Microhabitat preferences and depth distribution of combtooth blennies (Blenniidae) in the Gulf of Trieste (North Adriatic Sea)

The microhabitat preferences and depth distribution of blenniid species (Blenniidae) in the Gulf of Trieste (North Adriatic Sea) were surveyed using the all‐occurrence sampling method, a non‐destructive visual census method, aided by SCUBA diving. Fourteen species were identified during the entire survey. Four species showed to be indiscriminate in their microhabitat choice while 10 species were classified as infrequent in the surveyed coastal area. A statistically significant correlation was found between the blenniid assemblage and nine microhabitat variables. The blenniid assemblage was divided in two main groups, by the use of canonical correspondence analysis, electivity index, and the depth distribution analysis. The first group comprises species that dwell in surface waters and show a high positive correlation with boulders, the presence of Mytilus galloprovincialis, cirripeds and empty holes bored by Lithophaga lithophaga. The second group includes species that mostly inhabit deeper waters and show a high positive correlation with rocks covered by precoralligenous bioformations.     

On the recent warming of the southeastern Bering Sea shelf

During the last decade, the southeastern Bering Sea shelf has undergone a warming of 3 °C that is closely associated with a marked decrease of sea ice over the area. This shift in the physical environment of the shelf can be attributed to a combination of mechanisms, including the presence over the eastern Bering Sea shelf of a relatively mild air mass during the winter, especially from 2000 to 2005; a shorter ice season caused by a later fall transition and/or an earlier spring transition; increased flow through Unimak Pass during winter, which introduces warm Gulf of Alaska water onto the southeastern shelf; and the feedback mechanism whereby warmer ocean temperatures during the summer delay the southward advection of sea ice during winter. While the relative importance of these four mechanisms is difficult to quantify, it is evident that for sea ice to form, cold arctic winds must cool the water column. Sea ice is then formed in the polynyas during periods of cold north winds, and this ice is advected southward over the eastern shelf. The other three mechanisms can modify ice formation and melt, and hence its extent. In combination, these four mechanisms have served to temporally and spatially limit ice during the 5-year period (2001–2005). Warming of the eastern Bering Sea shelf could have profound influences on the ecosystem of the Bering Sea—from modification of the timing of the spring phytoplankton bloom to the northward advance of subarctic species and the northward retreat of arctic species.     

河口湾区生物扰动强度及扰动作用特征研究——以山海关大石河河口湾为例

通过野外实际观察和室内模拟分析,依据现代沉积中的底内生物扰动构造三维结构清晰可辨的特征,认为现代河口湾的动物潜穴均可按照规则的几何体求得个体扰动指数,在此基础上,对河口湾地区生物扰动特点作了研究     

Conservation Priority Index for Estuarine Fish (COPIEF)

Public awareness regarding environmental issues has increased in recent decades. The increasing number of impact assessment studies, management and conservation plans, as well as ecological monitoring studies, demand new and more efficient techniques. Indices are an important tool to aid biologists in these studies and should allow an easier comprehension of the data by managers, decision-makers and the general public. This study presents the first multi-metrical index able to establish a hierarchical ordination of the conservation priority of the estuarine fish species using 72 species from 16 estuarine systems (W and S coasts of Portugal). The index is composed of 10 metrics, comprising species life traits, distribution and population trends. The information needed to score each metric was gathered from the published literature and the index validation was done by external means. This methodology allowed the definition of those fish species most in need of conservation planning, and those less prone to extinction in Portuguese estuarine systems. The proposed index fills a gap in our knowledge and provides a useful tool to the scientific community and to the decision-makers, being a breakthrough in the field of conservation planning of estuarine fish species.     

基于生态足迹的近海坛紫菜养殖可持续发展评估——以福建晋江为例

紫菜养殖业是福建传统近海渔业养殖类型,具有很高的经济收益.采用生态足迹成分法对晋江近海紫菜养殖生态足迹和生态足迹指数进行了估算,以评估其可持续发展程度.结果表明,2015年该海区紫菜养殖生态足迹为197.313 ghm2,其中人工、能源、基建是对生态足迹贡献的主要因素,相比于鱼和虾的精养、半精养的水产养殖模式,紫菜养殖无需投入饲料,对环境的压力较小.紫菜养殖人均生态足迹为0.009 ghm2/人,生态足迹指数为76.76%,是一种"绿色化"的强可持续发展养殖模式.依据受损和未受损两种情况对生态补偿政策提出建议,需要市场、政府两种转移支付手段配合使用,通过具体措施鼓励和促进紫菜可持续发展模式的发展和优化.     

