{"id":6360,"date":"2026-02-21T00:26:36","date_gmt":"2026-02-21T00:26:36","guid":{"rendered":"http:\/\/versicolor.ca\/barbados\/?page_id=6360"},"modified":"2026-07-07T12:03:59","modified_gmt":"2026-07-07T12:03:59","slug":"coral-rubble-flats","status":"publish","type":"page","link":"https:\/\/versicolor.ca\/barbados\/obssg\/coral-rubble-flats\/","title":{"rendered":"Coral Rubble Flats, Algal & Gorgonian Pavements"},"content":{"rendered":"\n\n\n
NAVIGATION
\nThis page is a sub-page of ObsSG<\/strong><\/a>, a top-level page on
\nthe website Barbados Fringing Reefs and Seagrass
\nBeds<\/strong><\/a> (www.versicolor.ca\/barbados). Go to ObsSG<\/strong><\/a> for a
\nlist of other subpages in this section of the website.<\/small><\/td>\n		SUBPAGES OF THIS PAGE
\n– Bathsheba<\/strong><\/a> (photos)
\n– Martin’s Bay<\/strong><\/a> (photos)
\n– Frog Rock<\/strong><\/a> (photos)
\n– Bath<\/a><\/strong> (photos)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n
\"\"<\/a>

Coral Rubble Flat at Bath.
Click on images for larger versions<\/em><\/p><\/div>\n

ON THIS PAGE
\n1. Coral Rubble Flats at Bath<\/strong><\/a>
\n2. Coral Rubble Flats on the East Coast<\/strong><\/a>
\n3. “Algal Pavement” & “Gorgonian Pavement” at Bath<\/strong><\/a>
\n4. Recent Photos<\/strong><\/a>
\n5. Name equivalents to “Coral Rubble Flats”<\/strong><\/a>
\n6. On the Nature & Binding of “Coral Rubble”<\/strong><\/a>
\n7. A note on “Beackrock”<\/strong><\/a>
\n<\/a><\/p>\n

\n

1. CORAL RUBBLE FLATS AT BATH<\/p>\n

\u201cCoral Rubble Flats\u201d occurred in shallow water areas exposed on the lowest tides at Bath in 1969, and were still present in, superficially at least, the same condition and location in subsequent years up to my last visit to Barbados in 2025. These flats have irregular, hard, surfaces in which the rubble constituents are firmly bound\/cemented together. I remember them in the late 1960s as as sites where the seaweed Gracilaria deblis<\/em> was harvested to make “seamoss jelly” – Mel Goldstein, my PhD co-supervisor (with John Lewis) wrote a paper<\/a> on the topic.<\/p>\n

Seagrasses are absent from the flats except for occasional occurrence of T. testudinum<\/em> in tide pools within the flats, hence\u00a0 the Coral Rubble Flats were not identified as such in the Bath seagrass\u00a0maps of Patriquin (1971, 1975).<\/a><\/p>\n

The approx. areas of Coral Rubble flats and of “Algal Pavement<\/strong>”\u00a0 – likewise not identified as such on the original maps – are inserted as shown below:<\/p>\n

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Map 1.\u00a0 Bathymetry and Seagrass Distribution at Bath<\/strong> (Patriquin, 1971, 1975), with areas of Coral Rubble Flats and Algal Pavement inserted (2026); X is the approx. location of a large colony of Acropora palmata,<\/em> 5 to 7 m diameter, observed in 1994.<\/p><\/div>\n

<\/a><\/p>\n

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Map 2. Distribution of Seagrass Substrate Types\u00a0 at Bath<\/strong> (Patriquin, 1971, 1975), with area of Coral Rubble Flats and Algal Pavement inserted (2026).<\/a><\/p><\/div>\n

<\/a>Coral Rubble Flats similar to those at Bath\u00a0 occur elsewhere on the east coast of Barbados:\u00a0 \u00a0 Lewis (1960) referred to them as “extensive reef flats”:<\/p>\n

Extensive reef flats, 100 to 200 meters wide, front sand beaches and escarpments of the windward coast. These are formed of coral rock. They are covered by about a foot of water at mean low tide and are sometimes exposed along their inner edges at low water spring tides. A heavy cover of attached<\/em> Sargassum sp. is present along the outer edge and the flats are subject to heavy wave action, for at high tide long “rollers” pour over it continuously.<\/em><\/p>\n

