Tonnes Dry Weight Research Articles

Assessing the potential for seaweed cultivation in EU seas through an integrated modelling approach

The potential of large-scale seaweed cultivation to contribute to achieving ambitious EU-wide objectives, such as food security, energy independence, carbon neutrality and ecosystems restoration, is widely recognized. However, there is a lack of information on the suitability of EU marine regions for the installation of floating macro-algae cultivation infrastructures. In this study, we utilize the World Offshore Macro Algae Production Potential (WOMAPP) model in conjunction with state-of-the-art coupled hydrodynamic-biogeochemical models, to assess the environmental suitability of EU marine regions for seaweed cultivation. Our analysis reveals that the EU Atlantic regions are the most suitable areas for seaweed cultivation, particularly for cold-water and intermediate-water species. The potential cultivation area is extensive, spanning over 1 million km2, and even taking a precautionary approach by occupying only 1% of that area could yield a yearly production of over 30 million tonnes dry weight. Adding logistical constraints (water depth and distance to coast) further limit the potential production to 5 million tonnes per year, only considering EU member states' waters. Furthermore, we discuss the opportunity to use integrated multi-trophic aquaculture (IMTA), to increase the potential for seaweed cultivation.

Seaweeds farming for sustainable development goals and blue economy in Bangladesh

Seaweeds are primary producers and among the important marine ecosystem engineers capable of modifying their surrounding abiotic and biotic environments. The southern coast of Bangladesh has an excellent prospect for seaweeds farming due to favorable environmental conditions and natural availability of commercially important species. Through quantitative and qualitative analyses, the present study determines potential contribution of seaweeds toward achieving several targets of United Nations sustainable development goals (SDGs) and the blue economic development in Bangladesh. There are 300 households engaged in seaweeds farming, primarily along the southeast coast, producing 390 tonnes wet weight (= 97.5 tonnes dry weight) of seaweeds per annum with potential applications in food, feed, cosmetics and pharmaceuticals sectors. And the current seaweeds production can be increased yearly at ~50% rate, which is 50 million tonnes (dry weight) from ~5,000 km2 farming area when extrapolated to the year 2050. This may bring a positive change to issues regarding food security, gender equality, economic growth, nutrients removal, carbon sequestration, employment and aquatic environmental health. Overall, the benefits of seaweeds farming could reflect on 26 targets of 8 SDGs and potentially contribute US$0.7 million to the blue economy in Bangladesh.

Rehabilitation options for inland waterways impacted by sulfidic sediments – Field trials in a south-eastern Australian wetland

The accumulation of significant pools of sulfidic sediments in inland wetlands and creeks is an emerging risk for the management of inland waterways. We used replicated plot trials to appraise the viability of various strategies for neutralizing oxidized, acidified sulfidic sediments in a highly degraded wetland. Of the twenty different treatments trialed only addition of calcium hydroxide or calcium carbonate, burning of wood, and planting of Phragmites australis, Typha domingensis and Atriplex nummularia into beds prepared with CaCO3 or P. australis and T. domingensis into beds of sediment and mulch, decreased total actual acidity (TAA) in the top 5 cm of sediment in the first two weeks following treatment. Only the calcium hydroxide treatments and planting of P. australis, T. domingensis and A. nummularia into beds prepared with CaCO3 decreased TAA for a longer period of time (6 months). None of the treatments, except the planting of P. australis into beds prepared with lime, decreased TAA in the 5-30 cm layer of sediments. Therefore, the only effective treatment appears to be the application of highly alkaline ameliorants which need to be transported to the site. A survey of the wetland was undertaken to estimate the total amount of actual and potential acidity stored in the wetland's sediment and overlying water and showed that up to 1200 tonnes of calcium carbonate would be required to neutralise all of the actual and potential acidity in the 10 ha wetland. However, neutralisation of the remaining water in the wetland (about 12.5 ML) would produce approximately 2750 m3 of metal rich sludge (approximately 100 tonnes dry weight) that would require separate disposal.

Highlights for Agave Productivity

Agaves can grow in marginal arid and semiarid lands where their special ecological and physiological adaptations to environmental conditions give them the potential to produce substantial biomass. Agave americana was the first agave species shown to be a Crassulacean Acid Metabolism plant, with CO2 uptake occurring primarily at night and with high water-use efficiency (photosynthesis/transpiration). A. salmiana and A. mapisaga can have high nocturnal net CO2 uptake rates and high productivities averaging 40 tonnes dry weight ha−1 yr−1. Agaves can benefit from the increases in temperature and atmospheric CO2 levels accompanying global climate change. An Environmental Productivity Index can predict the effects of soil and environmental factors on CO2 uptake and hence on the regions appropriate for cultivating agaves. In turn, their increased cultivation can support the production of innovative earth-friendly commodities that can be used as new bioenergy feedstocks.

