Chemical and environmental factors driving germination of Solanum americanum seeds

Solanum americanum Mill. is a weed that occurs with a number of crops, and it is known for its high seed production and its staggered germination. The objective of this work was to evaluate the germination behavior of S. americanum seeds under the influence of chemical and environmental factors. In the laboratory, we tested the effect on germination of (i) constant and alternating temperatures, (ii) seed washing, (iii) exposure time and concentration of chemical treatments and (iv) seeding depth and soil covered with plant residue on seedling emergence. The variables analyzed were germination percentage, germination rate index, seedling emergence and length of the seedlings. The results indicated that alternating temperatures are the main way to promote germination of S. americanum; however, chemical treatments can help to increase the germination percentage and rate index. There was no increase in germination with seed washing, with the exception of KNO₃ application. A GA₃ concentration of 0.84 g L^?1 and an exposure time of 21.22 h in 0.2% of KNO₃ promoted the highest germination of S. americanum. Germination occurs when seeds remain on the soil surface and are not covered by crop residue.     

Growth performance, survival and maturation of Litopenaeus vannamei (Boone) in an inland CRS with no water reposition

Closed recirculation systems (CRS) present an alternative for providing organisms to the aquaculture. A CRS with zero water exchange was used in the present study; the CRS consisted of a culture and maturation facility, biofilter system and reservoirs tanks. During two consecutive trials, the CRS efficiency was evaluated by assessing the growth, survival and maturation of juveniles into adults Litopenaeus vannamei (Boone). Throughout the study, water quality parameters (temperature, pH, salinity, NH₃, NO₂ and NO₃) and ion concentration were monitored. Most parameters showed fluctuations without significant differences. However, a decrease in pH was observed during the maturation phase, and an increase in phosphorus was detected, in both the trials, compared with that in initial seawater. Growth and survival for juvenile and pre-adult shrimps presented similar variations without significant differences. Female gonadal maturation and spawning rate were not significantly different between trials. Unfortunately, shrimp eggs underwent lysis 6 h after spawning. These results show that the growth, survival and maturation obtained under CRS conditions are reproducible, and suggest the possibility of using these systems for biosecure shrimp culture, protected against eventual diseases outbreaks. The results of this study also suggest the importance of future studies addressing ion concentration changes in a CRS with zero water exchange.     

Eocene El Niño: evidence for robust tropical dynamics in the "hothouse"

Much uncertainty surrounds the interactions between the El Ni?o-Southern Oscillation (ENSO) and long-term global change. Past periods of extreme global warmth, exemplified by the Eocene (55 to 35 million years ago), provide a good testing ground for theories for this interaction. Here, we compare Eocene coupled climate model simulations with annually resolved variability records preserved in lake sediments. The simulations show Pacific deep-ocean and high-latitude surface warming of approximately 10 degrees C but little change in the tropical thermocline structure, atmosphere-ocean dynamics, and ENSO, in agreement with proxies. This result contrasts with theories linking past and future "hothouse" climates with a shift toward a permanent El Ni?o-like state.     

Understanding fishing and conservation of the Pacific seahorse (Hippocampus ingens) in Sinaloa,Mexico, through local ecological knowledge

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LAPAROSCOPIC SONOGRAPHY IN THE URINARY SYSTEM

This work reports the use of laparoscopic-transducer sonography for the examination of the urinary system in a swine model. Animals underwent a two-phase study. In the first phase, the urinary system was examined using laparoscopic sonography. In the second a partial ureteral obstruction was induced, and sonographic changes were recorded and evaluated. Sonography was used to evaluate kidneys, ureters, and bladder. Anatomic structures were evaluated and the following pathological findings were identified: renal cysts, one polycystic kidney, dilation of the renal pelvis, hydronephrosis, and one perirenal pseudocyst. Where necessary, contrast digital fluoroscopy (excretory urography and retrograde ureteropyelography) was also performed. Laparoscopic sonography mainly is used for evaluation prior to laparoscopic surgery to guide decisions relating to surgery. The quality of the images obtained laparoscopically is superior to that of percutaneous or transabdominal images, because artifacts are reduced and the contact surface of the transducer is placed directly over the study area. Laparoscopic sonography proved highly effective for studying renal and ureteral disorders prior to minimally invasive surgery.     

