Meiobenthic community underneath the carcass of a stingray: a snapshot after natural death

The impact of large food falls and carrion on meiobenthic communities remains little understood. The objective of the present study was to investigate whether the carcass of a stingray, encountered fortuitously in an Australian estuary, affects the underlying meiobenthic community, in particular nematode assemblages. The integrity of the skeleton and the low redox values observed under the carcass suggest that the cadaver had been slowly and chiefly decomposed by microbes. The abundance and number of meiofaunal taxa, as well as nematode abundance and nematode-species richness, were significantly lower under the carcass when compared to samples outside the carcass. Nonetheless, a few nematode species, typical of hypoxic/anoxic sediments, were more abundant under the carcass. Interestingly, all these species were absent or rare in samples near, but not under, the carcass, suggesting that they may take advantage of the reduced environment created by the carcass and the consequent lack of competition to prosper. As observed for other marine environments, carcasses in estuaries create a microhabitat that supports a characteristic meiobenthic fauna, distinct from those inhabiting the surrounding sediments, but similar to those of reduced habitats.

Net greenhouse gas fluxes in Brazilian ethanol production systems

Biofuels are both a promising solution to global warming mitigation and a potential contributor to the problem. Several life cycle assessments of bioethanol have been conducted to address these questions. We performed a synthesis of the available data on Brazilian ethanol production focusing on greenhouse gas (GHG) emissions and carbon (C) sinks in the agricultural and industrial phases. Emissions of carbon dioxide (CO(2)) from fossil fuels, methane (CH(4)) and nitrous oxide (N(2)O) from sources commonly included in C footprints, such as fossil fuel usage, biomass burning, nitrogen fertilizer application, liming and litter decomposition were accounted for. In addition, black carbon (BC) emissions from burning biomass and soil C sequestration were included in the balance. Most of the annual emissions per hectare are in the agricultural phase, both in the burned system (2209 out of a total of 2398 kg C(eq)), and in the unburned system (559 out of 748 kg C(eq)). Although nitrogen fertilizer emissions are large, 111 kg C(eq) ha-1 yr-1, the largest single source of emissions is biomass burning in the manual harvest system, with a large amount of both GHG (196 kg C(eq) ha-1 yr-1). and BC (1536 kg C(eq) ha-1 yr-1). Besides avoiding emissions from biomass burning, harvesting sugarcane mechanically without burning tends to increase soil C stocks, providing a C sink of 1500 kg C ha-1 yr-1 in the 30 cm layer. The data show a C output: input ratio of 1.4 for ethanol produced under the conventionally burned and manual harvest compared with 6.5 for the mechanized harvest without burning, signifying the importance of conservation agricultural systems in bioethanol feedstock production.

Use of blanks to determine in vitro net gas and methane production when using rumen fermentation modifiers

Blanks (flasks without substrate containing only inoculum and medium) are used in vitro to correct for gas. CH(4) and residual organic matter (OM) fermented in inoculum. However inclusion of rumen fermentation modifiers may affect fermentation of OM in the substrate and inoculum. Thus, data correction using blanks that lack additives may result in inaccurate adjustment for background fermentation. Our objective was to evaluate impacts of using blanks containing additive (i.e., specific blanks) or blanks without additive on estimation of in vitro net gas and CH(4) production. We used the semi-automatic in vitro gas production technique including monensin sodium at 2.08 mg/l of buffered rumen fluid (Experiment 1) or carvacrol, eugenol and 1,8-cineol at 667 mg/l (Experiment 2) in flasks with substrate and in blank flasks. At 16h of incubation, monensin reduced (P <= 0.02) total gas production in flasks containing substrate (162.0 ml versus 146.3 ml) and in blanks (84.4 ml versus 79.2 ml). Total methane production was also decreased (P <= 0.05) by adding monensin to flasks containing substrate (15.7 ml versus 11.9 ml) as well as in blanks (6.4 ml versus 5.0 ml). Inclusion of carvacrol or eugenol reduced (P <= 0.05) total gas and CH(4) production in flasks with substrate and in blanks, but in a more pronounced manner than monensin. For these three additives, correction for blank without additive resulted in lower net gas and CH(4) production than correction for a treatment specific blank. For instance, correcting carvacrol data using a blank without the additive resulted in negative net gas and CH(4) production (-6.5 and -1.5 ml. respectively). These biologically impossible results occurred because total gas and CH(4) production in blanks without carvacrol (46.1 and 2.1 ml, respectively) were higher than in flasks containing substrate plus carvacrol (39.7 and 0.6 ml, respectively). Results demonstrated that inclusion of rumen additives affected fermentation of OM in the substrate and the inoculum. Thus, correction of gas and CH(4) production using blanks without additives resulted in overestimation of these variables. Blanks containing the additive of interest should be included when rumen fermentation modifiers are evaluated in vitro. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. (C) 2011 Elsevier B.V. All rights reserved.

A new approach for in vitro bioassay to measure tannin biological effects based on a gas production technique

The aim of this paper was to study a method based on gas production technique to measure the biological effects of tannins on rumen fermentation. Six feeds were used as fermentation substrates in a semi-automated gas method: feed A - aroeira (Astronium urundeuva); feed B - jurema preta (Mimosa hostilis), feed C - sorghum grains (Sorghum bicolor); feed D - Tifton-85 (Cynodon sp.); and two others prepared mixing 450 g sorghum leaves, 450 g concentrate (maize and soybean meal) and 100 g either of acacia (Acacia mearnsii) tannin extract (feed E) or quebracho (Schinopsis lorentzii) tannin extract (feed F) per kg (w:w). Three assays were carried out to standardize the bioassay for tannins. The first assay compared two binding agents (polyethylene glycol - PEG - and polyvinyl polypirrolidone - PVPP) to attenuate the tannin effects. The complex formed by PEG and tannins showed to be more stable than PVPP and tannins. Then, in the second assay, PEG was used as binding agent, and this assay was done to evaluate levels of PEG (0, 500, 750, 1000 and 1250 mg/g DM) to minimize the tannin effect. All the tested levels of PEG produced a response to evaluate tannin effects but the best response was for dose of 1000 mg/g DM. Using this dose of PEG, the final assay was carried out to test three compounds (tannic acid, quebracho extract and acacia extract) to establish a curve of biological equivalent effect of tannins. For this, five levels of each compound were added to I g of a standard feed (Lucerne hay). The equivalent effect showed not to be directly related to the chemical analysis for tannins. It was shown that different sources of tannins had different activities or reactivities. The curves of biological equivalence can provide information about tannin reactivity and its use seems to be important as an additional factor for chemical analysis. (C) 2007 Elsevier B.V. All rights reserved.