Diaspore traits and inter-tidal zonation of non-viviparous mangrove species

Diaspore traits and germination of four non-viviparous mangrove species in Hong Kong, Lumnitzera racemosa (Jack.) Voigt., Heritiera littoralis (Drgand.) Ait., Excoecaria agallocha L. and Acanthus ilicifolius L., were investigated. L. racemosa fruits planted immediately after collection failed to germinate but those stored in wet condition for 35 or 50 d were successfully germinated. This suggested that L. racemosa had endogenous and morphological seed dormancy, with embryos continued to develop during the dormant period. Germination rates of L. racemosa decreased with increasing salinity and no germination was found at salinities over 25 ppt (ppt, parts per thausand). H littoralis seeds were easily germinated if the fruit coat was artificially removed. Fruit dissection significantly shortened time for root initiation and leaf expansion. E agallocha and A. ilicifolius seeds were also easy to germinate, initiating roots within 2 and 3 d, respectively. In terms of germination, A. ilicifolius had more tolerance to high salinity than L. racemosa. The four species exhibited three types of adaptation to unstable environments: (1) prolonged diaspore longevity as shown in L. racemosa and H littoralis; (2) shortened rooting time as in E agallocha and A. ilicifolius; and (3) produced sinking diaspores in L. racemosa. Diaspore buoyancy was one of the most important factors in determining inter-tidal zonation of non-viviparous mangrove species. Among the four species, L. racemosa was distributed in the most seaward zones because its diaspores were sinkers while diaspores of H. littoralis, E agallocha and A. ilicifolius, more abundant at backshore locations, were floaters. Root initiation was also important in influencing the inter-tidal zonation of the three species whose diaspores were floaters. H. littoralis with the longest rooting time, as compared to E agallocha and A. ilicifolius, was distributed in the most backshore zone. None of other factors including salinity of seawater, animal predation, diaspore size and seedling dimension could account for inter-tidal zonation of these species

The geoaccumulation index and enrichment factor of mercury in mangrove sediment of Port Klang, Selangor, Malaysia.

Mangrove areas are important to the ecosystem. One of its crucial functions is as a sink of pollutants, especially metal ions. However, the accumulation of metals in mangrove sediment can generate negative impacts on plant growth, microbial activity, and soil fertility. Apart from that, the severity of the impact is highly influenced by the type of metal found in the sediment and the quality of sediment itself. One of the metals that have adverse effects on the environment is mercury. The objectives of this study are to determine the concentration and distribution of mercury and to assess the enrichment of mercury in Port Klang mangrove sediment by using geoaccumulation index and enrichment factor. Sediment samples were collected from 30 sampling points that cover Langat River and Klang River estuaries, Lumut Straits, Pulau Klang, and Pulau Indah. During sampling, water parameters such as pH, salinity, electrical conductivity, and total dissolved solids were measured in situ, whereas the total mercury in sediment samples was determined at the laboratory using inductively coupled plasma mass spectrometry. In this study, mercury was found to be concentrated along Lumut Strait especially in the mixing zone near the confluence of Langat River and at the jetty to Pulau Ketam. The geoaccumulation index and enrichment factor (calculated using logarithmized data of the reference element) found that three stations were enriched with mercury. In addition, geoaccumulation index was also observed to be more objective compared to enrichment factor whose results were influenced by the concentration of reference element used

Natural and anthropogenic changes to mangrove distributions in the Pioneer River Estuary (QLD, Australia)

We analyzed a time series of aerial photographs and Landsat satellite imagery of the Pioneer River Estuary (near Mackay, Queensland, Australia) to document both natural and anthropogenic changes in the area of mangroves available to filter river runoff between 1948 and 2002. Over 54 years, there was a net loss of 137 ha (22%) of tidal mangroves during four successive periods that were characterized by different driving mechanisms: (1) little net change (1948– 1962); (2) net gain from rapid mangrove expansion (1962–1972); (3) net loss from clearing and tidal isolation (1972–1991); and (4) net loss from a severe species-specific dieback affecting over 50% of remaining mangrove cover (1991–2002). Manual digitization of aerial photographs was accurate for mapping changes in the boundaries of mangrove distributions, but this technique underestimated the total loss due to dieback. Regions of mangrove dieback were identified and mapped more accurately and efficiently after applying the Normalized Difference Vegetation Index (NDVI) to Landsat Thematic Mapper satellite imagery, and then monitoring changes to the index over time. These remote sensing techniques to map and monitor mangrove changes are important for identifying habitat degradation, both spatially and temporally, in order to prioritize restoration for management of estuarine and adjacent marine ecosystems

Organotin compounds in surface sediments of the Southern Baltic coastal zone: a study on the main factors for their accumulation and degradation