Effects of wood ash fertilization on forest floor greenhouse gas emissions and tree growth in nutrient poor drained peatland forests

Wood ash (3.1, 3.3 or 6.6 tonnes dry weight ha − 1 ) was used to fertilize two drained and forested peatland sites in southern Sweden. The sites were chosen to represent the Swedish peatlands that are most suitable for ash fertilization, with respect to stand growth response. The fluxes of carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2O) from the forest floor, measured using opaque static chambers, were monitored at both sites during 2004 and 2005 and at one of the sites during the period 1 October 2007–1 October 2008. No significant (p > 0.05) changes in forest floor greenhouse gas exchange were detected. The annual emissions of CO 2 from the sites varied between 6.4 and 15.4 tonnes ha − 1 , while the CH 4 fluxes varied between 1.9 and 12.5 kg ha − 1 . The emissions of N 2O were negligible. Ash fertilization increased soil pH at a depth of 0–0.05 m by up to 0.9 units (p < 0.01) at one site, 5 years after application, and by 0.4 units (p < 0.05) at the other site, 4 years after application. Over the first 5 years after fertilization, the mean annual tree stand basal area increment was significantly larger (p < 0.05) at the highest ash dose plots compared with control plots (0.64 m 2 ha − 1 year − 1 and 0.52 m 2 ha − 1 year − 1 , respectively). The stand biomass, which was calculated using tree biomass functions, was not significantly affected by the ash treatment. The groundwater levels during the 2008 growing season were lower in the high ash dose plots than in the corresponding control plots (p < 0.05), indicating increased evapotranspiration as a result of increased tree growth. The larger basal area increment and the lowered groundwater levels in the high ash dose plots suggest that fertilization promoted tree growth, while not affecting greenhouse gas emissions.

DIATOM FOULING PROBLEMS IN A TASMANIAN HYDRO CANAL, INCLUDING THE DESCRIPTION OF GOMPHONEMA TARRALEAHAE SP. NOV.

Open air freshwater hydrocanals in Tarraleah, Tasmania, Australia, exhibit significant diatom biofouling which leads to economic losses in hydroelectricity generation. These fast-flowing (flow velocity 2 m s−1) canals produce between 2 and 18 tonnes dry weight of fouling and 1–5 mg chlorophyll a/m 2 over a 20 km long course, with the canal surface area being 192,000 m2. Mostly monospecific diatom communities of Tabellaria flocculosa occur in canal sections with reduced flow, whereas a stalk-forming (up to 200 μm long) Gomphonema species dominates the majority of canal fouling in fast flowing areas. Gomphonema tarraleahae Perkins et Hallegraeff is newly described, the species differing from its close relative, G. angustatum (Kützing) Rabenhorst in its extreme stalking habit and distinctive head and footpoles. Low numbers of G. subclavatum (Grunow) Grunow and two other undescribed Gomphonema species were also present in fouling. Seasonal changes in biofouling are most likely related to temperature (5–15°C annually) and light intensity variation, with shaded, south-facing walls exhibiting higher fouling densities. Implications for fouling mitigation strategies are discussed.

Seasonal variation in the biomass, quantity and quality of agar from Gelidiella acerosa (Forsskal) Feldmann et Hamel (Gelidiales, Rhodophyta) from the Gulf of Mannar Marine Biosphere Reserve, India

