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首页> 外文期刊>Harmful Algae >Ecology and nutrition of invasive Caulerpa brachypus f. parvifolia blooms on coral reefs off southeast Florida, U.SA
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Ecology and nutrition of invasive Caulerpa brachypus f. parvifolia blooms on coral reefs off southeast Florida, U.SA

机译：入侵的短刺卡氏乳的生态与营养。在美国佛罗里达州东南部的珊瑚礁上盛开的小叶芹

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摘要

Coral reefs off southeast Florida have experienced an unprecedented succession of invasive chlorophyte blooms over the past two decades, most recently the non-native Caulerpa brachypus f. parvifolia. To better understand the ecology and nutrition of the C. brachypus invasion, we monitored benthic cover, water column dissolved inorganic nutrients, tissue C:N:P ratios and stable nitrogen isotopes (δ~(15)N) of C. brachypus and native chlorophytes (Caulerpa racemosa, Caulerpa verticillata, Caulerpa mexicana, Codium isthmocladum) quarterly at two reef sites - the Princess Anne (PA) and North Colonel's Ledge (NCL) - in 2003-2004. The PA site was influenced by stormwater discharges from the Lake Worth inlet whereas NCL was farther distant from these discharges. Between winter and spring of 2003, C. brachypus became the dominant benthic chlorophyte, expanding to >60% cover at both PA and NCL. Following cold temperatures (13 ℃) associated with strong upwelling and high nitrate concentrations (21 μM) at NCL in July 2003, C brachypus cover decreased, suggesting that upwelling can stress growth of this tropical alga. Mean ammonium (0.60 μM), nitrate (2.7 μM) and DIN (3.2 μM) concentrations were high for coral reef environments. Low mean C:N ratios of ～13 in C. brachypus at both PA and NCL indicated little, if any, N-limitation compared to higher C:N ratios (up to 24) and greater N-limitation in native chlorophytes. Despite a relatively high mean SRP concentration (0.21 μM), mean N:P ratios of ～39 in C. brachypus and other chlorophytes at PA and NCL suggested that these blooms were P-limited. Multiple lines of evidence support the hypothesis that land-based nutrient sources fueled the C brachypus invasion. First, more persistent blooms of C. brachypus at PA compared to NCL correlated with significantly lower tissue C:P and higher δ~(15)N values (wet season) at PA, the site most directly influenced by land-based stormwater runoff. Second, C:N, C:P, and δ~(15)N values of C. brachypus correlated with seasonal patterns of rainfall and stormwater runoff. Third, δ~(15)N values of C. brachypus and other chlorophytes decreased at NCL following strong upwelling in July 2003, confirming that upwelled nitrate was not the cause of the elevated δ~(15)N values observed in these blooms. Lastly, the mean δ~(15)N values of C. brachypus and other chlorophytes off southeast Florida (+4.9‰) were in the range of sewage nitrogen and significantly higher than values (+1.2‰) for reference chlorophytes in the Abacos, Bahamas, an area that experiences relatively little sewage input.
机译：在过去的二十年中，佛罗里达州东南部的珊瑚礁经历了前所未有的入侵性绿化植物大爆发，最近一次是非本地的Caulerpa brachypus f。花叶。为了更好地了解短臂梭菌入侵的生态和营养，我们监测了底栖动物盖层，水柱中溶解的无机养分，组织C：N：P比率以及稳定的短链梭菌和原生动物的氮同位素（δ〜（15）N）。 2003-2004年每季度在两个礁石站点-安妮公主（PA）和北上校的壁架（NCL）上每季度捕捞一次绿藻类（Caulerpa racemosa，Caulerpa verticillata，Caulerpa mexicana，Codium isthmocladum）。 PA站点受沃思湖入口的雨水排放量的影响，而NCL距离这些排放物的距离更远。在2003年冬季至春季之间，腕足梭菌成为主要的底栖叶绿体，在PA和NCL上的覆盖率均超过60％。在2003年7月NCL出现强烈的上升流和较高的硝酸盐浓度（21μM）导致的寒冷温度（13℃）之后，短螺旋藻的覆盖率下降，这表明上升流可以胁迫这种热带藻类的生长。在珊瑚礁环境中，平均铵（0.60μM），硝酸盐（2.7μM）和DIN（3.2μM）浓度很高。在PA和NCL处，短螺旋藻的平均C：N比值​​均低至〜13，与较高的C：N比值​​（最高24）和天然叶绿素中的N-限制值相比，N-限制几乎没有（如果有的话）。尽管平均SRP浓度相对较高（0.21μM），但PA和NCL处的短螺旋体和其他叶绿体中N：P的平均比率为〜39，表明这些开花是P限制的。有多种证据支持这样的假说，即陆地养分来源助长了短吻鳄的入侵。首先，与NCL相比，PA上的腕果念珠菌更持久的开花与PA上的组织C：P显着降低和δ〜（15）N值较高（湿季）有关，PA受到陆基雨水径流的最直接影响。其次，短枝梭菌的C：N，C：P和δ〜（15）N值与降雨和雨水径流的季节性模式相关。第三，2003年7月强烈上升流之后，NCL上的短枝梭菌和其他绿化植物的δ〜（15）N值降低，这证实硝酸盐上升并不是这些花中δ〜（15）N值升高的原因。最后，佛罗里达州东南部的腕蛙和其他绿藻的平均δ〜（15）N值（+ 4.9‰）在污水氮范围内，并且显着高于阿巴科斯地区参考绿藻的值（+ 1.2‰），巴哈马，污水输入相对较少的地区。

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