Modeling round goby Neogobius melanostomus range expansion in a Canadian river system

Jacob Brownscombe,Michael Fox,Laurence Masson,David Beresford

doi:10.3391/ai.2012.7.4.010

Abstract

Abstract We applied a gamma transit time model to predict the rate of range expansion of the round goby ( Neogobius melanostomus Pallas, 1814) in the Trent-Severn Waterway (Ontario, Canada). Gamma distributions were fit to actual transit times of the population front from 2009 to 2011. A lack of model fit in the second year is thought to be indicative of an upstream bait bucket introduction, and this model may be useful for identifying such events. Range expansion predictions were highest in high quality habitats at 9.3 km/year, with a 5% probability that highly mobile individuals may disperse 27 km/year. The model also predicts the arrival time of the population at any distance from the population front with a given confidence interval. The estimation of a timeline for range expansion and determining underlying factors affecting the spread of invasive species could inform preventative strategies. This model is potentially useful in predicting transit times of other invasive species expanding their range in linear space, and in separating natural population expansion from additional human-assisted movement in the same system.

Highlights

Once established, invasive species often undergo range expansion as individuals disperse from the population core (Shigesada and Kawasaki 1997)
The model was a good fit to the 2009−2010 range expansion data, but was a poor fit to the 2010−2011 unmodified dataset (Figure 2a,b; Figure 2: Probability distribution of actual and model transit times of round goby range expansion from (A) 2009 to 2010, (B) 2010 to 2011 including sites suspected to be sourced from an outside introduction 31 km upstream of the infested zone in 2009, (C) 2010 to 2011 excluding outside sourced sites, (D) 2009 to 2011 excluding outside sourced sites, (E) 2009 to 2011 low quality habitat sites, and (F) 2009 to 2011 high quality sites in the TrentSevern Waterway
The gamma transit time model was shown to be a useful tool for predicting many aspects of round goby range expansion in the Trent-Severn Waterway

Summary

Introduction

Invasive species often undergo range expansion as individuals disperse from the population core (Shigesada and Kawasaki 1997). Knowledge of current and potential distributions is crucial for assessing management options for invasive species (Gormley et al 2011), but it is very difficult to determine their distribution or rate of spread because their presence often goes undetected under lowdensity conditions during initial stages of invasion or at the edges of their range (VélezEspino 2010; Jarić 2012). Both current and future distributions can be estimated using probabilistic models (Matis et al 1992; Sharov and Liebhold 1998; Jarić et al 2012). By using transit times instead of times of transit, extreme observations of dispersal at the leading edge of population fronts can be included in the model, which can be used to make probabilistic predictions of arrival times of an invading population at locations of interest

Objectives

Methods

Conclusion