean Biology

3- Mating systems in caridean shrimp (Decapoda: Caridea) and their evolutionary consequences for sexual dimorphism and reproductive biology
CORREA, CRISTIÁN, MARTIN THIEL
2003 Revista chilena de historia natural

4- Population Structure and Operational Sex Ratio in the Rock Shrimp Rhynchocinetes Typus (Decapoda: Caridea)
Correa, Cristián, Martin Thiel
2003 Journal of Crustacean Biology

5- Female rock shrimp Rhynchocinetes typus mate in rapid succession up a male dominance hierarchy
Thiel, Martin, Cristi�n Correa
2004 Behavioral Ecology and Sociobiology

6- Chinook salmon invade southern South America
Correa, Cristián, Mart R. Gross
2007 Biological Invasions

7- Diversity of Aplochiton Fishes (Galaxiidea) and the Taxonomic Resurrection of A. marinus
Dominique Alò, Cristián Correa, Carlos Arias, Leyla Cárdenas
2013 PLoS ONE

8- Tissue preservation biases in stable isotopes of fishes and molluscs from Patagonian lakes
Correa, C.
2012 Journal of Fish Biology

9- Reciprocal trophic niche shifts in native and invasive fish: salmonids and galaxiids in Patagonian lakes
CORREA, CRISTIÁN, ANDREA P. BRAVO, ANDREW P. HENDRY
2012 Freshwater Biology

10- Invasive salmonids and lake order interact in the decline of puye grandeGalaxias plateiin western Patagonia lakes
Correa, Cristian, Andrew P. Hendry
2012 Ecological Applications

11- Fates beyond traits: ecological consequences of human-induced trait change
Palkovacs, Eric P., Michael T. Kinnison, Cristian Correa, Christopher M. Dalton, Andrew P. Hendry
2012 Evolutionary Applications

12- Testing the abundant-centre hypothesis using intertidal porcelain crabs along the Chilean coast: linking abundance and life-history variation
Rivadeneira, Marcelo M., Patricio Hernáez, J. Antonio Baeza, Sebastian Boltaña, Mauricio Cifuentes, Cristian Correa, Alejandra Cuevas, Erasmo del Valle, Iván Hinojosa, Niklas Ulrich, Nelson Valdivia, Nelson Vásquez, Anke Zander, Martin Thiel
2010 Journal of Biogeography