Data from: Chasing windows of opportunity for habitat formation: spatial and temporal determinants of oyster settlement rates

The establishment and recovery of biogenic habitats in marine and
terrestrial environments often rely on the co-occurrence of periods of
suitable environmental conditions and propagule availability (e.g., seeds,
larvae). However, despite the importance of these ‘windows of opportunity’
for species colonization, the temporal and spatial variability of these
periods across environmental gradients remains poorly understood. Eastern
Australian estuaries transit between periods of floods and droughts, which
strongly affect their salinity regimes. Here, we investigate how
variations in salinity and temperature influence the frequency and
duration of windows of opportunity for settlement and survival of
reef-building oyster Saccostrea glomerata across an estuarine salinity
gradient in eastern Australia. Oyster settlement probabilities were
calculated using empirical data from a 2-year settlement study performed
at 3 estuarine sites along a salinity gradient. Time series of salinity
and temperature from 2010 to 2024 were analysed for windows of opportunity
for oyster settlement, defined as periods in which the probability of
oyster settlement was equal to or higher than 0.25. Oyster habitat cover
was measured at seven intertidal sites along the estuarine salinity to
assess how differential settlement patterns and ‘windows of opportunity’
shape oyster habitat formation. We found that in eastern Australia, the
windows of opportunity for oyster settlement occur during the warmer
months and are more frequent and of longer duration at downstream
(seaward) portions of estuaries, where salinity is higher due to greater
oceanic influence. We also found that, although oysters can settle and
survive at upstream locations, oyster habitat cover decreases from
downstream to upstream locations along the estuarine salinity gradient,
reflecting fewer and shorter windows of opportunity for settlement.
Temporal fluctuations in salinity and temperature are critical in
determining when and where oyster settlement will occur within estuarine
salinity gradients. Consequently, to maximise the chances of ecological
restoration success, oyster reef restoration projects should focus on not
only prioritizing areas for restoration that have a higher likelihood of
species establishment, but also timing restoration activities to occur
during periods of suitable environmental conditions.

海洋与陆地环境中生物成因生境（biogenic habitats）的建立与恢复，往往依赖于适宜环境条件时段与繁殖体（propagule，如种子、幼体）的同步出现。然而，尽管这些‘机会窗口（windows of opportunity）’对于物种定植至关重要，但跨环境梯度的此类时段的时空变异性仍未得到充分认知。澳大利亚东部河口会在洪水期与干旱期交替，这会显著影响其盐度格局。本研究聚焦澳大利亚东部河口盐度梯度下，盐度与温度变化如何影响造礁牡蛎（Saccostrea glomerata）定植与存活的机会窗口的频率与持续时长。研究依托沿盐度梯度布设的3个河口站点开展的2年定植监测试验的实测数据，计算牡蛎定植概率；并分析2010-2024年的盐度与温度时间序列，以识别牡蛎定植的机会窗口——即牡蛎定植概率大于等于0.25的时段。此外，本研究沿河口盐度梯度布设7个潮间带站点测定牡蛎生境覆盖度，以评估差异化定植模式与机会窗口如何塑造牡蛎生境的形成。研究结果显示，在澳大利亚东部，牡蛎定植的机会窗口多出现在暖季，且在河口下游（向海侧）站点更为频繁、持续时长更长——该区域受海洋影响更强，盐度更高。同时发现，尽管牡蛎可在河口上游区域定植并存活，但沿盐度梯度从下游到上游，牡蛎生境覆盖度逐渐降低，这反映出该区域的定植机会窗口更少、持续时长更短。盐度与温度的时间波动，是决定河口盐度梯度内牡蛎定植发生时间与地点的关键因素。因此，为最大化生态修复成功的概率，牡蛎礁修复项目不仅应优先选择更有利于物种定植的区域开展修复，还应将修复活动的时间安排在适宜的环境条件时段内。