Água como fator limitante na distribuição das minhocas (Annelida, Oligochaeta) da Amazônia Central.

Abstract

Resumo Quarenta espécies de minhocas da Amazônia Central distribuídas em 8 famílias e 23 gêneros foram classificadas segundo o habitat preferencial. Esta classificação mostra um número alto (33) de espécies que ocorrem apenas nas proximidades da água, levando a crer que a água é fator limitante na distribuição das espécies. Poucas espécies (4) foram encontradas em diversos habitats, com grande variação de umidade (eurihígricas). Medidas experimentais de resistência à desidratação em Pontoscolex corethurus, Andiorrhinus amazonius e Meroscolex marcusi parecem confirmar esta hipótese. P. corethurus espécie eurihígrica. é extremamente resistente à desidratação em contraposição às outras duas espécies. Experimentos de anoxia mostraram que Andiorrhinus caudatus, espécie de ambientes muito úmidos, tem alta resistência à anoxia se comparada a P. corethurus que geralmente habita solos mais secos. Estes dados corroboram a ocorrência de um déficit de água nos solos de terra firme da Amazônia Central.

Continental biodiversity of South American oligochaetes: The importance of inventories.

“…In fact, there are few regional inventories of earthworms in Brazil: 18 species were reported for the state of Rio Grande do Sul (Knäpper 1972(Knäpper , 1977; Mato Grosso and Rondônia have 45 species (Righi 1990); the Manaus region, 40 species (Ayres & Guerra 1981); Paraná, 55 species (Brown et al 2004); and São Paulo State, 77 species (Brown & James 2007).…”

Recommendations for assessing earthworm populations in Brazilian ecosystems

“…However, most earthworms can survive short periods of anaerobiosis in case their burrows are flooded after heavy rains (Lee, 1985). Soil moisture is an extremely important factor for the survival of earthworms (Lee, 1985;Edwards, 2004) -first, because their bodies are formed by > 80% H 2 O (Caballero, 1979;Ayres & Guerra, 1981) and, second, because they breathe through their skin, which needs to be kept continuously moist. However, this attribute was reported in only 17% of the evaluated publications.…”

“…Lavelle et al (1987), for instance, found that the ideal soil moisture values for the optimum development of P. corethrurus were all well above the field capacity of 35% H 2 O in a Mexican clayey loam soil, with 31% clay and 40% sand. Hydrophilic species, such as most representatives of the Ocnerodrilidae, Sparganophilidae, Almidae, and Criodrilidae families (Righi, 1997), as well as some members of the Glossoscolecidae, Rhinodrilidae, and Acanthodrilidae families (Ayres & Guerra, 1981;Gavrilov, 1981;Barrion & Litsinger, 1997;Bartz et al, 2012), live in saturated soils with a low oxygen pressure. For instance, 33 of the 40 species from Central Amazon were found only next to water bodies, while 10% were collected in upland sites, being presumably more resistant to soil moisture variations (Ayres & Guerra, 1981).…”

“…Hydrophilic species, such as most representatives of the Ocnerodrilidae, Sparganophilidae, Almidae, and Criodrilidae families (Righi, 1997), as well as some members of the Glossoscolecidae, Rhinodrilidae, and Acanthodrilidae families (Ayres & Guerra, 1981;Gavrilov, 1981;Barrion & Litsinger, 1997;Bartz et al, 2012), live in saturated soils with a low oxygen pressure. For instance, 33 of the 40 species from Central Amazon were found only next to water bodies, while 10% were collected in upland sites, being presumably more resistant to soil moisture variations (Ayres & Guerra, 1981). Unfortunately, very little is known regarding the soil moisture preferences of most Brazilian earthworm species, which is an indicative that this is another important topic for basic biology research on earthworms.…”

Life history, distribution and abundance of the giant earthworm Rhinodrilus alatus RIGHI 1971: conservation and management implications

“…In Andiorrhinus caudatus, this phenomenon has been associated with anoxic conditions, as the species inhabits saturated soil and can survive 24 hours under water (Ayres and Guerra, 1981). Martin and Johansen (1992) observed autotomy for Glossoscolex giganteus under laboratory manipulations; as these authors observed that G. giganteus never Life history, distribution and abundance of Rhinodrilus alatus eliminates its entire intestinal contents, they proposed that autotomy could be a mechanism to protect against the accumulation of large particles in the intestine (Martin and Johansen, 1992).…”