Bioturbation
[5] This type of ecosystem change affects the evolution of cohabitating species and the environment,[5] which is evident in trace fossils left in marine and terrestrial sediments.
Other bioturbation effects include altering the texture of sediments (diagenesis), bioirrigation, and displacement of microorganisms and non-living particles.
[13] The most common set of groupings are based on sediment transport and are as follows: The evaluation of the ecological role of bioturbators has largely been species-specific.
[8] However, their ability to transport solutes, such as dissolved oxygen, enhance organic matter decomposition and diagenesis, and alter sediment structure has made them important for the survival and colonization by other macrofaunal and microbial communities.
[7] They show evidence of commensal morphological evolution because it is hypothesized that the lack of light in the burrows where the blind gobies reside is responsible for the evolutionary loss of functional eyes.
[37] In polluted sediments, bioturbating animals can mix the surface layer and cause the release of sequestered contaminants into the water column.
In the Baltic Sea, the invasive Marenzelleria species of polychaete worms can burrow to 35-50 centimeters which is deeper than native animals, thereby releasing previously sequestered contaminants.
[4] Small mammals such as pocket gophers also play an important role in the production of soil, possibly with an equal magnitude to abiotic processes.
Due to the high metabolic demands of their burrow-excavating subterranean lifestyle, pocket gophers must consume large amounts of plant material.
In addition, bioturbation increases the water column concentrations of nitrogen and phosphorus-containing organic matter, which can then be consumed by fauna and mineralized.
This activity, combined with chironomid's respiration within their burrows, decrease available oxygen in the sediment and increase the loss of nitrates through enhanced rates of denitrification.
[42] The increased oxygen input to sediments by macroinvertebrate bioirrigation coupled with bioturbation at the sediment-water interface complicates the total flux of phosphorus .
[42] The presence of macroinvertebrates in sediment can initiate bioturbation due to their status as an important food source for benthivorous fish such as carp.
[42] Of the bioturbating, benthivorous fish species, carp in particular are important ecosystem engineers and their foraging and burrowing activities can alter the water quality characteristics of ponds and lakes.
[47] The construction of salmon redds functions to increase the ease of fluid movement (hydraulic conductivity) and porosity of the stream bed.
[46] The net effect on sediment movement is the downstream transfer of gravel, sand and finer materials and enhancement of water mixing within the river substrate.
[47] Numerical modeling suggests that residence time of MDN within a salmon spawning reach is inversely proportional to the amount of redd construction within the river.
[44] The river ecosystem was found to switch from a net autotrophic to heterotrophic system in response to decreased primary production and increased respiration.
Coastal ecosystems, such as estuaries, are generally highly productive, which results in the accumulation of large quantities of detritus (organic waste).
These large quantities, in addition to typically small sediment grain size and dense populations, make bioturbators important in estuarine respiration.
[15] This ability to replenish oxygen and other solutes at sediment depth allows for enhanced respiration by both bioturbators as well as the microbial community, thus altering estuarine elemental cycling.
[53] Bioturbation by walrus feeding is a significant source of sediment and biological community structure and nutrient flux in the Bering Sea.
[1] Bioturbation is important in the deep sea because deep-sea ecosystem functioning depends on the use and recycling of nutrients and organic inputs from the photic zone.
[53][54] In low energy regions (areas with relatively still water), bioturbation is the only force creating heterogeneity in solute concentration and mineral distribution in the sediment.
[2] Bioturbation is thought to have been an important co-factor of the Cambrian Explosion, during which most major animal phyla appeared in the fossil record over a short time.
[2] Predation arose during this time and promoted the development of hard skeletons, for example bristles, spines, and shells, as a form of armored protection.
[2] Prior to the development of bioturbation, laminated microbial mats were the dominant biological structures of the ocean floor and drove much of the ecosystem functions.
[2] As bioturbation increased, burrowing animals disturbed the microbial mat system and created a mixed sediment layer with greater biological and chemical diversity.
[70] Root penetration and uprooting also enhanced soil carbon storage by enabling mineral weathering and the burial of organic matter.
[35][36] Bioturbation's importance for soil processes and geomorphology was first realized by Charles Darwin, who devoted his last scientific book to the subject (The Formation of Vegetable Mould through the Action of Worms).
