Spatial heterogeneity of wind forcing: application to artificial reef functioning influenced by the circulation in the Bay of Marseilles, France

In the frame of the largest French project of artificial production reefs, initiated by the city of Marseilles in 2001, the present study aimed at describing the hydrodynamic pattern of the coastal area considered, by the use of a 3D numerical modelling. Results were local wind statistics, bottom current fields and drifting particle maps. The knowledge of the hydrodynamic connexions between particle (such as larvae) sources or targeted areas linked to the reefs, allows us to explain the success or failure of the reefs' colonizing. Moreover, the study confirms the wind spatial variability and demonstrates the error resulting from the use of an average but locally absent wind direction.     

Overexpression of regucalcin suppresses cell death and apoptosis in cloned rat hepatoma H4-II-E cells induced by lipopolysaccharide, PD 98059, dibucaine, or Bay K 8644

The effect of regucalcin, a regulatory protein in intracellular signaling pathway, on cell death was investigated by using the cloned rat hepatoma H4-II-E cells overexpressing regucalcin. The hepatoma cells (wild-type) and stable regucalcin (RC)/pCXN2 transfectants were cultured for 72 h in medium containing 10% fetal bovine serum (FBS) to obtain subconfluent monolayers. After culture for 72 h, cells were further cultured for 12-72 h in medium without FBS containing either vehicle or lipopolysaccharide (LPS; 0.1 or 1.0 microg/ml). The number of wild-type cells was significantly decreased by culture for 24 or 48 h in the presence of LPS (0.1 or 1.0 microg/ml). The effect of LPS (0.1 or 1.0 microg/ml) in decreasing the number of hepatoma cells was significantly prevented in transfectants overexpressing regucalcin. However, the culture with LPS (0.1 or 1.0 microg/ml) for 72 h caused a significant decrease in cell number of transfectants. Ca(2+)/calmodulin-dependent nitric oxide (NO) synthase activity was significantly decreased by culture with LPS (1.0 microg/ml) for 24-72 h of wild-type cells. This decrease was significantly prevented in transfectants. LPS (0.1 or 1.0 microg/ml)-induced decrease in the number of wild-type cells was significantly prevented by culture with caspase-3 inhibitor (10(-8) M). Moreover, the number of wild-type cells was significantly decreased by culture with PD 98059 (10(-6) M), dibucaine (10(-6) M), or staurosporine (10(-6) M), which is an inhibitor of various protein kinases. The effect of PD 98059 or dibucaine on the number of wild-type cells was not observed in transfectants, although the effect of staurosporine was seen in transfectants. Culture with Bay K 8644 (2.5 x 10(-6) M), an agonist of Ca(2+) entry in cells, caused a significant decrease in the number of wild-type cells. Such an effect was not seen in transfectants. The presence of LPS did not significantly decrease the number of wild-type cells in the presence of Bay K 8644. Agarose gel electrophoresis showed the presence of low-molecular-weight deoxyribonucleic acid (DNA) fragments of adherent wild-type cells cultured with Bay K 8644, and this DNA fragmentation was significantly prevented in transfectants. This study demonstrates that overexpression of regucalcin has a suppressive effect on cell death induced by LPS or various intracellular signaling-related factors.     

The emergence of Cochlodinium along the California Coast (USA)

A sudden and nearly synchronous emergence of the red tide forming dinoflagellate Cochlodinium along more than 800 km of California coastline was initially observed in late summer 2004. Thereafter high cell concentrations have been detected on an annual basis. Here, we present quantitative and semi-quantitative data indicating that Cochlodinium was uncommon in the phytoplankton community in California prior to 2004 and is now persisting as a more regular component and one that seasonally can cause red tides. The quantitative portion of this study was primarily conducted in Monterey Bay, where cell densities reached at least 6 × 10⁴ cells L⁻¹ during the initial outbreak. A semi-quantitative comparison of California coastal counties by the California Department of Health Services (CDHS) was also made: of the 15 counties surveyed (most with multiple sites per county), cells were detected only from Los Angeles County in the south to San Mateo County in the central region (seven counties), but not in the northern part of the state (six counties). Two counties in the central region of the state, San Luis Obispo and Santa Cruz, displayed intense and frequent periods of elevated Cochlodinium cell abundances. Although not observed in the state-wide CDHS survey, we occasionally found cells in San Diego County with densities up to 2.7 × 10⁴ cells L⁻¹. Though these colonial dinoflagellates have been recognized in California for over 80 years, with several “blooms” recorded prior to 2004, the species’ geographic range and abundance in recent years suggest significant shifts in the nearshore phytoplankton community of this region of the eastern Pacific.     

