134 research outputs found
Chemical composition of the humus layer, mineral soil and soil solution of 150 forest stands in the Netherlands in 1990
No full textA nationwide assessment of the chemical composition of the humus layer, mineral topsoil (0-30 cm) and soil solution in both topsoil and subsoil (60-100 cm) was made for 150 forest stands in the year 1990. The stands, which were part of the national forest inventory on vitality, included seven tree species and were all located on non-calcareous sandy soils. Results show increased levels of nitrogen, aluminium, lead and cadmium in at least one of the various soil compartments, indicating the occurrenceof eutrophication, acidification and heavy-metal pollution. Tree species and stand characteristics, such as tree height and canopy coverage, appear to have the largest effect on the concentration level of the various chemical parameters by influencing the input by atmospheric deposition. The various assessments allowed the calculation of various parameters related to aluminium dissolution, cation exchange and phosphate adsorption, to be used in simulation models
Temperature dependence of UV radiation effects in Arctic and temperate isolates of three red macrophytes
No full textThe temperature dependence of UV effects was studied for Arctic and temperate isolates of the red macrophytes Palmaria palmata, Coccotylus truncatus and Phycodrys rubens. The effects of daily repeated artificial ultraviolet B and A radiation (UVBR: 280-320 nm, UVAR: 320-400 nm) treatments were examined for all isolates at 6, 12 and 18 degreesC by measuring growth, optimal quantum yield of PSII (F-v/F-m) and cyclobutane-pyrimidine dimer (CPD) accumulation, Furthermore, possible ecotypic differences in UV sensitivity between Arctic and temperate isolates were evaluated. Large species-specific differences in UV sensitivity were observed for all parameters: the lower subtidal species C. truncatus and P. rubens were highly sensitive to the UV treatments, whereas P. palmata. which predominantly occurs in the upper subtidal zone, was not affected by these treatments, Only minor differences were found between Arctic and temperate isolates, suggesting that no differences in UV sensitivity have evolved in these species. Relative growth rates were temperature-dependent. whereas species-specific UV effects on growth rates were relatively independent of temperature. In contrast. the species-specific decrease in F-v/F-m and its subsequent recovery were temperature-dependent in all species. UV effects on F-v/F-m were lower at 12 and 18 degreesC compared with 6 degreesC. In addition, UV effects on F-v/F-m decreased in the course of the experiment at all temperatures, indicating acclimation to the UV treatments. CPDs accumulated during the experiment in both isolates of P. rubens, whereas CPD concentrations remained low for the other two species. CPD accumulation appeared to be independent of temperature. The results suggest that summer temperatures occurring in temperate regions facilitate repair of UV-induced damage and acclimation to UV radiation in these algae compared with Arctic temperatures. Because the differences in UV effects on F-v/F-m, growth and CPD accumulation were relatively small over a broad range of temperatures, it was concluded that the influence of temperature on UV effects is small in these species
Monitoring toxic phytoplankton: comparison of immunofluorescence assays with conventional light microscopical techniques
No full textUso de biomarcadores de estresse oxidativo no diagnóstico ambiental em ostra, Crassostrea gigas e mexilhão, Perna perna em estações de malacocultura da Ilha de Santa Catarina
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-graduação em BiotecnologiaVários estudos sugerem que moluscos bivalves têm adquirido grande importância como sentinelas em programas de monitoramento da poluição marinha. Este trabalho teve como objetivo realizar um diagnóstico em estações de malacocultura incluindo a influência sazonal dos biomarcadores de estresse oxidativo em mexilhão e ostra, tentando correlacionálos com parâmetros físico-químicos e microbiológicos das estações. Os animais adultos (n=10) de cada estação foram coletados em 3 sítios: sítio sul, PS = Ribeirão da Ilha , síti
