Cumming Erin, Jarvis Jessie C, Sherman Craig D H, York Paul H, Smith Timothy M
Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University , Waurn Ponds , Victoria , Australia.
Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States; Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Queensland, Australia.
PeerJ. 2017 Mar 23;5:e3114. doi: 10.7717/peerj.3114. eCollection 2017.
In a series of experiments, seeds from a temperate seagrass species, collected in Port Phillip Bay, Victoria, Australia were exposed to a range of salinities (20 PSU pulse/no pulse, 25 PSU, 30 PSU, 35 PSU), temperatures (13 °C, 17 °C, 22 °C), burial depths (0 cm, 1 cm, 2 cm) and site specific sediment characteristics (fine, medium, coarse) to quantify their impacts on germination rate and maximum overall germination. In southern Australia the seagrass is a common subtidal species; however, little is known about the factors that affect seed germination which is a potential limiting factor in meadow resilience to natural and anthropogenic disturbances. Overall seed germination was low (<20%) with germination decreasing to <10% when seeds were placed in the sediment. When germination of seeds was observed, it was enhanced (greater overall germination and shorter time to germination) when seeds were exposed to a 20 PSU pulse for 24 h, maintained at salinity of 25 PSU, temperatures <13 °C, in sediments with fine or medium grain sand and buried at a depth of <1 cm. These results indicate that germination of seeds under conditions may be seasonally limited by temperatures in southern Australia. Seed germination may be further restricted by salinity as freshwater pulses reaching 20 PSU are typically only observed in Port Phillip Bay following large scale rainfall events. As a result, these populations may be particularly susceptible to disturbance with only a seasonally limited capacity for recovery.
在一系列实验中，从澳大利亚维多利亚州菲利普港湾采集的一种温带海草物种的种子，被置于一系列盐度（20 PSU脉冲/无脉冲、25 PSU、30 PSU、35 PSU）、温度（13℃、17℃、22℃）、埋藏深度（0厘米、1厘米、2厘米）以及特定地点的沉积物特征（细、中、粗）条件下，以量化它们对发芽率和最大总体发芽量的影响。在澳大利亚南部，这种海草是一种常见的潮下物种；然而，对于影响种子发芽的因素知之甚少，而种子发芽是草甸对自然和人为干扰恢复力的一个潜在限制因素。总体种子发芽率较低（<20%），当种子置于沉积物中时，发芽率降至<10%。当观察到种子发芽时，若种子在20 PSU的盐度脉冲下暴露24小时、保持在25 PSU的盐度、温度<13℃、处于细砂或中砂沉积物中且埋藏深度<1厘米，发芽会得到增强（总体发芽量更大且发芽时间更短）。这些结果表明，在澳大利亚南部，这种条件下种子的发芽可能会受到季节性温度限制。种子发芽可能会因盐度进一步受限，因为通常只有在大规模降雨事件后，菲利普港湾才会观测到达到20 PSU的淡水脉冲。因此，这些种群可能特别容易受到干扰，且恢复能力仅在季节性上有限。
