Manganese dynamics in a mangrove mud flat tidal creek in SE Brazil

This study investigated the behavior of soluble and particulate manganese, during tidal cycles in a mangrove tidal creek and adjacent mud flats in SE Brazil. We identify the major processes affecting manganese transport to mangroves. The results showed that manganese variability occurs both seasonally, and over the tidal cycle, in response to changing redox potentials. Tidal water flooding mud flats are enriched in manganese, originating from upward migration of reduced species and further adsorption onto suspended particles under oxic conditions. During the tidal cycle, particulate manganese concentrations are higher during flood periods, whilst dissolved concentrations are higher during ebb periods. Although quantitatively different, this pattern occurs both in winter and summer. The dynamics of manganese characterized in this study suggest that this metal may play a significant role as a conveyor of trace metals to mangrove ecosystems, as suggested by earlier studies.     

Vertical accretion and shallow subsidence in a mangrove forest of southwestern Florida,U.S.A.

Simultaneous measurements of vertical accretion from artificial soilmarker horizons and soil elevation change from sedimentation-erosion table(SET) plots were used to evaluate the processes related to soil building infringe, basin, and overwash mangrove forests located in a low-energy lagoonwhich receives minor inputs of terrigenous sediments. Vertical accretionmeasures reflect the contribution of surficial sedimentation (sedimentdeposition and surface root growth). Measures of elevation change reflectnot only the contributions of vertical accretion but also those ofsubsurface processes such as compaction, decomposition and shrink-swell. Thetwo measures were used to calculate amounts of shallow subsidence (accretionminus elevation change) in each mangrove forest. The three forest typesrepresent different accretionary environments. The basin forest was locatedbehind a natural berm. Hydroperiod here was controlled primarily by rainfallrather than tidal exchange, although the basin flooded during extreme tidalevents. Soil accretion here occurred primarily by autochthonous organicmatter inputs, and elevation was controlled by accretion and shrink-swell ofthe substrate apparently related to cycles of flooding-drying and/or rootgrowth-decomposition. This hydrologically-restricted forest did notexperience an accretion or elevation deficit relative to sea-level rise. Thetidally dominated fringe and overwash island forests accreted throughmineral sediment inputs bound in place by plant roots. Filamentous turfalgae played an important role in stabilizing loose muds in the fringeforest where erosion was prevalent. Elevation in these high-energyenvironments was controlled not only by accretion but also by erosion and/orshallow subsidence. The rate of shallow subsidence was consistently3–4 mm y^–1 in the fringe and overwash island forests butwas negligible in the basin forest. Hence, the vertical development ofmangrove soils was influenced by both surface and subsurface processes andthe processes controlling soil elevation differed among forest types.The mangrove ecosystem at Rookery Bay has remained stable as sea levelhas risen during the past 70 years. Yet, lead-210 accretion data suggest asubstantial accretion deficit has occurred in the past century (accretionwas 10–20 cm < sea-level rise from 1930 to 1990) in the fringe andisland forests at Rookery Bay. In contrast, our measures of elevation changemostly equalled the estimates of sea-level rise and our short term estimatesof vertial accretion exceeded the estimates by the amount of shallowsubsidence. These data suggest that (1) vertical accretion in this system isdriven by local sea-level rise and shallow subsidence, and (2) the mangroveforests are mostly keeping pace with sea-level rise. Thus, the vulnerabilityof this mangrove ecosystem to sea-level rise is best described in terms ofan elevation deficit (elevation change minus sea-level rise) based on annualmeasures rather than an accretion deficit (accretion minus sea-level rise)based on decadal measures.     

