Departamento de Oceanografía Biológica, Centro de Investigación Científica y Educación Superior de Ensenada, Baja California, México.
PLoS One. 2020 Nov 5;15(11):e0233071. doi: 10.1371/journal.pone.0233071. eCollection 2020.
Hyperiid amphipod species from the Gulf of Ulloa, Baja California, and the adjacent region (from the shelf break to 200 km offshore) were analyzed to evaluate diversity and abundances. This productive area supports small-scale commercial fisheries, including sand bass (Paralabrax nebulifer), California spiny lobster (Panulirus interruptus), abalones, clams, and others. Strong coastal upwelling events were observed during summer seasons of the period 2002-2008 between Punta Eugenia and Punta Abreojos. The upwelling plumes at Punta Abreojos are transported southward in slope waters bordering the coastal shelf of the Gulf of Ulloa, contributing to the separation of coastal and oceanic regions, and explain differences in amphipod diversity and abundances between both regions. In the offshore region, the most abundant species were Vibilia armata, Lestrigonus schizogeneios, Primno brevidens, and Eupronoe minuta, similar to previous findings in northern regions of Baja California and southern California. However, abundances of these species were lower (10-30 individuals/1000 m3), only reaching 20-50% of abundance levels reported off northern Baja California. In the coastal shelf of the Gulf of Ulloa, amphipods were virtually absent during 2002, 2003 and 2006. However, during 2004 and 2005, abundances of P. brevidens increased (54 and 20 ind/1000 m3, respectively). Moreover, during the late summer of 2007, abundances of L. schizogeneios, P. brevidens, Lycaea nasuta, Lycaea pulex, and Simorhynchotus antennarius increased considerably (261, 39, 31, 68, 416 ind/1000 m3, respectively), indicating occasional utilization of the coastal shelf by pelagic amphipods. Changes in gelatinous populations (medusae, siphonophores, ctenophores, doliolids, and salps) paralleled changes in hyperiid populations, with highest abundances in 2005-2008 in the coastal shelf. Significant correlations of 17 amphipod species with gelatinous taxa, which are often used as host organisms by hyperiid amphipods, suggest that gelatinous presence enhanced hyperiid abundance and promoted the progression of hyperiid amphipods onto the coastal shelf during parts of the 2002-2008 period.
对来自加利福尼亚湾乌略亚湾和邻近地区（从陆架边缘到 200 公里以外的海域）的 Hyperiidae 十足目动物进行了分析，以评估其多样性和丰度。这个多产的地区支持小规模商业渔业，包括沙鲈（Paralabrax nebulifer）、加利福尼亚刺龙虾（Panulirus interruptus）、鲍鱼、蛤蜊等。在 2002-2008 年期间的夏季，观察到厄瓜尼亚角和阿布雷霍斯角之间有强烈的沿海上升流事件。上升流羽流在乌略亚湾沿海大陆架边缘的斜坡水域向南输送，导致沿海和海洋区域分离，并解释了这两个区域之间十足目动物多样性和丰度的差异。在近海地区，最丰富的物种是 Vibilia armata、Lestrigonus schizogeneios、Primno brevidens 和 Eupronoe minuta，与加利福尼亚北部和南加利福尼亚先前的发现相似。然而，这些物种的丰度较低（10-30 个/1000 m3），仅达到北下加利福尼亚报告的丰度水平的 20-50%。在乌略亚湾的沿海大陆架上，2002 年、2003 年和 2006 年几乎没有十足目动物。然而，在 2004 年和 2005 年，P. brevidens 的丰度增加（分别为 54 和 20 个/1000 m3）。此外，在 2007 年夏末，L. schizogeneios、P. brevidens、Lycaea nasuta、Lycaea pulex 和 Simorhynchotus antennarius 的丰度大幅增加（分别为 261、39、31、68 和 416 个/1000 m3），表明浮游十足目动物偶尔会利用沿海大陆架。凝胶状种群（水母、管水母、栉水母、柔鱼和磷虾）的变化与十足目动物的变化平行，2005-2008 年沿海大陆架上的丰度最高。17 种十足目动物与凝胶状分类群的显著相关性，这些分类群通常是 Hyperiidae 十足目动物的宿主生物，表明凝胶状的存在增强了十足目动物的丰度，并在 2002-2008 年期间的部分时间促进了 Hyperiidae 十足目动物进入沿海大陆架。
