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Rotifer invasion? On appearance and abundance of tropical species in lakes of North-Eastern Poland

100%

Ejsmont-Karabin J.

Polish Journal of Ecology

2014

tom 62

nr 4

Trichocerca simoneae De Smet described in 1989 has since been found in tropical and subtropical areas, but was not recorded in Poland before World War II. A bibliography of Polish rotifers by Wiszniewski (1953), although very comprehensive, does not refer to T. simoneae. However, in the studies of plankton of the dystrophic lake, i.e. humic one with water rich in humic acids, acidic pH and brown coloured, carried out in the years 1998–2000, the species dominated. Here, studies in 39 small, inter-forest lakes of north-eastern Poland revealed T. simoneae in 15 of them, often at high densities, up to ca 6000 ind L-1. The possible reasons for this ‘invasion’ are: (1) zooplankton communities in dystrophic lakes are unsaturated with biotic interactions too weak to exclude invaders; CCA and RDA analyses showed that T. simoneae preferred habitats with low number of zooplankton species of low density and dystrophic lakes seem to offer such habitats; (2) long-term deposition of rotifer resting eggs is probably more successful in sediments decaying at low rates. The latter possibility seems to be confirmed by observed in the littoral zone of dystrophic lakes appearance from time to time, of rare, mostly tropical species of Rotifera (e.g., Lecane hornemnni, L. monostyla, L. sola).

Diet of the cloud forest shrew Cryptotis meridensis [Insectivora: Soricidae] in the Venezuelan Andes

100%

Diaz d. P. A., De Ascencao A. A.

Acta Theriologica

2000

tom 45

nr 1

The diet of Cryptotis meridensis Thomas, 1898 was studied by analysing stomach contents of 55 shrews collected by pitfall trapping in the cloud forest of Monte Zerpa, Mérida, Venezuela. The aims of the study were to describe the diet of this unknown tropical species and test the prediction that this species should be more of a subterranean feeder according to its morphological adaptations. The diet was composed of 35 different prey taita distributed in six invertebrate classes (Gastropoda, Annelida, Arachnida, Crustacea, Myriapoda and Insecta). The most important components of the diet were hypogeal invertebrates: Oligochaeta, Gastropoda, Theraposidae, Isopoda, Scolopendridae, Phasmatidae, Blatiidae, Lepidoptera larvae and pupae, Diptera larvae, adult Carabidae, Staphilinidae, Elateridae larvae, Passalidae and Scarabaeidae larvae. Their contribution was 69.44% of the overall diet composition. Oligochaeta were the most frequent prey. Ephigeal invertebrates (Lycosidae, Acrididae, Gryllidae, adult Scarabaeidae and Lycosidae) accounted for only 27,24%. The preferences for soil invertebrates found in this study confirmed our prediction that C. meridensis uses mostly a subterranean foraging mode in accord with its morphological adaptations similar to other shrews in temperate habitats.

Ograniczanie wyników

1 Acta Theriologica

1 Polish Journal of Ecology

1 De Ascencao A. A.

1 Diaz d. P. A.

1 Ejsmont-Karabin J.

1 2014

1 2000

Wyniki wyszukiwania

Rotifer invasion? On appearance and abundance of tropical species in lakes of North-Eastern Poland

Diet of the cloud forest shrew Cryptotis meridensis [Insectivora: Soricidae] in the Venezuelan Andes