Spatial patterns of soil attributes and components in a mangrove system in Southeast Brazil (São Paulo)

Purpose

Among environmental factors governing innumerous processes that are active in estuarine environments, those of edaphic character have received special attention in recent studies. With the objectives of determining the spatial patterns of soil attributes and components across different mangrove forest landscapes and obtaining additional information on the cause–effect relationships between these variables and position within the estuary, we analyzed several soil attributes in 31 mangrove soil profiles from the state of São Paulo (Guarujá, Brazil).

Materials and methods

Soil samples were collected at low tide along two transects within the Crumahú mangrove forest. Samples were analyzed to determine pH, Eh, salinity, and the percentages of sand, silt, clay, total organic carbon (TOC), and total S. Mineralogy of the clay fraction (<2 mm) was also studied by X-ray diffraction analysis, and partitioning of solid-phase Fe was performed by sequential extraction.

Results and discussion

The results obtained indicate important differences in soil composition at different depths and landscape positions, causing variations in physicochemical parameters, clay mineralogy, TOC contents, and iron geochemistry. The results also indicate that physicochemical conditions may vary in terms of different local microtopographies. Soil salinity was determined by relative position in relation to flood tide and transition areas with highlands. The proportions of TOC and total S are conditioned by the sedimentation of organic matter derived from vegetation and by the prevailing redox conditions, which clearly favored intense sulfate reduction in the soils (～80% of the total Fe is Fe-pyrite). Particle-size distribution is conditioned by erosive/deposition processes (present and past) and probably by the positioning of ancient and reworked sandy ridges. The existing physicochemical conditions appear to contribute to the synthesis (smectite) and transformation (kaolinite) of clay minerals.

Conclusions

The results demonstrate that the position of soils in the estuary greatly affects soil attributes. Differences occur even at small scales (meters), indicating that both edaphic (soil classification, soil mineralogy, and soil genesis) and environmental (contamination and carbon stock) studies should take such variability into account.

     

Effects of gemcitabine and gemcitabine in combination with carboplatin on five canine transitional cell carcinoma cell lines

Objective-To evaluate in vitro effects of gemcitabine alone and in combination with carboplatin on canine transitional cell carcinoma (TCC) cell lines. Sample-In vitro cultures of 5 canine TCC cell lines. Procedures-Cells were treated with gemcitabine, carboplatin, or a combination of both at various concentrations. Cell proliferation was assessed via a fluorescence-based microplate cell proliferation assay. Cell cycle was evaluated via propidium iodide staining, and apoptosis was assessed by measurement of caspase 3 and 7 enzymatic activity. Synergy between gemcitabine and carboplatin was quantified via combination index analyses. Results-Treatment of 5 canine TCC cell lines with gemcitabine or carboplatin decreased cell proliferation, increased apoptosis, and induced cell cycle arrest. Cell cycle arrest and apoptosis were markedly increased when cell lines were treated with both gemcitabine and carboplatin simultaneously or sequentially. Order of administration during sequential treatment did not consistently affect cell proliferation results in TCC cell lines. When TCC cell lines were treated with gemcitabine and carboplatin in combination at therapeutically relevant concentrations (gemcitabine concentration, < 10μM; carboplatin concentration, < 250μM), a significant decrease in cell proliferation was observed, compared with cell proliferation following treatment with gemcitabine or carboplatin alone. In combination, the effects of gemcitabine and carboplatin were synergistic in 3 of 5 cell lines and additive in the other 2. Conclusions and Clinical Relevance-Gemcitabine had antitumor effects on canine TCC cells in vitro, and the combination of gemcitabine and carboplatin had synergistic activity at biologically achievable concentrations.     

Aurantiochytrium sp. meal can replace fish oil in practical diets for the juvenile Pacific white shrimp

This study evaluated the use of microalgae (Aurantiochytrium sp.) meal as a substitute for fish oil in the diet of juvenile Pacific white shrimp (Litopenaeus vannamei) reared in a clear‐water system. Dietary treatments at five replacement levels (0%, 25%, 50%, 75%, 100%) were performed in triplicate. After 46 days, only a slight difference in shrimp final weight was observed among treatments (0.61 g). An increase in final weight was observed with replacement of up to 50% fish oil for microalgae meal, while the optimal percentage of replacement estimated was 44.7%. Feed conversion rate (FCR) of animals fed a diet of Aurantiochytrium sp.meal to replace up to 50% fish oil decreased, and the optimal percentage of replacement estimated was 49.3%. The fatty acids profile in shrimp muscle tissue demonstrated an increase in docosahexaenoic acid (DHA) from 10.03% to 14.28% with increased replacement of fish oil by microalgae meal in the diet. Therefore, the partial replacement of fish oil by microalgae meal resulted in improved shrimp growth and FCR, and total replacement of dietary fish oil had no negative effects on these parameters. In addition, inclusion of microalgae meal raises the level of DHA in shrimp muscle.     