Abstract Sediment samples were collected in the Gulf of Gdańsk, and the Vistula and Szczecin Lagoons—all located in the coastal zone of the Southern Baltic Sea—just after the total ban on using harmful organotins in antifouling paints on ships came into force, to assess their butyltin and phenyltin contamination extent. Altogether, 26 sampling stations were chosen to account for different potential exposure to organotin pollution and environmental conditions: from shallow and well-oxygenated waters, shipping routes and river mouths, to deep and anoxic sites. Additionally, the organic carbon content, pigment content, and grain size of all the sediment samples were determined, and some parameters of the nearbottom water (oxygen content, salinity, temperature) were measured as well. Total concentrations of butyltin compounds ranged between 2 and 182 ng Sn g−1 d.w., whereas phenyltins were below the detection limit. Sediments from the Gulf of Gdańsk and Vistula Lagoon were found moderately contaminated with tributyltin, whereas those from the Szczecin Lagoon were ranked as highly contaminated. Butyltin degradation indices prove a recent tributyltin input into the sediments adjacent to sites used for dumping for dredged harbor materials and for anchorage in the Gulf of Gdańsk (where two big international ports are located), and into those collected in the Szczecin Lagoon. Essential factors affecting the degradation and distribution of organotins, based on significant correlations between butyltins and environmental variables, were found in the study area

A review of the distribution of particulate trace elements in urban terrestrial environments and its application to considerations of risk

We review the evolution, state of the art and future lines of research on the sources, transport pathways, and sinks of particulate trace elements in urban terrestrial environments to include the atmosphere, soils, and street and indoor dusts. Such studies reveal reductions in the emissions of some elements of historical concern such as Pb, with interest consequently focusing on other toxic trace elements such as As, Cd, Hg, Zn, and Cu. While establishment of levels of these elements is important in assessing the potential impacts of human society on the urban environment, it is also necessary to apply this knowledge in conjunction with information on the toxicity of those trace elements and the degree of exposure of human receptors to an assessment of whether such contamination represents a real risk to the city’s inhabitants and therefore how this risk can be addressed

Assessing toxicity of spent pig litter using a seed germination technique

The phytotoxicity of spent litter collected from pig pens employing the '[pig-on-litter' system at various times was evaluated using seed germination and root elongation techniques. The percentage seed germination of four plant species (lettuce, Chinese cabbage, tomato and green beans) was not affected by the water extracts of spent litter samples collected in the first 30 weeks of production. Seed germination was significantly retarded by litter extracts from 34 weeks onwards. The percentages of seed germination at the end of the 45 weeks study were 1% for lettuce, 16% for cabbage, 21% for tomato, and 44% for green beans. Compared with seed germination, root elongation was more sensitive to the toxicity of the spent litter. The root lengths of all seedlings except green beans were less than 50% of the control (deionized water) throughout the experiment. The inhibitory effects of spent litter on root elongation increased with the age of the litter. The final root lengths of lettuce, Chinese cabbage and tomato seedlings were 14%, 24% and 28% of the control, respectively. Green beans behaved very differently from the other species; spent litter extracts stimulated root growth throughout the study, except the last week. The elevated concentrations of heavy metals (in particular extractable Cu) and nutrients (especially NH4+N) present in spent litter were the main factors responsible for the phytotocicty of the spent litter. The aged spent litter had accumulated more salts, nutrients and heavy metals and imposed more toxic effects on seed germination than did the young spent litter. © 1994.http://deepblue.lib.umich.edu/bitstream/2027.42/191290/2/JA1-1994-PDF.pdfPublished versio

Effect of ammonia concentrations on growth of Chlorella vulgaris and nitrogen removal from media

The effect of ammonia concentration on growth and physiology of a unicellular green alga, Chlorella vulgaris, was investigated. Growth occurred in all ammonia concentrations examined (10-1000 mg N l(-1)) although less growth was found in cultures containing either very low (10 mg N l(-1)) or very high (750 and 1000 mg N l(-1)) ammonia concentrations. At NH3-N concentrations between 20 and 250 mg N l(-1) there were no significant differences in specific growth rates and maximal cell densities attained. Growth in these media was comparable to growth in the commercial Bristol medium which contains nitrate as the nitrogen source. Higher chlorophyll and protein contents were found in cell cultures with higher ammonia concentrations. The algal growth was accompanied by a decrease in nitrogen content in the medium, indicating that nitrogen removal was due to algal uptake and assimilation. In cultures containing nitrogen lower than 40 mg N l(-1), nitrogen was completely removed at the end of the cultivation period Over 95\% ammonium removal was found in cultures containing 40-80 mg N l(-1). The percentage N reduction decreased with the initial N concentrations in cultures containing more than 80 mg N l(-1). Copyright (C) 1996 Elsevier Science Ltd