A new species of Eugenia (Myrtaceae) from south‐eastern Brazil

A new species, Eugenia marambaiensis M.C.Souza & M.P.Morim, is described and illustrated. It is characterized by having large translucent gland dots densely distributed on the leaves, with a caudate apex and slightly wavy margins and a glabrous raceme, with only two flowers. Eugenia marambaiensis was only found in the locality of Restinga da Marambaia, Rio de Janeiro, Brazil. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 306–308.     

Characterization of unisexual flower development in the endangered mahogany tree Swietenia macrophylla King. (Meliaceae)

The selection of candidate plus trees of desirable phenotypes from tropical forest trees and the rapid devastation of the natural environments in which these trees are found have created the need for a more detailed knowledge of the floral and reproductive biology of tropical tree species. In this article, the organogenic processes related to unisexual flower development in tropical mahogany, Swietenia macrophylla , are described. Mahogany inflorescences at different developmental stages were evaluated using scanning electron microscopy or optical microscopy of histological sections. The unisexual flowers of S. macrophylla are usually formed in a thyrse, in which the positions of the female and male flowers are not random. Differences between male and female flowers arise late during development. Both female and male flowers can only be structurally distinguished after stage 9, where ovule primordia development is arrested in male flowers and microspore development is aborted in female flower anthers. After this stage, male and female flowers can be distinguished by the naked eye as a result of differences in the dimensions of the gynoecium. The floral characteristics of S. macrophylla (distribution of male and female flowers within the inflorescence, and the relative number of male to female flowers) have practical implications for conservation strategies of this endangered species.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 529–535.     

Does leaf quality mediate the stimulation of leaf breakdown by phosphorus in Neotropical streams?

1. Lowland tropical streams have a chemically diverse detrital resource base, where leaf quality could potentially alter the effect of high nutrient concentrations on leaf breakdown. This has important implications given the extent and magnitude of anthropogenic nutrient loading to the environment. 2. Here, we examine if leaf quality (as determined by concentrations of cellulose, lignin and tannins) mediates the effects of high ambient phosphorus (P) concentration on leaf breakdown in streams of lowland Costa Rica. We hypothesised that P would have a stronger effect on microbial and insect processing of high‐ than of low‐quality leaves. 3. We selected three species that represented extremes of quality as measured in leaves of eight common riparian species. Species selected were, from high‐ to low‐quality: Trema integerrima > Castilla elastica > Zygia longifolia. We incubated single‐species leaf packs in five streams that had natural differences in ambient P concentration (10–140 μg soluble reactive phosphorus (SRP) L^?1), because of variable inputs of solute‐rich groundwater and also in a stream that was experimentally enriched with P (approximately 200 μg SRP L^?1). 4. The breakdown rate of all three species varied among the six streams: T. integerrima (k‐values range: 0.0451–0.129 day^?1); C. elastica (k‐values range: 0.0064–0.021 day^?1); and Z. longifolia (k‐values range: 0.002–0.008 day^?1). Both ambient P concentration and flow velocity had significant effects on the breakdown rate of the three species. 5. Results supported our initial hypothesis that litter quality mediates the effect of high ambient P concentration on leaf processing by microbes and insects. The response of microbial respiration, fungal biomass and invertebrate density to high ambient P concentration was greater in Trema (high quality) than in Castilla or Zygia (low quality). Variation in flow velocity, however, confounded our ability to determine the magnitude of stimulation of breakdown rate by P. 6. Cellulose and lignin appeared to be the most important factors in determining the magnitude of P‐stimulation. Surprisingly, leaf secondary compounds did not have an effect. This contradicts predictions made by other researchers, regarding the key role of plant secondary compounds in affecting leaf breakdown in tropical streams.     