Science,capacity building and conservation knowledge: The empowerment of the local community for marine conservation in Rapa Nui

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Daily rhythms of cortisol and glucose and the influence of the light/dark cycle on anaesthesia in Nile tilapia (Oreochromis niloticus): Does the timing of anaesthetic administration affect the stress response?

Although daily variations in drug pharmacokinetics have been reported for a variety of teleost species, the influence of this daily variation on the cortisol response following anaesthesia remains poorly understood. To address this, two experiments were performed. The first experiment described the daily patterns of cortisol and glucose secretion in tilapia (Oreochromis niloticus). The second experiment investigated how the timing of anaesthetic administration (specifically at mid‐light [ML] or at mid‐dark [MD]) affects the induction and recovery times and plasma cortisol and glucose levels of juvenile Nile tilapia exposed to benzocaine, clove oil or tricaine methanesulphonate (MS‐222). The results revealed that the effect on the stress response associated with the moment when anaesthesia took place (ML or MD) varied according to the treatment (p < 0.05). Cortisol levels were significantly higher at ML for MS‐222 (ML = 116.23 ± 25.55; MD = 48.25 ± 22.33 ng/dl) (p < 0.05) and clove oil (ML 59.73 ± 14.27; MD 38.26 ± 12.07 ng/dl) (p < 0.05), whereas no significant differences were found between ML and MD cortisol levels for the control treatment (ML = 72.91 ± 18.42; MD = 64.80 ± 10.68 ng/dl) (p > 0.05) or in the benzocaine‐treated group (ML = 38.7 ± 4.90; MD = 38.60 ± 3.69 ng/dl) (p > 0.05). The highest plasma cortisol level in ML was found in the MS‐222‐treated group. All the tested anaesthetics had similar cortisol levels at MD (p > 0.05).     

Effects of dietary live yeast Debaryomyces hansenii on the immune and antioxidant system in juvenile leopard grouper Mycteroperca rosacea exposed to stress

This study investigated the effects of the dietary intake of live yeast Debaryomyces hansenii (CBS 8339) on the immune response of juvenile leopard groupers Mycteroperca rosacea and on their resistance to infection by dinoflagellates Amyloodinium ocellatum.During 4 weeks, juvenile groupers were fed either a diet supplemented with D. hansenii at 10⁶ cfu g^− 1 or a control diet. Both groups were then transferred to a system infected with A. ocellatum and maintained in this stressful environment, for one week. Rearing conditions were favorable to the proliferation of the dinoflagellate and, at 7 days post-infection, the cumulative mortality rate of the control group was 89.5%, suggesting that the yeast-enriched diet conferred protection against the parasite. Only fish with yeast-supplemented diet recovered from the A. ocellatum challenge.The immunological response of both groups of fish was evaluated. Samples were collected at weeks 4 (stressed fish) and 7 (recovering fish) to determine the levels of hemoglobin, plasmatic protein, and immunoglobulin M (IgM) as well as the activity of antioxidant enzymes (SOD and CAT). IgM increased significantly (P ≤ 0.05) in the recovering fish, which had all been fed the yeast diet. A significantly increase was also observed in superoxide dismutase activity in juvenile fish fed the yeast diet; however catalase activity was not affected by the dietary yeast supplement. Overall, fish that received the yeast supplement in their diet have an enhanced immune response as compared with their control counterparts. The present results show that a diet supplemented with D. hansenii stimulates the immune system of juvenile M. rosacea thus enhancing their resistance against A. ocellatum.     

Spatial and temporal variability of physical properties of Aquands under different land uses in southern Chile

The aquands found in southern Chile are derived from volcanic ash and contain high levels of organic matter. Due to the presence of an impermeable stratum, they have shallow soil profiles, which induce waterlogging for several months each year. These fragile soils, locally known as ‘Ñadi’, cover an area of 475 000 hectares and have undergone intensive land use changes, which have affected the soil physical properties. These are still not well understood but are relevant for the design of efficient drainage systems. The aim of this research was to analyse the impact of the land use change in Ñadi soils on the spatial and temporal variability of their soil physical properties. For the land use change from secondary native forest (sNF) to naturalized grassland (NG), the effective soil depth was measured at defined points. Time‐ and space‐dependent changes of water‐table depth and penetration resistance were recorded. Volumetric water content and soil temperature were measured with sensors installed at three depths and the water retention curve and air permeability at these depths were also determined. The changes in land use over time have induced a reduction in soil depth. Soils under NG showed a smaller soil water storage capacity, air capacity and permeability compared with soils under sNF, as well as waterlogging during winter and greater mechanical strength and soil profile temperatures during summer. Therefore, the land use change affected the spatial and temporal variability of soil physical functions across the field.