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How did changing sea levels affect bottom-dwelling Silurian animals?

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Silurian paleogeography — Silurian Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the middle part of the Silurian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Throughout the Silurian Period, global sea levels experienced recurring fluctuations of 30 to 50 meters. Unlike the more severe impacts seen during the preceding Ordovician-Silurian extinction, these later Silurian changes did not drastically alter the amount of available habitat or cause widespread disruption to bottom-dwelling (benthic) invertebrates.12

Instead, these animals demonstrated resilience by adapting to their changing environments through simple migration. As sea levels rose and fell, benthic faunas maintained their preferred living conditions by shifting their populations upslope or downslope along bathymetric gradients. This behavior allowed communities to remain within their established ecological zones, which were defined by specific levels of light, temperature, and wave energy.31

While some local changes in seafloor depth were driven by tectonic activity or volcanism, the broader, global cycles of sea level change were likely linked to the expansion and contraction of the Gondwanan ice cap.1