Planktonic and benthic microalgal community composition as indicators of terrestrial influence on a fringing reef in Ishigaki Island, Southwest Japan

Microalgal-based indicators were used to assess terrestrial influence on Shiraho coral reef of Ishigaki Island (Okinawa, Japan). A typhoon occurred on 4-5 August 2005 and sampling were made on three occasions thereafter (6, 8, and 11 August). Pre-typhoon sampling was conducted on 26 July. The typhoon-enhanced terrestrial discharges increased reef nutrient levels (e.g. average NO(3)(-)-N: 0.088mg/L pre-typhoon to 0.817mg/L post-typhoon). This elevated chlorophyll-a concentrations by four times and shifted phytoplankton composition (spectral class-based) from an initial dominance of diatoms and green microalgae to the dominance of bluegreen microalgae (cyanobacteria) and cryptophytes. Cyanobacteria later increased by more than 200% and accounted for as much as 80% of total chl-a ( approximately 0.29microg/L), possibly assisted by favorable nutrient availability. In outer reef waters, diatoms and green microalgae predominated whereas cyanobacteria and cryptophytes were nearly undetectable. Due to detrital decomposition and river discharge, the CDOM was much higher in the inner reef than in the outer reef. Benthic bluegreen microalgae were relatively more abundant in areas close to the river mouth and coastal agricultural fields. At these locations, nutrient concentrations were much higher due to river discharge and potentially significant groundwater discharge. Thus, phytoplankton and benthic microalgae can serve as indicators of terrestrial influence on coral reefs.     

Study on210Po in marine organisms in North China Waters

The concentrations of natural radionuclide²¹⁰Po in various components of the marine organisms of North China coastal waters are described and its contribution to the radiation exposure of marine organisms and man are estimated. Data on its concentrations in different species show that, in general, its concentration in crustaceans and molluses is higher than that in fish, where its concentrations in liver and gut are much higher than that in bone and muscle. An estimation of the dose to marine organisms and man due to exposure to²¹⁰Po is very necessary for any assessment of the impacts of man-made radionuclides from coastal nuclear power installations.     

延安典型丹霞地貌景观特征及发育演化研究

本文是在延安典型丹霞地貌景观特征分析的基础上, 采用宇宙成因核素10Be和26Al技术获得暴露年龄和侵蚀速率, 研究“黄土覆盖型沟谷丹霞”地貌景观的演化历史。研究结果显示: 延安典型丹霞地貌的类型有狭缝式、石蘑菇式、天生桥式, 其中狭缝式丹霞的景观特征为“窄狭、多弯、韵律、多彩”, 同时也是典型的“黄土覆盖型沟谷丹霞”, 石蘑菇式丹霞造型奇特, 天生桥式丹霞地貌整体规模宏大, 这两者发育都严格受控于垂直节理和外力作用的侵蚀; 运用宇宙成因核素10Be和26Al技术, 计算获得志丹猫巷狭缝式丹霞地貌的暴露年代有两期, 分别为(0.75±18)~(0.83±0.14) ka和(1.14±13)~(1.29±0.30) ka, 安塞王家湾石蘑菇式丹霞地貌暴露年代为(1.76±0.45)~(1.77±0.15) ka, 这两处丹霞地貌暴露地表的年代都在全新世(Qh), 前者晚于后者, 地貌较年青; 运用宇宙成因核素10Be-26Al计算获得两处典型丹霞地貌侵蚀速率为(39±3.3)~(104±24.4) cm·ka–1, 与目前国内外学者研究地表和基岩得到的侵蚀速率对比, 这两处典型丹霞地貌的侵蚀速率较大, 结果还有待进一步研究; 延安典型丹霞地貌景观发育的演化始于白垩纪红层的堆积, 大致都经历了四个演化阶段, 初步揭示了地质构造、上覆黄土盖层以及流水等多种因素共同控制和影响延安典型丹霞地貌的形成, 演化阶段总体都处于青年晚期。     

Shore exposure affects mussel population structure and mediates the effect of epibiotic algae on mussel survival in SW Ireland

On rocky shores, the relative importance of abiotic and biotic processes that regulate community structure are thought to vary with levels of shore exposure. This can lead to characteristic features found on sheltered and exposed shores. This study identified differences in the population structure of mussels on exposed and sheltered rocky shores on Atlantic coasts of south-west Ireland. Direct interactions between epibiotic algae and their host mussels were also examined to test if potential effects varied with shore exposure. Mussel beds on sheltered shores were less dense and comprised larger mussels with greater rates of individual survival and growth than those on exposed shores. The results of a field experiment showed that algal epibionts had a negative effect on mussel survival on sheltered shores but not on exposed shores. Surprisingly, the presence of algal epibionts had no effect on mussel growth on either shore type. These findings contrast with those of previous studies. The effects of shore exposure and algal epibionts on mussels may be species-specific and may interact with other factors across different regions. This study shows that predictions of effects of exposure on mussel populations and their epibionts should only be based on specific experimental evidence and cannot be generalised across regions.     

