<?xml version="1.0" ?>
<EFGs>
   <EFG code="M1.8" update="2020-05-29" version="v2.0">
      <Realms>
         <Realm>Marine</Realm>
      </Realms>
      <Biome>M1. Marine shelf biome</Biome>
      <Name>M1.8 Subtidal mud plains</Name>
      <Short-name>M1.8 Subtidal mud plains</Short-name>
      <Contributors>
         <contributor>BA Polidoro</contributor>
         <contributor>SE Swearer</contributor>
         <contributor>DA Keith</contributor>
         <map-contributor>DA Keith</map-contributor>
         <map-contributor>JR Ferrer-Paris</map-contributor>
      </Contributors>
      <Short-description>These low energy, muddy ocean shelf ecosystems are moderately productive and typically dominated by microalgal and bacterial primary producers, microbial decomposers, and larger deposit feeders like burrowing polychaete worms and molluscs. Unlike subtidal sand beds (M1.7), the microbial community has a strong influence on biogeochemical cycles. Low oxygen zones can form where concentrations of organic matter and associated high bacterial activity deplete this limited resource.</Short-description>
      <Ecological-traits updated="2020-06-15 11:33:28">The muddy substrates of continental and island shelves support moderately productive ecosystems based on net allochthonous energy sources. In situ primary production is contributed primarily by microphytobenthos, mainly benthic diatoms with green microalgae, as macrophytes are scarce or absent. Both decline with depth as light diminishes. Drift algae can be extensive over muddy sediments, particularly in sheltered waters. Abundant heterotrophic microbes process detritus. The microbial community mediates most of the biogeochemical cycles in muddy sediments, a feature distinguishing these ecosystems from subtidal sand beds (M1.7). Deposit feeders (notably burrowing polychaetes, crustaceans, echinoderms, and molluscs) are important components of the trophic network as the low kinetic energy environment promotes vertical food fluxes, which they are able to exploit more effectively than suspension-feeders. The latter are less abundant on subtidal mud plains than on rocky reefs (M1.6) and Subtidal sand beds (M1.7) where waters are more turbulent and generate stronger lateral food fluxes. Deposit feeders may also constrain the abundance of co-occurring suspension-feeders by disturbing benthic sediment that resettles and smothers their larvae and clogs their filtering structures. Nonetheless, suspension-feeding tube worms may be common over muddy sediments when settlement substrates are available. Although such interference mechanisms may be important, competition is generally weak. In contrast, foraging predators, including demersal fish, may have a major structuring influence on these systems through impacts on the abundance of infauna, particularly on settling larvae and recently settled juveniles, but also adults. Burrowing is a key mechanism of predator avoidance and the associated bioturbation is influential on microhabitat diversity and resource availability within the sediment.</Ecological-traits>
      <Key-ecological-drivers updated="2020-06-15 11:33:28">These depositional systems are characterised by low kinetic energy (weak turbulence and currents), which promotes the accumulation of fine-textured, stable sediments that are best developed on flat bottoms or gentle slopes. The benthic surface is relatively homogeneous, except where structure is engineered by burrowing organisms. The small particle size and poor interchange of interstitial water limit oxygen supply, and anaerobic conditions are especially promoted where abundant in-fall of organic matter supports higher bacterial activity that depletes dissolved oxygen. On the other hand, the stability of muddy substrates makes them more conducive to the establishment of permanent burrows. Bioturbation and bio-irrigation activities by a variety of benthic fauna in muddy substrates are important contributors to marine nutrient and biogeochemical cycling as well as the replenishment of oxygen.</Key-ecological-drivers>
      <Distribution updated="2020-06-15 11:33:28">Globally distributed in the low-energy waters of continental and island shelves.</Distribution>
      <Map code="M1.8.IM.orig" version="v1.0">These are ecosystem functional groups that are widespread through the global extent of the marine shelf biome. Reliable data on their precise distribution are limited. To represent regional uncertainty, their indicative distributions were mapped in as minor occurrences through the full extent of the marine ‘shelf’ base layer as mapped by Harris et al. (2014b). Occurrences were converted to 30 arc second spatial resolution.</Map>
      <References>
         <Reference name="Byers JE, Grabowski JH  2014">Byers JE, Grabowski JH  (2014) Soft-sediment communities Marine community ecology and conservation (Eds. MD Bertness, JF Bruno, BR Silliman, JJ Stachowicz), pp227-249. Sinauer, Sunderland DOI:None</Reference>
         <Reference name="Harris PT et al. 2014">Harris PT, Macmillan-Lawler M, Rupp J, Baker EK  (2014) Geomorphology of the oceans Marine Geology 352: 4-24 DOI:10.1016/j.margeo.2014.01.011</Reference>
         <Reference name="Snelgrove PVR  1999">Snelgrove PVR  (1999) Getting to the bottom of marine biodiversity: sedimentary habitats  Bioscience 49: 129-138 DOI:10.2307/1313538</Reference>
      </References>
   </EFG>
</EFGs>
