Community Structure of Fish in Nanji Islands National Nature Reserve and Its Relationship with Environmental Variation

Community structure of fish in relation to environmental variation was investigated in Nanji Islands National Nature Reserve (NINNR). In order to test this relationship, we delineated 25 survey stations with bottom trawling and measured environmental variables. Samples were taken from November 2013 (autumn), February 2014 (winter), May 2014 (spring) and September 2014 (summer). We found a very strong correlation in space and time between temperature and salinity;abundance and biomass in winter;depth and DO in summer then a strong correlation was found respectively between temperature and biomass;salinity and biomass in winter too and finally a moderate correlation between depth and biomass in spring, (P-value < 0.01) with positive correlation (that the other variable or factor has a tendency to increase). We also found out a negative correlation (P-value < 0.05), respectively between salinity and DO;DO and chlorophyll in summer;temperature and salinity;salinity and DO in spring period (mean that the other variable or factor has a tendency to decrease). A negative correlation observed between temperature, salinity and chlorophyll in winter, spring and autumn period were due by a temperature and salinity window open for species blooms through the movement of the TWC and Jiangzhe coastal current close to shore. By comparing diversity of fish species with environmental factors, the community structure of fish varied significantly as physicochemical parameters changed between different stations for each season. As results and according to the species referencing of environmental factors;species diversity, abundance and evenness vary among different stations, corresponding to significant differences of environmental factors (e.g. physicochemical parameters and chlorophyll-a concentration in different sites). Species richness of microfauna was negatively correlated with salinity levels. Furthermore, they were related to the fish community according to the results. This may be due to the fish community’s adaptability in these different variations of environmental factors, but only tolerant members remaining.

Seasonal variations in the phytoplankton community and the relationship between environmental factors of the sea around Xiaoheishan Island in China

Seasonal variations in the phytoplankton community and the relationship between environmental factors of the sea area around Xiaoheishan Island are investigated in the present study. Xiaoheishan Island is located at 37°58′14″N and 120°38′46″E in Shandong Province, China. A total of 65 species of phytoplankton belonging to three phyla and 27 genera were identified, with Bacillariophyta having the largest number of species. The annual average chlorophyll a concentration for this area was 3.11 μg/L, and there occurs a Skeletonema costatum bloom in winter. The Shannon-Weaver indexes(log_2) of the phytoplankton from all stations were higher than 1, and the Pielou indexes were all higher than 0.3. The results of the canonical correspondence analysis(CCA) indicated that water temperature, PO_4^(3ˉ) and Cu were the environmental factors that had the greatest influence on the distribution of the phytoplankton community throughout the entire year. Although the concentration of heavy metal is well up to the state standards of the first grade of China(GB 3097-1997), these metals still have an impact on the phytoplankton community from this area.

Paleoenvironmental significance investigation of loess magnetic fabric in a semiarid region

Here we report our recent magnetic fabric investigation of loess deposition in Shagou section, located at the northeastern Qilian Mountains, the northeastern rim of the Tibetan Plateau. On the basis of environmental magnetism data, we indicate that the variation of anisotropy of magnetic susceptibility (AMS) parameters, especially the foliation (F) and degree of anisotropy (P), might be more sensitive to the environmental change in the arid and semiarid regions than the magnetic susceptibility fluctuation. During the investigated interval, from 0.83 to 0.128 Ma, most of the middle to late Pleistocene significant climate change can be unraveled by the AMS parameters, such as the strengthening of cold/dry climate, the step drying event occurred nearly 250 ka, and the severe environmental change in MIS16. Our results also suggest that there is strong correlation between median diameter (Md) of grain size, F, and P. We propose that the AMS parameters can act as an important paleoenvironmental change indicator in the arid and semiarid regions.

