Timing is Everything / Dinner is Served

Algae in the Pond, 3/22/21 (Can you spot the fairy shrimp? Click photo to view larger)

Water Plants Beginning to Grow in the Pond, 3/22/21 (Can you find the isopod?  Click photo to view larger)

Every animal has to eat. The two pictures above show a lush aquatic garden in the pond, perfect for algae and plant-eating pond inhabitants. Contrast that though with the picture below taken just four months prior. There is no water, let alone any algae or pond plants. In an ephemeral pond like this, the whole food chain has to be rebuilt almost from scratch every year, and the timing is of course important. Essentially, the aquatic food web has to be reconstructed from the bottom up so that everything present has something to eat when it needs it. 

Detritus, the dead plants and animals and animal waste are the foundation of the temporary pond food web and as you can see in the photo below, dead plant material is ready and waiting for the pond to refill. Algae (which deserves a blog post of its own) grows quickly from spores left from previous years. Many microscopic organisms feed on the detritus or algae and in turn feed filter feeders such as the fairy shrimp and other larger organisms. Aquatic plants are nourished also by the decaying materials found at the bottom of the pond and in turn feed the pond's herbivores.

One of the things that got me thinking about the complexity of the temporary pond's food web is the huge influx of protein that in a sense is coming from outside the system right now. The boreal chorus frogs and spring peepers themselves are not residents of the pond but live in the surrounding prairie and forest. Nevertheless, they come by the hundreds or perhaps thousands early in the spring and contribute heavily to the food sources in the pond by depositing their eggs and soon-to-be tadpoles, which are resident for weeks and become part of the food chain in the pond, feeding on algae and being fed upon by many of the pond's predators. This is a huge boost in the food available and I'm fairly confident that many of the predator species that call the pond home make their appearances timed to take advantage of the bountiful supply of tadpoles that will soon be arriving. With the hundreds of female spring peepers each laying 800 to 1000 eggs and the female boreal chorus frogs each laying perhaps a hundred eggs, there will be enough to ensure future generations, but plenty of them will end up feeding other species along the way. And of course the frogs themselves, while visiting, become fair game in the pond's food chain. There will be other frog species coming to visit in the weeks ahead as well as the resident frogs, who spend much more of their lives in the pond, who have started reproduction now as well (upcoming blog post).

Please see the food chain graphic linked below for a fuller picture of the complexity of this topic. I've barely scratched the surface at best in this post, but expect to explore more of this aspect of the life of the wetland as my observations continue in the days ahead. I cannot though help but be reminded of the psalmist's observation that "These all look to you to give them their food at the proper time."* Timing is everything as the food web is rebuilt every time the pond refills.

Dry Pond Area, 12/26/20

 
For more information on the food web of a temporary pond, these resources were useful to me:

• https://www.researchgate.net/figure/A-generalized-vernal-pool-food-web-Herbivorous-grazer-scrapers-and-filterfeeders-feed-on_fig1_300353610 -- this is a nice graphic showing a generalized food web for a temporary pond. It is much more extensive than my simple examples above.
• https://www.sacsplash.org/critter/detritus -- a very nice page on detritus and the organisms that depend on it in the temporary pond food web, together forming much of the foundation for food supply in a temporary pond

*Psalm 104:27 -- Psalm 104 is a personal favorite.