SUMMARYThe Gulf of Mannar on the southeast coast of India, which has recently been declared as biosphere reserve, is the main harvesting place of Gelidiella acerosa for the Indian agar industry. The biomass harvested from natural stocks was estimated to be over 10 000 tonnes dry weight (DW) in the last two decades and is a serious cause of concern on long term sustainability of this valuable resource from this region. The present study reports the seasonal variation in the biomass and agar yield and quality from G. acerosa in four different habitats such as Rameswaram (rocky intertidal), Ervadi (lower intertidal), Sethukarai (subtidal) and Krusadai Island (lagoon reef area). A maximum biomass of 260 ± 26 g DW m−2 was recorded from Ervadi, whereas Sethukarai showed the highest percentage cover (69.83 ± 4.83%) and density (208.20 ± 30.16 plants m−2). Biomass, percentage cover and density were lowest in Rameswaram and significantly lower (P &lt; 0.001) than the other three stations. A single peak in biomass was observed with autumn maxima in Ervadi and Rameswaram and southwest monsoon maxima in Sethukarai and Krusaidai Island. Length of G. acerosa was maximum (9.65 ± 0.25 cm) in Ervadi and the branch index value was maximum (24.70 ± 4.01 br−1 g−1 DW) for Rameswaram. Agar yield (37.24 ± 7.59%) and gel strength (448.66 ± 6.50 g/cm2) were higher in Sethukarai plants. The agar yields attained a peak in the northeast monsoon and decreased in summer, whereas a reverse trend was observed for gel strength. Evidently, agar yield showed a strong negative correlation with gel strength (P &lt; 0.0001) and gelling (P &lt; 0.0001) and melting temperatures (P &lt; 0.01). The single annual peak in biomass observed in the present study, as compared with two peaks reported earlier, are attributed to the continuous overharvesting that would have had an effect on the overall annual biomass production. The findings of this study reveal that a single harvest during the autumn months (January to March) could yield optimum biomass with moderate agar and that would be the best for sustainable usage and conservation of this resource from this region.

Time-series analysis of hydrological and biological variability on the Prince Edward Island (Southern Ocean) shelf

Eulerian time-series were completed at three sites on the south eastern shelf of the Sub-Antarctic Prince Edward Islands (PEI), from 9 to 27 April 2000, to investigate the spatial and temporal variability of mesozooplankton communities in relation to on-shelf hydrodynamics. Surface temperature and phytoplankton biomass were recorded daily at all three sites, while two Bongo net tows and vertical temperature profiles were collected daily at two sites. Con- trary to predictions of on-shelf water retention at low ambient current velocities, cross-correlation analysis iden- tified a northward advection of *8.23 cm s -1 over the study area. Day to day changes in both physical and bio- logical parameters were associated with cross-shelf advection. However, sea temperature had a narrow range of 6.2-7.4C, while average between sample Bray-Curtis similarity in zooplankton communities was high, exceeding 75%. The relatively consistent average sample biomass amounted to *494 tonnes dry weight of mesozooplankton per day being advected onto the south eastern sector of the PEI shelf. We hypothesise that the observed stability of both physical and biological parameters was due to the Sub- Antarctic Front, with its high volume transport and steep physical gradients, being far to the north of the islands. Spatial and temporal variability of hydrodynamics on the PEI shelf, and particularly its relationship to shifting frontal positions, is highlighted as a future research area necessary to quantify the gross delivery of allochthonous biomass to the PEI ecosystem.

A 25-year record of polycyclic aromatic hydrocarbons in soils amended with sewage sludges

We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per 10,000 m2 from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long periods of time, on a human scale.

Biomass and potential commercial utilization of Ulva lactuca (Chlorophyta, Ulvaceae) beds along the north-west coast of the Gulf of California

The biomass of Ulva lactuca beds on the west coast of the Gulf of California was evaluated in 1995, 1996, 1998 and 2000. The total biomass was estimated at four localities, for a total of 12 km of the coastline and a total Ulva bed area of 2.2 km2, and amounted to > 350 tonnes dry weight per year. The pristine conditions of the area make this biomass particularly suitable for commercial utilization as food, food ingredients and fodder. Lower biomass in 1998 apparently reflects an ENSO event.

Environmental productivity indices and productivity for Opuntia ficus‐indica under current and elevated atmospheric CO2 levels*

Abstract. The productivity of the prickly‐pear cactus Opuntia ficus‐indica, which is cultivated worldwide for its fruits and stem segments, was predicted based on the responses of its net CO2 uptake to soil water status, air temperature and photosynthetic photon flux density (PPFD). Each of these environmental factors was represented by an index with a maximum value of unity when that factor was not limiting net CO2 uptake over a 24‐h period. The water index, the temperature index, and the PPFD index were determined for 87 sites in the contiguous United States using data from 189 weather stations and for 148 sites worldwide using data from 1464 weather stations. The product of these three indices, the environmental productivity index (EPI), was used to predict the productivity of O. ficus‐indica under current climatic conditions and under those accompanying a possible increase in the atmospheric CO2 level to 650μumol mol−1. Sites with temperatures always above ‐10°C and hence suitable for prickly‐pear cultivation numbered 37 in the United States and 110 worldwide; such sites increased by 43 and 5%, respectively, for the global warming accompanying the elevated CO2. Productivity of O. ficus‐indica was at least 15 tonnes dry weight hectare−1 year−1, comparable to that of many agronomic crops, for 20 sites with temperatures always above ‐10°C in the contiguous United States and for 12 such sites worldwide under current climatic conditions; such sites increased by 85 and 117%, respectively, under the elevated CO2 condition, mainly because of direct effects of the atmospheric CO2 level on net CO2 uptake. In summary, simulations based on EPI indicate that O. ficus‐indica may presently be advantageously cultivated over a substantial fraction of the earth's surface, such regions increasing markedly with a future doubling in atmospheric CO2 levels.