Respostas biológicas de macroalgas vermelhas submetidas à radiação ultravioleta-B: análises bioquímicas, celulares e fisiológicas
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Biologia Celular e do DesenvolvimentoKappaphycus alvarezii é uma macroalga de grande importância econômica, devido a extração de kappa carragenana de suas paredes celulares. Apresenta diversas variantes pigmentares tais como: vermelho escuro, marrom, amarelas e diferentes tonalidades de verde. A radiação ultravioleta-B (RUVB) afeta as macroalgas em diversas maneiras importantes, incluindo a redução nas taxas de crescimento, redução na produtividade primária, e mudanças na biologia celular e na organização ultraestrutural. Portanto, nós examinamos o efeito da RUVB na variante marrom de K. alvarezii durante 28 dias de cultivo sendo 3 h diárias de exposição. As plantas controle apresentaram taxas de crescimento de 7.27% dia-1, enquanto as plantas expostas a RUVB cresceram apenas 4.0% dia-1. Diferenças significativas nas taxas de crescimento e nas concentrações de ficobiliproteínas entre controle e plantas a RUVB foram verificadas. Comparado com as plantas controle, as concentrações das ficobiliproteínas apresentaram redução após a exposição RUVB. Além disso, a concentração da clorofila a diminuiu e mostrou diferenças significativas após a exposição RUVB. A RUVB ocasionou mudanças na ultraestrutura das células corticais e subcorticais, incluindo o aumento da espessura da parede celular e o número de plastoglóbulos, redução nos espaços intracelulares, alterações no contorno das células e destruição de organização interna dos cloroplastos. A reação com azul de Toluidina evidenciou um aumento na espessura da parede celular, e o ácido periódico Schiff mostrou uma diminuição no número de grãos de amido. Pelas mudanças significativas nas taxas de crescimento, nas concentrações dos pigmentos fotossintetizantes, e mudanças ultraestruturais observadas, torna-se evidente que RUVB afeta negativamente as macroalgas intermareais e sua viabilidade econômicaThe effects of ultraviolet radiation-B (UVBR) in apical segments of the red macroalgae Gracilaria domingensis (Kützing) Sonder ex Dickie were examined in vitro. Over a period of 21 days, the segments were cultivated and exposed to photosynthetically active radiation (PAR) at 80 µmol photons m-2 s-1 and PAR +UVBR at 1.6 Wm-2 for 3 h per day. The samples were processed for electron microscopy, as well as histochemical analysis, and growth rate, photosynthetic pigment contents and photosynthetic performance were measured. Toluidine Blue reaction showed metachromatic granulations in vacuole and lenticular thickness, while Coomassie Brilliant Blue showed a higher concentration of cytoplasmic organelles, and Periodic Acid Schiff stain showed an increase in the number of floridean starch grains. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included an increased number of plastoglobuli, changes in mitochondrial organization, destruction of chloroplast internal organization, and the disappearance of phycobilisomes. The algae cultivated under PAR-only showed growth rates of 6.0% day-1, while algae exposed to PAR +UVBR grew only 2.8% day-1. Compared with algae cultivated with PAR-only, the contents of photosynthetic pigments, including chlorophyll a, phycoerythrin, phycocyanin and allophycocyanin, decreased after exposure to PAR + UVBR, and significant differences were observed. Finally, analysis of these four photosynthetic parameters also showed reduction after exposure to PAR + UVBR: maximum photosynthetic rate, photosynthetic efficiency, photoinhibition and relative electron transport rate. Taken together, these findings strongly suggested that UVBR negatively affects the agarophyte G. domingensi
Does ultraviolet radiation affect the xanthophyll cycle in marine phytoplankton?
