Benthic terrain morphology

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[1][15][16][17]. 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[8][6]. 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[3]. Pits and pockmarks are often indicative of high productivity that is associated with groundwater discharge (e.g. wonky holes[13]). They are biodiversity hotspots for fish and benthic infauna (e.g. filter feeders), providing corridors for mobile fauna e.g. intertidal and subtidal channels[14] and passages, shelf palaeochannels[5], swales between dunes[10], submarine canyons[9], and wonky holes.

The depth of the sea floor can be used to create three-dimensional digital elevation models (e.g. 3D GBR[2]). 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[7]. 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[11].

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

Additional Information

• Project 3DGBRL Great Barrier Reef and Coral Sea Geomorphic Features

References

1. ^ Andutta, FP, Ridd, PV & Wolanski, E (2011), 'Dynamics of hypersaline coastal waters in the Great Barrier Reef', Estuarine, Coastal and Shelf Science, vol. 94, no. 4, pp. 299-305, Elsevier.
2. ^ Beaman, RJ (2010), '3DGBR: A high-resolution depth model for the Great Barrier Reef and Coral Sea', Marine and Tropical Sciences Facility (MTSRF) Project, vol. 2.
3. ^ Benthuysen, JA, Tonin, H, Brinkman, R, Herzfeld, M & Steinberg, C (November 2016), 'Intrusive upwelling in the Central Great Barrier Reef: INTRUSIVE UPWELLING', Journal of Geophysical Research: Oceans. [online], vol. 121, no. 11, pp. 8395-8416. Available at: http://doi.wiley.com/10.1002/2016JC012294 [Accessed 23 July 2019].
4. ^ Bolongaro-Crevenna, A, Torres-Rodríguez, V, Sorani, V, Frame, D & Arturo Ortiz, M (2005), 'Geomorphometric analysis for characterizing landforms in Morelos State, Mexico', Geomorphology, vol. 67, no. 3, pp. 407-422, Elsevier.
5. ^ Courtney, AJ, Spillman, CM, Lemos, R, Thomas, J, Leigh, G & Campbell, A (2015), Physical oceanographic influences on Queensland reef fish and scallops. FRDC Project #2013/020 Final Report, p. 153.
6. ^ Darling, ES, Graham, NAJ, Januchowski-Hartley, FA, Nash, KL, Pratchett, MS & Wilson, SK (June 2017), 'Relationships between structural complexity, coral traits, and reef fish assemblages', Coral Reefs. [online], vol. 36, no. 2, pp. 561-575. Available at: http://link.springer.com/10.1007/s00338-017-1539-z [Accessed 23 July 2019].
7. ^ a b Dove, D, Bradwell, T, Carter, G, Cotterill, C, Gafeira Goncalves, J, Green, S, Krabbendam, M, Mellett, C, Stevenson, A & Stewart, H (2016), Seabed geomorphology: a two-part classification system, British Geological Survey.
8. ^ Graham, NAJ & Nash, KL (2013), 'The importance of structural complexity in coral reef ecosystems', Coral Reefs, vol. 32, no. 2, pp. 315-326, Springer.
9. ^ Huang, Z, Schlacher, TA, Nichol, S, Williams, A, Althaus, F & Kloser, R (December 2018), 'A conceptual surrogacy framework to evaluate the habitat potential of submarine canyons', Progress in Oceanography. [online], vol. 169, pp. 199-213. Available at: https://linkinghub.elsevier.com/retrieve/pii/S0079661117301817 [Accessed 23 July 2019].
10. ^ Improving Fishing Mortality Rate Estimates for Management of the Queensland Saucer Scallop Fishery - Exploratory analyses on the relationship between saucer scallop abundance and bottom substrate (FRDC 2017-048) (2018), James Cook University, Townsville, ed. J D Daniell.
11. ^ International Hydrographic Organisation, Undersea Feature Terms and Definitions. [online] Available at: http://www.kosbidb2.co.kr:8080/recommend/ [Accessed 16 November 2014].
12. ^ a b Lecours, V, Dolan, MFJ, Micallef, A & Lucieer, VL (2016), 'A review of marine geomorphometry, the quantitative study of the seafloor', Hydrology and Earth System Sciences, vol. 20, no. 8, p. 3207, Copernicus GmbH.
13. ^ Mukherjee, S (2015), 'Review of the Role of Remote Sensing for Submarine Groundwater Discharge', New Water Policy and Practice. [online], vol. 2, no. 1. Available at: https://www.researchgate.net/publication/293644200_Review_of_the_Role_of_Remote_Sensing_for_Submarine_Groundwater_Discharge [Accessed 23 July 2019].
14. ^ Nagelkerken, I, Sheaves, M, Baker, R & Connolly, RM (2015), 'The seascape nursery: a novel spatial approach to identify and manage nurseries for coastal marine fauna', Fish and Fisheries, vol. 16, no. 2, pp. 362-371, Wiley Online Library.
15. ^ Wolanski, E & Hamner, WM (8 July 1988), 'Topographically controlled fronts in the ocean and their biological influence', Science (New York, N.Y.), vol. 241, no. 4862, pp. 177-181, United States.
16. ^ Wolanski, E, Asaeda, T, Tanaka, A & Deleersnijder, E (1996), 'Three-dimensional island wakes in the field, laboratory experiments and numerical models', Continental Shelf Research, vol. 16, no. 11, pp. 1437-1452, Elsevier.
17. ^ Wolanski, E (2001), Oceanographic Processes of Coral Reefs. Physical and Biological Links in the Great Barrier Reef, CRC Press, Boca Raton, ed. E Wolanski.

Last updated: 23 July 2019