Factors influencing the distribution of coastal lichens Hydropunctaria maura and Wahlenbergiella mucosa

Responses to abiotic and biotic stresses that potentially drive the vertical zonation of the intertidal lichens Hydropunctaria maura, an upper littoral lichen, and Wahlenbergiella mucosa, a lower littoral lichen, were investigated in field and laboratory experiments. When transplanted, both lichens exhibited an inability to survive outside their normal vertical distribution range. W. mucosa appeared to be unable to tolerate prolonged periods of desiccation following translocation from lower to upper littoral regions, whereas H. maura was unable to survive in lower littoral zones possibly owing to increased grazing pressure. The effect of desiccation in both lichens was compared using pulse amplitude modulated chlorophyll fluorescence and infra‐red gas analysis; results indicated a more hydration‐dependent nature of W. mucosa. Photosynthetic (algal) pigments and phenolic compounds were determined in both lichen thalli, and a range of additional coastal lichens occupying a natural gradient from upper to lower shore levels. Pigment composition and concentration in both lichen thalli were similar whereas levels of phenolic compounds were up to three times higher in W. mucosa than H. maura. Pigment and phenolic concentration and composition exhibited some seasonality across 13 different lichens originating from different shore levels. Phenolic concentration increased towards the lower shore, suggesting a potential anti‐herbivory function. This marks the first study of pigments and phenolics in coastal lichen communities, and prompts further investigations on the particular physiological features of marine and maritime lichens that enable them to thrive in this extreme environment.     

Effect of photochemical self-action of carbon-containing aerosol: Wildfires

It has been shown by numerical simulation that the rate of formation of secondary organic aerosols (SOAs) in smoke plumes caused by vegetation and peat fires under real conditions can significantly depend on the aerosol optical thickness (AOT). The AOT determines the photodissociation rate and hydroxyl radical concentration, which in turn determines the rate of SOA generation as a result of oxidation of semivolatile organic compounds. Quantitative analysis has been carried out for the situation that took place in European Russia during the 2010 Russian wildfires. The state-of-the-art 3D chemical transport model is used in this study; the simulations are optimized and validated using the data of monitoring of the particulate matter in the Moscow region and Finland. The findings indicate that it is important to allow for this effect in studies focused on the analysis and prediction of air pollution due to wildfires, as well as climate and weather studies, whose results may depend on the assumptions about the content and properties of atmospheric carbon-containing aerosol.     

Numerical modeling of ocean hydrodynamics with variational assimilation of observational data

Models and methods of the numerical modeling of ocean hydrodynamics dating back to the pioneering works of A.S. Sarkisyan are considered, with emphasis on the formulation of problems and algorithms of mathematical modeling and the four-dimensional variational assimilation of observational data. An algorithm is proposed for studying the sensitivity of the optimal solution to observational data errors in a seasurface temperature assimilation problem in order to retrieve heat fluxes on the surface. An example of a solution of the optimal problem of the World Ocean hydrodynamics with the assimilation of climatic temperature and salinity observations is offered.     

Methods for retrieval of sea wave spectra from aerospace image spectra

An approach to the retrieval of sea wave spatial spectra based on satellite optical imagery in linear and nonlinear approximations is described. Physical mechanisms of the formation of disturbed sea surface brightness fields recorded by remote sensing equipment are analyzed. Wave spectra retrieval methods using brightness field formation models that consider linear and nonlinear dependencies on sea surface slopes are suggested. A method for the construction of operators that retrieve the spatial spectra of surface wave slopes and elevations from aerospace imagery and take into account nonlinear modulations of disturbed sea surface brightness fields is developed. This method is based on the numerical simulation of sea surface images and the construction of a retrieving operator with respect to a set of parameters determined by aerospace imaging conditions. Examples of the use of the developed methods are given.     

Development of hyperbaric technologies of oceanologic research

This paper provides analysis and substantiation of scientific efficiency of diving and laboratory hyperbaric methods and technologies for oceanologic research.     

