Stability of soil organic carbon and potential carbon sequestration at eroding and deposition sites

Purpose

This study aims to explore the dynamics of the factors influencing soil organic carbon (SOC) sequestration and stability at erosion and deposition sites.

Materials and methods

Thermal properties and dissolved aromatic carbon concentration along with Al, Fe concentration and soil specific surface area (SSA) were studied to 1 meter depth at two contrasting sites.

Results and discussion

Fe, Al concentrations and SSA size increased with depth and were negatively correlated with SOC concentration at the erosion site (P?<?0.05), while at the deposition site, these values decreased with increasing depth and were positively correlated with SOC concentration (P?<?0.05). TG mass loss showed that SOC components in the two contrasting sites were similar, but the soils in deposition site contained a larger proportion of labile organic carbon and smaller quantities of stable organic carbon compared to the erosion site. SOC stability increased with soil depth at the erosion site. However, it was slightly variable in the depositional zone. Changes in SUVA₂₅₄ spectroscopy values indicated that aromatic moieties of DOC at the erosion site were more concentrated in the superficial soil layer (0–20 cm), but at the deposition site they changed little with depth and the SUVA₂₅₄ values less than those at the erosion site.

Conclusions

Though large amounts of SOC accumulated in the deposition site, SOC may be vulnerable to severe losses if environmental conditions become more favorable for mineralization in the future due to accretion of more labile carbon. Deep soil layers at the erosion site (>30 cm deep) had a large carbon sink potential.

     

Association between the body weight of growing pigs and the functional capacity of their gut microbiota

Gastrointestinal microbiota impact host's biological activities, including digestion of indigestible feed components, energy harvest, and immunity. In this study, fecal microbiota of high body weight (HW) and low body weight (LW) growing pigs at 103 days of age were compared. Principal coordinates analysis separated the HW and LW groups into two clusters, indicating their potential differences between microbial community composition. Although the abundances of two major phyla, Firmicutes and Bacteroidetes, did not significantly differ between the HW and LW groups, some genera showed significant differences. Among them, Peptococcus and Eubacterium exhibited strong positive correlations with body weight (BW) and average daily gain (ADG) (Rho > 0.40), whereas Treponema, Desulfovibrio, Parabacteroides, and Ruminococcaceae_unclassified exhibited strong negative correlations with BW and ADG (Rho < ?0.40). Based on these results, the structure of intestinal microbiota may affect growth traits in pigs through host–microbe interactions. Further in‐depth studies will provide insights into how best to reshape host–microbe interactions in pigs and other animals as well.     

The ecology and culture of landscape sustainability: emerging knowledge and innovation in landscape research and practice

Landscape researchers and practitioners, using the lens of sustainability science, are breaking new ground about how people’s behaviors and actions influence the structure, function, and change of designed landscapes in an urbanizing world. The phrase—the scientific basis of the design for landscape sustainability—is used to describe how sustainability science can contribute to translational landscape research and practice about the systemic relationships among landscape sustainability, people’s contact with nature, and complex place-based problems. In the first section of this article, important definitions about the scientific basis of the design for landscape sustainability are reviewed including the six Es of landscape sustainability—environment, economic, equity, aesthetics, experience, and ethics. A conceptual framework about the six Es of landscape sustainability for designed landscapes is introduced. The interrelatedness, opportunities, contradictions, and limitations of the conceptual framework are discussed in relation to human health/security, ecosystem services, biodiversity, and resource management. The conceptual framework about the six Es of landscape sustainability for designed landscapes follows the tradition in which landscape researchers and practitioners synthesize emerging trends into conceptual frameworks for advancing basic and applied activities.     

Socio-economic significance of reed forests in a rural community: A case study from the greater Sylhet Region of Bangladesh

The reed forests that are the subject of this study are scattered over five thanas of the Sunamganj and Sylhet Districts of the Sylhet Division of Bangladesh. Their total area is 23,590 ha and they have great ecological, economic, commercial and socio-economic importance due to the diversified resources they supply. However, the forests are commonly encroached on by local people who are perceived to be seriously depleting the resource. This paper deals with the socio-economic status of the people residing near these reed forests, and examines their dependency on the resources provided by the reed forests. A socio-economic survey, participatory rural appraisal and interviews were used to obtain baseline data of the reed forest resource and the local communities. The study reveals that the communities in the study region have higher income than other areas of Bangladesh. Most survey respondents have other occupations in addition to farming. The literacy rate is 28.8%. Among the illiterate, 68% engage in collecting reeds. Although the Forest Department has a management plan for sustainable use of the reed forests, encroachers receive backing from political leaders and local elites, so their eviction is difficult. In order to achieve long-term productivity and sustainability from the reed forests, this study recommends a strategy of developing an integrated joint management plan between the Forest Department and the local people.     

