Aschenbrenner A, Ferreira B P, Rooker J R
Universidade Federal de Pernambuco, Departamento de Oceanografia, Recife, 50740-550, Brazil.
Department of Marine Biology, Texas A&M University, Texas Clipper Road, Galveston, TX, 77554, U.S.A.
J Fish Biol. 2016 Jul;89(1):753-69. doi: 10.1111/jfb.13003. Epub 2016 Jun 3.
Otolith chemistry of juvenile and adult individuals of the Brazilian snapper Lutjanus alexandrei was measured to assess the utility of natural markers for investigating individual movements. Individuals were collected over a 3-year period (2010-2012) along the north-eastern coast of Brazil from both estuarine (juvenile to sub-adult stages) and coastal (sub-adult to adult stages) areas. Six elements ((7) Li, (24) Mg, (55) Mn, (59) Co, (88) Sr and (137) Ba) were measured in sectioned otoliths of L. alexandrei using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Edge composition analysis indicated that element:Ca ratios in the otoliths of juvenile and sub-adult L. alexandrei from estuaries were not significantly different among the three consecutive years (2010, 2011 and 2012), suggesting that physicochemical conditions within the nursery area investigated were temporally stable. Similarly, apart from two elements (Ba and Co), element:Ca ratios for larger L. alexandrei inhabiting coastal waters were also similar. In contrast, otolith chemistry of similar sized L. alexandrei from estuarine and coastal areas was significantly different (based on recently accreted material). Otolith Mn:Ca and Ba:Ca were both significantly higher for L. alexandrei collected in estuaries compared to fish from adjacent coastal reefs, while the opposite trend was observed for Sr:Ca. Given the pronounced differences in otolith chemistry between estuarine and coastal areas, element:Ca transects were constructed from the core to margin of the otoliths for adults (age 7+ years) collected on reefs to determine the timing of movement (ontogenetic migration) from estuarine to coastal areas. Based on observed patterns of decline for both Mn:Ca and Ba:Ca, it appears that L. alexandrei begin the move to more coastal habitats (i.e. lower element:Ca ratios) after age 2 years. The patterns observed for this species highlight the importance of conserving connectivity between coastal habitats to maintain sustainable fish stocks exploited by artisanal fisheries.
对巴西笛鲷（Lutjanus alexandrei）幼鱼和成鱼的耳石化学特征进行了测量，以评估天然标记物在研究个体移动方面的实用性。在三年期间（2010 - 2012年），沿着巴西东北海岸，从河口区域（幼鱼到亚成鱼阶段）和沿海区域（亚成鱼到成鱼阶段）采集了个体。使用激光烧蚀电感耦合等离子体质谱法（LA - ICPMS）对巴西笛鲷的耳石切片中的六种元素（锂 - 7、镁 - 24、锰 - 55、钴 - 59、锶 - 88和钡 - 137）进行了测量。边缘成分分析表明，来自河口的巴西笛鲷幼鱼和亚成鱼耳石中的元素与钙的比率在连续三年（2010年、2011年和2012年）之间没有显著差异，这表明所研究的育苗区内的物理化学条件在时间上是稳定的。同样，除了两种元素（钡和钴）外，栖息在沿海水域的较大巴西笛鲷的元素与钙的比率也相似。相比之下，来自河口和沿海区域的相似大小的巴西笛鲷的耳石化学特征存在显著差异（基于最近沉积的物质）。与来自相邻沿海珊瑚礁的鱼类相比，在河口采集的巴西笛鲷的耳石中锰与钙和钡与钙的比率都显著更高，而锶与钙的比率则呈现相反的趋势。鉴于河口和沿海区域之间耳石化学特征的明显差异，构建了从在珊瑚礁上采集的成鱼（7岁以上）耳石核心到边缘的元素与钙的剖面图，以确定从河口到沿海区域的移动（个体发育洄游）时间。根据观察到的锰与钙和钡与钙比率下降的模式，似乎巴西笛鲷在2岁后开始向更多沿海栖息地移动（即元素与钙的比率更低）。该物种观察到的模式凸显了保护沿海栖息地之间连通性对于维持小型渔业所开发的可持续鱼类种群的重要性。
