Distribution, condition, and growth of newly settled southern flounder (Paralichthys lethostigma) in the Galveston Bay Estuary, TX

Several flatfish species, including southern flounder (Paralichthys lethostigma) recruit to estuaries during early life. Therefore, evaluation of estuarine sites and habitats that serve as nurseries is critical to conservation and management. The present study used density data in conjunction with biochemical condition and growth measurements to evaluate settlement sites used by southern flounder in the Galveston Bay Estuary (GBE). In 2005, beam-trawl collections were made in three major sections of the GBE (East Bay, Galveston Bay, West Bay). Three sites were sampled in each bay. Within each sampling site, replicate collections were taken from three habitats: 1) marsh edge (< 1 m depth), 2) intermediate zone (10–20 m from marsh interface;  1 m depth), and 3) bay zone (typically > 100 m from marsh interface; depth > 1 m). Average size of southern flounder collected was 12–19 mm standard length, and peak densities occurred in January and February. Catch data indicated that densities of southern flounder were significantly greater in East Bay (2.75 per 100 m²) than in Galveston Bay (0.91 per 100 m²) or in West Bay (0.45 per 100 m²). Densities were statistically similar among habitats. Otolith-based estimates of age indicated that the majority of southern flounder collected were 35–45 days old and derived from early December to early January hatch-dates. Growth rates were similar among bays and among habitats, with the average growth rate being 0.40 mm day^− 1 (range: 0.21–0.76 mm day^− 1). RNA:DNA was above the established baseline value for nutritional stress, indicating that newly settled southern flounder in the GBE were in relatively high condition. Habitat-specific differences in RNA:DNA ratios were not observed; however, ratios were significantly lower in West Bay (average 8.0) than in East Bay (average 9.5) or in Galveston Bay (average 9.8), suggesting the condition of new recruits may vary spatially within the GBE. Findings from the current study suggest density and condition of newly settled southern flounder vary at the bay scale, suggesting that parts of GBE do not function equally as nurseries.     

菲律宾蛤仔(Ruditapes philippinarum)大连群体家系建立及生长比较

于2008年6月,以大连野生型蛤仔为材料,采用巢式设计即1个雄性亲本与3个雌性亲本交配的方式建立了菲律宾蛤仔15个半同胞家系(A,B,…,O)和45个全同胞家系(A1,A2,A3,…,O1,O2,O3)。对各家系的壳长、壳宽、壳高、鲜重等各项指标进行了方差分析和多重比较。结果表明,3、4、5月龄,菲律宾蛤仔45个全同胞家系的表型性状具有显著差异,且各月龄的差异趋势基本一致。5月龄时,从其生长性状上看,家系F2、G2、G3表现出明显的生长优势,壳长分别提高28.43%、24.72%、30.53%,壳宽分别提高21.14%、22.3%、25.58%,壳高分别提高30.88%、26.96%、25.25%,鲜重分别提高50.00%、68.42%、44.12%。从其存活上看,家系E3的四个表型性状在全同胞家系中最小,但存活数量最多为2269粒,表现出很强的抗逆性;具有生长优势的家系F2存活个数最少仅为43粒,抗逆性相对最差。从其产量上看,家系N3、I1、E3、C1、N1、G2产量较高,分别比平均产量提高了77.8%、75.61%、75%、69.45%、53.96%、50.19%。综合以上各项指标家系G2、G3、N3、E3、I1、C1、N1可作为优良的家系育种材料,在下一步育种工作中可以利用家系选择及家系杂交的方法对7个家系进行遗传改良。     

江苏南部海岸牡蛎礁演化的几何模型

牡蛎礁是具有重要生态功能的海岸带生境,并且记录了丰富的环境演化信息。根据碳酸盐沉积层序模拟的方法,提出了一个牡蛎礁演化模型,由海平面波动过程、碎屑沉积物顶面高程、牡蛎礁垂直生长率、牡蛎礁顶部高程等四个模块所构成。垂向生长率函数的输入参数通过牡蛎礁沉积环境分析和古今地貌对比方法而确定。应用该模型探讨了江苏海岸小庙洪牡蛎礁的定殖、生长和最终被埋藏的演化历程。模拟结果显示,牡蛎礁顶部水深和河口湾环境参数是牡蛎礁演化的两大限制因素,小庙洪牡蛎礁的最大垂向生长率约为12mm/a,礁体发育初期以垂向增生为主,大约910年前礁体出露于平均低潮面后,转向以侧向扩张为主。该礁体的出露规模在330年前达到最大,目前牡蛎礁的生长几乎停滞,并将在250年后被埋藏,其时牡蛎礁的最大可能厚度达12m。牡蛎礁演化模型显示牡蛎礁建造过程具有复杂性,是海平面变化、地面沉降速率、碎屑沉积速率、盐度、悬沙浓度等诸多因素共同作用的结果。牡蛎礁顶板应看成是低于当时海平面的标志,并不代表海平面高度。     

