Network analysis to inform invasive species spread among lakes

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.     

Network analysis to inform invasive species spread among lakes

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.     

Influx of Streaming Methane into Anoxic Waters of the Black Sea Basin

Oceanology - Based on long-term data on the spatial distribution and fluxes of streaming (bubbling) methane in the Black Sea, the study considers various types of streaming gas emissions...     

Oceanographic Studies in the Northwest Pacific and Seas of Japan and Okhotsk on Cruise 73 of the R/V Professor Gagarinskiy and Cruise 53 of the R/V Akademik Oparin

Oceanology - During cruise 73 of the R/V Professor Gagarinskiy and cruise 53 of the R/V Akademik Oparin, oceanographic studies of the Sea of Japan and Sea of Okhotsk and the Northwest Pacific were...     

Long-Term Variability of the Dissolved Oxygen Content and Water Temperatures in the Upper Layer of the Black Sea

Oceanology - Based on the archival oceanographic databank of the Institute of Natural and Technical Systems, the annual and interannual variability was analyzed for the dissolved oxygen content and...     

On the Contribution of the Eddy Transport to the Annual Mean Heat Budget of the Upper Layer in the North Atlantic

According to Ocean Re-Analysis System 3 (ORA-S3) data, all components of the annual mean heat budget of the upper quasi-homogeneous ocean layer (UQL) in the North Atlantic for the period of 1959–2011 have been calculated and errors of these estimates have been determined. It has been shown that the contribution of the horizontal eddy diffusivity (estimated as a residual term of the UQL heat balance equation) to changes in the UQL annual mean temperature is significantly overestimated. This takes place mainly due to neglecting the covariances of seasonal fluctuations of current velocity vector components and UQL temperature gradients in calculations carried out with the use of annual average values. These covariances play an important role in the annual mean heat budget in some regions of the North Atlantic, especially in tropical latitudes. Changes in the annual average UQL temperature in the central and eastern parts of the North Atlantic are significantly affected by errors related to an inaccuracy of estimates of annual average heat fluxes on the ocean surface. The maximum contribution of the horizontal eddy diffusivity to the interannual variability of the UQL temperature is observed in the northwestern part of the North Atlantic and the region of the Subpolar Gyre.     

Sub-inertial oscillations in the Black Sea generated by the semidiurnal tidal potential

The Black Sea shelf is a region of intense manifestation of various dynamical processes. Under the influence of different natural forces, eddy-wave phenomena develop here, which influence the general circulation of sea waters, biological productivity, and the condition of the engineering structures. Modern numerical models allow us to simulate and analyze the processes of the joint dynamics of marine circulation and large-scale waves. In this work, we study the spatiotemporal spectral characteristics of the sea level and velocity fluctuations formed due to atmospheric forcing and tidal potential. The hydrophysical fields are calculated using the Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), σ model based on primitive equations. We use the CORE data as atmospheric forcing at the sea surface; the tidal potential is described by the semidiurnal lunar constituent M₂. Analyzing the simulation results makes it possible to emphasize that accounting for the semidiurnal tidal potential not only improves the accuracy of the sea-level calculation at coastal stations, but also generates subinertial baroclinic oscillations previously found in the Black Sea from the data of in situ observations.     

Holocene Faunal Trends in West Siberia and Their Causes

Based on an analysis of the transformation of vertebrate and invertebrate fauna of West Siberia in the Holocene, the classification and periodization of the main faunal trends are presented. Against the background of changing environmental conditions, the key regularities of the faunal dynamics, and the ways some species penetrate into the territory of the region and others disappear from the beginning of the Holocene to the present time have been indicated. Three global and four fluctuating trends are identified. The anthropogenic trend is ascertained separately. A conclusion is made about the prevailing causes of these changes, associated primarily with periodic climatic processes of different levels, determined by planetary geological and cosmic cycles. It is emphasized that, in the historical period, anthropogenic factors play a significant role in the regional faunal dynamics.     

Is there a relationship between abyssal scleractinian corals and the global oceanic conveyor belt?

The investigation data on Scleractinia of the abyssal zone have been generalized. Based on an analysis of maps of the distribution pattern of these corals, it can be concluded that there is a close correlation between the spread of their species and the position of the ocean currents that form the global oceanic conveyor belt. The maps were compiled from published and our own data collected on expeditions of the Shirshov Institute of Oceanology of the Russian Academy of Sciences. We analyzed data on 106 stations. The location of the global oceanic conveyor belt was shown in the maps. The distribution pattern of abyssal coral species confirms our assumption that there are two possible ways of origin of abyssal fauna. We suppose that the genera Fungiacyathus and Leptopenus are ancient and have evolved in deep oceanic layers, while the species D. parvulus obviously originated from shallow-water ancestors and then migrated deep into the abyssal zone as a result of the transition to neotenic development.     

Modelling of sediment movement in the surf and swash zones

Under the action of marine currents, non-cohesive sediments evolve by bed-load, by saltation or suspension depending on their granulometry. Several authors have considered that the movement of sediment...