A few species of corals are found on the flats. At the inner edge around the bases of holes and tide pools small colonies of<\/em> Porites divaricata, Siderastrea radians, Favia fragum, and<\/em> Porites astreoides occur.<\/em> – from\u00a0 p 1141\u00a0The Coral Reefs and Coral communities of Barbados, W.I<\/a>., by J.B. Lewis in <\/em>Canadian Journal of Zoology\u00a0 38(6): 1133-1145, 7 Plates<\/em><\/a><\/p><\/blockquote>\n

3. “ALGAL PAVEMENT” & “GORGONIAN PAVEMENT” AT BATH<\/p>\n

Beyond the seagrass at Bath and leading out past “The Platform” (Rocks at MLW level and Rocks above HWS in Map 1 above), is hard bottom; it was mapped by Brathwaite & Oxenford (2008, p. 36) who described it\u00a0 as “Algal Pavement”\u00a0 extending in deeper water to “Gorgonian Pavement”.<\/p>\n

The powerful, rolling ocean waves and crashing breakers of the east coast provide a high energy and formidable undersea environment. These waves, coupled with continued re-suspension of eroded clays brought down by rivers from the Scotland District, mean that few corals exist anywhere offshore between Bathsheba and Gay’s Cove. At Cattlewash and Bathsheba huge boulders of Pleistocene limestone, the work of long dead corals, take a battering in the breaker zone. Further south at Bath and Conset, a shallow coastal lagoon is protected on its seaward side by a reef crest made up of coral rock boulders, supporting a few colonies of fire coral, brain corals and an abundance of macroalgae. Beyond this and stretching some distance offshore is an algal and gorgonian pavement.\u00a0 -In\u00a0\u00a0Barbados : a coral paradise by\u00a0<\/strong>Angelique Brathwaite. & Hazel Oxenford\u00a0Ramon Roach Publisher: Miller Publishing Co. Ltd., Barbados, 2008<\/em><\/p><\/blockquote>\n

The Algal Pavement extending in deeper water to the Gorgonian Pavement of Brathwaite & Oxenford (2008) seems to correspond location-wise to benthic habitat classified as “Mixed Reef Hard Ground” by Baldwin et al., (2019):<\/p>\n

Name: Mixed reef hard ground. Code: MRHG.\u00a0 General Description: Usually on flat pavement with sand veneer or rubble. Diverse dense community – usually gorgonian or seafan dominated but other classes (hard coral, sponges, macroalgae) may be equally or almost as dominant. – In\u00a0\u00a0Developing a benthic habitat classification scheme and island-wide map for Barbados based on remote sensing and comprehensive ground-truthing<\/a> by K. Baldwin et al., 2019. CERMES Technical Report No. 94<\/small><\/em><\/p><\/blockquote>\n

Lewis (1960) provides this description”<\/p>\n\n\n\n
Along the outer edge of the flats the water deepens to 8 to 10 ft or drops sharply to about 60 ft. Vertical sides are thus formed which face directly into the prevailing wind. Strong alongshore currents prevail and the water is heavily laden with sediment. Visibility is limited to less than 10 ft during most of the year. The vertical faces are deeply undercut with deep caves penetrating far into the rock and large block and debris falls are found at their bases.<\/p>\n

The most characteristic feature of the zone seaward of the reef flat is the complete absence of branching corals. Furthermore, the massive species I such as Montastrea<\/em>, Siderastrea<\/em>, and Diploria<\/em> do not form rounded heads but are encrusting and flattened.<\/p>\n

At the outer edge of the reef, from depths of 8 or 10 f t to 60 ft, and 011the sides of the vertical walls, the following species occur:
\n\"\"<\/a>Less than 50% of the surface area of the reef rock is covered with living coral. Of the other invertebrate members in the community, Millepora<\/em> forms low, stoutly branching colonies. The sea urchin, Diadema antillarum<\/em>, is conspicuously absent. There are a number of alcyonarians present of which the commonest is the sea fan, Rhipidigorgia flabellum<\/em>. It forms small colonies with a broad base.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

