Midge Additions Increase Arthropod Densities

Authors

  • David Hoekman,

  • Jamin Dreyer,

  • Randall D. Jackson,

  • Philip A. Townsend,

  • Claudio Gratton


Aquatic insects are a common and important subsidy to terrestrial systems. Hoekman et al. simulated lake-to-lake insect deposition in a field experiment in northern Iceland. They hypothesized a positive bottom-up response of detritivores that would be transmitted to their predators and would persist into the following year. Midge addition resulted in significantly different arthropod communities and increased arthropod densities, especially detritivores. By manipulating the nutrient pulse delivered by midges, they were able to elucidate food web consequences of midge deposition and subsequent spatial and temporal dynamics.

Figure Photo 1.

Some of our 1 × 1 midge addition plots near Lake Helluvaðstjörn. The following photos show the process of collecting midges, spreading them on plots, and collecting and processing arthropod samples from each plot. Photograph by Claudio Gratton.

Figure Photo 2.

Collecting midges near Lake Mývatn. Photograph by Jamin Dreyer.

Figure Photo 3.

Spreading dried midge carcasses on an experimental plot at Helluvaðstjörn. Photograph by David Hoekman.

Figure Photo 4.

Vacuum sampling for arthropods in our experimental plots at Helluvaðstjörn. Photograph by David Hoekman.

Figure Photo 5.

Berlese funnels used to extract arthropods from vacuum samples. Photograph by Claudio Gratton.

Figure Photo 6.

Counting arthropods in vacuum samples in alcohol using dissecting microscopes in the lab. Photograph by Bernd Shumacher.

These photographs illustrate the article “Lake to land subsidies: Experimental addition of aquatic insects increases terrestrial arthropod densities” by David Hoekman, Jamin Dreyer, Randall D. Jackson, Philip A. Townsend, and Claudio Gratton, which appeared in Ecology 92:2063–2072, November 2011. doi: http://dx.doi.org/10.1890/11-0160.1

Ancillary