...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>ICES Journal of Marine Science >Strategies of space occupation by anchovy and sardine in the southern Benguela: the role of stock size and intra-species competition
【24h】

Strategies of space occupation by anchovy and sardine in the southern Benguela: the role of stock size and intra-species competition

机译：本格拉南部南部cho鱼和沙丁鱼对空间的占领战略：种群规模和物种内部竞争的作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Strategies of space occupation by anchovy and sardine populations in the southern Benguela during cruises in 1994 (low biomass) and 2001 (high biomass) are investigated using geostatistical tools. The spatial expansion of anchovy and sardine during the high-density year resulted in an increase in the number and density of hotspots and, in the case of anchovy, a relative increase in the contribution of mid- to high-density intervals to the overall survey biomass. Variogram autocorrelation ranges were larger in the high-biomass year. Otherwise, similarities and differences in the strategies of space occupation between anchovy and sardine are consistent between years of low and high biomass, and are therefore density-independent. Variograms of indicator variables revealed comparable structures for both species and years, with autocorrelation ranges of 30 nautical miles for the smallest indicator (0.1 g m~(-2)) and 10 miles for the largest (100 g m~(-2)), reflecting intrinsic spatial structures independent of stock size. The ideal survey inter-transect distance, defined as the autocorrelation range of the highest density indicator, was not influenced by the expanded distribution of both species. Cumulative frequency distributions and cross-variograms revealed differences in space occupancy between both species. Despite the areal expansion, and in contrast to anchovy, a significant portion of the sardine biomass continued to be contributed by a few very high-density areas with little spatial structure, as indicated by large nugget effects in the variograms and lack of transitions in the cross-variograms. Both species were spatially segregated in the low-biomass year, but overlapped extensively in the high-biomass year.
机译：使用地统计工具研究了1994年（低生物量）和2001年（高生物量）航行期间本格拉南部的an鱼和沙丁鱼种群的空间占用策略。高密度年份cho鱼和沙丁鱼的空间扩展导致热点数量和密度的增加，而在an鱼的情况下，中高密度区间对总体调查的贡献相对增加生物质。高生物量年份的方差图自相关范围较大。否则，an鱼和沙丁鱼在空间占用策略上的相似性和差异在低生物量和高生物量的年份之间是一致的，因此与密度无关。指标变量的方差图揭示了物种和年份的可比结构，最小相关指标（0.1 gm〜（-2））的自相关范围为30海里，最大相关指标（100 gm〜（-2））的自相关范围为10海里。与存量大小无关的内在空间结构。理想的测量样线间距离定义为最高密度指标的自相关范围，不受两个物种的扩展分布的影响。累积频率分布和交叉变异函数揭示了两个物种之间的空间占用差异。尽管面积扩大，并且与an鱼相反，沙丁鱼生物量的很大一部分仍由少数几个非常高密度的区域贡献，而这些区域的空间结构却很少，如变异函数中较大的金块效应和突变的缺乏所表明的那样。交叉变异函数。两种物种在低生物量年在空间上是隔离的，但在高生物量年广泛重叠。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号