PDF(Pubmed)
Abstract：
OBJECTIVE: Kelp forests underpin temperate marine ecosystems but are declining due to ocean warming, causing loss of associated ecosystem services. Projections suggest significant future decline but often only consider the persistence of adult sporophytes. Kelps have a biphasic life cycle, and the haploid gametophyte can be more thermally tolerant than the sporophyte. Therefore, projections may be altered when considering the thermal tolerance of gametophytes.
METHODS: We undertook thermal tolerance experiments to quantify the effect of temperature on gametophyte survival, relative growth rate (RGR) and sex ratio for three genetically distinct populations of Ecklonia radiata gametophytes from comparatively high, mid- and low latitudes (43°, 33° and 30°S). We then used these data to project the likely consequences of climate-induced thermal change on gametophyte persistence and performance across its eastern Australian range, using generalized additive and linear models.
RESULTS: All populations were adapted to local temperatures and their thermal maximum was 2-3 °C above current maximum in situ temperatures. The lowest latitude population was most thermally tolerant (~70 % survival up to 27 °C), while survival and RGR decreased beyond 25.5 and 20.5 °C for the mid- and low-latitude populations, respectively. Sex ratios were skewed towards females with increased temperature in the low- and high-latitude populations. Spatially explicit model projections under future ocean warming (2050-centred) revealed a minimal decline in survival (0-30 %) across populations, relative to present-day predictions. RGRs were also projected to decline minimally (0-2 % d-1).
CONCLUSIONS: Our results contrast with projections for the sporophyte stage of E. radiata, which suggest a 257-km range contraction concurrent with loss of the low-latitude population by 2100. Thermal adaptation in E. radiata gametophytes suggests this life stage is likely resilient to future ocean warming and is unlikely to be a bottleneck for the future persistence of kelp.
METHODS: We undertook thermal tolerance experiments to quantify the effect of temperature on gametophyte survival, relative growth rate (RGR) and sex ratio for three genetically distinct populations of Ecklonia radiata gametophytes from comparatively high, mid- and low latitudes (43°, 33° and 30°S). We then used these data to project the likely consequences of climate-induced thermal change on gametophyte persistence and performance across its eastern Australian range, using generalized additive and linear models.
RESULTS: All populations were adapted to local temperatures and their thermal maximum was 2-3 °C above current maximum in situ temperatures. The lowest latitude population was most thermally tolerant (~70 % survival up to 27 °C), while survival and RGR decreased beyond 25.5 and 20.5 °C for the mid- and low-latitude populations, respectively. Sex ratios were skewed towards females with increased temperature in the low- and high-latitude populations. Spatially explicit model projections under future ocean warming (2050-centred) revealed a minimal decline in survival (0-30 %) across populations, relative to present-day predictions. RGRs were also projected to decline minimally (0-2 % d-1).
CONCLUSIONS: Our results contrast with projections for the sporophyte stage of E. radiata, which suggest a 257-km range contraction concurrent with loss of the low-latitude population by 2100. Thermal adaptation in E. radiata gametophytes suggests this life stage is likely resilient to future ocean warming and is unlikely to be a bottleneck for the future persistence of kelp.
摘要：
目标：海带森林支撑着温带海洋生态系统，但由于海洋变暖，造成相关生态系统服务的损失。预测表明未来会出现显着下降，但通常只考虑成年孢子体的持久性。海带有一个双相的生命周期,单倍体配子体可以比孢子体更耐热。因此,当考虑配子体的耐热性时，投影可能会改变。
方法：我们进行了耐热性实验，以量化温度对配子体存活的影响，来自相对较高的三个遗传上不同的Eckloniaradiata配子体种群的相对增长率（RGR）和性别比，中低纬度（43°，33°和30°S)。然后，我们使用这些数据来预测气候引起的热变化对整个澳大利亚东部地区的配子体持久性和性能的可能后果，使用广义加法和线性模型。关键结果所有种群均适应当地温度，其最大热温度比当前最大原位温度高2-3°C。最低纬度人群的耐热性最高（最高可达27°C的存活率约为70％），尽管中低纬度人群的存活率和RGR下降超过25.5°C和20.5°C，分别。在低纬度和高纬度人群中，随着温度的升高，性别比向女性倾斜。未来海洋变暖（以2050为中心）下的空间明确模型预测显示，种群的存活率下降幅度最小（0-30％），相对于目前的预测。RGRs也预计最低限度下降(0-2%d-1)。结论：我们的结果与辐射大肠杆菌孢子体阶段的预测相反，这表明到2100年，257公里范围的收缩与低纬度人口的减少同时发生。E.radiata配子体的热适应表明，这个生命阶段可能对未来的海洋变暖具有弹性，并且不太可能成为海带未来持久性的瓶颈。
方法：我们进行了耐热性实验，以量化温度对配子体存活的影响，来自相对较高的三个遗传上不同的Eckloniaradiata配子体种群的相对增长率（RGR）和性别比，中低纬度（43°，33°和30°S)。然后，我们使用这些数据来预测气候引起的热变化对整个澳大利亚东部地区的配子体持久性和性能的可能后果，使用广义加法和线性模型。关键结果所有种群均适应当地温度，其最大热温度比当前最大原位温度高2-3°C。最低纬度人群的耐热性最高（最高可达27°C的存活率约为70％），尽管中低纬度人群的存活率和RGR下降超过25.5°C和20.5°C，分别。在低纬度和高纬度人群中，随着温度的升高，性别比向女性倾斜。未来海洋变暖（以2050为中心）下的空间明确模型预测显示，种群的存活率下降幅度最小（0-30％），相对于目前的预测。RGRs也预计最低限度下降(0-2%d-1)。结论：我们的结果与辐射大肠杆菌孢子体阶段的预测相反，这表明到2100年，257公里范围的收缩与低纬度人口的减少同时发生。E.radiata配子体的热适应表明，这个生命阶段可能对未来的海洋变暖具有弹性，并且不太可能成为海带未来持久性的瓶颈。
