The Dietary Importance of Kelp-Derived Detritus to Pelagic and Benthic Consumers along the West Coast of Vancouver Island, Canada

Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations along the west coast of Vancouver Island (WCVI), Canada. The study used region-specific kelp isotope values (δ13C and δ15N) and season-specific phytoplankton isotope values to model dietary contributions of kelp-derived detritus (KDD). In general, KDD contributions were moderate to high in most plankton size fractions during the summer and decreased during the winter, particularly in the kelp sparse region. Hypothesized regional and spatial (distance from the coast) differences in kelp detritus contributions to zooplankton were not evident. Modeled estimates of the KDD contribution to benthic invertebrates were high (>40%) and independent of the organism size, among regions and between seasons, with the exception of Astraea gibberosa in the kelp abundant region. Local oceanography, natural kelp isotope signature variation, and significant overlap between kelps’ and blooming phytoplankton isotope values led to a large uncertainty in the assessed KDD contributions in benthic organisms. These results highlighted the importance of the KDD as a widespread and stable year-round food source in coastal kelp populated regions.

Importance of kelp-derived organic carbon to the scallop Chlamys farreri in an integrated multi-trophic aquaculture system

Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture （IMTA） systems. A beneficial relationship between seaweed and bivalve in the seaweed- based IMTA system has been confirmed, but the trophic importance of seaweed-derived particulate organic materials to the co-cultured bivalve is still unclear. We evaluated the trophic importance of the kelp Saccharinajaponica to the co-cultured scallop Chlamysfarreri in a typical IMTA farm in Sungo Bay （Weihai, North China）. The dynamics of detritus carbon in the water were monitored during the culturing period. The proportion of kelp-derived organic matter in the diet of the co-cultured scallop was assessed via the stable carbon isotope method. Results showed that the detritus carbon in the water ranged from 75.52 to 265.19 ~tg/L, which was 25.6% to 73.8% of total particulate organic carbon （TPOC） during the study period. The amount of detritus carbon and its proportion in the TPOC changed throughout the culture cycle of the kelp. Stable carbon isotope analysis showed that the cultured scallop obtained 14.1% to 42.8% of its tissue carbon from the kelp, and that the percentages were closely correlated with the proportion of detritus carbon in the water （F=0.993, P=0.003）. Evaluation showed that for 17 000 tons （wet weight） of annual scallop production, the kelp contributed about 139.3 tons of carbon （535.8 tons of dry mass）. This confirms that cultured kelp plays a similar trophic role in IMTA systems as it does in a natural kelp bed. It is a major contributor to the detritus pool and supplies a vital food source to filter-feeding scallops in the IMTA system, especially during winter and early spring when phytoplankton are scarce.

Shaly detritus embedded epoxy-resin coated proppants

Proppant plays a significant role in the hydraulic fracturing process, which can affect the production of oil and gas wells. Due to the high density and low adhesion force, the settling speed of traditional proppants is fast, which will lead to the blockage of a crack channel. In this study, a proppant with double layer structure is fabricated by coating epoxy-resin and shaly detritus on ceramic proppants for the first time,respectively. The epoxy-resin enables the shaly detritus to be coated on the proppant successfully, which can provide a new method for shaly detritus treatment. The adhesive ability of shaly detritus and epoxyresin coated proppants(SEPs) is improved by 10.4% under the load force of 500 n N, which prolongs the time for the fracture to close. At the same time, the suspending ability of SEPs is two times higher than the uncoated proppants. Once the guar gum solution concentration is 0.3 wt%, the settling time of SEPs is36.7% longer than that of the uncoated proppants, which can effectively reduce the settlement of proppants in the crack. In addition, the hydrophobicity of the SEPs is enhanced, which reduces the wateroil ratio of crude oil and increases the liquid conductivity tested by deionized water. In summary, this new proppant is expected to promote the development of unconventional oil and gas resources.

Carboniferous Mixed Terrigenous Clastic, Carbonate and Sulphate Sediments in the Bachu Area, Xinjiang

The Carboniferous system in the Xiaohaizi area, Bachu County, Xinjiang Uygur Autonomous Region, composed of typical mixed terrigenous clastic, carbonate and sulphate sediments, was mainly deposited in the tidal flat and lagoon environments. The mixed sediments occur as the following eleven types: 1. limestone intercalated with siltstone; 2. interbeds of shale and limestone; 3. gypsolyte interbedded with limestone; 4. gypsolyte intercalated with siltstone; 5. gypsolyte interbedded with shale; 6. gypsolyte intercalated with siltstone, limestone and dolomite; 7. siltstone interbedded with gypsolyte and limestone; 8. terrigenous detritus scattered in carbonate matrix; 9. carbonate as cement in clastic rocks; 10. mixed sediments of carbonate and terrigenous mud; 11. mixed sediments of carbonate grains with terrigenous sand. Based on the analysis of the dynamic mechanism of mixed sediments, it is believed that these types of mixed sediments in the study area were controlled by climate, sea level change and sources of sediments.