Dietary value of benthic diatoms for post-larval abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis> associated with feeding transitions

ABSTRACT:   The feeding behavior and growth of post-larval Haliotis diversicolor with initial shell lengths (SL) of approximately 500 μm (Exp. 1-1 and 1-2), 800 μm (Exp. 2), and 1200 μm (Exp. 3) were studied in a laboratory setting while they fed on four species of benthic diatom Achnanthes longipes , Cocconeis sublittoralis , Cylindrotheca closterium , and Navicula ramosissima . Exp. 1-1 and 1-2 revealed no marked differences in post-larval growth rates (mean 24–39 μm SL/day) among the diatom species. However, marked differences in growth rates among the species were revealed in Exp. 2 and 3. Three species, A. longipes , Co. sublittoralis, and Cy. closterium , produced faster growth (Exp. 2 mean 29–51 μm/day, Exp. 3 mean 36–44 μm/day) than N. ramosissima (Exp. 2 mean 18 μm/day, Exp. 3 mean 23 μm/day). Post-larvae fed N. ramosissima had lower digestion efficiency (42.8%) than those fed other diatom species (90.7–100%). Diatom extracellular substances appeared to be principally used from post-settlement to 800 μm SL, and diatom cell contents were required to produce rapid growth of larger post-larvae (>800 μm SL). It is likely that the availability of each diatom for post-larvae was affected by diatom morphology, attachment strength, frustule strength, and post-larval size.     

Modelling of common European cockle <Emphasis Type="Italic">Cerastoderma edule</Emphasis> fishing grounds aimed at sustainable management of traditional harvesting

In the Bay of Saint-Brieuc, a 3,110-ha tidal bay in NW France, English Channel, the cockle Cerastoderma edule has been collected by traditional fishing methods for many decades without any evaluation or management of this resource taking place. Since 2001, the National Natural Reserve of the bay of Saint-Brieuc has carried out an evaluation of the stock and a mapping of the cockle fishing grounds each year. Analysis of the spatial structure of the population is approached by cartography through interpolation of the data using the kriging method. The recruitment zones are geographically quite well defined and located in areas limited to the mean-tide zone. The distribution of the population was affected by passive displacement of juvenile cockles. Evaluation using the matrix of individual numbers for each age group found the inter-annual mortality rates to be about 60%. Somatic production was estimated and expressed in ash-free dry weight. The average annual production ranged from 7.4 to 14.5 g/m2. In the autumn of 2006, the minimum legal fishing size changed from 30 to 27 mm (corresponding to individuals aged about 2.5 years). The model developed shows that this change has led to a doubling of the fishable stock.     

An attempt to improve the reproductive efficiency of Nile tilapia brood stock fish

A field study was conducted on brood stock Nile tilapia to increase the propagation. Both sexes were individually stocked into Habas (enclosures) in an earthen pond and fed for 19 days on a basal diet supplemented with different additives at graded levels of each (0.5, 1.0 and 2.0 g Therigon^®; 1.0, 2.0, and 3.0 g Nuvisol Hatch P^®; 20, 40 and 60 mg Gibberellic acid and 700, 900 and 1,100 mg L-carnitine/Kg diet). The obtained results were evaluated, and the best treatment for each sex was chosen for mating. Results indicated that all pretreatments for male and female brood stocks of Nile tilapia positively affected the total count of the offspring produced. Yet, the Haba, in which the females were pretreated with 0.5 g Therigon^®/Kg diet and the males pretreated with 700 mg L-carnitine/Kg diet, gave the highest total count of the offspring comparing with the other Habas. But, because of the high feed cost due to the additives cost, 0.5 g Therigon^®/kg diet as pretreatment for ♀ only (3rd Haba), 2 g Nuvisol Hatch P^®/Kg diet as pretreatment for ♀ only (5th Haba), followed by 0.5 g Therigon^® and 700 mg L-carnitine/Kg diet for ♀ and ♂, respectively (4th Haba), respectively were the best economically.     

Evaluation of housekeeping genes as references for quantitative real-time PCR analysis of gene expression in the murrel <Emphasis Type="Italic">Channa striatus</Emphasis> under high-temperature stress

Quantitative real-time polymerase chain reaction is the most advanced method of quantifying gene expression studies; however, the significance of the obtained results strongly depends on the normalization of the data to compensate for differences between the samples. In the present study, expression analysis of six different constitutively expressed genes viz. 18S ribosomal RNA, glyceraldehyde-3-phosphate dehydrogenase (gapdh), beta actin (βactin), ribosomal binding protein L13, tubulin and TATA-box-binding protein (tbp) were carried out to test their efficacy as reference genes in three different tissues, namely liver, gill and muscle of murrel Channa striatus exposed to high temperature for variable time periods. The stability and suitability of the genes were determined by using bioinformatic tools: GeNorm, NormFinder and BestKeeper. Based on the results, tub/βactin could be used as the reference genes for liver and gill tissues and βactin/gapdh could be the reference genes for muscle tissues in Channa striatus under both short- and long-term thermal stress.     

Preliminary study on homing,site fidelity,and diel movement of black rockfish <Emphasis Type="Italic">Sebastes inermis</Emphasis> measured by acoustic telemetry

Several species of fish exhibit strong homing ability and distinct site fidelity to their original habitats and spawning sites. We have studied the homing ability, site fidelity, and diel movement patterns of three nocturnal black rockfish Sebastes inermis. The patterns were studied by radio-linked acoustic positioning system (VRAP) and fixed monitoring receivers (VR2) in Maizuru Bay, Japan from June to July 2004. All tagged fish were displaced by 80–120 m, but they returned to their respective captured sites at dusk, regardless of the time of release. The fish tagged with a depth sensor transmitter displayed active vertical movement just after the release, and subsequently swam near the bottom depth around the captured site. After homing, they displayed small home ranges [average 815 ± 265 m² (SD)] around a single rocky area with one or two core areas (average 64 ± 30 m²). One core area was utilized during the daylight and dark periods, whereas the other was used primarily during the dark period. The depth-tagged fish primarily used the depth of the rock crevice during the daylight, and it spent its dark period between the surface and the deeper bottom depth.