Resource Partitioning by Two Freshwater Invertebrate Predators with Contrasting Foraging Strategies

10.2307/4203 ◽  
1979 ◽  
Vol 48 (3) ◽  
pp. 909 ◽  
Author(s):  
Colin R. Townsend ◽  
Alan G. Hildrew
Keyword(s):  
Resource Partitioning ◽  
Foraging Strategies ◽  
Invertebrate Predators ◽  
Freshwater Invertebrate

Cadmium and Zinc Uptake by Two Species of Aquatic Invertebrate Predators from Dietary and Aqueous Sources

1992 ◽  
Vol 49 (4) ◽  
pp. 655-662 ◽  
Author(s):  
Klaas R. Timmermans ◽  
Elly Spijkerman ◽  
Marcel Tonkes ◽  
Harrie Govers
Keyword(s):  
Experimental Period ◽  
Zinc Uptake ◽  
Contaminated Water ◽  
Chironomid Larvae ◽  
Zn Uptake ◽  
Invertebrate Predators ◽  
Uptake Rates ◽  
Freshwater Invertebrate ◽  
Caddisfly Larvae ◽  
Free Metal

Cadmium and Zn uptake rates via food and water were determined under laboratory conditions for two species of freshwater invertebrate predators. Water mites (Limnesia maculata) and caddisfly larvae (Mystacides spp.) were exposed for 4 wk to either contaminated chironomid larvae (Chironomus riparius, 288–639 μg Cd∙g−1 or 778–1152 μg Zn∙g−1) or contaminated water (0.1 mg Cd∙L−1 or 1.0 mg Zn∙L−1). Cadmium was readily accumulated in the two species from both dietary and aqueous sources. A clear difference between exposed and untreated organisms was established. Zinc uptake was generally lower than that of Cd, resulting in small differences between exposed and nonexposed organisms. Cadmium uptake from food and Zn uptake from water dominated in both species. It is concluded that, in addition to uptake of free metal ions from aqueous sources, invertebrate predators can accumulate trace metals from their food. This is an underestimated source of contamination for freshwater invertebrate predators. Changes in internal metal concentrations in the predators are described with a first-order one-compartment uptake model. This model was appropriate where steady-state conditions were approached. When uptake continued throughout the experimental period, uptake rate constants were estimated using linear regression.

scholarly journals Species-specific foraging strategies of the syntopical and synchronous bees Panurgus calcaratus (Scopoli, 1763) and Dasypoda hirtipes (Fabricius, 1793) (Hymenoptera: Apidae).

2000 ◽  
Vol 50 (1) ◽  
pp. 179-191
Author(s):  
Eva-Maria Levermann ◽  
Inge Bischoff ◽  
Thomas Wagner
Keyword(s):  
Optimal Foraging ◽  
Resource Partitioning ◽  
Foraging Strategies ◽  
Separation Mechanisms ◽  
Species Specific

Die Sammelstrategie der beiden endogäischen, oligolektischen syntop und synchron auftretenden Wildbienenarten Panurgus calcaratus (Scopoli, 1763) und Dasypoda hirtipes (Fabricius, 1793) wurden im Naturschutzgebiet Wahner Heide (Rheinland, BRD) untersucht. Saisonale und diurnale Rhythmik sowie die Sammelstrategien beider Arten wurden erfaßt, um eventuell bestehende Trennungsmechanismen oder Nischendiffenzierung aufzudecken. Neben dem Verproviantierungsverhalten der Bienen wurde die Oligolektie durch Pollenentnahme von Weibchen und durch Beobachtung an den Pollenquellen überprüft. Beide Arten nutzen ausschließlich gelbe, photonastische, zungenblütige Asteraceae als Pollenquellen, präferieren sandige Flächen mit geringer Vegetation als Nistplatz und sind von Anfang Juli bis Ende August aktiv. Eine Spezialisierung innerhalb der Oligolektie auf einzelne Arten zungenblütiger Asteraceae konnte nicht erkannt werden. Dasypoda hirtipes wies eine allgemein längere diurnale Aktivität auf und war zudem auch bei geringeren Temperaturen noch aktiv. Die Pollensammelaktivitäten werden bei beiden Arten maßgeblich von den photonastischen Pollenquellen limitiert. Desweiteren ist die Bienenaktivität von klimatischen Faktoren wie Lichtintensität, Bewölkung und Lufttemperatur abhängig. Artspezifische diurnale und saisonale Verhaltensweisen und Aktivitätsrhythmen werden im Hinblick auf Körpergröße und -farbe, Hitzeabsorptions- und Reflektions-Fähigkeit, Überhitzungsgefahr sowie Effekte der Ekto- und Heterothermie auf den Wärmehaushalt diskutiert. Jede Art verfolgt eine eigene Sammelstrategie, welche hauptsächlich durch ultimative Faktoren wie die Physiologie der jeweiligen Bienenart beeinflußt und zugleich limitiert wird. Weder Nistplatzangebot noch die Ressourcen Pollen oder Nektar sind im Untersuchungsgebiet begrenzt, so daß keine Evidenz für Konkurrenz zwischen den beiden Arten besteht.StichwörterInterspecific competition, oligolecty, optimal foraging strategies, photonasty, resource partitioning, separation mechanisms.