Hydrological properties of the epiphyte mass of a montane tropical rain forest, Colombia

The effect of a well-developed epiphytic vegetation on the interception of rainfall was investigated in an upper montane rain forest at an altitude of 3370 m in the Cordillera Central of the Colombian Andes. Total epiphyte mass was estimated at 12 tonnes dry weight per hectare, most of it being bryophytes and dead organic matter. The hydrological properties of the epiphyte mass were studied using detached branches. Water gain (during rainfall) and water loss (after experimental saturation) were determined gravimetrically in the field. Rain falling on epiphyte-covered branches was efficiently captured. Drainage of water (held temporarily in excess of the retention capacity) was very gradual. Water loss through evaporation was slow. The observations are in accordance with previously reported data for rainfall interception in the forest studied. The potentially large influence of the exceptionally high canopy storage capacity is restricted due to the clumped distribution of epiphytes and associated low turnover rates of water in the epiphyte mass.

THE ECOLOGICAL ROLE OF THE RED-KNOBBED COOTFULICA CRISTATAGMELIN AT THE BOT RIVER ESTUARY SOUTH AFRICA: A PRELIMINARY INVESTIGATION

SUMMARY The red-knobbed coot Fulica cristata constitutes over 90% of the waterfowl numbers at the Bot River estuary, South Africa. In order to determine the impact of the birds on the submerged aquatic macrophytes at the estuary, aspects of the bioenergetics of the red-knobbed coot were studied. Captive birds of mean mass 720,4 g had a daily metabolized energy of 516 kJ per bird. The daily energy expenditure of the coots in the wild was estimated to be 691 kJ per bird. The birds assimilated 57,9% of their gross energy intake when feeding on Ruppia maritima L. and Potamogeton pectinatus L. and consumed approximately 82,4 g dry weight of macrophyte per bird per day during free existence. On the basis of their energy requirements, it is estimated that the coot population on the Bot River estuary consumed 759,5 tonnes dry weight, approximately 9,9-12,5% of the submerged macrophyte production in 1980–1981. Guano released into the water during the same period is estimated at 470,1 tonnes dry weight.

Comment

The market for synthetic polymer emulsions in Belgium, France, West Germany, Italy, the Netherlands and the UK was over 850,000 tonnes dry weight in 1982. Although there is some pressure against the use of solvent‐based products which might be expected to favour use of aqueous emulsions, only slow growth to about 940,000 tonnes is forecast in 1987. Of more interest are changes in the types of emulsions used, particularly in the synthetic resin emulsion sector where the pressure polymers VA‐E and VA‐E‐VC are expected to show above average growth mainly at the expense of the more traditional PVA homo‐polymer and co‐polymers.

EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE‐MAINE12

ABSTRACTThe, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire‐Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice‐rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.

Production of the euphausiid Nyctiphanes australis in Storm Bay, south-eastern Tasmania

The euphausiid Nyctiphanes australis Sars is an important food item for a wide range of seabirds and commercially exploited fish in coastal waters of south-eastern Tasmania. During most of the year, N. australis forms the major component of the zooplankton biomass in Storm Bay, particularly during the summer months when it swarms in dense aggregations. Production was calculated using methods devised for individuals with continuous recruitment. Estimates of production, integrated for the whole of Storm Bay (approx 18.5km3) were from 78.3 to 84.8 mg m-3 yr1. The P:B ratio obtained for the period December 1979 to March 1981 was about 14. The production of exuviae was also calculated based on certain assumptions about moulting rate and dry weight of the moult, supported by some experimental data. The production of exuviae was 41.03 mgm-3yr-1 or 7.6 times the mean biomass. This gives a total production of flesh and exuviae of 2 212 tonnes dry weight per year for Storm Bay.