粤港澳大湾区背景下高职校企协同育人的对策研究

随着粤港澳大湾区战略规划的发布和推进,将粤港澳大湾区打造成为教育和人才高地,粤港澳大湾区职业教育发展迎来了历史性机遇。在粤港澳大湾区背景下,提出了高职院校的发展需要三地政府企业学校和社会共同合作,引进先进的职教理念,加强职业教育与产业发展无缝对接,调动行业企业参与职业教育的积极性,发挥各自的资源优势,优化资源配置和功能整合,协同培养适应经济发展需要的高素质技术技能人才,为大湾区经济建设与社会发展提供有力的人力支撑。     

The spectre of past spectral conditions: colour plasticity,crypsis and predation risk in freshwater sculpin from newly deglaciated streams

Whiteley AR, Bergstrom CA, Linderoth T, Tallmon DA. The spectre of past spectral conditions: colour plasticity, crypsis, and predation risk in freshwater sculpin from newly deglaciated streams. Ecology of Freshwater Fish 2011: 20: 80–91. © 2010 John Wiley & Sons A/S Abstract – Coastrange sculpin (Cottus aleuticus) have colonised recently deglaciated streams of Glacier Bay National Park, Alaska, USA, within the last 200 years. Highly cryptic colouration across a marked gradient of stream substrate colours within Glacier Bay could result from physiological (rapid) or morphological (slower) colour change. Laboratory experiments revealed that physiological colour plasticity occurred on the order of minutes, with significant variation in the degree of colour change among individuals and between populations. In contrast, morphological colour plasticity occurred on the order of weeks to months. Experimentally manipulated spectral conditions influenced the magnitude and variance of subsequent physiological colour plasticity. In‐stream predation trials revealed significantly more predation attempts on higher background contrast sculpin models, providing evidence that background colour matching has strong fitness consequences. Colour plasticity with apparent fitness consequences occurs at multiple interacting time scales in coastrange sculpin and may play an important role in the colonisation of recently deglaciated streams.     

胶州湾大型底栖动物次级生产力

根据2016―2017年在胶州湾开展的大型底栖动物调查获得的资料,分析报道了胶州湾大型底栖动物次级生产力及其与环境的关系。结果表明,本次调查中胶州湾大型底栖动物年平均栖息密度为119.17 ind/m~2,年平均生物量为20.57 [g(去灰干重, AFDW)/m~2],年平均次级生产力和P/B值分别为9.64 [g(AFDW)/(m~2·a)]和0.47/a;空间分布上,次级生产力在湾内北部的养殖区和湾口处较高,形成两处次级生产力高值区,向四周逐渐减小;在季节上,次级生产力为春季冬季夏季秋季;环境因子与次级生产力的相关程度均不显著(P0.05),在湾内养殖区的次级生产力与底质类型相关性较大,而湾外是溶解氧的含量影响较大;胶州湾海域次级生产力高于我国北方大部分海域,但P/B值较低,表明群落组成中个体较小、生命周期较短和新陈代谢快的物种所占比例少于其他海域。     

海州湾3种䲗属鱼类生长参数的年际变动

䲗属（）鱼类是海州湾地区常见的小型底栖饵料鱼类,但一直以来被渔业研究者忽视。本研究通过2011-2019年共18个航次的海州湾底拖网调查数据,分析了3种常见的䲗属鱼类——瓦氏䲗（C.richardsoni）的年际数量变化,并基于Bootstrap重抽样法,使用电子体长频率分析法（electronic length frequency analysis,ELEFAN）计算其冯·贝塔朗菲生长方程（von Bertalanffy growth function,VBGF）参数。结果表明,2011-2019年3种䲗属鱼类在海州湾地区表现出了极限体长由21.60 cm下降至13.96 cm,生长参数由19.72 cm下降至19.35 cm,生长参数由18.74 cm下降至14.91 cm,生长参数由0.45下降至0.43。3种䲗属鱼类总体上呈现数量下降与小型化趋势。本研究旨为䲗属鱼类生长特征研究提供参考资料,并为渔业资源评估提供基本参数依据。     

