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Mangroves are highly productive environments that play important ecological and socioeconomic roles; however, they have been impacted to different degrees in most countries worldwide. The knowledge of which organisms inhabit this environment and their ecological interactions is the first step towards its conservation. The natural variability of environmental factors in mangroves provides numerous niches available to different species. Meiofauna have patchy patterns of distribution that are related to the availability of resources. Hence, meiofauna are expected to present a high diversity of different taxa occupying the different microhabitats offered by mangroves. This work aims to test the hypothesis that the assemblage structure of Nematoda varies significantly among mangrove microhabitats and to contribute knowledge on the meiofauna diversity in mangrove environments. This work was carried out in a mangrove region at Pernambuco state, Northeastern Brazil. Qualitative samples were collected in nine microhabitats which show different characteristics mainly in terms of presence of vegetation or another organism and sediment grain size. Univariate and multivariate analysis were applied to Nematoda genera abundance data. Our results demonstrate the existence of significant differences among microhabitats regarding nematode assemblage structure corroborating the hypothesis. Different Nematoda assemblages are present in at least seven microhabitats. These assemblages are composed of nematode genera with different trophic and morphological features, demonstrating a strong relationship between morphological diversity and ecological plasticity. Furthermore, this study also demonstrates the importance of the conservation of this ecosystem and its attributes.

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Thirty-eight taxa of Zygomycetes distributed in 15 genera were recorded from tapir (Tapirus terrestris), camel (Camelus bactrianus), horse (Equus caballus), deer (Cervus elaphus), agouti (Dasyprocta aguti), donkey (Equus asinus), llama (Llama glama) and waterbuck (Kobus ellipsiprymnus) dung collected at the Reserva Ecológica de Dois Irmãos located in Recife, State of Pernambuco, Northeast Brazil. The samples were collected on a monthly basis from June 2005 to May 2006, taken to the laboratory and incubated in moist chambers. Higher number of taxa was observed in the excrements of tapir, followed by deer and donkey. The highest number of species was detected for Mucor, followed by Pilobolus. Statistical analyses showed significant differences in richness of Zygomycetes taxa between the herbivore dung types. Differences of species composition, however, were weak. Seasonality influenced the Zygomycetes species composition but not its richness. Variations in taxa composition between ruminants and non-ruminants dung were non significant.

Nineteen taxa of Mucorales, belonging to Absidia, Apophysomyces, Cunninghamella, Fennellomyces, Lichtheimia, Mucor, Mycotypha, Rhizopus and Syncephalastrum were isolated from 36 composite soil samples in three semiarid areas in the State of Pernambuco (Triunfo, Cabrobó and Belém de São Francisco), Northeast Brazil, which are characterized by Caatinga vegetation. Triunfo is preserved, whereas Cabroró and Belém de São Francisco are experiencing low and severe desertification processes, respectively. Mucorales were isolated in Petri dishes in triplicate from 5 mg samples of soil placed on the surface of wheat germ agar plus chloramphenicol and Cercobin [Dimethyl 4,49-(103 phenylene) bis (3-thioallophanate)] medium. The plates were left on a bench at room temperature (28 ± 2 °C) for 72 h of alternating dark and light periods. Absidia cylindrospora presented the highest amount of CFU/g of soil, followed by L. hyalospora, C. phaeospora and C. echinulata var. echinulata. The latter, and R. microsporus var. microsporus, presented the highest frequencies of occurrence. Soils from Triunfo showed higher diversity of Mucorales than the samples from the other areas, although without differing statistically in relation to species richness. The communities of Mucorales from the degraded areas were more similar, while that from the preserved area was quite different. Most of the identified specimens have been commonly isolated from soil in other Brazilian regions, which indicates that they are not endemic of the semiarid. Eleven taxa are registered for the first time in this ecosystem, while F. heterothallicus is reported for the first time in Brazil.