Microbial-meiofaunal interrelationships in some tropical intertidal sediments

Interrelationships among microbial and meiofaunal communities were examined for one year at four intertidal mangrove and sandflat habitats in tropical northeastern Australia. None of the microbial and meiofaunal communities correlated with physical factors over the year as densities of most microbial and meiofaunal groups, bacterial productivity and specific growth rates (μ) of bacteria fluctuated significantly over time at each habitat with no distinct seasonality. However, over a tidal cycle, bacterial growth rates were significantly affected by tidal flooding and exposure on the sandflat; bacterial growth rates increased with increasing sediment temperatures upon exposure during daylight. Protozoan and meiofaunal abundances generally did not change significantly over tidal cycles. There were few significant correlations and no time lags of bacterial growth rates, and bacterial and microalgal (as chlorophyll a) densities with protozoans and meiobenthos (including nematode species and trophic groups) over the year or during tidal cycles. In concert with the very high rates of bacterial productivity (–x = 475 mgC ˙ m–2 d–1; range; 45-1725 mgC ˙ m–2 d–1) measured in these tropical sediments, the results suggest that protozoan and meiofaunal communities may not be tightly coupled to the dynamics of bacterial and microalgal communities in some tropical intertidal habitats

Effect of physical disturbance on population dynamics and trophic interactions among microbes and meiofauna

A series of laboratory experiments was conducted to assess the effects of physical disturbance of surface sediments on trophic interactions among bacteria, protozoa and meiofauna. Bacteria, zooflagellates, and populations of the hypotrich ciliate Aspidisca sp. and the nematode Diplolaimella chitwoodi were, at most sampling periods, not significantly affected by small-scale, daily disturbances. However, populations of the epibenthic harpacticoid copepod Tisbe holothuriae became disproportionately abundant in disturbed cultures.Bacterial numbers, growth rates and doubling times were affected little by the presence of meiofauna. The response of zooflagellates was not clear; populations of the ciliate Aspidisca sp. were, at most sampling intervals, significantly more abundant in the presence of either meiofauna species.Small-scale disturbances of surface sediments, perhaps regardless of cause, do not appear to be important mechanisms in the structuring and functioning of infaunal meiobenthos-microbial food webs. The dynamics of microbe-meiofauna interactions in sediments are ultimately regulated by the amounts of essential nutrients derived from detritus. Disturbances may be more important for some epifaunal meiobenthos dependent upon migration to disturbed habitats for their survival

The dynamics of benthic nutrient pools and fluxes in tropical mangrove forests

Variations in benthic nutrient pools and rates of dissolved nutrient exchange between the forest floor and tidal waters were examined over a 5-yr period in mixed Rhizophora forests lining Coral Creek on Hinchinbrook Island in Queensland, Australia. Seasonal and spatial changes in redox status, porewater and solid-phase nutrients, and in exchange rates were not consistent and did not correlate with temperature. Below-ground roots, on average, accounted for ≈79%, 37% and 26% of bulk sediment TOC, total N and total P pools, respectively. Porewater nutrient concentrations were dominated by Si(OH)4+ and DON with consistently low levels of NO2− + NO3−. At most sampling periods, porewater NH4+ and PO43− concentrations were higher in creek bank sediments than in mangrove sediments indicating uptake by trees. These sediments have low adsorption capacity (K = 0.17–0.47) for NH4+, but a moderate capacity (K = 0.8–4.8) for PO43− adsorption. Most measured benthic fluxes of dissolved nitrogen and phosphorus showed uptake by sediments, prop roots and timber lying on the forest floor. Relative (per ha) estimates indicate that low-intertidal Rhizophora forests import ≈2220 mmol N ha−1d−1 and ≈496 mmol P ha−1d−1, with sediments accounting for nearly all uptake while Si is exported (≈2475 mmol ha−1d−1. Mid-intertidal forests import ≈1385, 93 and 4720 mmol ha−1d−1 of N, P and Si, respectively; sediments, prop roots and timber respectively account for 36%, 62% and 2% of the N import. Mid-intertidal sediments account for all net P uptake, but prop roots and sediments account for 60% and 40% of total Si uptake. On an absolute basis, low-intertidal forests (78 ha total area) in Coral Creek import ≈881 kgN yr−1, 436 kgP yr−1 and export 1963 kgSi yr−1, and the mid-intertidal forests (338 ha total area) import ≈2392 kgN yr−1, 356 kgP yr−1 and 16300 kgSi yr−1. The sum of these estimates equates to ≈95% of the net annual import of total dissolved N and ≈66% of the net annual import of total dissolved P into the Coral Creek tidal basin from adjacent coastal waters. By difference, ≈14337 kgSi yr−1 is imported into the system. This indicates that mangrove forests are a very efficient sink of dissolved nitrogen, phosphorus and silicon in this tidally-driven coastal ecosystem. This import may be driven by the consistently high rates of microbial and plant growth and productivity within the forests

