Formation and Propagation of Feeding Fronts in Benthic Marine Invertebrates: A Modeling Approach

Abstract

Feeding fronts are a striking pattern of spatial distribution observed in both marine and terrestrial ecological systems. These fronts not only determine the abundance and distribution of prey populations, but on a broader scale they may also affect the structure and dynamics of entire communities. Several mechanisms leading to the formation of feeding fronts have been proposed, and chemotaxis has been suggested as an important component.Here we develop two mathematical models that show front formation can occur with simple kinesis (and without chemotaxis) in two marine invertebrates with different feeding habits: a microphagous sea star (Oreaster reticulatus) that feeds on sediments and an herbivorous sea urchin (Strongylocentrotus droebachiensis) that grazes kelp beds. We utilize a large body of detailed empirical information on movement pattern, foraging behavior, and front dynamics for each species to develop, parameterize, and evaluate our models. We found that our model predictions for the rate of advance of a front and its relationship to the density of consumers at the front were in close agreement with independently collected, empirical observations in both systems. This work shows that simple local interactions between mobile consumers and a stationary resource can result in large-scale heterogeneous patterns of abundance of both species.

Testing the level of ant activity associated with quorum sensing: An empirical approach leading to the establishment and test of a null-model

“…Table 1). Table 1 A plot of the time-intervals produced during the entire course of an experiment ( The simplest interpretation of these data is that the ants move independently within the nesting area, without any aggregation (Parrish and Edelstein-Keshet, 1999, Ame et al, 2004, 8 Jeanson et al, 2005, Lauzon-Guay et al, 2008 or recruitment behaviour (Wilson, 1962), and some ants randomly encounter the bridge and use it to leave the nesting area. The mean rate with which ants fall from the bridge has, we assume, contributions from both the geometry of the problem (the larger the diameter of the wire, constituting the bridge, the larger the probability of encountering it) and the level of activity of the ants (the more active or fastmoving the ants, the greater the chance they have of encountering the bridge).…”

Spatial dynamics, ecological thresholds and phase shifts: modelling grazer aggregation and gap formation in kelp beds

“…The dynamics of kelp within each cell follows the model of front formation of Strongylocentrotus droebachiensis developed by Lauzon-Guay et al (2008, 2009. At each time step (1 d) seaweed biomass (S t ) is calculated in each cell as:…”

“…Once seaweed biomass reached zero, it was reset to 50 g at the next time step to account for a constant supply of spores from adjoining cells. We used the same parameter estimates as those used in Lauzon-Guay et al (2008, 2009, which resulted in a good agreement between model predictions and field observations. Sea urchin movement.…”

“…, Mohn & Miller 1987, Lauzon-Guay et al 2008) and sea urchin density at the average reported for this species in kelp beds (14 urchins m -2 , Meidel & Scheibling 2001). Only adult sea urchins (individual mass = 50 g) are considered in our model of front formation, and all references to sea urchin density are for adults.…”

Production efficiency of mussel bottom culture

“…Maximum feeding rates are reached at temperatures between 10 and 13 °C (Agüera et al 2012). Sea stars are capable of wiping out entire mussel beds in a short amount of time, especially because they aggregate in large swarms and form a moving feeding front on a mussel (seed) bed (Dare 1982, Lauzon-Guay et al 2008. Agüera (2015) suggested that, in the development of mussel beds, sea stars establish themselves and grow sat a faster rate than the mussels.…”