Sea level change and the area of shallow-marine habitat: implications for marine biodiversity

Analysis of a global elevation database to measure changes in shallow-marine habitat area as a function of sea level reveals an unexpectedly complicated relationship. In contrast to prevailing views, sea level rise does not consistently generate an increase in shelf area, nor does sea level fall consistently reduce shelf area. Different depth-defined habitats on the same margin will experience different changes in area for the same sea level change, and different margins will likewise experience different changes in area for the same sea level change. Simple forward models incorporating a species-area relationship suggest that the diversity response to sea level change will be largely idiosyncratic. The change in habitat area is highly dependent on the starting position of sea level, the amount and direction of sea level change, and the habitat and region in question. Such an idiosyncratic relationship between diversity and sea level reconciles the widespread evidence from the fossil record for a link between diversity and sea level change with the lack of quantitative support for such a relationship throughout the Phanerozoic.

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Changes in area of shallow siliciclastic marine habitat in response to sediment deposition: implications for onshore-offshore paleobiologic patterns

Paleobiology ◽

10.1666/12053 ◽

2013 ◽

Vol 39 (4) ◽

pp. 511-524 ◽

Cited By ~ 8

Author(s):

Steven M. Holland ◽

Max Christie

Keyword(s):

Shallow Water ◽

Sea Level ◽

Sea Level Change ◽

Specific Response ◽

Marine Habitat ◽

Shallow Marine ◽

Marine Area ◽

Level Change ◽

Water Region ◽

Shallow Water Region

Models presented here of shallow-marine siliciclastic deposition show that the widths of depth-defined regions differ markedly in response to sea-level change. These models add to recent studies that have emphasized the highly specific response of habitat area to sea-level change. Collectively, these studies indicate that a particular bathymetric zone on a particular margin may vary substantially in area during a sea-level change, while other such zones and margins may experience little or even opposite responses. In the models presented here, intermediate-depth and deep-water regions tend to show sinusoidal variations in width, with widening during relative falls in sea level and narrowing during relative rises. The shallow-water region displays markedly non-sinusoidal change and is consistently characterized by abrupt widening at the beginning of the highstand systems tract and an equally abrupt narrowing at the onset of sea-level fall at the beginning of the falling-stage systems tract. These onshore-offshore differences in how width and area change with sea level may explain why taxa in shallow-water settings tend to be more abundant, eurytopic, and widespread than those in deeper-water settings. Likewise, these models suggest that the evolution of novelty in nearshore habitats may be a response to wide variation in shallow-marine area during sea-level change.

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