title: Distribution of Herbivorous Fish Is Frozen by Low Temperature.
abstract: The number of herbivores in populations of ectothermic vertebrates decreases with increasing latitude. At higher latitudes, fish consuming plant matter are exclusively omnivorous. We assess whether omnivorous fish readily shift to herbivory or whether animal prey is typically preferred. We address temperature as the key factor causing their absence at higher latitudes and discuss the potential poleward dispersion caused by climate changes. A controlled experiment illustrates that rudd (Scardinius erythrophthalmus) readily utilize plant matter at water temperatures above 20 °C and avoid its consumption below 20 °C. Field data support these results, showing that plant matter dominates rudd diets during the summer and is absent during the spring. Utilizing cellulose requires the enzyme cellulase, which is produced by microorganisms growing at temperatures of 15-42 °C. Water temperatures at higher latitudes do not reach 15 °C year-round; at our latitude of 50°N~150 days/year. Hence, the species richness of omnivorous fish decreases dramatically above 55° latitude. Our results provide support for the hypothesis that strict herbivorous specialists have developed only in the tropics. Temperatures below 15 °C, even for a short time period, inactivate cellulase and cause diet limitations for omnivorous fish. However, we may expect increases in herbivory at higher latitudes caused by climate change.
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.|Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31, 37005 České Budějovice, Czech Republic.
authors.forename: Ivana
authors.initials: I
authors.lastname: Vejříková
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Lukáš
authors.initials: L
authors.lastname: Vejřík
authors.affiliation: Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark.|Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Syväranta
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Kiljunen
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Čech
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Blabolil
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Mojmír
authors.initials: M
authors.lastname: Vašek
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Sajdlová
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Son Hoang The
authors.initials: SH
authors.lastname: Chung
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Šmejkal
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Jaroslava
authors.initials: J
authors.lastname: Frouzová
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Peterka
mesh_terms: D000818:Animals; D044822:Biodiversity; D018533:Biomass; D057231:Climate Change; D003080:Cold Temperature; D018153:Czech Republic; D017753:Ecosystem; D005399:Fishes / Q000502:physiology*; D005843:Geography; D060434:Herbivory; D007413:Intestinal Mucosa / Q000378:metabolism; D007448:Invertebrates; D016014:Linear Models; D010944:Plants; D011157:Population Dynamics; D011336:Probability; D012621:Seasons; D012624:Seaweed / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water