武汉东湖底栖藻类在不同基质上生长的比较

测定了富营养化武汉东湖中的底栖藻类在不同人工基质上建群发展为成熟群落的生物量(Chl.a),定性分析了人工和天然基质上成熟硅藻群落的种类组成和结构特征.通过比较建群期间底栖藻类在花岗岩、玻璃、塑料(PVC)和木板4种不同人工基质上的生物量变化,发现底栖藻类在PVC上的生物量峰值(Chl.a,71.0μg/cm2)明显高于其它人工基质,说明PVC是最适合底柄藻类生长的人工基质.分析发现人工基质花岗岩上底柄硅藻群落的种类组成、主要优势种类、群落的相似性指数、多样性指数都和天然基质上的硅藻群落是高度相似的,显示该人工基质能够代表天然基质上的藻类群落,表明花岗岩应该是以底栖藻类作指示生物监测和评价水质的理想人工基质.     

Development of benthic macroinvertebrates sediment index(BSI) for bioassessment of freshwater sediment

Sediment quality has been evaluated in a variety of ways since the early 1990s in studies from Europe. In South Korea, most studies have used an indicator value for benthic macroinvertebrates based on water quality, not sediment quality. To date, few studies have examined the biological integrity of benthic macroinvertebrate communities in South Korea. In the current study, the tolerance valency and value in samples and the indicator weight values were measured for 43 benthic macroinvertebrate taxa from 73 sampling units in South Korea from 2014 to 2016. Total organic carbon, the amount of heavy metals, and total ammonia nitrogen were analyzed. The average grade for each pollutant was used as the sediment quality index. A benthic macroinvertebrates sediment index was developed for bioassessment of freshwater sediment. The benthic macroinvertebrates sediment index, which is based on the relative frequency of occurrence of macroinvertebrates, was highly correlated with pollution levels in the sediment. This index can be used in the field to assess the contamination of freshwater sediment. As the sample size was small in the current study and there were taxonomic limitations of Chironomidae larvae, further research is needed to improve the reliability of the benthic macroinvertebrates sediment index.     

Detecting,sourcing, and age-dating dredged sediments on the open shelf,southern California,using dead mollusk shells

Molluscan shell debris is an under-exploited means of detecting, sourcing, and age-dating dredged sediments in open-shelf settings. Backscatter features on the Southern California shelf are suggestive of dredged sediment hauled from San Diego Bay but deposited significantly inshore of the EPA-designated ocean disposal site. We find that 36% of all identifiable bivalve shells > 2 mm (44% of shells > 4 mm) in sediment samples from this 'short dump' area are from species known to live exclusively in the Bay; such shells are absent at reference sites of comparable water depth, indicating that their presence in the short-dump area signals non-compliant disposal rather than natural offshore transport or sea level rise. These sediments lack the shells of species that invaded California bays in the 1970s, suggesting that disposal preceded federal regulations. This inexpensive, low-tech method, with its protocol for rejecting alternative hypotheses, will be easy to adapt in other settings.     

Benthic macroinvertebrate field sampling effort required to produce a sample adequate for the assessment of rivers and streams of Neuquén Province,Argentina

This multi-year pilot study evaluated a proposed field method for its effectiveness in the collection of a benthic macroinvertebrate sample adequate for use in the condition assessment of streams and rivers in the Neuquén Province, Argentina. A total of 13 sites, distributed across three rivers, were sampled. At each site, benthic macroinvertebrates were collected at 11 transects. Each sample was processed independently in the field and laboratory. Based on a literature review and resource considerations, the collection of 300 organisms (minimum) at each site was determined to be necessary to support a robust condition assessment, and therefore, selected as the criterion for judging the adequacy of the method. This targeted number of organisms was collected at all sites, at a minimum, when collections from all 11 transects were combined. Subsequent bootstrapping analysis of data was used to estimate whether collecting at fewer transects would reach the minimum target number of organisms for all sites. In a subset of sites, the total number of organisms frequently fell below the target when fewer than 11 transects collections were combined.Site conditions where <300 organisms might be collected are discussed. These preliminary results suggest that the proposed field method results in a sample that is adequate for robust condition assessment of the rivers and streams of interest. When data become available from a broader range of sites, the adequacy of the field method should be reassessed.