No full textThis Perspective summarizes the state of knowledge of the impact of ultraviolet radiation on the photoprotective xanthophyll cycle in marine phytoplankton. Excess photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet radiation (UVR; 280-400 nm) affect various cellular processes and can potentially lead to reduced growth or viability loss in situ. Algae deploy photoprotective mechanisms that limit the hazardous effects of excess light exposure. Xanthophyll cycle pigments play a crucial role in photoprotection via the development of non-photochemical fluorescence quenching (NPQ) during excess radiation exposure. Research on the interacting effects of excess PAR and UVR exposure on xanthophyll cycle pigment synthesis and xanthophyll cycle activity has produced contrasting views. The current contribution summarizes research on photoprotection via photoregulation (xanthophyll cycle activity) and photoacclimation (adjustment of the xanthophyll cycle pigment pool) for marine phytoplankton. Subsequently, UVR effects on the xanthophyll cycle and on xanthophyll cycle pigment pools are discussed and results of supporting experiments with the common diatom Thalassiosira weissflogii are presented. We show that UVR exposure may enhance xanthophyll cycle pigment synthesis. This suggests that UVR-induced reduction in de-epoxidation state does not necessarily imply reduced energy dissipating potential
Management plan for the natural resources of the EEZ of the Dutch Caribbean
No full textOn the 10th of October 2010 the governmental entity known as the Netherlands Antilles is scheduled to cease to exist. Each island will aquire a new status within the kingdom. Following the declaration of an Exclusive Fishery Zone (EFZ) in 1993, an Exclusive Economic Zone (EEZ) has been declared in the Dutch Caribbean on the tenth of June 2010. The EEZ area concerned, is a large expanse of sea which harbours exceptional biodiversity, and represents an important natural renewable resource potential. The Netherlands Antilles, Aruba and The Netherlands have, therefore, opted to draft a management plan for the EEZ. This initiative began in the year 2005 when the first conference regarding the management of the biodiversity in the EEZ was held. The consensus was that despite a fragmented Dutch Caribbean, the EEZ should always be integrally managed. In 2009 the participants of the second conference confirmed the need for common management and developed common goals, principles and a framework for the management of the Dutch Caribbean waters. Resulting from this conference a management plan was drafted, circulated to all stakeholders and discussed on the 1st of June 2010. Based on the input and feedback received, as well as subsequent correspondence, this final management plan was jointly developed
Effects of UV-B-induced damage and photoinhibition on growth of temperate marine red Macrophytes: habitat-related differences in UV-B tolerance
No full textThe sensitivity to UV-B radiation (UVBR: 280-315 nm) was tested for littoral (Palmaria palmata [L] O Kuntze, Chondrus crispus Stackhouse) and sublittoral (Phyllophora pseudoceranoides S. G. Gmelin, Rhodymenia pseudopalmata [Lamouroux] Silva, Phycodrys rubens [L.] Batt, Polyneura hilliae [Greville] Kylin) red macrophytes from Brittany, France. Algal fragments were subjected to daily repeated exposures of artificial UVBR that were realistic for springtime solar UVBR at the water surface in Brittany, Growth, DNA damage, photoinhibition, and UV-absorbing compounds were monitored during 2 weeks of PAR + UV-A radiation (WAR) + UVBR, whereas PAR + UVAR and PAR treatments were used as controls. The littoral species showed a higher UV tolerance than the sublittoral species. After 2 weeks, growth of P. palmata and C, crispus was not significantly affected by UVBR, and DNA damage, measured as the number of cyclobutane-pyrimidine dimers per 10(6) nucleotides, was negligible. Photoinhibition, determined as the decline in optimal quantum yield, was low and decreased during the course of the experiment, coinciding with the production of UV-absorbing compounds in these species. In contrast, no UV-absorbing compounds were induced in the sublittoral species. Growth rates of P. pseudoceranoides and R. pseudopalmata were reduced by 40% compared with the PAR treatment. Additionally, constant levels of DNA damage and pronounced photoinhibition were observed after the UVBR treatments. Growth was completely halted for Phycodrys rubens and Polyneura hilliae, whereas DNA damage accumulated in the course of the experiment. Because Phycodrys rubens and Polyneura hilliae showed the same degree of photoinhibition as the other sublittoral species, it appears that the accumulation of DNA damage may have been responsible for the complete inhibition of: growth. The results suggest an important role of DNA repair pathways in determining the UV sensitivity in red macrophytes
Monitoring toxic phytoplankton: comparison of immunofluorescence assays with conventional light microscopical techniques
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