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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >The distribution and behaviour of Patiriella mortenseni and P. regularis in the extreme hyposaline conditions of the Southern New Zealand Fiords
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The distribution and behaviour of Patiriella mortenseni and P. regularis in the extreme hyposaline conditions of the Southern New Zealand Fiords

机译：新西兰南部峡湾极端下盐条件下的Patiriella mortenseni和P. Regularis的分布和行为

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Echinoderms are a stenohaline phylum, however some species can tolerate varying degrees of exposure to hyposaline conditions. These exposures typically are limited in duration to a few hours to no more than a day or two, and hyposalinity levels range from ～8‰ to <30‰. The unique climatological and hydrographic conditions in Fiordland of southwest New Zealand produce a near-freshwater layer (Low Salinity Layer = LSL) on top of marine (34‰) water. The relative depth of the LSL varies both tidally and with rainfall. This halo-boundary presents a particularly stressful osmotic challenge to organisms found in shallow water. A series of transects in Doubtful Sound and the more northern Milford Sound quantified differences in density and bathymetric distribution of two species of seastars. The surveys revealed that Patiriella mortenseni occurs primarily below the LSL whereas Patiriella regularis is found well within the range of the LSL. Video observations of P. regularis over a rising tide were correlated with salinity measurements and showed a strong correlation between increased salinity and general vertical displacement upwards of the seastars observed moving. Activity coefficients (AC) were used to estimate the degree of neuro-muscular coordination and stress levels of these seastars in two hyposalinity experiments. Reciprocal transplants showed that P. regularis performed equally well in deeper, marine-salinity waters, as in shallow hyposalinity conditions, whereas P. mortenseni showed significantly impaired performance in the hyposaline conditions. These performance estimates were refined in a second experiment by quantifying AC of both species in a seawater dilution series. To rule out the possibility of heretofore unknown osmoregulatory capacity, we exposed both species to 0‰, 5‰, 15‰, 25‰, and 34‰ and recorded the osmolarity of the body fluid after 24 h. P. mortenseni died at salinities below 25‰. In contrast, P. regularis survived and the body fluid was nearly isotonic with the surrounding water. Two final experiments established the hyposalinity-tolerance limits of P. regularis. In a righting-time (RT) experiment we exposed P. regularis to hyposaline water of 5‰ for: 12, 24, 36, 48, 60, 84, and 133 h and recorded righting times immediately after re-immersing them in sea water. All individuals survived and the mean RT ranged from 18 min to 27 h (control group = 1.6 min). Finally, a lethal-exposure experiment to 0‰ (deionized water) confirmed that P. regularis can withstand far greater levels of extreme hyposalinity than has been reported for any other echinoderm.
机译：棘皮动物是蛇眼石的门，但是有些物种可以耐受不同程度的次生理盐水暴露。这些暴露的持续时间通常被限制在几个小时至不超过一两天，并且低盐度的水平范围从〜8‰至<30‰。新西兰西南部峡湾地区独特的气候和水文条件，在海水（34‰）之上形成了近淡水层（低盐度层= LSL）。 LSL的相对深度在潮汐和降雨条件下都会变化。这种晕圈边界对浅水中发现的生物造成了特别大的压力渗透挑战。 “可疑声音”和更北部的米尔福德声音中的一系列样带量化了两种海星的密度和测深分布的差异。调查显示，摩根氏疟原虫主要发生在LSL之下，而Regularis则存在于LSL范围内。在潮汐中对正则体育的录像观察结果与盐度测量值相关，并且显示出盐度增加与观察到的移动的海星向上的总体垂直位移之间存在很强的相关性。在两个低盐度实验中，使用活动系数（AC）来估计这些海星的神经肌肉协调程度和压力水平。相互移植表明，在深海盐度水域中，普通波氏疟原虫在浅水次盐度条件下的表现相同，而在低盐度条件下，摩氏疟原虫表现出明显受损。在第二项实验中，通过量化海水稀释系列中两种物种的AC来完善这些性能估计值。为了排除迄今为止未知的渗透调节能力的可能性，我们将两种物质暴露于0‰，5‰，15‰，25‰和34‰，并记录24 h后的体液渗透压。 P. mortenseni死于盐度低于25‰。相反，普通疟原虫存活下来，体液几乎与周围的水等渗。两项最终实验确定了普通假单胞菌的低盐度耐受极限。在校正时间（RT）实验中，我们将普通疟原虫暴露于5‰的次盐水中：12、24、36、48、60、84和133 h，并在将它们重新浸入海水后立即记录校正时间。所有个体均存活，平均RT为18分钟至27小时（对照组= 1.6分钟）。最后，在0‰（去离子水）的致死性暴露实验中证实，与其他棘皮动物相比，普通疟原虫能承受的盐分水平要高得多。

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