Benthic terrain morphology
Benthic terrain morphology is defined as the shape of the sea floor, analogous to the basic shapes that are measured through the process of marine geomorphometry. Other definitions may include a number of other physical substrate attributes in their definition of morphology (e.g. shape, size, texture, various spatial attributes such as sinuosity etc.).
Morphology is one of several attributes contributing to geomorphological descriptors in a terrain typology. Terrain morphs (such as a plane) can also be classified into a typology incorporating the slope attribute e.g. gently sloping plane, steeply sloping plane etc.
Terrain morphology defines the basic three-dimensional shapes that underpin the features of the intertidal area and sea floor. These shapes are recognizable at a range of scales (levels) from the regional (e.g. continental shelf, slope and abyss) through to habitat (e.g. beach ridges, intertidal channels, gutters, holes) and community levels (e.g. rock pools). Morphology of the sea floor directly influences water column energy and subsequent geomorphological (e.g. transport & depositional) processes. The shape of the sea floor and intertidal area interacts with tidal, current and wave energy, creating eddies and currents that swirl above sea floor peaks and upwellings that interact with the continental shelf and slope.
Morphological features (including the underlying matrices formed by dead organisms – see substrate composition and substrate consolidation attributes) can provide the structural complexity that creates many microhabitat types and increases diversity and abundance. Typically peaks and crests on the sea floor are associated with consolidated (reef) substrates, often more biodiverse than featureless areas such as flat planes. Channels and depressions are often high in structural complexity, providing conduits for currents and upwellings. Pits and pockmarks are often indicative of high productivity that is associated with groundwater discharge (e.g. wonky holes). They are biodiversity hotspots for fish and benthic infauna (e.g. filter feeders), providing corridors for mobile fauna e.g. intertidal and subtidal channels and passages, shelf palaeochannels, swales between dunes, submarine canyons, and wonky holes.
The depth of the sea floor can be used to create three-dimensional digital elevation models (e.g. 3D GBR). Using this data and other terrain derivatives as a base, the terrain of the sea floor is broken down into morphological features (morphs), the basic shapes that constitute the landform shape. This process is akin to identifying ‘landform element’ in terrestrial mapping (e.g. soils mapping) as it simplifies 3D shapes into 2D representations suitable for mapping.
The basic shapes above can be applied at each successive scale to inform the pattern of the level below and is informed by elevation relative to the surrounding area. The attribute category table below lists morphs that are topographic highs including: ridges (a linear high), peaks (a high that rises to a single or circular point), and other crests which do not form either a linear or point pattern. Terrain morphs that are topographic lows include: channels (a linear low), pits (a low that descends to a single or circular point) and other depressions that do not form either a linear or point pattern. Planes are uniform in their elevation trend and are neither distinguished as a high or low.
The International Hydrographic Organisation (IHO) lists geomorphological features for navigational purposes but, does not describe the underlying attributes or typology. Applying this attribute, at the regional scale IHO’s term ‘abyssal plain’ is a ‘plane’ morph, combining with the attribute of depth (4000 m) - IHO 2014.
Queensland Intertidal and Subtidal Classification Scheme
Terrain morphology falls under the 'Terrain' theme of attributes for the Intertidal and Subtidal Classification Scheme. It refers to the shape of the landform surface.
Attribute category table - Terrain Morphology
Last updated: 23 July 2019
This page should be cited as:
Department of Environment and Science, Queensland (2019) Benthic terrain morphology, WetlandInfo website, accessed 27 October 2023. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/ecology/aquatic-ecosystems-natural/estuarine-marine/itst/terrain-morph/