Community structure and spatial-temporal variation of netzphytoplankton in the Bering Sea in summer

Marine biodiversity is changing in response to altered physical environment, subsequent ecological changes as well as anthropogenic disturbances. In this study, phytoplankton samples in situ collected in the Bering Sea in July of 1999 and 2010 were analyzed to obtain phytoplankton community structure and spatial-temporal variation between the beginning and end of this decade, and the correlation of phytoplankton community dynamics and environmental factors was investigated. A total of 5 divisions, 58 genera and 153 species of phytoplankton belonging to 3 ecological groups were identified. The vast majority of phytoplankton consisted of diatoms accounting for 66.7% of the total species and 95.2% of the total abundance. Considering differentiation in spatial extent and phytoplankton sample types, there were subtle changes in species composition, large altering in abundance and significant variation in spatial distribution between two surveys. The abundance peak area was located at the Bering Strait while sub peak was found at the Bering Sea Basin. The boreal-temperate diatom was the dominant flora, which was subsequently replaced by eurythermal and frigid-water diatom. Phytoplankton community in the Bering Sea was not a simplex uniform community but composed of deep-ocean assemblage and neritic assemblage. The deep-ocean assemblage was located in the northwestern Pacific Ocean and Bering Sea Basin, dominated by boreal-temperate species（Neodenticula seminae, Thalassiothrix longissima, Amphiprora hyperborean, Chaetoceros atlanticus, Thalassiosira trifulta, etc.） and eurychoric species（Thalassionema nitzschioides, Ch. compressus, Rhizosolenia styliformis, etc.）, and characterized by low abundance, even interspecies abundance allocations, diverse dominant species and high species diversity. The neritic assemblage was distributed on the continental shelf and slope of Bering Sea and was mainly composed of frigid-water species（Th.nordenski？ldii, Ch. furcellatus, Ch. socialis, Bacteriosira fragilis, etc.） and eurythermal and euryhaline species（L.danicus, Ch. curvisetus, Coscinodiscus curvatulus, etc.）, and it was characterized by high abundance, uneven interspecies allocations, prominent dominant species and low species diversity. Spatial-temporal variation of species composition and abundance of phytoplankton in the Bering Sea was directly controlled by surface circulation,nutrient supply and ice edge.

Gravity variation before the Akto Ms6.7 earthquake, Xinjiang

The relationship between gravity variation and the Akto Ms6.7 earthquake on November 11, 2016, was studied by use of mobile gravity observation data from the China continental structural environmental monitoring network. The result revealed that before the Akto earthquake, a high positive gravity variation was observed in the Pamir tectonic knots region （within a maximum magnitude of approximately ＋80 microgal）, which was consistent with the existing knowledge of gravity abnormality and the locations of strong earthquakes. In view of the recent strong seismic activities in the Pamir tectonic knots region, as well as the strong upward crust movement and compressive strain, it is believed that gravity change in the Pamir tectonic knots region reflects the recent strong seismic activities and crust movement.

The evolution of phenotypic plasticity in fish swimming

Fish have a remarkable amount of variation in their swimming performance, from within species dif- ferences to diversity among major taxonomic groups. Fish swimming is a complex, integrative phenotype and has the ability to plastically respond to a myriad of environmental changes. The plasticity of fish swimming has been observed on whole-organismal traits such as burst speed or critical swimming speed, as well as underlying phenotypes such as muscle fiber types, kinematics, cardiovascular system, and neuronal processes. Whether the plastic responses of fish swimming are beneficial seems to depend on the environmental variable that is changing. For example, because of the effects of temperature on biochemical processes, alterations of fish swimming in response to tem- perature do not seem to be beneficial. In contrast, changes in fish swimming in response to variation in flow may benefit the fish to maintain position in the water column. In this paper, we examine how this plasticity in fish swimming might evolve, focusing on environmental variables that have received the most attention： temperature, habitat, dissolved oxygen, and carbon dioxide variation. Using examples from previous research, we highlight many of the ways fish swimming can plastic- ally respond to environmental variation and discuss potential avenues of future research aimed at understanding how plasticity of fish swimming might evolve. We consider the direct and indirect ef- fects of environmental variation on swimming performance, including changes in swimming kine- matics and suborganismal traits thought to predict swimming performance. We also discuss the role of the evolution of plasticity in shaping macroevolutionary patterns of diversity in fish swimming.