Impact of the zebra mussel Dreissena polymorpha invasion on the budget of suspended material in a shallow lagoon ecosystem

The role of the zebra mussel Dreissena polymorpha in redistribution of total particulate material (TPM) between the water column and bottom sediment was estimated using the TPM budget for a mussel bed in the Curonian lagoon, the Baltic Sea. Seasonal clearance rates were derived from the TPM budget assuming two resuspension scenarios: no resuspension and full resuspension of biodeposits. Estimated clearance rates for both scenarios were compared with the rates calculated from the population clearance rate model. Seasonal clearance rates estimated using the population model (1.1 and 11.8 l g⁻¹ SFDW day⁻¹) fitted well into the interval of seasonal clearance rates calculated from TPM budgets assuming no resuspension of biodeposits (3.2 and 21.4 l g SFDW⁻¹ day⁻¹). In the scenario with biodeposits resuspension clearance rates were much higher (57.4 and 148.9 g SFDW⁻¹ day⁻¹). The ratio of clearance to residence time was highly dependent on the fate of biodeposits. Therefore its use in interpretation of the species impact on TPM was limited. An alternative measure based on the ratio of the amount of TPM biodeposited to TPM transported into the bed was used. It was found that zebra mussels are able to deposit between 10 and 30% of the incoming TPM, and the amount of biodeposited material was correlated with water residence time. Results indicate that the impact of zebra mussels on TPM in the lagoon is small relative to the high transport rates of TPM over the bed. However, annual biosedimentation rate (~590 g m⁻²) in the mussel bed was higher than physical deposition rate (~380 g m⁻²) in accumulation areas devoid of large suspension feeders. We suggest that a local impact due to enhanced availability of organic material to other trophic groups of associated benthic organisms may be more significant than effects on TPM pathways at an ecosystem scale.     

Distribution and diversity of palms in a tropical biodiversity hotspot (Thailand) assessed by species distribution modeling

Species distribution modeling has been widely used to address questions related to ecology, biogeography and species conservation on global and regional scales. Here, we study palms (Arecaceae) in a tropical biodiversity hotspot (Thailand) using species distribution modeling to assess range‐limiting factors and estimate distribution and diversity patterns based on a comprehensive compilation of occurrence records. We focused on palms as a model group due to their key‐stone importance for ecosystem functioning and socio‐economics. Different combinations of climatic, non‐climatic environmental and spatial predictors were used. The most accurate models as indicated by the ‘area under the receiver operating characteristic curve’ (AUC) statistic were those that combined all predictors. The four strongest single predictors of palm species distributions were, in decreasing order of importance, 1) latitude, 2) precipitation of driest quarter, 3) annual precipitation, and 4) minimum temperature of the coldest month, suggesting rainfall patterns and latitudinal spatial constraints as the main range determinants. Overlaying the predicted distributions revealed that potential palm hotspots are situated in the provinces of Satun and Yala in southern Thailand where vast areas remain relatively open to the discovery of new palm records and perhaps even new species.     

Pathological and immunological evaluation of different regimens of praziquantel treatment in a mouse model of Schistosoma mansoni infection

BackgroundOne of the considerable challenges of schistosomiasis chemotherapy is the inefficacy of praziquantel (PZQ) at the initial phase of the infection. Immature schistosomes are not susceptible to PZQ at the curative dose. Here, we investigated the efficacy of different PZQ regimens administered during the initial stage of Schistosoma mansoni infection in mice.Methodology/Principal findingsTwo months-old mice were individually infected with 80 S. mansoni cercariae and divided into one infected-untreated control group (IC) and four PZQ-treated groups: PZQ at 100 mg/kg/day for five consecutive days (group PZQ1), PZQ at 100 mg/kg/day for 28 days (group PZQ2), PZQ at 18 mg/kg/day for 28 days (group PZQ3) and a single dose of PZQ at 500 mg/kg (group PZQ4). The treatment started on day one post-infection (p.i), and each group of mice was divided into two subgroups euthanized on day 36 or 56 p.i, respectively. We determined the mortality rate, the parasitological burden, the hepatic and intestinal granulomas, the serum levels of Th-1, Th-2, and Th-17 cytokines, and gene expression. The treatment led to a significant (p < 0.001) reduction of worm burden and egg counts in the intestine and liver in groups PZQ2 and PZQ3. On 56^th day p.i, there was a significant reduction (p < 0.001) of the number and volume of the hepatic granulomas in groups PZQ2 and PZQ3 compared to group PZQ1 or PZQ4. Moreover, in group PZQ3, the serum levels of IFN-γ, TNF-α, IL-13, and IL-17 and their liver mRNA expressions were significantly reduced while IL-10 and TGF-β gene expression significantly increased. The highest mortality rate (81.25%) was recorded in group PZQ2.Conclusion/SignificanceThis study revealed that the administration of PZQ at 18 mg/kg/day for 28 consecutive days was the optimal effective posology for treating S. mansoni infection at the initial stage in a murine model.     

Territory Defence in Black Redstarts,Phoenicurus ochruros: Effects of Intruder and Owner Age?

European black redstarts, Phoenicurus ochruros, vigorously defend all-purpose territories and exhibit delayed plumage maturation, most subadult males looking exactly female-like in their first breeding season. We tested the hypotheses that such dull subadult male plumages are beneficial in order to reduce aggression of adult males either by deception or by honest signalling of subordinance status, and that, in turn, conspicuous (adult) plumage colorations are able to intimidate contenders because they act as a signal of fighting ability and aggressive motivation. Adult and dull yearling black redstart territory owners were confronted with intruders mimicked by stuffed mounts of either a conspicuous adult or a dull subadult male. Our results do not support the hypotheses tested: dull plumages of young intruders did not reduce aggression from adult territory owners and aggressiveness towards intruders was significantly higher in yearling territory owners as compared with adult owners. Conspicuous intruders did not deter dull territory owners and we found no indications that conspicuous male coloration is a signal of fighting ability or aggressive motivation in this species. Instead, the amount of aggressive response to intruders showed considerable individual variance within age classes regardless of the plumage of the intruder and the status of the owner.     

Lipids from the brown alga Cystoseira barbata

Two new diunsaturated lipids, related to palmitic acid, were isolated from the brown alga Cystoseira barbata, one of which is toxic to mice during P388 lymphocytic leukemia tests.     

Evolution of taxodiaceous Cupressaceae (Coniferopsida)

The evolution of taxodiaceous Cupressaceae has been discussed controversially, because phylogenetic analyses using non-molecular data show major differences to molecular analyses. To solve this problem, we used non-molecular data with a high probability of homology. With these type of data, we could show for the first time in taxodiaceous Cupressaceae that phylogenetic trees of molecular and non-molecular data share the same topology. Investigation of female cone development also contributes to better understanding of morphology and anatomy in taxodiaceous Cupressaceae. Additional developmental, fossil and cone configuration data support the topology constructed by using the molecular and non-molecular data.