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Organisms and their environment, including other

Ecology investigates: colonization Resource and distribution Succession Reproduction and development Production

6CO2 + 6H20  C6H1206 + 6O2

Decomposition

C6H1206 + 6O2  6CO2 + 6H20

Energy = carbon (C) Ultimately measured in kilocalories/calories Nutrients = (N) (P) (K) (Mg) Several other elements and compounds

zymogenous Acquires energy through autochthonous Acquires energy through Plants, algae eating

Humans, mammals, birds, , fungi, , etc. Can be viewed from two perspectives: 1. Taxonomy: what is doing the decomposing? 2. : what processes are taking place? Most decomposition is biologically mediated (minimum 80%)

Microorganisms (bacteria, fungi) Insects (, beetles)

Catalysis—enzymatic and chemical reactions transforming complex to simple. Comminution—physical breakdown of resource. Leaching—soluble material moved by Resource Quality

Decomposer Physicochemical environment

Physicochemical Environment

Four primary modulators of decomposition: Moisture Aeration (, ) pH A high quality carbon:nitrogen resource Wood 145:1 Straw 100:1 An ephemeral Leaf litter 50:1 resource Manure 25:1 patch/ A source of water A for

Stages of Decomposition In reality: 1. Fresh Stages do not exist 2. Bloated Stage 3. Active Decay characteristics can 4. Advanced Decay blend from one stage into another 5. Stages provide a convenient means for taphonomists to assess decomposition • starts: abiotic breakdown of cells and tissues • Associated with start of mortis triad • Little release of fluids and disturbance of surroundings • Flies first colonize: looking for place to lay eggs. • If too cold: microbes and scavengers dominate • If outside: and surface covered. The mortis triad

Algor mortis—body temperature changes to ambient temperature —temporary stiffening of the joints —settling and pooling of ; blood will become “fixed” after a period of time. Gunn (2009) Gunn (2009) Fresh Stage (biological changes) Initial colonization (response to chemical disturbance, i.e. presence of corpse) Release of , sulphuric , carbon dioxide, nitrogen Increased microbial activity (response to physical disturbance) Initial shift in bacterial and fungal community structure (response to physical disturbance) Fresh Stage (chemical changes)

• Increase in Increase in gravesoil atmospheric + • ammonium (NH4 ) • carbon dioxide - • nitrate (NO3 ) (CO ) 2 • phosphorus (P) • (CH ) 4 • soil pH •

(H2S)

• nitrogen (N2)

• ammonia (NH3) Bloat Stage Decomposition

• Enteric microbial community produces gases () • Purge fluids released from orifices: mouth, nose, anus, etc. • Buildup of gas can cause rupturing, fluids released from ruptures in skin. • larvae () are active Gunn (2009) Bloated (biological changes)

Maggot activity

Elevated microbial activity (CO2 respiration) Shift in bacterial community structure Bloated (chemical changes) Increased in gravesoil: ammonium chloride fatty (butyric, propionic, valeric) magnesium organic N, ammonium, nitrate phosphorus potassium sodium sulphate Active Decay

activity at its peak • Increased release of fluids • Increased marbling, slippage of skin • Exposure of internal organs

Active Decay (biological changes)

Peak insect activity of associated vegetation (not sure why) Elevated microbial activity Shift in bacterial community structure Active Decay (chemical changes) Same elevated concentrations as observed in the bloated stage. Increased: phosphorus activity Protease activity Phosphodiesterase activity Total nitrogen Total phosphorus Advanced Decay (biological changes)

Maggots have migrated. Corpse comprises skin, organs, hair and . Declining microbial and activity, but still greater than non-gravesoil. Fruiting of postputrefaction fungi. Shift in bacterial community structure. Advanced Decay (chemical changes) Same as observed during bloated and active decay.

Postputrefaction Skeleton Stage Decomposition • Can persist from weeks to millenia • Materials present: bone, teeth, hair, dried skin

Gunn (2009) Gunn (2009) Time

Advanced Fresh Bloated Active Decay Skeleton Decay

•Declining •Increased •Initial microbial microbial disturbance •Increased •Increased activity and activity, •Increased microbial microbial biomass biomass microbial activity, activity •early phase •Succession of Gravesoil activity biomass •Shift in postputrefactio fungi from early •Shift in •Shift in Biology bacterial n fungi phase to late bacterial and bacterial community •Shift in phase fungal community structure bacterial •Shift in community structure community bacterial structure structure community

•Increased ammonium, butyric acid, •See Bloated calcium, •See Bloated •Increased •Increased chloride, •Increased lipid ammonium, •Initial amino acids, magnesium, phosphorus, electrical disturbance nitrate, ninhydrin- protease conductivity, •Increased ninhydrin- Gravesoil reactive N, activity, ninhydrin- ammonium, reactive nitrate, phosphodiester reactive Chemistry carbon dioxide, nitrogen, total potassium, ase activity, nitrogen, lipid nitrate, nitrogen, total phosphate, total nitrogen, phosphorus, phosphate phosphorus , total total nitrogen, •Decreased pH sodium, phosphorus total sulphate, phosphorus valeric acid •Increased pH Gunn A (2009) Essential Forensic Biology. Wiley- Blackwell.

Hopkins DW (2008) The role of soil organisms in terrestrial decomposition. In: Tibbett M, Carter DO; Soil Analysis in Forensic Taphonomy. CRC Press: 53-66.