Paleoceanographic records and sea ice extension history on the slope of the northern Bering Sea over the last 100 ka B.P.

Quantitative analytic results of the biogenic components in Core B2-9 fromthe northern Bering Sea slope indicate that the coarse fraction and opal content, serving as proxiesof surface productivity, have increased stepwise since the marine isotope stageCMISJS.S, reflectingperiodic enhancement in surface productivity.The surface productivity attained its highest levelduring the Holocene, followed by MIS 3.2 to 2 and then MIS 5.3 to 3.3 with a lowest level. Hightotal organic carbon(TOC) contents, together with high C/N ratios, which stand mostly between 7 and20, show that the TOC was deposited from mixing sources. Therefore,one has to be cautious to use TOCas a proxy of surface productivity.The high TOC and C/N ratio during MIS 5.1, 3.3 to 3.2 and theHolocene reflect that the terrigenous organic matter input increased during interglacialperiods.Increases in the fine- and silt-grained terrigenous components from MIS 5.3 to the middleHolocene imply that with the cooling climate, sea ice on the Bering Sea slope extended continuously.Ice-rafted and charcoal detritus increased during glacial, interstadial and the last deglaciationperiods and decreased during interglacial periods, suggesting that sea ice on the slope increasedand melted, respectively, during glacial and interglacial periods. The extension of sea ice duringglacial periods.which was linked with the climate over the North American Continent, responded toglobal climate change during late Quaternary glacial and interglacial cycles.

Ice rafting history and paleoceanographic reconstructions of Core 08P23 from southern Chukchi Plateau, western Arctic Ocean since Marine Isotope Stage 3

Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral） （Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.

Limnological Changes in the Lake Kinneret (Israel) Ecosystem: The Beginning and Its Significance

The Lake Kinneret (Israel) ecosystem has undergone limnological changes. The trend of changes started in the mid 1990’s. The deviation from the previously known as stable long-term structure of the ecosystem included, among others, phytoplankton community structure, nutrient dynamics, zooplankton densities, water temperature increase, water level decline, and fishery management. This study is aimed at identifying ecosystem stability by focusing on three major compartments of the ecosystem: Total Dissolved Solids (TSS), Plankton (Phyto and Zoo), and Detritus (TSS minus plankton). It is suggested that although significant temporary changes of biotic and abiotic parameters were recorded and despite the existence of the normal seasonal fluctuations, the major compartments’ structural relations were not modified. The objective of the study is to analyze the process initiation of the modification trend. Previous studies and reports were focused on descriptive evaluation of the modified parameters. The expected outcome is a comprehensive evaluation of the modification process. Consequently, resulted prediction might be a tool for managers to improve management design.

Micronutrient input into a mangrove ecosystem in Jobos Bay,Puerto Rico,by the exotic green iguana Iguana iguana

Biological invasions are an important and growing component of global environmental change （Vitousek et al., 1996）. Hundreds of billions of dollars are lost each year to invasive species damage and management （Pimentel et al., 2001）. Scientists have responded by conducting research to understand the biology of the invasive species itself, in the hope that such information will allow effective control, and examining the impact of the invader on native taxa to determine the nature and magnitude of its effect.

Decay of Rhizophora apiculata(Blume)and Xylocarpus granatum(Koenig)detrital sources in the Sarawak Mangrove,Malaysia

Decaying mangrove detritus plays a significant role in nutrient cycling and fueling in both the forests and aquatic habitats where the detritus stems from estuarine and coastal food webs.Detrital decay rates partly depend on the type of detritus,but most studies have thus far focused on leaf litter decay and decomposition,whereas other detrital sources(except for roots)have largely been ignored.We compare the decay rates of Rhizophora apiculata and Xylocarpus granatum non-leafy detritus(flowers,propagules,stipules,and twigs)with mangrove leaf litter in field studies,using litter bags during the dry and the wet seasons in the tropical mangrove forest of Sibuti,Sarawak,Malaysia.We observed higher microbial decay rates of stipules,flowers,propagules,and twigs for both the R.apiculata and X.granatumduring the wet months.By contrast,leaf decay rates were higher during the dry months.Decay rates depended on the lignin content of the detrital sources of both species,both during dry and wet months.Accordingly,the half-life(T0.5)and 95%lifespan(T0.95)of non-leaf materials(flowers,propagules,stipules and twigs)for both species were remarkably longer than those of leaf litter.Slowly decaying non-leafy detritus may play a significant role in nutrient and carbon cycling over longer time,when leaf litter is either being decomposing rapidly and/or being washed away by tidal flush and river runoff.Hence,non-leafy(flowers,propagules,stipules and twigs)detritus should be taken into account when budgeting organic matter turnover in mangroves.

