Input matching and patch use by native and invasive minnows

Abstract

When members of a population choose patches that maximise individual net energy gain without interference, they are input matching, a strategy derived from the ideal free distribution (IFD) that results in equal rewards across all patches. We investigated the input matching abilities of yellowfin shiner, a recent invader, and rosyside dace, a common native minnow, found in Coweeta Creek, North Carolina, USA. To test the species' relative input matching abilities, we varied food abundance within the range found in the natural habitat in a twopatch laboratory stream to document the distribution of foragers when food densities differed in the ratio of 2:1. We then applied simple IFD model predictions to determine whether the observed distribution of foragers was best described by (i) the IFD, (ii) differing competitive abilities or (iii) the ideal despotic distribution and/or other unequal competitor models, and to ascertain whether the invader demonstrated a superior ability to track resource distributions. Yellowfin shiner was more likely to move between patches, which resulted in increased ability to match the distribution of food when prey abundance increased. The distribution of rosyside dace between patches did not change in response to increased food abundance. Despite a considerable range of competitive abilities within intraspecific groups, the 'equal competitors' IFD was as good at predicting fish distributions as 'unequal competitor' models. The ability to track local resource availability in highly variable environments facilitates maximising energy intake and likely promoted the establishment of yellowfin shiner in a southern Appalachian stream.

Patchiness in food resources drives fish abundances in emergent macrophytes under field and experimental conditions

“…Note: BIO biofilm, DAPH Daphniidae spp., CHYD Chydoridae spp., CHIR total chironomids, OSTR Ostracoda spp., TINV total invertebrates demonstrate that fish had moved back into habitats only when invertebrate densities had increased to the point of making it profitable to forage in a given PATCH. Such movement of fish among patches to track resource levels has also been found for yellowfin shiners under experimental conditions (Wagner & Grossman, 2013). Overall, the experimental results confirm our hypothesis that carp gudgeons will select habitats based on food availability.…”

Long‐term persistence, density dependence and effects of climate change on rosyside dace (Cyprinidae)

“…There is no doubt that populations within most assemblages likely are affected by both types of processes, although at times, one may be dominant (Grossman et al, 2006(Grossman et al, , 2012. The mechanism by which rosyside dace populations are regulated by density dependence most likely is intraspecific competition for profitable foraging positions via intraspecific aggression (Freeman & Grossman, 1992b;Rincon & Grossman, 2001;Wagner & Grossman, 2013). Although many dace are non-aggressive, others display intraspecific aggression, excluding conspecifics from favourable foraging spots with higher food availability, and thus obtaining higher foraging rates (Freeman & Grossman, 1992b;Rincon & Grossman, 2001;Hazelton & Grossman, 2009).…”

Pattern of invasion by Weed Shiner (Notropis texanus), a nonindigenous cyprinid in the Bear Creek system (Tennessee River drainage), USA

“…Similar to traditional agriculture, pine monoculture of loblolly and shortleaf pines, exerted a significant influence on Weed Shiner presence which differed from native mixed hardwoodpine forests (Letson et al 2010;Shankman and Wills 1995). Pine monoculture can increase discharge Table 2 continued Site number variability and decrease total water availability (D'Angelo and Webster 1991;Feeley et al 2011;Swank and Miner 1968). Theses hydrological alterations are similar to those caused by impoundments and land-use changes which have been documented to promote cosmopolitan invasive species such as Weed Shiner (Light and Marchetti 2007).…”

“…Nonindigenous fishes that successfully establish are often cosmopolitan generalists that fill an unoccupied niche, have flexible diet and habitat requirements, and are adapted to variable flow regimens (Bunn and Arthington 2002;Kiernan et al 2012;Kopp et al 2012;Meador and Carlisle 2012;Wagner and Grossman 2013;Walser et al 2000). Anthropogenic disturbance in a system can further support nonindigenous generalist fish establishment through changes to the flow regimen, reduction of water availability, and nutrient loading.…”

“…(Brisbois et al 2008;Dowling 2012;Kopp et al 2012;Leprieur et al 2008; Moyle and Light 1996;Phillips and Johnston 2004a) Flow depletion and reduced flow variability have been demonstrated to favor generalists over fluvial specialists in a number of studies in the Southeastern United States (Alexandre et al 2013;Clavero and Hermoso 2011;Kanno and Vokoun 2010) as well as the arid western United States (Propst et al 2008). Beyond providing favorable abiotic conditions to introduced species, anthropogenic disturbance can influence community level interactions between nonindigenous species and native competitors by giving the invaders a competitive advantage for prey and increased reproductive potential compared to native fishes (Dowling 2012;Johnston and Maceina 2009;Phillips and Johnston 2004b;Wagner and Grossman 2013).…”