Energy storage during the transition from endogenous to exogenous feeding in Australian redclaw crayfish Cherax quadricarinatus (Von Martens, 1898)

Summary

The Australian redclaw crayfish Cherax quadricarinatus hatches at an advanced stage. Two post-hatching stages rely on yolk reserves before the organism becomes a juvenile. After a juvenile appears, the yolk is depleted and young crayfish might spend a few days among female pleopods before starting to feed independently. During this phase, the juvenile organism needs alternative energy sources. Offspring from three females were analyzed with histological and histochemical techniques, from hatching until reaching the 2-week juvenile stage, to trace digestive system development and internal organ lipid and glycogen accumulation. Neutral lipids are stored in specialized cells of the hepatopancreatic tissue until the juvenile stage is reached. An increasing rate of accumulation was found. Glycogen was stored in hepatopancreas and tail muscle cells until post-embryo II, and no increasing or decreasing rate was found in storage functions.     

Stable isotope analysis indicates microalgae as the predominant food source of fauna in a coastal forest stream,south‐east Brazil

Abstract: Stable isotope studies of food webs in floodplains, large rivers, mangroves, and seagrasses have shown that, although a large proportion of the biomass may come from higher plants, microalgae provide a disproportionate amount of carbon assimilated by metazoan consumers. Evidence is building that this may also be the case for streams, especially those in the tropics. At the level of individual consumer species we also see that the apparent diet may not be reflected in the carbon assimilated. Tropical streams commonly have omnivore‐detritivore species that potentially show this phenomenon. We tested these concepts in four moderately shaded sites in a stream in well‐preserved Atlantic rainforest at Ilha Grande, Rio de Janeiro. We sampled aquatic insects, shrimps and fish as well as potential terrestrial and aquatic primary food sources. Carbon stocks from terrestrial sources predominated over carbon of algal origin (>99% of total). The primary sources of carbon showed distinctly different isotopic signatures: terrestrial sources had δ¹³C values close to ?30‰, microalgae were ?20‰ and macroalgae were ?25‰. All fauna had δ¹³C values consistent with a carbon source derived from microalgae. Baetid mayflies and atyid shrimps exert a strong grazing pressure on periphyton and organic sediments but appear to assimilate predominantly microalgae. The palaemonid shrimp Macrobrachium olfersi also ingests large amounts of detritus of terrestrial origin, but apparently assimilates animal prey with algal δ¹³C signatures. These results support the growing view that tropical stream food chains are primarily algal based.     

Positive interaction between invasive plants: The influence of Pyracantha angustifolia on the recruitment of native and exotic woody species

Abstract: Positive interactions between species are known to play an important role in the dynamics of plant communities, including the enhancement of invasions by exotics. We studied the influence of the invasive shrub Pyracantha angustifolia (Rosaceae) on the recruitment of native and exotic woody species in a secondary shrubland in central Argentina mountains. We recorded woody sapling recruitment and micro‐environmental conditions under the canopies of Pyracantha and the dominant native shrub Condalia montana (Rhamnaceae), and in the absence of shrub cover, considering these situations as three treatments. We found that native and exotic species richness were higher under Pyracantha than under the other treatments. Ligustrum lucidum (Oleaceae), an exotic bird‐dispersed shade‐tolerant tree, was the most abundant species recruiting in the area, and its density was four times higher under the canopy of Pyracantha. This positive interaction may be related to Pyracantha's denser shading, to the mechanical protection of its canopy against ungulates, and/or to the simultaneous fruit ripening of both woody invaders.     

Physical illness in patients with severe mental disorders. II. Barriers to care, monitoring and treatment guidelines, plus recommendations at the system and individual level

Physical disorders are, compared to the general population, more prevalent in people with severe mental illness (SMI). Although this excess morbidity and mortality is largely due to modifiable lifestyle risk factors, the screening and assessment of physical health aspects remains poor, even in developed countries. Moreover, specific patient, provider, treatment and system factors act as barriers to the recognition and to the management of physical diseases in people with SMI. Psychiatrists can play a pivotal role in the improvement of the physical health of these patients by expanding their task from clinical psychiatric care to the monitoring and treatment of crucial physical parameters. At a system level, actions are not easy to realize, especially for developing countries. However, at an individual level, even simple and very basic monitoring and treatment actions, undertaken by the treating clinician, can already improve the problem of suboptimal medical care in this population. Adhering to monitoring and treatment guidelines will result in a substantial enhancement of physical health outcomes. Furthermore, psychiatrists can help educate and motivate people with SMI to address their suboptimal lifestyle, including smoking, unhealthy diet and lack of exercise. The adoption of the recommendations presented in this paper across health care systems throughout the world will contribute to a significant improvement in the medical and related psychiatric health outcomes of patients with SMI.     

