How to deal with a bad neighbor? Strategies of sympatric freshwater decapods (Crustacea) for coexistence

Abstract

Species with similar niches may exhibit adaptations to diminish competitive pressure and allow sympatry; freshwater decapods are interesting models for the investigations of these strategies. We studied the behavior of two co-occurring decapod species: the anomuran Aegla longirostri and the crayfish Parastacus pilimanus, and investigated the following: (1) whether the species use the stream similarly; (2) if they present zonation within it; (3) if they have different activity levels; and (4) whether their activity patterns overlap. For this, we radiotracked individuals of both species in their natural environment. Aeglids had larger home ranges than crayfish when considering only the stream. However, crayfish remained in burrows more than in the stream, and the total home ranges did not differ significantly from aeglids. Stream sections used by both species highly overlap, indicating no zonation. Aeglids used the stream more often and more intensively than crayfish, but their diel activity patterns were similar. Despite the lack of zonation in the stream and of temporal segregation, there seems to be some degree of spatial segregation. Differential habitat use seems to be the one of the mechanisms allowing crayfish to coexist with aeglids.

Population structure and habitat occupation in two sympatric Aegla species (Decapoda, Anomura, Aeglidae) in Atlantic Forest, Brazil

“…The results here suggest that the coexistence of A. jarai and A. muelleri is most likely due to their occupation of distinct microhabitats, or space partitioning, and the distinct size ranges of these species help to support this assumption. Competing species have been known to choose different microhabitats in the same area or concentrate their activity at different periods of the day (Rosas et al, 1994;Castro-Souza and Bond-Buckup, 2004;Baumart et al, 2015). Niche overlap between sympatric species of the genus Aegla has been reported in other studies (de Castro-Souza and Bond-Buckup, 2004).…”

Underwater compensation for exaggerated weaponry: The role of morphology and environment on crab locomotor performance

“…After the individuals acclimated for 7 days, we proceeded to the locomotor performance test. The temperature was kept around 13 (±2)°C throughout acclimation and experiments, which is the temperature individuals face during late winter/spring when they are most active (Baumart, Dalosto, Gonçalves, Palaoro, & Santos, ). None of the individuals died during acclimation.…”

“…We recorded all trials with a Sony Handycam HDR‐CX560® (Sony Electronics Inc., San Diego, CA) positioned above the aquarium, and had three incandescent red‐light bulbs (40 W) positioned equidistantly from the corridor. Due to aeglid nocturnal behaviour, we performed the experiments at night (Baumart et al, ), and used red light because crustaceans have low sensitivity for this wavelength (Turra & Denadai, ). After the experiments, all individuals were euthanized by cryoanesthesia to measure the size and muscle content of their legs.…”

“…Unfortunately, we only have indirect evidence that maintaining a territory might be important in aeglids. First, males are regularly seen fighting in headwater streams (Baumart et al, 2015); second, females prefer large males (Siqueira, Palaoro, & Santos, 2013); third, males with larger weapons are more likely to win fights (Siqueira et al, 2013); fourth, males do not have high displacement rates, typically staying for long periods of time in the same area (Baumart et al, 2015). Therefore, fighting, large sizes, and large weapons might be important for males, and these are all variables that correlate with dominance but not necessarily walking speed (Oufiero & Garland, 2007).…”

Diversity and characterization of bacterial communities of five co‐occurring species at a hydrothermal vent on the Tonga Arc

“…Sympatric organisms occupying the same ecological niche generally have strategies to avoid competition for food resources and habitat (Baumart et al, 2015;Friedlaender et al, 2015). In chemosynthetic ecosystems, two bathymodiolin mussel species are occasionally found at the same sites, and such species show different gill symbiont compositions (Table 2).…”