Beach Biodiversity

Explanation: OK, how many different species can you identify in the above image that covers only about 40 square centimeters (6.2 square inches)? A dozen? Two dozen? The shards of broken shells make it difficult to determine, and some -- probably many -- species are likely buried out of sight below the sand.

Next, how many individual organisms are present in this image?

And how many individual organisms are there, by species?

This is a lesson in metrics of biodiversity -- various ways to measure the diversity of our biotic world -- such as species richness (number of species), population density (total number of individuals), and abundance distribution (numbers of individuals among species).

But moreover, it is a lesson in the scaling of biodiversity.

If this tiny patch of wet sand -- here on the balmy beach of Puerto Peñ asco, northwest Mexico -- can have so many species and individuals, then what does that imply for even tinier scales, say the sub-macroscopic and the microscopic scales of sand flies, sand fleas, bacteria, microalgae, and many other inhabitants of this habitat?

And what if you scale it up and ask the same questions about biodiversity metrics at the macro scale, say, the entire shoreline?

And then what if you did all that, across all those spatial scales, but also across all seasons, or across years, and added it all up?

The point here is that there is no one single measure, and no one single scale, at which "biodiversity" is measured. It is a dynamic feature of nature across various measurements, and across sundry scales of space and time.

And at any scale, it can be wonderfully picturesque.

EPOW - Ecology Picture of the Week