This area of Algal Pavement in Map 1\u00a0 is very turbulent and hard to visit\/examine in detail most of the time. In relation to Lewis’s (1960) description, in 1994 I observed a large colony of Acropora palmata<\/em> on the algal pavement at about 1.5 m depth at Low Water (see “X” in Map 1 above).\u00a0 The area that\u00a0 lies roughly between 0.5 and 1 meter depth (MLW) in Map 1 is where in 1968\/9 I observed many rhodoliths<\/strong><\/a>. Closer to shore, over the outer seagrass bed area (of 1969), detached, healthy appearing sea fans were common in 1968, and more recently..<\/a><\/p>\n

4.\u00a0 PHOTOS
\nOf Coral Rubble Flats & Beach Rock on East Coast of Barbados<\/em><\/p>\n

Photos at Bathsheba, Martin’s Bay & Bath (2025) and Frog Rock (2017)<\/strong><\/p>\n

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Google Earth Map: Regional Setting for Observations on Coral Rubble Flats on the east (windward) coast of Barbados<\/strong> in 2017 (Frog Rock) and 2025 (3 others)<\/p><\/div>\n\n\n\n
\n

\n

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Photo B<\/strong> 2025 #782. Beach Rock at Bathsheba Mar 21, 2025.<\/strong>, View\u00a0 \u00a0More Pics<\/a><\/strong><\/p><\/div><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n
\n

\n

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Photo D<\/strong> 2025 #119 Coral Rubble Flats at Bath, Mar 2, 2025.<\/strong>\u00a0View More Pics<\/a><\/strong><\/a><\/p><\/div><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Photo E<\/strong> 2017 #207\u00a0Coral Rubble Flats at Frog Rock, Mar 17, 2017. <\/strong>View More Pics<\/strong><\/a><\/p><\/div>\n

5. NAME EQUIVALENTS TO “CORAL RUBBLE FLATS”<\/p>\n

– “Extensive Reef Flats<\/strong>”
\nLewis (1960) as. quoted above<\/a>.<\/p>\n

– “Intertidal Reefs – Rock Platforms”<\/strong>
\nAs described in\u00a0Marine Assets of Yorke Peninsula. Volume 2 of report for Natural Resources – Northern and Yorke, South Australia<\/a>\u00a0by J.L. Baker,\u00a0 2015.\u00a0“Common forms in the NY NRM region include rock platforms, boulder and cobble fields, and pebble shores. Some of the rock platforms are heavily dissected and contain abundant rock pools, or channels and crevices between the rock slabs. There are many micro-habitats on and in intertidal reefs, such as under ledges \/ overhangs, in rock pools, in crevices, and underneath rock slabs and cobble.”<\/small><\/p>\n

– “Intertidal Reef Flats”<\/strong> e.g.,
\nAs described in\u00a0Extreme Corals: Resilience in the world of intertidal reef flats<\/a><\/strong> by Louise Anderson in Reef Bites Apr 16, 2018 “Coral reef ecologists are generally envisaged working on the classically beautiful, tropical reefs of the kind portrayed in Blue Planet II. Less well-known is that there is also ample opportunity to paddle around in the strange, diverse world of intertidal coral reef flats. The Thai island of Phuket is home to several excellent examples of this kind of habitat. These sites completely changed my own perception of coral reefs, and the remarkably hardy corals that live in this environment are particularly exciting to reef scientists because of their ability to thrive under such challenging conditions.”<\/small>
\n& As described in\u00a0Community structure and dietary pathways for invertebrates on intertidal coral reef flats<\/a> by JP Davis et al., 2015 in Food Webs.<\/em>\u00a0Refs removed: “Intertidal reef flats are undervalued habitats relative to their area and distribution on coral reefs, especially given the food sources they provide for both humans and fishes. These habitats are different from other reef zones because reef flat animals are more exposed tophysiological stresses from the extremes of tidal exposure, temperature changes and high turbidity than on subtidal reef flats or reef crests.”<\/a><\/small><\/p>\n