大气环流模式与春玉米生长模拟模式联接的影响评估模拟试验

根据春玉米田间试验资料和历史气候资料,对春玉米生长模拟模式进行了验证与灵敏性分析,在此基础上,运用逐步订正法将当前气候前景和大气环流模式输出资料结合历史气候资料生成的未来气候情景订正到１ｏ×１ｏ网格点上,与春玉米生长模拟模式相联接,就未来气候变化对我国东北地区春玉米生长、发育和最终产量的可能影响进行了网格化定量模拟,并对一些适应性对策的效果进行了定性或定量的分析。结果表明,在ＤＫＲＺＯＰＹＣ模拟的未来情景下,若保持当前作物品种和生产技术措施不变,研究区域除北部将平均增产７０％外,其余地区都将有不同程度的减产,幅度在－１０％～－５０％之间,而在ＮＣＡＲ模拟的情景下,中西部地区将增产,其它地区可维持当前产量水平。适应性对策将对开发利用未来可能的气候资源,减缓未来气候变化的负效应,充分发挥其正效应起到积极作用,进而绝大部分区域将受益于未来水热条件的改变。     

饲料中铁对美国红鱼(Sciaenops ocellatus)生长和免疫的影响

采用单因子实验设计方法,进行了饲料中添加铁对美国红鱼生长(增重率、存活率、特定生长率和饲料效率)、免疫反应(血清溶菌酶活性、总补体活性和超氧化物歧化酶活性(Superoxide dismutase,SOD)和组织中铁积累量影响的研究。结果表明,各饲料组美国红鱼的成活率(93.33%-95.00%)无显著性差异(P>0.05);饲料铁含量在327.2、368.1mg/kg时饲料效率显著高于285.3、303.5、443.7mg/kg组(P<0.05);随着饲料中铁含量从285.3mg/kg增加到327.2mg/kg,美国红鱼的增重率和特定生长率显著升高(P<0.05),而饲料中铁含量达到443.7mg/kg之后,其增重率和特定生长率显著下降;以特定生长率为指标,通过回归拟合分析美国红鱼最佳生长性能的饲料铁含量为330mg/kg左右。各饲料组肌肉中铁积累量无显著性差异(P>0.05);随着饲料中铁含量从285.3mg/kg增加到443.7mg/kg,美国红鱼肝脏中铁积累量显著增加(P<0.05)。饲料铁含量在368.1mg/kg时血清溶菌酶活性达到最高值,并显著高于285.3、303.5、327.2mg/kg组(...     

The German Bight (North Sea) is a nursery area for both locally and externally produced sprat juveniles

To better understand the role of the German Bight (GB) as a nursery area for juvenile North Sea sprat Sprattus sprattus we sought to determine whether the area may receive only locally or also externally produced offspring. We sampled juveniles during 3 trawl surveys in the GB in August, September, and October 2004 and applied otolith microstructure analysis in order to reconstruct their distributions of the day-of-first-increment-formation (dif). These were contrasted with spatial and seasonal patterns of sprat egg abundance in the GB and its adjacent areas, observed during 6 monthly plankton surveys. It was found that the majority of juveniles originated mainly from April/May 2004, coinciding with high spawning activity west of the GB, whereas spawning and larval production inside the GB peaked notably later, in May/June. This indicated that a large proportion of juveniles was produced outside the GB and transported subsequently into it through passive and/or active migration. Shifts to later mean difs from one survey to the next and length distributions indicative of the simultaneous presence of multiple cohorts, supported the notion that the GB is a complex retention and nursery area for sprat offspring from different North Sea spawning grounds and times. Later born juveniles had significantly faster initial growth rates than earlier born conspecifics, which was likely temperature-mediated, given the strong correlation between back-calculated growth histories and sea surface temperature as a proxy for thermal histories of juveniles (r² = 0.52).     