条斑紫菜对胶州湾湿地浅海富营养化状况的生物修复效果

对胶州湾湿地海域条斑紫菜Porphyra yezoensis Ueda养殖区水环境进行了现场调查和研究,对紫菜生长吸收N、P营养盐的效果进行了实验研究,在此基础上综合分析了紫菜对富营养化海水的生物修复效果。研究结果表明,条斑紫菜养殖对胶州湾湿地海水中过剩的营养盐有明显的控制作用,养殖区氮、磷营养盐和有机碳含量以及水质营养指数均低于周边对照区。实验条件下,紫菜生长吸收N、P营养盐和降低海水富营养化程度的效果显著。各实验周期水体中的无机氮含量下降幅度为17.15%～21.26%,活性磷酸盐含量下降幅度为55.73%～61.12%,表明紫菜叶状体生长对磷的吸收量明显高于对氮的吸收量。另外,各换水周期实验海水的营养指数值由2.211～2.592降至0.749～0.873,降低幅度为63.32%～69.39%,海水富营养化等级由"中度富营养"降至"贫营养"。根据胶州湾湿地海域的环境条件,通过大规模栽培大型海藻,可大量去除海水中的N、P、C等生源要素,有效降低海水富营养化水平。     

莱州湾芙蓉岛人工鱼礁区鮻资源分布特征及其与环境因子的相关性分析

为研究环境因子对人工鱼礁区鰉分布的影响,实验以莱州湾芙蓉岛人工鱼礁区鰉为对象,根据2014—2017年春季和秋季礁区三重刺网调查数据,主要应用GAM模型研究了水温、盐度、pH、溶解氧、饵料生物和人工鱼礁等环境参数以及年份、月份对鰉单位捕捞努力量渔获量(CPUE)和各站位平均体长的影响。结果显示,春季礁区和非礁区CPUE差异不显著,秋季礁区CPUE高于非礁区,是非礁区的3.53倍。礁区和非礁区体长差异不显著。三因素方差分析表明,鰉CPUE受到年份、月份、人工鱼礁、年份和月份的交互作用影响,平均体长则主要受到年份的影响。Delta GAM模型表明,人工鱼礁和水温对CPUE影响显著,鰉在人工鱼礁区出现的概率大于非礁区,随着水温的升高,鰉出现的概率降低;CPUE呈现先升高后降低的趋势,并在8°C达到最高值;饵料浮游植物丰度和浮游动物丰度是影响鰉平均体长的关键因子,当硅藻丰度小于3×10~5个/m~3时,鰉平均体长随硅藻丰度上升而下降,随后趋于稳定;鰉平均体长随浮游动物丰度增加而呈现降低趋势。研究表明,鰉主要分布在秋季水温较低时的人工鱼礁区,体长较大的鰉主要出现在硅藻丰度和浮游动物丰度较低的区域。     

Accumulation of paralytic shellfish poisoning toxin by the swimming crab <Emphasis Type="Italic">Charybdis japonica</Emphasis> in Kure Bay,Hiroshima Prefecture

The accumulation of paralytic shellfish poisoning (PSP) toxin in the crab Charybdis japonica was investigated in Kure Bay, when a bivalve Mytilus galloprovincialis, in the same water, showed toxicity caused by PSP toxin. In 2005, 17 specimens of the crab had PSP toxin over 4 MU/g in the hepatopancreas, and the highest toxicity was at 37.4 MU/g. Since the regulation limit of PSP for crab hepatopancreas was set in 2004, this is the first observation of regulatory level of PSP toxin in C. japonica. Unlike in the hepatopancreas of the crab, the hazardous level of the toxin was not detected in the muscle of the cephalothorax and the appendage. The toxin accumulation in the crab was also investigated by feeding toxic mussels to the crab. The crab retained the toxin mainly in the hepatopancreas, and the ratio of retention in the crab was from 12.9 to 24.6%. The toxin profiles, shown in the feeding experiments, suggest that the transformation of PSP toxin occurs in the crab because dcGTX2 and dcGTX3 was detected in all crab specimens despite the lack of these analogs in the mussels used as feed.