Performance and fate of tree seedlings on and around nests of the leaf‐cutting ant Atta cephalotes: Ecological filters in a fragmented forest

Habitat fragmentation is currently the most pervasive anthropogenic disturbance in tropical forests and some species of leaf‐cutting ants of the genus Atta (dominant herbivores in the neotropics) have become hyper‐abundant in forest edges where their nests directly impact up to 6% of the forest area. Yet, their impacts on the regeneration dynamics of fragmented forests remain poorly investigated. Here we examine the potential of Atta cephalotes nests to function as ecological filters impacting tree recruitment. Growth, survival and biomass partitioning of experimentally planted seedlings (six tree species) were examined at eight spatially independent A. cephalotes colonies in a large Atlantic Forest fragment. Seedling performance and fate (leaf numbers and damage) were monitored up to 27 months across three habitats (nest centre, nest edge and forest understorey). Plants at illuminated nest centres showed twice the gross leaf gain as understorey individuals. Simultaneously, seedlings of all species lost many more leaves at nests than in the forest understorey, causing a negative net leaf gain. Net leaf gain in the shaded understorey ranged from zero (Licania and Thyrsodium species) to substantial growth for Copaifera and Virola, and intermediate levels little above zero for Protium and Pouteria. Also seedling survival differed across habitats and species, being typically low in the centre and at the edge of nests where seedlings were often completely defoliated by the ants. Lastly, seedling survival increased strongly with seed size at nest edges while there was no such correlation in the forest. Our results suggest that Atta nests operate as ecological filters by creating a specific disturbance regime that differs from other disturbances in tropical forests. Apparently, Atta nests favour large‐seeded tree species with resprouting abilities and the potential to profit from a moderate, nest‐mediated increase in light availability.     

Do abandoned nests of leaf‐cutting ants enhance plant recruitment in the Atlantic Forest?

The role played by abandoned nests of leaf‐cutting ants (Atta spp.) as a small‐scale disturbance regime that affects plant recruitment, species coexistence and forest regeneration remains poorly investigated. Here we examine whether abandoned nests of Atta cephalotes serve as regeneration niches and operate as particular plant recruitment habitats, favouring forest regeneration after ant activities cease and leading to the establishment of taxonomically/ecologically distinct plant assemblages. Soil properties, canopy openness, light availability and regenerating plant assemblages were evaluated across 18 nests and adjacent control plots in a large remnant of Atlantic Forest in north‐east Brazil from December 2004 to December 2005. Surprisingly, nests and control plots exhibited very similar light environments irrespective of nest age, but nest soils exhibited substantial reductions in carbon content (1.45 ± 0.24 vs. 1.79 ± 0.13%) and organic matter (2.50 ± 0.41 vs. 3.08 ± 0.23%), and proved to be much more resistant to penetration (30.57 ± 6.08 vs. 39.48 ± 7.53 mm). Functional signature of regenerating plant assemblages exhibited little variation across both habitat types, as they were dominated by pioneer, small‐seeded and vertebrate‐dispersed species. However, abandoned nests exhibited less dense, impoverished and more homogeneous regenerating plant assemblages at local and landscape scale; they clearly lacked nest‐dependent plant species and represented floristic subsets of the flora inhabiting the undisturbed forest. This recruitment bottleneck was transient in the long term because nest‐related effects ameliorated in older nests. Our results suggest that, unlike treefall gaps, abandoned nests represent temporary (relatively long‐lasting) islands of unsuitable substrate that reduce plant recruitment, retard forest regeneration, and fail in providing a special regeneration niche able to promote species coexistence and plant diversity.