Contribution of different generations of the brown shrimp Crangon crangon (L.) in the Dutch Wadden Sea to commercial fisheries: A dynamic energy budget approach

In this paper a contribution is made to the ongoing debate on which brown shrimp generation mostly sustains the autumn peak in coastal North Sea commercial fisheries: the generation born in summer, or the winter one. Since the two perspectives are based on different considerations on the growth timeframe from settlement till commercial size, the Dynamic Energy Budget (DEB) theory was applied to predict maximum possible growth under natural conditions. First, the parameters of the standard DEB model for Crangon crangon L. were estimated using available data sets. These were insufficient to allow a direct estimation, requiring a special protocol to achieve consistency between parameters. Next, the DEB model was validated by comparing simulations with published experimental data on shrimp growth in relation to water temperatures. Finally, the DEB model was applied to simulate growth under optimal food conditions using the prevailing water temperature conditions in the Wadden Sea. Results show clear differences between males and females whereby the fastest growth rates were observed in females. DEB model simulations of maximum growth in the Wadden Sea suggest that it is not the summer brood from the current year as Boddeke claimed, nor the previous winter generation as Kuipers and Dapper suggested, but more likely the summer generation from the previous year which contributes to the bulk of the fisheries recruits in autumn.     

不同土壤盐浓度和淹水条件对芦苇生长影响的田间试验

在田间条件下,研究了不同土壤和灌溉水盐体积浓度对芦苇生长的影响。结果表明:随着灌溉水盐浓度的增加,土壤盐浓度和养分变化均较大,总的趋势是距河口越远土壤盐浓度越低,土壤氮含量越高,钾含量越低,而磷含量变化不明显;土壤和灌溉水的盐体积浓度越低,芦苇的生长指标越好,叶绿素含量和干物质重越高,根状茎发育量越多,产量越高;早春及时灌溉,可降低土壤盐浓度,有利于芦苇发芽,显著增加芦苇的密度和株高。根据芦苇的耐盐特性和需水习性,应实行灌排结合的技术措施,促进芦苇根系发育和植株生长,提高芦苇产量。     

Timing of basin inversion on the Isle of Wight: New evidence from geophysical log correlation, seismic sections and lateral facies change in the Palaeogene Headon Hill Formation

Paleogene thickness patterns across the Bouldnor Syncline and Porchfield Anticline in the northwestern Isle of Wight have been deduced using outcrop information, borehole correlation, gamma-ray logs and seismic reflection data. The thickness patterns provide evidence for an early phase of basin inversion at around the Bartonian-Priabonian boundary (Late Eocene) in the Isle of Wight. Paleogene strata older than the Becton Sand Formation show little evidence for significant lateral changes in thickness, even though the boreholes are located at various structural positions around the Bouldnor Syncline and Porchfield Anticline. In contrast, both seismic reflection and borehole data provide evidence for marked thinning of Paleogene strata onto the Porchfield Anticline at around the level of the Becton Sand Formation and basal Headon Hill Formation (Totland Bay Member) which probably results from an episode of basin inversion and growth folding. The inversion event was relatively minor and short-lived and continues to point toward the main phase of the basin inversion being late Oligocene or younger. However, it still has important implications for understanding structural control on sedimentation patterns in the Headon Hill Formation, with the migration of sandy channelised depositional systems into the axis of the Bouldnor Syncline, and the sequence stratigraphic significance of the important Bartonian-Priabonian regression event, which may related to tectonics rather than global sea-level change.     

Spartina densiflora demonstrates high tolerance to phenanthrene in soil and reduces it concentration

The present study was conducted to investigate the tolerance of Spartina densiflora to phenanthrene, and to test its ability in phenanthrene dissipation. A glasshouse experiment was designed to investigate the effect of phenanthrene from 0 to 1000 mg kg⁻¹ on growth and photosynthetic apparatus of S. densiflora by measuring chlorophyll fluorescence parameters, gas exchange and photosynthetic pigments. We also performed chemical analysis of plant samples, and determined the concentration of phenanthrene remaining in soil. S. densiflora survived to concentrations as high as 1000 mg kg⁻¹ phenanthrene in soil; in fact, there was no significant difference in RGR among the treatments after 30 days. Otherwise, phenanthrene affected photosynthetic apparatus at 100 and 1000 mg kg⁻¹; thus, the lower Φ_PSII could be explained by the declined photosynthetic pigment concentrations. Soil extraction indicated a more marked rate of phenanthrene disappearance in the soil in the presence of S. densiflora.