Assessing the suitability of five benthic indices for environmental health assessment in a large subtropical South American estuary

Despite the increased and widespread usage of benthic indices for environmental health assessment, some methodological ambiguities remain to be solved. We tested the congruence and consistency of the benthic indices ITI, BO2A, BENTIX, AMBI and M-AMBI in a subtropical estuary (Paranaguá Bay, Brazil). Indices were applied to non-vegetated tidal flats increasingly contaminated by sewage to test: (i) correlations with molecular biomarkers of sewage (consistency); and (ii) evaluate the overall agreement/similarity of responses (congruence). The responses of the benthic indexes ITI, AMBI and BO2A were congruent among themselves and consistent with molecular biomarkers values. BENTIX and M-AMBI were less consistent and congruent and possibly need a readjustment of boundaries for subtropical habitats. The indices seemed robust to natural background yearly variations not related to contamination. Faecal sterols associated to nutrient contents suitably supported the validation of indices and could integrate reference conditions for sewage impacted coastal habitats. Benthic indices can successfully integrate management guidelines, but their suitable application demands further research on tolerance shifts of key indicator species.     

Announcing a Still Bay industry at Sibudu Cave, South Africa

Sibudu Cave in KwaZulu-Natal, South Africa, has a long Middle Stone Age (MSA) sequence with good organic preservation. The uppermost MSA sequence includes industries attributed to the final and late MSA and the Howiesons Poort. Below the Howiesons Poort are two layers containing some thin, bifacial lanceolate points, mostly in the form of distal and proximal fragments. These double-pointed foliates are the fossile directeur of the Still Bay Industry, and importantly, this Sibudu industry provides confirmation that the Still Bay predates the Howiesons Poort Industry. Technologically, the points from Sibudu are comparable to those from other South African sites with Still Bay occurrences (e.g., Blombos Cave and Hollow Rock Shelter). Although dating of the Sibudu Still Bay is preliminary, its age falls within the range of that at Blombos. For the past two decades, archaeologists have rejected the idea of a Still Bay Industry occurring outside of the Western Cape, but the Still Bay at Sibudu shows that this industry was, indeed, geographically widespread.     

Vertical distribution and germination ability of Alexandrium spp. cysts (Dinophyceae) in the sediments collected from Kure Bay of the Seto Inland Sea, Japan

The vertical distribution of Alexandrium tamarense/ catenella (hereinafter Alexandrium spp.) cysts was investigated with special attention to living cysts filled with fresh protoplasm and empty cysts. In addition, based on the incubation experiments of Alexandrium spp. cysts, the germination ability of the cysts was examined. A sediment core 63 cm in length, collected from Kure Bay of the Seto Inland Sea, West Japan, in September 2000, was provided for an analysis on the vertical distribution of Alexandrium spp. cysts. Samples from every 1 cm interval depth from the top down to 13 cm depth of the same core were taken to examine the germination ability of the cysts. Results show that Alexandrium spp. cysts were continuously observed from 59 to 60 cm depth to the top. The cyst densities in the upper parts of the core (from 9 to 10 cm depth to the top) were much more abundant those that in the lower parts (below 10–11 cm depth). The relationship between living and empty cysts in each depth did not reveal a positive correlation with the sediment depth. Based on the sedimentation rate of the core sediment (approximately 1.6 cm/year), Alexandrium spp. cysts have been produced since 1962, and a remarkable increase of these cysts was observed from ca 1993. Such a rapid increase of Alexandrium spp. cysts has probably been as a result of dense blooms of A. tamarense occurring since 1992 in Hiroshima Bay, including Kure Bay. The germination of Alexandrium spp. cysts was observed in samples collected from the top to 12–13 cm depth of the core. It suggests that the Alexandrium spp. cysts can keep the germination ability for more than 8 years.     

