thumbnail

The role of larval chironomidae in the production of lacustrine copropel in Mud Lake, Marion County, Florida

Limnology and Oceanography
By:  and 

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time
  • Download citation as: RIS | Dublin Core

Abstract

Mud Lake is a shallow (avg 45 cm), alkaline (pH 7.7–10.2), brown‐water lake having an area of about 180 ha. A study of its organic sediment was undertaken because it appears to be a present‐day analogue of the richly organic lacustrine oozes that were the precursors of the oil shales of the Green River Formation (Eocene). The water contains about 200 ppm total dissolved solids. The soft ooze is about 1 m thick and consists of minute fecal pellets produced primarily by larvae of Chironomus (Chironomus) sp. Mean numbers of larvae ranged from 120 to 580 m−2; such a small population may reflect extensive predation by fish. The small diversity of Chironomidae at this latitude may reflect the fact that few organisms can tolerate the physical conditions produced by the shallow water.

Experiments with laboratory‐reared Mud Lake midges showed that the numbers of fecal pellets produced generally increased with the concentration of algal cells available; that only when the larvae were fed blue‐green algae were the fecal pellets coherent and durable—larvae fed green algae produced pellets that disintegrated, returning the undigested algae to the food supply; and that larvae fed blue‐green algae changed from filter‐feeding to grazing on the fecal pellets when suspended algal cells became sparse. We conclude that the sediment in Mud Lake is pelletal because only blue‐green algae are available for food and that the larvae probably graze because all the blue‐greens live only on, or in, the fecal pellets. Early instars produce ovoid pellets; later instars produce longer, cylindrical pellets.

The analogy between the Mud Lake pelletal ooze and the Eocene precursors of the Green River Formation oil shale is enhanced by the facts that some oil shale thin sections show minute fecal pellets and that certain beds of rich oil shale contain numerous unmineralized remains of immature chironomids.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The role of larval chironomidae in the production of lacustrine copropel in Mud Lake, Marion County, Florida
Series title Limnology and Oceanography
Volume 14
Issue 6
Year Published 1969
Language English
Publisher Association for the Sciences of Limnology and Oceanography
Description 8 p.
First page 989
Last page 905
Country United States
State Florida
County Marion County
Other Geospatial Mud Lake
Google Analytic Metrics Metrics page
Additional publication details