Reef fishes recruited at midwater coral nurseries consume biofouling and reduce cleaning time in Seychelles,Indian Ocean

In coral reef restoration, coral gardening involves rearing coral fragments in underwater nurseries prior to transplantation. These nurseries become fish-aggregating devices and attract biofouling. We hypothesised that: (1) the presence of corals at a nursery is critical to recruit fish assemblages and (2) the recruited fish assemblages control biofouling, reducing person-hours invested in nursery cleaning. Three midwater coral nurseries were deployed at 8?m depth for 27 months within the marine protected area of Cousin Island Special Reserve, Seychelles, Indian Ocean. Each nursery consisted of a 6?m×6?m PVC pipe frame, layered with a recycled 5.5-cm-mesh tuna net. Human cleaning effort was calculated based on daily dive logs. Nursery-associated fish assemblages and behaviour were video-recorded prior to harvesting corals after a 20-month growth period and seven months post-coral harvesting. The density (ind. m–2) of blue-yellow damselfish Pomacentrus caeruleus was 12–16 times higher when corals were present than when corals were absent at the nurseries. Fish assemblages recruited into the nurseries included three trophic levels, from herbivores to omnivores, in six families: Ephippidae, Pomacentridae, Labridae (Scarinae), Gobiidae, Siganidae and Monacanthidae. Higher abundance of large fish (total number of individuals) resulted in 2.75 times less person-hours spent in nursery cleaning. These results have important implications for cost-effective coral reef restoration.     

Metazoan meiofauna in deep-sea canyons and adjacent open slopes: A large-scale comparison with focus on the rare taxa

Metazoan meiofaunal abundance, total biomass, nematode size and the richness of taxa were investigated along bathymetric gradients (from the shelf break down to ca. 5000-m depth) in six submarine canyons and on five adjacent open slopes of three deep-sea regions. The investigated areas were distributed along >2500 km, on the Portuguese to the Catalan and South Adriatic margins. The Portuguese and Catalan margins displayed the highest abundances, biomass and richness of taxa, while the lowest values were observed in the Central Mediterranean Sea. The comparison between canyons and the nearby open slopes showed the lack of significant differences in terms of meiofaunal abundance and biomass at any sampling depth. In most canyons and on most slopes, meiofaunal variables did not display consistent bathymetric patterns. Conversely, we found that the different topographic features were apparently responsible for significant differences in the abundance and distribution of the rare meiofaunal taxa (i.e. taxa accounting for <1% of total meiofaunal abundance). Several taxa belonging to the temporary meiofauna, such as larvae/juveniles of Priapulida, Holothuroidea, Ascidiacea and Cnidaria, were encountered exclusively on open slopes, while others (including the Tanaidacea and Echinodea larvae) were found exclusively in canyons sediments. Results reported here indicate that, at large spatial scales, differences in deep-sea meiofaunal abundance and biomass are not only controlled by the available food sources, but also by the region or habitat specific topographic features, which apparently play a key role in the distribution of rare benthic taxa.     

Thermodynamic characteristics of water in natural water bodies with a high mineralization

To adequately describe the hydrophysical processes in water bodies with a high mineralization, it is necessary to take into account the dependence that the thermodynamic characteristics of water have on the amount of salts contained in it. This work investigates some widely known formulas for calculating a number of thermodynamic parameters of mineralized water. The density, freezing temperature, specific heat of evaporation, and relative pressure of saturated vapor over the surface are considered. The possibilities of using these formulas when modeling hydrophysical processes in water bodies with salinity in the range of 0–250 pro mille are analyzed. It is shown that the formulas under consideration should be used when the salinity does not exceed 100 pro mille. If the mineralization is higher, it is necessary to elaborate more suitable formulas on the basis of an approximation of in situ data or data from handbooks.     

A review of EU bio-economic models for fisheries: The value of a diversity of models

The lessons learned from a review of thirteen existing European bio-economic models used in the evaluation of EU policies are presented. How these models compare and differ in terms of their biological and economic components, the integration between the components, which indicators are selected and how they are used, are described and analysed. The article concludes that the multitude of construction differences reflects the necessity of adapting the modelling approach to answer different questions. Since real life questions in fisheries are so diverse, answering them requires a diversity of models.     

Interference of the mechanisms of influence that weak extremely low-frequency electromagnetic fields have on the human body and animals

This review is devoted to the problem of interference between the mechanisms of biological action of natural and artificial electromagnetic fields (EMFs) for different levels of the organization of life. We discuss the problem of specific and nonspecific responses of the human body and animals to the action of EMFs on cellular and organismal levels.     

Terrigenous pyroclastic matter as a source of dissolved calcium in the ocean

It has been found experimentally that the intensity of the leaching under the interaction of volcanic ash and seawater decreases as Ca > Mg > Si, and the mobilization of calcium and magnesium is more intense compared to silicon by factors of 30?C70 and 20?C50, respectively. Calcium and magnesium supplied to seawater owing to the halmyrolysis of the terrigenous pyroclastic matter may then interact with the products of organic matter oxidation to fix the free carbon dioxide in the form of autochthonous carbonates. It was shown that the halmyrolysis of terrigenous pyroclastic matter could not provide the complete immobilization of the autochthonous CO₂ produced in the ocean by the oxidation of organic matter. Thus, some other sources exist for the reactive silicates of calcium and magnesium, and these might probably be the silicates of the continental runoff of solid substances.     

Habitat Provision for Meiofauna by Fucus serratus Epifauna with Particular Data on the Flatworm Monocelis lineata

Abstract. Fucus serratus provides a habitable site For much epifauna if conditions are right. Epifaunal colonies in their turn as well Provide habitats in which meiofauna can dwell. Thus micro-environment is provided which is Dependent on colony-species, -size and silt for its riches. Analysis of population data shows the facts are Turbellarian abundance rarely relates to other taxa, However the flatworms' population count Closely relates to total meiofaunal amount. Experiments on bryozoan-choice by Monocelis lineata show This worm prefers Flustrellidra as a place to go. This may in part be due to thigmotactic deference But mainly seems related to a feeding preference. In addition to behaviour towards food and concavity, Responses are shown to light, temperature, current and gravity. In the discussion thus it is partly explained How meiofauna finds epifauna and there is maintained.     

Transverse vibrations of a rectangular cantilever plate with thickness varying in a discontinuous fashion

A numerical solution is obtained for the title problem by means of the popular finite element method. An experimental investigation of the problem is also presented for plates of square planform. The agreement between theoretical and experimental values is very good in the case of the fundamental frequency, and reasonably good when the second and third normal modes of transverse vibration are considered. It is concluded that beneficial effects are obtained in the sense that one generates a lighter structural element with higher fundamental frequency of transverse vibration. Hence, dynamic stiffening is achieved.