High-resolution last deglaciation record from the Congo fan reveals significance of mangrove pollen and biomarkers as indicators of shelf transgression

High abundances of mangrove pollen have been associated with transgressive cycles on tropical margins, but the detailed relations between systems tracts and the taphonomy of the pollen are unclear. We report here the occurrence and high abundance of Rhizophora pollen, in association with taraxerol, a Rhizophora-sourced biomarker, from a high-resolution Congo fan core covering the last deglaciation. An age model based on ¹⁴C dates enables the temporal changes in taraxerol content and the percentage frequencies and flux (pollen grains (pg) cm⁻² (10³ yr)⁻¹) of mangrove pollen to be compared quantitatively with the lateral rate of transgression across the flooding surface (derived from glacio-hydro-isostatic model output and the bathymetry of the margin). Rhizophora pollen concentrations and taraxerol content of the sediment are very strongly positively correlated with the lateral rate of transgression and indicate, independently of any sequence stratigraphic context, that mangrove pollen spikes are associated with the transgressive systems tract rather than the highstand systems tract or maximum flooding surface. Lower-resolution longer-term records from this margin indicate an association between taraxerol concentrations and transgressive rather than regressive phases. The flux of these materials to the Congo fan is interpreted as a function of the erosion of flooded mangrove swamp on the shelf and, less importantly, changing extent of mangrove habitat, during sea-level rise. Congo River palaeoflood events also result in reworking of mangrove pollen and supply to the fan, but this mechanism is subdominant. Rhizophora pollen has been underestimated in many palynological studies undertaken on cores from the African margin because of inappropriate sieve mesh size used during laboratory preparation.     

海滨红树林花粉与古环境研究进展

红树林是热带海洋潮间带一种特有的植被类型钉求有独特的生态环境。论述了红树花粉研究在古环境分析中的意义，介绍国际上的研究进展，综述国内的研究现状，并对我国今后研究提出了展望。     

香港海岸带的红树林

香港海岸带红树林是香港植被中一个重要类型。它的组成种类尚丰富，类型也多样，也是我国红树林分布的一个重要地段。它对香港的海岸生态环境保护、生态旅游、科学研究和教学等均有重要意义。     

珠江口红树群落太阳光合有效辐射利用效率的研究

本文通过对珠江口红树热植、群落能量现存量、群落能量净固定量和太阳光合有效辐射利用效率的研究，为珠江口红树林保护、造林提供依据。     

鱼藤对红树林植物的危害及管理

广西北海市合浦县党江镇南流江入海口红树林遭受鱼藤危害。鱼藤通过攀援覆盖,蔓延成灾,导致连片红树林植物枯死,从而破坏了红树林生态系统。鱼藤是红树林常见攀援类伴生物种,在全球变化背景下,局部地区鱼藤已变成了危害红树林湿地的"植物杀手",急需采取措施保护受危害的红树林湿地。     

木榄胚轴萌发及幼苗生长与生理对水渍和底质条件的响应

采用模拟半日潮系统研究了水渍和底质条件对红树植物木榄(Bruguieragymnorrhiza)的影响。水位上升和淹水时间延长导致红树林底质的酸化,且壤质底质的酸化比沙质底质严重;对木榄的萌苗速度无显著影响;促进木榄的早期生长,尤其是导致最初2个月茎高生长的增加,但后2个月木榄的相对生长率受抑制;地下部/地上部生物量比值下降,沙质底质中尤为如此;粗根比例明显增加;叶绿素含量增加,叶绿素a/b比值无显著影响;叶面积减少;壤质底质上生长植株的叶片气孔密度增加,沙质底质无显著变化;根N含量无显著变化,P含量显著增加。     

深圳红树林湿地的现状及生态旅游开发对策

红树林是生长在热带和亚热带沿海潮间带的木本植物群落,有其独特的生态系统。它具有极其重要的生态、社会和经济效益,同时也是一种新兴的生态旅游资源。介绍了深圳红树林湿地的现状、面临的主要威胁,并结合实际情况对开发红树林生态旅游提出了建议。     

人为干扰对滨海红树林湿地的影响

红树林是热带和亚热带的重要滨海湿地类型,在维护海岸生态平衡方面有独特的作用。国内外学者对人为干扰红树林湿地进行了广泛研究,这些人为干扰可分为6个类型,包括具有显性影响的土地利用转化、城市化及工业化、木材及薪材过度利用和具有隐性影响的污染物排放、林内挖捕、林内禽畜放养。具有显性影响的干扰类型较容易得到重视与研究,具有隐性影响的干扰类型往往被忽视,而这些隐性影响也严重地危害红树林湿地的健康。针对这些人为干扰,提出了保护滨海红树林湿地的有效管理措施。     

A case study of in situ oil contamination in a mangrove swamp (Rio De Janeiro, Brazil)

Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation.     

Ciliate communities in a constructed mangrove wetland for wastewater treatment

In wetlands constructed for treating municipal and industrial wastewater, including mangroves, the effect of wastewater discharged on the substrate has often been neglected. Ciliates, an important group of protozoa, are sensitive to pollutants and any changes in ciliate diversity and community structure reflects the habitat quality. The ciliate communities at six sections along a constructed mangrove belt (33 m in length) planted with Aegicerascorniculatum were investigated in Shenzhen, South China. In all samples collected in both rainy and dry seasons, 183 ciliate species were observed. Most species (56%) were free-swimming forms, while only 10.8% were sessile ciliates. The abundance and species number of ciliates were both found to decrease from the anterior (the wastewater inlet) to the posterior (the outlet) parts of the wetland belt, indicating that organic matter and bacteria in wastewater, which served as food for most ciliates, were gradually removed by the constructed wetland. The r/K (number of r- and K-selected species) ratios at the six sections were relatively small, between 0.2 and 0.4, whereas the C/P (abundance of colpodids and polyhymenophorans) quotient at some sections was higher than 1. These results indicate that although most of the environments along the constructed wetland belt were not stressful for ciliate communities, there were habitats that favored colpodids in high abundances.