Micro-habitat use within a guild of newt larvae (Trituridae) in an Alpine lake

Biologia ◽  
2006 ◽  
Vol 61 (5) ◽  
Author(s):  
Milan Vogrin
Keyword(s):  
Resource Partitioning ◽  
Niche Breadth ◽  
Niche Overlap ◽  
Microhabitat Use ◽  
Invertebrate Predators ◽  
Triturus Alpestris ◽  
Crested Newt ◽  
Ecological Parameters ◽  
Alpine Newt ◽  
Ecological Differences

AbstractPopulation and ecological parameters such as numbers of larvae, microhabitat use, niche breadth and niche overlap of three species of syntopic larval newts (Alpine newt Triturus alpestris, Italian crested newt T. carnifex, and common newt T. vulgaris) were studied for two years in a small pond at 1160 m a.s.l. in NE Slovenia. Differences in microhabitat partitioning among larval newts were small. The largest niche breadth was estimated for larval T. alpestris, and the narrowest estimate was for larval T. carnifex in both years. Ecological differences seem to be very small and quite variable among sites and years. It appears that the developmental stage and size of newt larvae are more important in explaining resource partitioning than the characteristics of each species. Because of the absence of potential invertebrate predators and adult newts in the second half of the breeding season, the injuries could only be caused by intra-and interspecific predation attempts.

Influence of shelf oceanographic variability on alternate foraging strategies in long-nosed fur seals

2019 ◽  
Vol 615 ◽  
pp. 189-204 ◽  
Author(s):  
D Foo ◽  
C McMahon ◽  
M Hindell ◽  
S Goldsworthy ◽  
F Bailleul
Keyword(s):  
Foraging Strategies ◽  
Fur Seals

Effects of marine reserves on predator-prey interactions in central California kelp forests

2020 ◽  
Vol 655 ◽  
pp. 139-155
Author(s):  
DC Yates ◽  
SI Lonhart ◽  
SL Hamilton
Keyword(s):  
Species Interactions ◽  
Size Structure ◽  
Marine Reserves ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Negative Effects ◽  
Central California ◽  
Invertebrate Predators ◽  
Predatory Fishes ◽  
Density And Biomass

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.

Dietary overlap and food resource partitioning among fish species of a tropical estuary in Northeastern Brazil

Gaia Scientia ◽  
2016 ◽  
Vol 10 (4) ◽  
pp. 86-95 ◽  
Author(s):  
Adna Ferreira da Silva Garcia ◽  
Ana Lúcia Vendel
Keyword(s):  
Resource Partitioning ◽  
Species Coexistence ◽  
Food Resource ◽  
River Estuary ◽  
Niche Overlap ◽  
Northeastern Brazil ◽  
Dietary Overlap ◽  
Feeding Niche ◽  
Tropical Environments ◽  
Food Resource Partitioning

The current work investigates dietary overlap and food partitioning among nine abundant carnivorous fishes caught in the shallow waters of the Paraíba do Norte river estuary, Paraíba State, Brazil. Fishes were sampled with a beach seine net between January and December 2008 and a total of 958 specimens had their stomach content analyzed. Crustacea was the dominant food resource for Lutjanus alexandrei, L. jocu and Bathygobius soporator, whereas Telostei were consumed mainly by Centropomus undecimalis and C. parallelus. In contrast, Polychaeta were preyed upon mainly by Diapterus rhombeus, Eucinostomus argenteus, Sciades herzbergii and S. parkeri. Although most species consumed similar food items, they did that in varying proportions and amounts. Overall, the niche overlap among species was low (< 0.60), but there were several cases where pair of species had their feeding niche highly overlapped (between 0.72 and 0.97). These findings corroborate the hypothesis that food resource partitioning determines species coexistence in estuarine tropical environments.

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