Hydrocotyle ranunculoides (floating pennywort).

H. ranunculoides is a perennial, aquatic plant native to the Americas. It was introduced outside of its native range through the aquatic nursery trade and has since naturalized in many countries around the world. Like many aquatic weeds, H. ranunculoides possesses a number of characteristics which contributes to its invasiveness: high growth rates, adaptability to prevailing nutrient conditions, very effective vegetative propagation, plasticity in growth response, overwintering to avoid low temperature stress, resistance to herbivory, resistance to chemical control, and absence of specific pests and diseases in introduced environments. Its rapid growth means that H. ranunculoides can produce dense, interwoven floating mats across slow-flowing waters. These mats restrict the light available for submerged macrophytes, decreases oxygen levels and therefore decrease the overall biodiversity of an area. It can also increase the risk of flooding and block channels. H. ranunuloides is considered a serious invader in Belgium, the Netherlands, and the UK in particular and was added to the EPPO alert list in 2004 (EPPO, 2004) and Schedule 9 of the Wildlife and Countryside Act in the UK. It is also banned from sale in the Netherlands. It has spread into water bodies in a number of other European countries including France, Belgium, Germany and Italy. In 2016, the European Commission's Implementing Regulation (2016/1141) was published, which includes H. ranunculoides among the list of 14 invasive alien plant species of Union concern.

Double-diffusive mixing makes a small contribution to the global ocean circulation

Double-diffusive processes enhance diapycnal mixing of heat and salt in the open ocean. However, observationally based evidence of the effects of double-diffusive mixing on the global ocean circulation is lacking. Here we analyze the occurrence of double-diffusive thermohaline staircases in a dataset containing over 480,000 temperature and salinity profiles from Argo floats and Ice-Tethered Profilers. We show that about 14% of all profiles contains thermohaline staircases that appear clustered in specific regions, with one hitherto unknown cluster overlying the westward flowing waters of the Tasman Leakage. We estimate the combined contribution of double-diffusive fluxes in all thermohaline staircases to the global ocean’s mechanical energy budget as 7.5 GW [0.1 GW; 32.8 GW]. This is small compared to the estimated energy required to maintain the observed ocean stratification of roughly 2 TW. Nevertheless, we suggest that the regional effects, for example near Australia, could be pronounced.

Use of the bio-engineering technologies in the construction and upgrade of complex installations for obtaining energy from three renewable sources. Complex installations for flowing waters

In the context of the sustainable development, the problem of the widespread use of renewable energy resources, which are clean and inexhaustible, is becoming more acute. In this regard, it is necessary to develop some capture installations that use renewable energy sources as efficiently as possible and with low impact on the environment. This paper presents a patented installation that integrates three sources of renewable energy: wind energy, solar energy and hydraulic energy of water current. The efficiency of this complex installation is given by the fact that the simultaneous capitalization of the three renewable energy sources leads to a high efficiency, in relation with the occupied area. To increase the renewable energy absorption level, both the air turbine and the hydraulic turbine have been equipped with different bioengineering models of blades and paddles. Following the testing of the two turbines equipped with blades and paddles with bioengineering geometry, a significant improvement of their efficiency was found, compared to the initial blades and paddles.

Two new species from the Hygrobates nigromaculatus-complex (Acariformes, Hydrachnidia, Hygrobatidae), based on morphological and molecular evidence

We analyse the taxonomic structure of the Hygrobates nigromaculatus-complex from the Balkan Peninsula. We describe two new species: Hygrobates lacrima Pešić sp. nov. (Montenegro) and H. limnocrenicus Pešić sp. nov. (Montenegro, North Macedonia). Although both species are morphologically similar, the average K2P-distance between DNA-barcode sequences from H. limnocrenicus sp. nov. and its closest relative H. setosus was 12.43% (SD = 1.47), and between H. lacrima sp. nov. and its closest relative H. nigromaculatus 15.87% (SD = 1.74). The new species exhibit distinct differences in terms of habitat preference: H. lacrima sp. nov. inhabits pools and shallow eddies along faster flowing waters, whereas H. limnocrenicus sp. nov. prefers deeper, fast flowing water, typically found in the outflow of a limnocrenic springs or lake outlets. The finding of these two new species suggests that efforts to investigate mites of the H. nigromaculatus-complex in the Balkans should be intensified.