6. ON THE NATURE AND BINDING OF “CORAL RUBBLE”<\/p>\n\n\n\n
– Holocene coral reef rubble and its binding agents<\/a><\/strong> (PDF)
\nM.W. Rasser \u00c6 B. Riegl. 2002 In Coral Reefs<\/em> 21:57\u201372Abstract [Paragraphing and bolding inserted]A literature review regarding reef rubble (defined as mechanically or chemically abraded parts of frame builders or reef rock larger than sand fraction)<\/strong> and its binding agents<\/strong> is presented.Rubble is produced by natural and man-made events such as storms, wave agitation, earthquakes, bioerosion, ship groundings, and dynamite fisheries. The regeneration of reefs after rubble-forming processes requires rigid rubble binding, which is always preceded by preliminary stabilization.Preliminary stabilization<\/strong> can be achieved by a decline in hydrodynamic energy, interlocking of components, seagrass, and overgrowth by sponges or algae.Rigid binding is primarily achieved by diagenetic cementation<\/strong>. The literature indicates that binding by coralline algae or other organisms (corals, worms, bryozoans) is only of subordinate importance.Highest rates of rigid rubble binding are known from fore-reef areas with low sloping angles above fair-weather wave base; rigid rubble binding is particularly rare in deeper fore-reef environments and not described from the reef crest.<\/strong>Rigid binding by diagenetic cementation is generally known from inter- and supra-tidal near-shore ramparts<\/strong> as well as back-reef, reef-flat, and shallow fore-reef rubble accumulations, while coralline algae rigidly bind rubble only in very shallow fore-reef environments.\u00a0<\/strong>Rubble binding does not appear to be easily achieved<\/strong> and fewer reports of bound rubble were found than of loose rubble.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n
On Binding<\/strong>
\n– Coral rubble dynamics in the Anthropocene and implications for reef recovery<\/strong><\/a>, T.M.Kenyon et al. 2023 in Limnology & Oceanography. <\/em>References were removed in the extract below.
\nRubble binding\u00a0\u00a0<\/em><\/strong>
\nIn describing rubble binding processes, we consider rubble that is \u201cstabilized<\/strong>\u201d to be not moving, but not necessarily bound. Loose rubble can be stabilized, for example, by being transported into a sheltered, low-energy environment, such as a depression, or by becoming interlocked with other rubble pieces.Under certain conditions, stabilized rubble can become bound<\/strong> and provide a stable substrate for coral recruitment.Rubble binding can be caused by:
\n(1) biogenic binding<\/strong> by soft organisms that produce flexible binds, or by more rigidly-binding calcifying organisms; and\/or
\n(2) cementation<\/strong>, the physically or biologically induced precipitation of calcium carbonate (CaCO3) from seawater to form inter- and intra-skeletal cements.Thus, we use the term \u201cbound\u201d to describe rubble that is connected to other rubble by a binding organism,<\/strong> but binds bridging between rubble pieces may be flexible<\/strong> (e.g., macroalgae, sponges), while the terms \u201cconsolidated\u201d<\/strong> and \u201ccemented\u201d<\/strong> are used to describe a subset of bound rubble where (1) the binder is calcifying, producing inflexible binds that remain after binder mortality (e.g., crustose coralline algae\u2014CCA, coral), and (2) where binds are formed through cementation processes, respectively.Binding processes are important precursors to the lithification*<\/strong> of rubble to reef rock, although we have a limited understanding of the succession of binding organisms (including competitive interactions), effective binding rates and strengths, particularly because soft binding organisms are not well preserved in the geological record.
\n*See Encyclopedia Brittania definition of Lithification<\/a><\/strong>.” lithification, complex process whereby freshly deposited loose grains of sediment are converted into rock. Lithification may occur at the time a sediment is deposited or later. Cementation is one of the main processes involved, particularly for sandstones and conglomerates. In addition, reactions take place within a sediment between various minerals and between minerals and the fluids trapped in the pores…”<\/a><\/small><\/p>\n
\n