Post-fire resprouting ability of 15 non-dominant shrub and tree species in Mediterranean areas of NE Spain

Post-fire resprouting ability of the non-dominant tree and shrub species of the Mediterranean Basin has not yet been experimentally tested, although this group contributes to maintain the richness of Mediterranean plant communities. In this study, we have analyzed the post-fire recovery ability of 15 woody species that occur in relatively low abundance in dry and sub humid Mediterranean areas in NE of Spain. The main goals have been: (i) to determine experimentally the post-fire resprouting ability of these species and (ii) to compare the abundance of these species in areas affected by wildland fires and in unburned areas. We have observed a high resprouting ability after prescribed burning of most species except for Juniperus communis and J. phoenicea which showed a null resprouting. As the species with high resprouting ability showed similar presence in burned and unburned areas, we can conclude that wildfires are not a factor that constrains the presence of these species in Mediterranean woodlands. However, we found a reduction in the abundance of J. communis and J. phoenicea at the regional level after wildland fires.     

Post-fire selective thinning of Arbutus unedo L. coppices keeps animal diversity unchanged: the case of ants

Context

In the Mediterranean area, different post-fire management strategies are used for coppices of resprouting species to promote a more regular forest structure, enhance plant growth, and reduce fire risk. However, the effects of these management treatments on forest-associated fauna are unknown, which in turn could be limiting their beneficial effects.

Aims

The aim of this work was to determine whether forest management of a recently burned area dominated by a vigorous resprouting tree species (Arbutus unedo L.) affects ant communities.

Methods

Ant communities, sampled using pitfall traps, were examined from unmanaged and selective thinning coppices of A. unedo. Ants are here used as bioindicators of ecosystem health and surrogates for other animal groups.

Results

Very limited effects of these post-fire management strategies on the structure and composition of ant communities were found. The lack of effects could be due to the reported small changes in physical conditions among treatments; or either, the most sensitive ant species to these post-fire management treatments might be the same ones affected by fire and, consequently, the ant species that would potentially be affected most were no longer in the study area.

Conclusion

The lack of any significant effects caused by these post-fire management practices on the associated fauna of A. unedo coppices points out the suitability of these treatments in these circumstances.     

Secondary succession in a fragmented Atlantic Forest landscape: evidence of structural and diversity convergence along a chronosequence

Changes in physiognomy, species composition and structure, and dispersal mechanisms of canopy and subcanopy plant assemblages were investigated along a chronosequence of three ages: 12, 20, and 50+ years old (=old-growth), three replications in each, in an Atlantic Forest landscape in Northeastern Brazil. Our objective was to investigate whether there is floristic and structural convergence along secondary succession. There were significant differences between secondary and old-growth forests in density and basal area only for the subcanopy. Differences in density between forest ages were noted when the assemblage was analyzed per diameter and height classes. Richness of canopy species of both secondary ages differed from those of old-growth forests. Some dominant species in the canopy of secondary forests showed a significant decrease in density with increasing age, which indicates an ongoing process of floristic changes. The low level of shared species between secondary and old-growth forests supports the idea that species composition is one of the last components to recover during successional process. Zoochory was the most important dispersal guild in species percentage and number, irrespective of stand age. Although regenerating areas can take alternative pathways, our results indicate that secondary Atlantic Forest sites have a high potential for natural regeneration. This recovery is recorded as a physiognomic convergence of the canopy layer in as little as 12 years, and progressive introductions of later successional species into the plant assemblage that lead to convergence in terms of the diversity and richness of the subcanopy and of dispersal guilds just 20 years after abandonment.