Tidal height,rather than habitat selection for conspecifics,controls settlement in mussels

Settlement is a major determinant of intertidal populations. However, the energy costs of lost larvae are very high. Accordingly, arrival and attachment on suitable substrata are essential requirements for species’ survival. On the intertidal, the presence of cues left by adult or juvenile conspecifics could be vital for the successful establishment of larvae arriving on the shore. Two mussel species, the indigenous Perna perna and the invasive Mytilus galloprovincialis, co-occur on the lower eulittoral zone on the south coast of South Africa. P. perna dominates the low and M. galloprovincialis the high mussel zones, with co-existence in the mid mussel zone. This study tested the hypothesis of settlement selectivity for conspecifics in these two mussel species, to understand whether the final adult distribution of mussels on the shores is determined by active behavioural and chemical mechanisms. Preferential selection by larvae for conspecifics was tested in the field during the peak settlement period in 2004 in natural mussel beds across zones and through manipulative experiments in the mid-zone where the species co-exist. On natural beds, settlement was determined by counts of settlers attached over 48 h onto artificial collectors. Collectors were placed on beds of P. perna and M. galloprovincialis present at both high- and low-adult densities, as well as in mixed beds. On such natural beds, settlers of both species consistently favored low-zone P. perna beds. Settlement patterns over 24 h onto experimentally created mussel patches consisting of P. perna, M. galloprovincialis or the two species combined beds, set in the mixed zone, did not conform with the results of the natural beds study: settlers of both species settled with no discrimination among different patches. The results indicate that mussels, which are sedentary, lack attraction to conspecifics at settlement. This highlights the importance of tidal height in setting settlement rates, and of post-settlement events in shaping populations of these broadcast spawners.     

Hyperactivity and tree-top disease induced by the baculovirus AcMNPV in Spodoptera exigua larvae are governed by independent mechanisms

Although many parasites are known to manipulate the behavior of their hosts, the mechanisms underlying such manipulations are largely unknown. Baculoviruses manipulate the behavior of caterpillar hosts by inducing hyperactivity and by inducing climbing behavior leading to death at elevated positions (tree-top disease or Wipfelkrankheit). Whether hyperactivity and tree-top disease are independent manipulative strategies of the virus is unclear. Recently, we demonstrated the involvement of the protein tyrosine phosphatase (ptp) gene of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in the induction of hyperactivity in Spodoptera exigua larvae. Here we show that AcMNPV ptp is not required for tree-top disease, indicating that in S. exigua baculovirus-induced hyperactivity and tree-top disease are independently induced behaviors that are governed by distinct mechanisms.     

Fetoscopic tracheal occlusion for treatment of non-isolated congenital diaphragmatic hernia

Fetoscopic endotracheal occlusion (FETO) is a prenatal treatment that may increase survival in severe congenital diaphragmatic hernia (CDH). In the USA, FETO is offered for isolated severe left-sided CDH in the context of an FDA-approved feasibility study. FETO in non-isolated cases of severe CDH is only performed with a compassionate use exemption from US regulatory bodies. Anomalies frequently associated with CDH include congenital cystic lesions of the lung and cardiac defects. We describe two cases of non-isolated severe left-sided CDH that underwent prenatal FETO, survived after birth and underwent postnatal surgical repair. The potential benefit of FETO in this setting is discussed. © 2017 John Wiley & Sons, Ltd.     

Fluxes of dissolved organic matter in larch forests in the cryolithozone of central Siberia

Fluxes of dissolved organic matter (DOM) in larch biogeocenoses and its export from the drainage basin have been studied in the zone of continuous permafrost. A comparative assessment of DOM input into the soil has been made on slopes of northern and southern exposures (as variants reflecting the current state and warming). The dynamics of DOM export in a creek depending on the increasing depth of the active soil horizon in the drainage area have been revealed. It is concluded that an increase in the depth of the seasonally thawing layer induced by global warming will not have any significant effect on the amount of annual DOM export. Reduction of DOM export may be expected upon a decrease in litter stocks under the effect of their mineralization and forest fires.     

A Modeling System to Assess Land Cover Land Use Change Effects on SAV Habitat in the Mobile Bay Estuary

Estuarine ecosystems are largely influenced by watersheds directly connected to them. In the Mobile Bay, Alabama watersheds we examined the effect of land cover and land use (LCLU) changes on discharge rate, water properties, and submerged aquatic vegetation, including freshwater macrophytes and seagrasses, throughout the estuary. LCLU scenarios from 1948, 1992, 2001, and 2030 were used to influence watershed and hydrodynamic models and evaluate the impact of LCLU change on shallow aquatic ecosystems. Overall, our modeling results found that LCLU changes increased freshwater flows into Mobile Bay altering temperature, salinity, and total suspended sediments (TSS). Increased urban land uses coupled with decreased agricultural/pasture lands reduced TSS in the water column. However, increased urbanization or agricultural/pasture land coupled with decreased forest land resulted in higher TSS concentrations. Higher sediment loads were usually strongly correlated with higher TSS levels, except in areas where a large extent of wetlands retained sediment discharged during rainfall events. The modeling results indicated improved water clarity in the shallow aquatic regions of Mississippi Sound and degraded water clarity in the Wolf Bay estuary. This integrated modeling approach will provide new knowledge and tools for coastal resource managers to manage shallow aquatic habitats that provide critical ecosystem services.     

Variable Irrigation District Action in Water Trading

Irrigation districts (IDs) in the American west are highly diverse in their economic attributes and local water scarcity circumstances. This diversity may affect reallocative action via water transactions as scarcity rises. The institutional background defining and constraining IDs is described here. For a Texas study region the progress of permanent water right transfers involving IDs is documented and examined. An econometric analysis of multiple decades of ID water transfer activities in the Lower Rio Grande Valley finds that IDs with larger initial water right holdings and higher populations in nearby cities are more likely to participate in agricultural‐to‐municipal water transfer activities. The findings suggest that consolidation of smaller water right holding IDs may be an avenue for quickening the pace of reallocation, especially in more populated areas.