Morphological and Morphometrical Variations of Selected Rotifer Species in Response to Predation: a Seasonal Study of Selected Brachionid Species from Lake Xochimilco (Mexico)

Self Cite

The combined effect of temperature, food level and the presence of an invertebrate predator on the body size of the rotifer Brachionus havanaensis were tested in this study. B. havanaensis was cultured at 15, 20, and 25°C under three different Chlorella vulgaris levels (0.5 · 10 6 , 1.0 · 10 6 and 2.0 · 10 6 cells ml À1 ) in the presence and in the absence of Asplanchna girodi. For each treatment we maintained three replicates and constant (0.4 ind ml À1 ) population density of B. havanaensis. In treatments containing A. girodi, the predator was separated from the prey by a mesh (pore size 50 mm). On the last day of the experiment, a portion of the B. havanaensis population was sampled for several morphometric measurements (adult lorica length, width, posterior spine length, body volume, and the egg volume). Size measurements were done by drawing the specimens using a calibrated camera lucida. Statistically significant impact of temperature as well as the predator's presence was observed on the lorica length, posterior spine, and egg volume of B. havanaensis. The interactions of food · temperature, or predatoŕs presence · food · temperature were non-significant (P > 0.05) for lorica length, spine length, body volume, and egg volume. Regardless of the type of treatment, there was a direct positive correlation between lorica length and width. Egg volume was linearly related to the adult size. Notably long posterior spines were observed in treatments containing the presence of A. girodi.

Section: Discussionsupporting

confidence: 82%

“…In lake Xochimilco, a highly eutrophic lake in Mexico city, this species is known to show seasonal shifts in morphology, generally strongly correlated with Asplanchna abundance (Garza-Mouriño et al, 2005). However, more laboratory studies are needed to quantify the predatorinduced morphological responses of this species.…”

Section: Introductionmentioning

confidence: 99%

Combined effects of temperature, food (Chlorella vulgaris) concentration and predation (Asplanchna girodi) on the morphology of Brachionus havanaensis (Rotifera)

Pavón-Meza

Sarma

2007

Self Cite

“…Historically, many workers have focused on the morphological and ecological aspects of spine induction in prey species, such as B. calyciflorus and K. cochlearis, that have posterior spines of variable length (from complete absence to 100 lm) (Koste, 1978;Gilbert, 1998). However, some species have permanent posterior spines, such as Brachionus havanaensis and Plationus macracanthus (formerly Brachionus macracanthus), which show small variations in the presence of predators such as Asplanchna under field conditions (Garza-Mouriño et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Morphometric and demographic responses of brachionid prey (Brachionus calyciflorus Pallas and Plationus macracanthus (Daday)) in the presence of different densities of the predator Asplanchna brightwellii (Rotifera: Asplanchnidae)

Sarma

Lara‐Reséndiz

2010

Self Cite

We quantified the indirect effects of different densities (1, 4, 16 individuals per jar) of the predator Asplanchna brightwellii on the morphometry and demography of their prey Brachionus calyciflorus and Plationus macracanthus. Population growth and life table demography experiments were separately conducted for each of the two prey rotifer species while keeping A. brightwellii in indirect contact. The brachionids were fed the green alga Chlorella vulgaris at a density of 1 9 10 6 cells ml -1 . As compared to those cultured in the absence of the predator, in the presence of A. brightwellii the postero-lateral spines of P. macracanthus increased by about 15 lm, while in B. calyciflorus the increase was more ([80 lm). For both the brachionid species, the peak population density significantly decreased in the presence of A. brightwellii. The reproductive variables viz., net reproductive rate, generation time, and the rate of population increase of B. calyciflorus and P. macracanthus were negatively affected in the presence of kairomones from A. brightwellii.

“…These include the presence of large and small spines in Plationus macracanthus and Brachionus budapestinensis, respectively (Garza-Mouriño et al, 2005), darting behaviour in Filinia longiseta and Hexarthra mira (Iyer & Rao, 1996), small body size in Anuraeopsis fissa (Sarma & Nandini, 2007), epizoic behaviour in Brachionus rubens (Iyer & Rao, 1995) and colonial life or production of toxins as in Sinantherina semibullata (Felix et al, 1995). Little information is available on the defense strategies of littoral rotifers.…”

Section: Introductionmentioning

confidence: 99%

Predatory and toxic effects of the turbellarian (Stenostomum cf leucops) on the population dynamics of Euchlanis dilatata, Plationus patulus (Rotifera) and Moina macrocopa (Cladocera)

Nandini

Dumont

2010

Self Cite

Catenulid turbellarians, common in shallow, tropical ponds, affect their rotifer prey via the production of toxins. There is, however, no quantitative information on their effect on the demography of their prey. Here, we test the impact of Stenostomum cf leucops on the population dynamics of the rotifers Euchlanis dilatata and Plationus patulus, and the cladoceran Moina macrocopa. Experiments were initiated with rotifers at 0.5 ind. ml(-1) and the cladoceran at 0.2 ind. ml(-1); growth patterns were compared in the absence and presence of worms (2 Stenostomum ind. per 50 ml). Results revealed that brachionids were most adversely affected: there was a lower growth rate of the rotifers in the presence of worms (P < 0.01, repeated measures ANOVA), although at the densities applied, the predator did not wipe out its prey. These littoral predators may therefore regulate rotifer prey in natural conditions. In Moina, the population evolved differently; initially, we found no difference between control and treatment, but after about 10 days, the population collapsed, irrespective of a direct or indirect contact with the predator. This delayed effect deserves more study, as it could represent flatworm toxin accumulation by the cladoceran