Cotton in the new millennium: advances, economics, perceptions and problems

Cotton is the most significant natural fibre and has been a preferred choice of the textile industry and consumers since the industrial revolution began. The share of man-made fibres, both regenerated and synthetic fibres, has grown considerably in recent times but cotton production has also been on the rise and accounts for about half of the fibres used for apparel and textile goods. To cotton’s advantage, the premium attached to the presence of cotton fibre and the general positive consumer perception is well established, however, compared to commodity man-made fibres and high performance fibres, cotton has limitations in terms of its mechanical properties but can help to overcome moisture management issues that arise with performance apparel during active wear. This issue of Textile Progress aims to: i. Report on advances in cotton cultivation and processing as well as improvements to conventional cotton cultivation and ginning. The processing of cotton in the textile industry from fibre to finished fabric, cotton and its blends, and their applications in technical textiles are also covered. ii. Explore the economic impact of cotton in different parts of the world including an overview of global cotton trade. iii. Examine the environmental perception of cotton fibre and efforts in organic and genetically-modified (GM) cotton production. The topic of naturally-coloured cotton, post-consumer waste is covered and the environmental impacts of cotton cultivation and processing are discussed. Hazardous effects of cultivation, such as the extensive use of pesticides, insecticides and irrigation with fresh water, and consequences of the use of GM cotton and cotton fibres in general on the climate are summarised and the effects of cotton processing on workers are addressed. The potential hazards during cotton cultivation, processing and use are also included. iv. Examine how the properties of cotton textiles can be enhanced, for example, by improving wrinkle recovery and reducing the flammability of cotton fibre

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Nitrogen Cycling and Mass Balance in the World’s Mangrove Forests

Nitrogen (N) cycling in mangroves is complex, with rapid turnover of low dissolved N concentrations, but slow turnover of particulate N. Most N is stored in soils. The largest sources of N are nearly equal amounts of mangrove and benthic microalgal primary production. Dissolved N fluxes between the forests and tidal waters show net uptake, indicating N conservation. N2-fixation is underestimated as rapid rates measured on tree stems, aboveground roots and cyanobacterial mats cannot currently be accounted for at the whole-forest scale due to their extreme patchiness and the inability to extrapolate beyond a localized area. Net immobilization of NH4+ is the largest ecosystem flux, indicating N retention. Denitrification is the largest loss of N, equating to 35% of total N input. Burial equates to about 29% of total inputs and is the second largest loss of N. Total inputs slightly exceed total outputs, currently suggesting net N balance in mangroves. Mangrove PON export equates to &asymp;95% of PON export from the world&rsquo;s tropical rivers, but only 1.5% of the entire world&rsquo;s river discharge. Mangrove N2O emissions, denitrification, and burial contribute 0.4%, 0.5&ndash;2.0% and 6%, respectively, to the global coastal ocean, which are disproportionate to their small worldwide area

Impact of Global Change on Nutrient Dynamics in Mangrove Forests

The cycling of essential nutrients is central to mangrove productivity. A mass balance shows that mangroves rely on soil ammonification, nitrification, and dissimilatory reduction to ammonium for available nitrogen. Mangroves are often nutrient limited and show tight coupling between nutrient availability and tree photosynthesis. This relationship and, thus, forest productivity can be disrupted by various disturbances such as deforestation, changes in hydrology due to impoundments, land-use change, increasing frequency and intensity of storms, increasing temperatures, increasing atmospheric CO2 concentrations, and a rising sea-level. Deforestation and hydrological changes are the most devastating to soil nutrient-plant relations and mangrove productivity. Land-use changes can result in positive and negative impacts on mangroves and can also results in increasing frequency of storms and intensity of storms. Increasing temperatures and atmospheric CO2 levels have an initially enhanced effect on mangroves and microbial transformation rates of nitrogen and phosphorus. The effects of rising seas are complex and depend on the local rate of sea-level rise, the soil accretion rate, the subsidence or uplift rate, and the tidal position. If mangroves cannot keep pace with a sea-level rise, seaward mangroves will likely drown but landward mangroves will expand and show enhanced growth and more rapid nutrient cycling if space permits