Longitudinal and depth variation of bacterioplankton productivity and related factors in a temperate estuary

Bacterioplankton productivity (BP) spatial variation was investigated in relation to potential resources, including primary productivity and dissolved organic matter, in the micro-tidal Neuse River–Pamlico Sound estuarine system, North Carolina, USA. Estuarine BP was predicted to correlate with the trophic gradient, decreasing along the salinity gradient in parallel with the decrease in organic matter and primary productivity. This prediction was tested over four years at spatial scales ranging from kilometers to meters along the riverine axis and with depth. The general pattern of BP across the salinity gradient was unimodal and matched the phytoplankton patterns in peak location and variability. Peak locations varied with discharge, especially in 2003 when above average discharge moved peaks downstream. Spatial coherence of BP with other variables was much less at short time scales. The effect of temperature, nutrients, and phytoplankton on BP varied by location, especially fresh versus brackish stations, although only temperature explained more than 20% of the BP variation. Depth variation of BP was as great as longitudinal variation and bottom samples were often higher than surface. BP was strongly correlated with particulate organic carbon at the pycnocline and bottom, highlighting the importance of particulate matter as a resource. Station-averaged BP and phytoplankton data corresponded well with two published meta-analyses, although the offset of the freshwater station suggested longitudinal differences in community composition or resource availability.     

Evaluation of Liquefaction Potential Index Along Western Coast of South Korea Using SPT and CPT

For South Korea, liquefaction potential along the western coast has not been widely assessed because South Korea is considered to be a low seismic hazard. However, recent earthquake events and historical records indicate that the seismic hazard of South Korea should not be ignored. Moreover, as artificial fills are extensively used along the western coast for development, liquefaction evaluation of the soils in this area is necessary. In this paper, we present: (1) the seismic characteristics of the study area; (2) procedures for evaluating liquefaction potential, focusing on the liquefaction potential index (LPI) approach; and (3) LPI distributions at several representative locations along the western coast of South Korea under various seismic scenarios. The liquefaction potential index represents the liquefaction potential over the upper 20 m of a boring or sounding. Using cone penetration test (CPT) and standard penetration test (SPT) data from two coastal sites, we compare and discuss CPT-based and SPT-based LPI values, particularly values computed in nonplastic, silt-rich soils. In these soils, it appears that the CPT yields lower liquefaction resistance, resulting in large LPI values. Finally, discussion and suggestions are provided for CPT- and SPT-based liquefaction assessment of low plasticity and high fines content soils.     

Influence of Seawater on the Suction and Swelling Behavior of Clayey Soils

The present study examines the suction characteristics and swelling behavior of clayey soils when exposed to natural seawater with respect to distilled water. The effects of saline waters on the engineering behavior of soils need to be determined since the salinity of the pore fluid of soils near coastal areas increases continuously. Six clayey soil samples with different mineralogy and characteristics were gathered and tested to determine the suction and swelling characteristics in the presence of natural seawater and distilled water. The results show that the total suction values of the samples are higher in the presence of seawater than in distilled water. The samples with high swelling potential have lower matric suction values than nonswelling soils. Moreover, in contrast to swelling-type soils, the matric suction values of the nonswelling soils remain similar in the presence both distilled water and seawater. The modified free swell index (MFSI) of the samples is well correlated with the liquid limit (LL), plasticity index (PI), and cation exchange capacity (CEC) in distilled water. However, coefficients of determination decreased in the presence of seawater. Also, there is no significant correlation existing between total and matric suction values and the MFSI values of the samples.     

New Zealand estuary benthic health indicators summarised nationally and by estuary type

ABSTRACT

Ecological data are often collected at small geographic scales. However, analysing data collectively over wider scales can reveal results and patterns not shown in the smaller-scale data. We summarised data for intertidal benthic ecological (physico-chemical and biological) health indicators from New Zealand estuaries and compared the results against thresholds above which ecological impacts are expected to occur. Values for the sediment physico-chemical indicators mud and nutrients (nitrogen and phosphorus collectively) were above thresholds for at least 50% and at 31% of sites measured respectively. Sediment organic content and metal concentrations were generally low, with only maximum values exceeding the thresholds. Scores for biological indicators were within (or better than) the moderate health category for either at least 50%, or at least 75%, of sites. When compared across estuary types (based on a geomorphic classification system) we found statistically significant differences for thirteen of the sixteen indicators. Differences (among mean values) for highly significant results were relatively large compared to the range of values observed nationally for those indicators. However, the differences, except those for mud, were smaller than their respective ecological health threshold values. Our summary provides a reference for future comparisons of estuary indicators nationally and across estuary types.