High Vegetation of Lake Ayakagitma in Bukhara Region and Their Distribution

More than 500 lakes are found in Uzbekistan. Ayakagitma Lake is located on the border of the Northern Gijduvon and Shafirkon districts of Bukhara region. This lake was formed in 1985-1986 at the expense of the waters of the sewage dump collector. The area of the lake is 8200 hectares, the maximum depth is 35 m, on average 10 - 15 m, the minimum is 3 - 5 meters. The chemical composition of lake water is chloride-sulfate and has a calcareous character. 67 species of high plants belonging to 22 families were found in this area. 17 of these species are found in the water of the lake and 50 species are found around it. Of the most common species, Phragmites communis reach a height of 4.5 - 5.5 meters. Phragmites communis make up the total area of the lake 8 - 10 hectares.

Variability in the Light Absorption Coefficient by Phytoplankton,Non-Algal Particles and Colored Dissolved Organic Matter in the Northern Gulf of California

Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. The changes observed in the absorption by three seawater components (phytoplankton, detritus and chromophoric dissolved organic matter or CDOM) were analyzed in relation to changes in bio-optical regions and composition of the phytoplankton community (determined based on phytoplankton pigments). Two regions with unique bio-optical characteristics were identified separated by a narrow transition zone: the Upper Gulf of California (UGC) and Northern Gulf of California (NGC). Despite the temporal changes in their spatial distribution they maintained particular characteristic. UGC is characterized by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms and dinoflagellates) and a stronger contribution of detritus to total light absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the predominance of picophytoplankton, characterized by the dominance of zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker pigment for green algae), along with a co-dominium by CDOM and phytoplankton to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus and CDOM to total light absorption what has to be considered for the selection of bio-optical models for each specific region what can also help to a better definition of the related uncertainties.

Changes in soil faunal density and microbial community under altered litter input in forests and grasslands

Root and foliar litter inputs are the primary sources of carbon and nutrients for soil fauna and microorganisms,yet we still lack a quantitative assessment to evaluate the effects of root and foliar litter on various groups of soil organisms across terrestrial ecosystems.Here,we compiled 978 paired observations from 68 experimental sites to assess the directions and magnitudes of adding and removing foliar and root litter on the soil faunal density and microbial biomass that was evaluated by phospholipid fatty acids(PLFAs)across forests and grasslands worldwide.We found that litter addition had only a marginal effect on soil faunal density but significantly increased the soil total microbial-,fungal-and bacterial-PLFAs by 13%,14%,and 10%,respectively,across ecosystems,suggesting that the soil microbial community is more sensitive to carbon source addition than soil fauna,particularly in soils with low carbon to nitrogen ratios.In contrast,removing litter significantly decreased the soil faunal density by 17%but had few effects on soil microorganisms.Compared with foliar litter,root litter input had a more positive effect on the development of soil fungal taxa.The effect of both litter addition and removal on soil faunal density and microbial biomass did not differ between humid and arid regions,but a greater influence was observed in grasslands than in forests for soil microbial community.Our results highlight that the increasing litter production under a global greening scenario would stimulate microbial activity in grasslands more than in forests,and this stimulation would be greater for soil microbes than soil fauna.

Heinrich layer in Antarctic marine sediments and its significance to global changes

Results of grain size analysis and rock magnetic measurements of core NP95-1 from Prydz Bay, Antarctica revealed two series of ice-rafted detritus layers, which correspond to cold climatic events, Younger Dryas and Heinrich event 1, occurring at about 11.7-10.3 and 14.3-13.6 kaB.P. respectively. Studies also show that the sequence of paleoclimatic changes in Antarctica can be correlated with that in other parts of the world, and that the millennial climate of the earth could change synchronously and globally. In addition, magnetic fabric analysis also shows a close relationship between paleoclimatic change and ocean circulation re-assemblage.