Bioturbation by crabs may affect processes associated with organic matter decomposition in mangrove soils. This study examines how two crabs (Uca maracoani and Ucides cordatus), which are of substantial ecological and economic importance in semiarid coastal areas of Brazil, affect biogeochemical processes in mangrove soils. For this purpose, the physicochemical and geochemical parameters of the soils at different sites were analyzed. The redox potential was always positive at bioturbated sites (+12 to +218 mV), indicating more oxidizing conditions conducive to the oxidation of pyrite and precipitation of oxyhydroxides. In contrast, anoxic conditions prevailed at the control site (Eh<0 mV), and the most abundant form of iron was Fe-pyrite. The highest degree of iron pyritization (DOP) was observed in soils from the control site (∼48%) and the lowest in the bioturbated soils (5-16%), indicating that crabs have an oxidative effect on iron sulfides. The results also suggest that U. cordatus has a higher oxidizing capacity than U. maracoani, probably because it constructs larger and deeper burrows. The results demonstrate that both crabs must be considered as important bioturbators in Brazilian semiarid mangrove soils, being capable of enhancing organic matter decomposition and also shifting the dominant pathway of organic matter degradation.

Seasonality and crab activity affects the nutrients and physicochemical parameters in mangrove soils, thus, affecting the emissions of greenhouse gases, such as nitrous oxide (N2O). Climate change may intensify rainfall and/or enhance droughts, affecting mangroves and associated biota. Crabs are natural soil bioturbators responsible for soil aeration and turnover. We evaluated the effect of Ucides cordatus crab on N2O emissions from mangrove soils under a semiarid climate in Northeastern Brazil. Soil and gas samples were collected over the rainy and dry seasons in crab-naturally-bioturbated and crab-exclusion mangrove plots. We measured the soil’s pH, redox potential, and the total contents of carbon, nitrogen, and sulfur. We found higher N2O emissions in the crab-exclusion sites compared to the bioturbated sites, as well as higher N2O emissions in the rainy season compared to the dry season. The fluxes of N2O (µg m−2 h−1) were 47.3 ± 9.7 and 8.9 ± 0.5 for the crab-exclusion sites, and 36.5 ± 7.8 and 4.5 ± 2.1 for the bioturbated sites (wet and dry seasons, respectively). The soil turning over by macrofauna led to lower N2O fluxes in natural crab-bioturbated areas, and seasonality was the environmental factor that contributed the most to the changes in N2O emissions. Broadly, anthropic activities and seasonality influence nitrogen fate, N2O emissions, and ecological services in coastal ecosystems.

Objetivou-se avaliar a relação entre os índices reprodutivos (intervalo entre parto e período de serviço) e a produção de leite (produção por lactação, duração da lactação e persistência de lactação) em vacas mestiças de média-baixa e média produção. Foram utilizados dados de um controle leiteiro de 40 vacas mestiças, Holandês- Gir, de diferentes composições genéticas, todas multíparas (4 a 10 o número de lactações), no período de maio de 2015 a maio de 2016. Os animais foram divididos em dois grupos: Grupo 1 constituído de vacas de produção diária menor que 15 litros de leite, e Grupo 2 constituído de vacas com produção diária entre 15 e 20 litros de leite, sendo essa divisão fundamentada no princípio de que vacas de alta produção demoram mais a retornar ao estro e consequentemente pode influenciar na fertilidade. Os indicadores zootécnicos analisados foram: duração da lactação, média de produção diária, produção por lactação, intervalo entre parto (IEP) e período de serviço. Apenas o IEP não diferiu (P>0,05) entre os grupos. A eficiência reprodutiva das vacas de média produção (15 até 20 litros/dia) não foi influenciada pela produção de leite, sendo mais viável ao produtor além de apresentar maior persistência de lactação.