不同风浪条件下太湖梅梁湾光合有效辐射的衰减

基于2003年7月12～17日在太湖梅梁湾进行的连续6d原位水下光场观测资料,分析了不同风浪条件下光合有效辐射(PAR)的衰减和真光层深度,探讨了影响水下光合有效辐射的主导因子.结果表明,整个观测期间向下PAR衰减系数为2.63～4.71·m^-1(均值为3.63±0.47·m^-1),对应的真光层深度为0.98～1.75m(均值为1.29±0.18m),显示1.5m以下深度浮游植物、沉水植物基本上无法获取足够的太阳光能进行光合作用.从小风浪到中风浪、大风浪向下PAR衰减系数分别是2.63、3.72和4.37·m^-1,衰减系数分别增加了41%、66%.透明度、PAR衰减系数、真光层深度与悬浮物浓度存在显著性线性相关,并且与悬浮物中无机颗粒物相关性最好,而与叶绿素a、脱镁叶绿素及溶解性有机碳相关性很低.多元逐步线性回归表明,叶绿素a和溶解性有机碳最先被剔除方程,说明在梅梁湾由于风浪扰动引起悬浮物浓度的改变是影响水下光场的主导因素.     

Variable responses within epiphytic and benthic microalgal communities to nutrient enrichment

We evaluated how changes in nutrient supply altered the composition of epiphytic and benthic microalgal communities in a Thalassia testudinum (turtle grass) bed in Florida Bay. We established study plots at four sites in the bay and added nitrogen (N) and phosphorus (P) to the sediments in a factorial design. After 18, 24, and 30 months of fertilization we measured the pigment concentrations in the epiphytic and benthic microalgal assemblages using high performance liquid chromatography. Overall, the epiphytic assemblage was P-limited in the eastern portion of the bay, but each phototrophic group displayed unique spatial and temporal responses to N and P addition. Epiphytic chlorophyll a, an indicator of total microalgal load, and epiphytic fucoxanthin, an indicator of diatoms, increased in response to P addition at one eastern bay site, decreased at another eastern bay site, and were not affected by P or N addition at two western bay sites. Epiphytic zeaxanthin, an indicator of the cyanobacterial/coralline red algae complex, and epiphytic chlorophyll b, an indicator of green algae, generally increased in response to P addition at both eastern bay sites but did not respond to P or N addition in the western bay. Benthic chlorophyll a, chlorophyll b, fucoxanthin, and zeaxanthin showed complex responses to N and P addition in the eastern bay, suggesting that the benthic assemblage is limited by both N and P. Benthic assemblages in the western bay were variable over time and displayed few responses to N or P addition. The contrasting nutrient limitation patterns between the epiphytic and benthic communities in the eastern bay suggest that altering nutrient input to the bay, as might occur during Everglades restoration, can shift microalgal community structure, which may subsequently alter food web support for upper trophic levels.     

渤海湾两株H2亚型禽流感病毒的 遗传进化分析

野鸟是禽流感病毒的自然储存库,病毒可以随着宿主的迁徙传播给其他野鸟与家禽。渤海湾是鸟类南北迁徙的重要停歇地,也是东亚-澳大利西亚鸟类迁徙通道的重要组成部分,每年有大量水鸟在渤海湾停歇,促进了禽流感病毒的传播。为了解渤海湾地区禽流感病毒的传播及进化与水鸟迁徙的相关性,2018年春季鸟类迁徙期间的4和5月份,在渤海湾采集鸻鹬类粪便样品2 120份,对样品进行检测,分离出2株H2亚型禽流感病毒。对这2株H2亚型禽流感病毒进行了分子特征及遗传进化分析,并结合渤海湾水鸟的环志回收数据,对H2亚型病毒的重组及遗传进化与水鸟迁徙的联系进行了分析。结果表明,2株分离株的HA蛋白裂解位点符合低致病性禽流感病毒的分子特征,它们的8个基因片段同源性均不高,其中879-H2N7的8个基因片段分别与我国福建和澳大利亚的毒株同源性最高,遗传关系最近;854-H2N8的8个基因片段分别与我国湖南以及日本、韩国、孟加拉国和越南的毒株同源性最高,遗传关系最近。渤海湾水鸟的环志回收数据分析表明,879-H2N7随着野鸟的迁徙在渤海湾、福建沿海和澳大利亚之间进行传播与扩散;854-H2N8可能跨越东亚-澳大利西亚和中亚-印度两条通道之间进行基因重组和进化,并会随着鸟类迁徙进行传播和扩散。     

大亚湾红树林研究1.澳头港的红树植物群落

本文报道了大亚湾澳头港附近的红树植物群落的种类组成、结构、外貌及演替。该地区红树群落的主要类型有７个,即白骨壤群落、白骨壤桐花树群落、白骨壤＋秋茄桐花树群落、海漆木榄群落、海漆桐花树群落、桐花树群落、老鼠勒群落。