Observations of a cycle of intense coastal upwelling and downwelling at the research site of the Shirshov Institute of Oceanology in the Black Sea

The paper presents the results of joint analysis of the response of vertical temperature and current velocity profile distributions in the coastal zone of the Gelendzhik region of the Black Sea to strong wind forcing in the third ten-day period of September 2013. This forcing was caused by the propagation of an atmospheric cyclone, which first initiated coastal upwelling that was later replaced by downwelling. We formulate a criterion for the development of full coastal upwelling and demonstrate its efficiency. We assume that frequent events of incomplete coastal upwelling and downwelling are associated with changes in the water dynamics (variations in the intensity and direction of the alongshore current) generally not related to local wind forcing.     

Laboratory Study for Influence of Clay Content (CC) on Wave-Induced Liquefaction in Marine Sediments

In this artice, the influence of clay content on the wave-induced liquefaction in marine sediments was reported. The one-dimensional (1-D) equipment was setup with a vertical cylinder and 1.8–m–thick clayey sandy deposit and 0.2–m–thick water above the deposit. Unlike the previous experimental study for a single soil layer, this study used sand-kaolin mixtures, sand-illite mixtures, and sand-bentonite mixtures as the experimental samples. A series of experiments with 3,000 wave cycles in each test were conducted under numerous wave and soil conditions, which allowed us to examine the influence of clay content (CC) on wave-induced liquefaction in marine sediments. The experimental results showed that the clayey sandy deposit will become prone to liquefaction with the increase of CC when CC is less than a critical value, which depends on the type of clay. However, when CC is greater than the critical value, liquefaction depth will decrease as CC increases. Furthermore, when the CC value reaches a certain level, liquefaction will not occur. For example, no liquefaction occurs when CC ≥ 33% for both kaolin-sand and illite-sand mixtures and CC ≥ 16.36% for bentonite-sand mixtures.     

Regional Variability in Occurrence and Distribution of Polymetallic Nodules in the Central Indian Basin

Regional scale morphological studies on different-sized polymetallic nodules from the Central Indian Basin show that only 2–5 cm sized nodules have highest occurrence per station (92–94% along latitudes; 88–94% along longitudes). A nodule size shows an inverse relationship with the nodule distribution, grade, and abundance. Interestingly, only 3–4 and 4–5 cm sized nodules have highest grade, abundance, and distribution percentages along longitudes in P₁, first generation mine site and relinquished area, which further implies that the nodule mining along the longitude would be beneficial. Different-sized nodule groups suggest their formation under variable environmental conditions that existed in the Central Indian Basin. The coexistence of different-sized nodules suggests different environmental conditions existed in the Central Indian Basin.     

Ontogenic variation and effect of collection procedure on leaf biomechanical properties of Mediterranean seagrass Posidonia oceanica (L.) Delile

Leaf mechanical traits are important to understand how aquatic plants fracture and deform when subjected to abiotic (currents or waves) or biotic (herbivory attack) mechanical forces. The likely occurrence of variation during leaf ontogeny in these traits may thus have implications for hydrodynamic performance and vulnerability to herbivory damage, and may be associated with changes in morphologic and chemical traits. Seagrasses, marine flowering plants, consist of shoot bundles holding several leaves with different developmental stages, in which outer older leaves protect inner younger leaves. In this study we examined the long‐lived seagrass Posidonia oceanica to determine ontogenic variation in mechanical traits across leaf position within a shoot, representing different developmental stages. Moreover, we investigated whether or not the collection procedure (classical uprooted shoot versus non‐destructive shoot method: cutting the shoot without a portion of rhizome) and time span after collection influence mechanical measurements. Neither collection procedure nor time elapsed within 48 h of collection affected measurements of leaf biomechanical traits when seagrass shoots were kept moist in dark cool conditions. Ontogenic variation in mechanical traits in P. oceanica leaves over intermediate and adult developmental stages was observed: leaves weakened and lost stiffness with aging, while mid‐aged leaves (the longest and thickest ones) were able to withstand higher breaking forces. In addition, younger leaves had higher nitrogen content and lower fiber content than older leaves. The observed patterns may explain fine‐scale within‐shoot ecological processes of leaves at different developmental stages, such as leaf shedding and herbivory consumption in P. oceanica.