Spatial and temporal distribution of macronutrients and phytoplankton before and after the invasion of the ctenophore,Mnemiopsis leidyi, in the Southern Caspian Sea

A significant correlation was observed between satellite derived chlorophylla(Chla) concentrations and the biomass of the invasive comb jellyfishMnemiopsis leidyiin the southern Caspian Sea. By consuming the herbivorous zooplankton, the predatory ctenophoreM. leidyimay have caused levels of Chlato rise to very high values ( mg ) in the southern Caspian Sea. There might also be several other factors concurrent with predation effects ofM. leidyiinfluencing Chlalevels in this region, such as eutrophication and climatic changes which play major roles in nutrient, phytoplankton, and zooplankton variations. The decrease in pelagic fishes due to overfishing, natural, and anthropogenic impacts might have provided a suitable environment forM. leidyito spread throughout this enclosed basin.

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Spatiotemporal relationships between life stages of the invasive ctenophore, Mnemiopsis leidyi, and environmental parameters in the southern Caspian Sea

Journal of Great Lakes Research ◽

10.1016/j.jglr.2020.07.020 ◽

2020 ◽

Vol 46 (5) ◽

pp. 1262-1276

Author(s):

Nemat Mahmoudi ◽

Manoochehr Babanezhad ◽

Jafar Seyfabadi ◽

Mohammad Reza Ahmadi

Keyword(s):

Caspian Sea ◽

Environmental Parameters ◽

Mnemiopsis Leidyi ◽

Life Stages ◽

Southern Caspian Sea ◽

Spatiotemporal Relationships

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NonLinear Effects of Environmental Regulation on Eco-Efficiency under the Constraint of Land Use Carbon Emissions: Evidence Based on a Bootstrapping Approach and Panel Threshold Model

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16101679 ◽

2019 ◽

Vol 16 (10) ◽

pp. 1679 ◽

Cited By ~ 5

Author(s):

Haoran Yang ◽

Hao Zheng ◽

Hongguang Liu ◽

Qun Wu

Keyword(s):

Land Use ◽

Carbon Emission ◽

Industrial Structure ◽

Threshold Model ◽

Temporal Distribution ◽

Nonlinear Effects ◽

Threshold Value ◽

Threshold Effect ◽

Spatial And Temporal Distribution ◽

Before And After

Eco-efficiency has been receiving attention worldwide, and the effective implementation of environmental regulations (ERs) has become crucial to regional eco-efficiency. This paper uses a method combining mixed directional distance function and bootstrapping approach to investigate the spatial and temporal distribution characteristics of eco-efficiency under the constraint of land use carbon emission in China from 2004 to 2016. The nonlinear relationship between ER and eco-efficiency is observed with a panel threshold model. Results from empirical tests reveal that eco-efficiency in China during the study period has an upward trend, and the spatial and temporal distribution of eco-efficiency is unbalanced and concentrated. Technical innovation and land marketization (LM) shows double threshold, whereas industrial structure (IS) has a single threshold effect. LM has a promotional effect on eco-efficiency, which differs in the promotion before and after promotion across the threshold value. Reasonable ER can reduce cost by stimulating the innovation of green production technology and achieves a win-win situation between environment and output. This finding further verifies that the ER for eco-efficiency under the constraint of land use carbon emission conforms to the Porter hypothesis. The effect of ER on eco-efficiency changes from negative to positive with the increase of IS level. Adjusting the ownership structure and increasing the proportion of green achievements in the promotion and assessment of officials are important measures in the upgrading of eco-efficiency.

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