Syn-depositional alteration of coral reef framework through bioerosion, encrustation and cementation: Taphonomic signatures of reef accretion and reef depositional events<\/strong><\/a>
\nC.T. Perry and L.J. Hepburn, 2008 in Earth-Science Reviews <\/em>. “The development of coral reef framework and the preservational character of both in-situ and rubble coral is strongly influenced by a range of physical, chemical and biologically-mediated taphonomic processes. These operate at, or just below, the reef framework\u2013water interface and can be defined as having either a constructive or destructive effect upon primary reef framework (i.e., coral) constituents. Constructional activities<\/strong> add additional calcium carbonate<\/a> to the primary framework structure via secondary framework growth and early cementation<\/a>. Destructive processes,<\/strong> which remove or degrade primary (and secondary) framework carbonate, are associated with the effects of either physical (mainly storm) disturbance or biological erosion (termed bioerosion<\/a>). Key bioeroding groups<\/strong> include the grazing fish and echinoid groups, as well as the activities of an array of infaunal borers. These include specific groups of sponges, bivalves and worms (termed macroborers), as well as cyanobacteria, chlorophytes, rhodophytes and fungi (termed microborers). The relative importance of each process and the rates at which they operate vary spatially across individual reef systems. In addition, many of these processes leave distinctive signatures on, or in, the coral framework<\/strong>. In some cases (e.g., calcareous encrusters) these are the skeletons of the organisms themselves, whilst in other cases the organism may leave behind a trace of their activity (e.g., macro- and microborers). These represent useful palaeoenvironmental tools, firstly because they often have good preservation potential and, secondly because the range and extent of many of the individual species, groups and processes involved exhibit reasonably well-constrained environment and\/or depth-related distributions. As a result these taphonomically important organisms or processes can be used to delineate between reef environments in core or outcrop, and to aid the interpretation of reef depositional processes<\/a> and \u2018events\u2019. This review summarises current understanding regarding the distribution of these species\/processes within contemporary reef settings and considers the suites of taphonomic signatures that may aid in the recognition and interpretation of depositional environments<\/a> and events.”<\/small><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

7. A NOTE ON “BEACHROCK”
\n“Beachrock”, found on beaches around Barbados is quite distinct from Coral Rubble Flats.<\/p>\n\n\n\n
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Figure B49 <\/strong>[screencapture]\u00a0“Multiple unit beachrock exposure at barrio Rio Grande de Aguada, Puerto Rico. The sculpted morphology, development of a nearly vertical landward edge, and dark staining of outer surface by cyanobacteria indicate that this beachrock has experience extended exposure. Landward relief and imbricate morphology of beachrock units define shore- parallel runnels that impound seawater (photo R. Turner).”<\/p><\/div>From Turner, RJ. 2005. <\/a>Beachrock<\/a>, in Schwartz, ML, ed., Encyclopedia of Coastal Science. Kluwer Academic Publishers, The Netherlands. Pp. 183-186.
\nFormation and Distribution of Beachrock \u00a0<\/strong>[bolding inserted below]<\/a>
\nBeachrock is defined<\/strong> by Scoffin and Stoddart (1987, 401) as “the consolidated deposit that results from lithification by calcium carbonate of sediment in the intertidal and spray zones of mainly tropical coasts.”<\/strong> <\/a>Beachrock units form under a thin cover of sediment and generally overlie unconsolidated sand<\/strong>, although they may rest on any type of foundation.<\/a> Maximum rates of subsurface beachrock cementation are thought to occur in the area of the beach that experiences the most wetting and<\/em> drying<\/strong> – below the foreshore in the area of water table excursion between the neap low and high tide levels (Amieux et al, 1989; Higgins, 1994). Figure B49 shows a beachrock formation displaying typical attributes…<\/a>Rates of beachrock formation<\/strong> are undoubtedly variable but are generally believed to be quite rapid,<\/strong> on the scale of months to years (Frankel, 1968). For example, Hopley (1986) reported that beachrock formed within six months on Magnetic Island near Townsville, Australia, while Moresby (1835) wrote that Indian Ocean natives made an annual harvest of beachrock for building stone and within a year they had a new lithified crop.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Page drafted Feb 21, 2026
\nPage “published” with related post Mar 4, 2026
\nUpdate (added Frog Rock) Mar 6, 2026<\/small><\/p>\n","protected":false},"excerpt":{"rendered":"

NAVIGATION This page is a sub-page of ObsSG, a top-level page on the website Barbados Fringing Reefs and Seagrass Beds (www.versicolor.ca\/barbados). Go to ObsSG for a list of other subpages in this section of the website. SUBPAGES OF THIS PAGE … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":5266,"menu_order":10,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-6360","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/pages\/6360","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/comments?post=6360"}],"version-history":[{"count":160,"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/pages\/6360\/revisions"}],"predecessor-version":[{"id":8837,"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/pages\/6360\/revisions\/8837"}],"up":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/pages\/5266"}],"wp:attachment":[{"href":"https:\/\/versicolor.ca\/barbados\/wp-json\/wp\/v2\/media?parent=6360"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}