Effects of habitat heterogeneity in seagrass beds on grazing patterns of parrotfishes

Maciá, Silvia; Robinson, Michael

doi:10.3354/meps303113

Cited by 28 publications

(17 citation statements)

References 29 publications

(34 reference statements)

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“…On Lee Reef, St. Ann's Bay (see Maciá & Robinson 2005 for map), we observed highly patchy recovery of urchins. Before the die-off, the density of D. antillarum was 5.9 urchins m -2 at a site 2 km west of Lee Reef (Hughes et al 1985).…”

Section: Introductionmentioning

confidence: 83%

Experimental dispersal of recovering Diadema antillarum increases grazing intensity and reduces macroalgal abundance on a coral reef

Maciá

Robinson²,

Nalevanko³

2007

Mar. Ecol. Prog. Ser.

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The 1983 mass mortality of the sea urchin Diadema antillarum greatly decreased grazing intensity on Caribbean reefs, contributing to widespread increases in algal abundance and exacerbating decreases in coral cover. Urchin populations have been recovering in some areas, most notably the reefs of Jamaica's north coast. We manipulated the density of D. antillarum in the buttress zone of a previously unstudied Jamaican reef where the recovering urchins have a clumped distribution. Some buttresses have a large number of urchins while others nearby have none. We transplanted half of the urchins from high urchin density donor buttresses to low urchin density recipient buttresses. Transplantation significantly decreased the percent cover of macroalgae and increased the amount of bare space. These changes occurred despite a generally low retention of transferred urchins on recipient buttresses. Those urchins remaining on the recipient buttresses aggregated at rugose locations around which algae-free barrens appeared. Transplantation of urchins decreased their local density while maintaining overall density on the reef. The increase in algal consumption after transplantation implies that aggregated urchins compete for algae. Whereas aggregated D. antillarum tend to graze within the same area and have only a localized effect on algae, dispersed urchins compete less and eat more. Increased bare space could enhance recruitment of corals, further improving reef health. Our methods could potentially be used as an inexpensive reef restoration tool. Such restoration projects would be most effective if recipient sites with natural or artificially increased rugosity are used.

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Section: Introductionmentioning

confidence: 83%

Experimental dispersal of recovering Diadema antillarum increases grazing intensity and reduces macroalgal abundance on a coral reef

Maciá

Robinson²,

Nalevanko³

2007

Mar. Ecol. Prog. Ser.

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“…Erosional processes can scour channels through the mats, resulting in the formation of 1-3 m high and up to 500 m long escarpments (Serrano et al, 2016; Figure 1). Previous studies also reported the presence of blowouts in Thalassia testudinum meadows, consisting of bare areas with an eroding edge that forms a vertical wall with overhanging seagrass roots and rhizomes (Patriquin, 1975;Wanless, 1981;Maciá and Robinson, 2005). The mechanisms behind escarpment formation can be related to natural processes (e.g., wave action, tidal flow, and hurricanes) or to anthropogenic activities, such as dredging, vessel groundings, and propeller scars (Whitfield et al, 2002).…”

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confidence: 99%

Seagrass Meadows Provide 3D Habitat for Reef Fish

Serrano

Inostroza³

et al. 2017

Front. Mar. Sci.

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For large fishes, seagrass canopies typically provide a relatively flat habitat on seabeds, but seagrasses in the genus Posidonia can provide additional habitat complexity by forming organic-rich deposits known as mats. Erosional processes can scour channels through the mats, resulting in the formation of escarpments with caves. Here we report that reef fishes, such as groupers, inhabit the caves found within mat escarpments. The characteristics of the cavities are highly variable, ranging from small-elongated holes to deep caves with large entrances. The origin of these caves (biological and/or geological) is unknown, but it is possible that fish behavior enhance their formation. Posidonia seagrass escarpments provide a complex 3D habitat for reef fish that is not provided by typical canopy structure of seagrass. Further studies are required to gain insights into the natural history of seagrass escarpments and their ecological importance.

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“…Gradients in abundance and/or composition of vegetation with increasing distance from refugestermed grazing haloes -have been observed in terrestrial, intertidal and other marine habitats (reviewed by Huntley 1991). Grazing haloes can be readily observed and quantified where changes in vegetation are profound or occur over large (metres to 10s of metres) spatial scales, as is the case for some species of sea urchins (Ogden et al 1973), foraging lagomorphs (McIntire & Hik 2005), parrotfish (Macia & Robinson 2005), prairie dogs (Whicker & Detling 1988) and assemblages of small animals (Bartholomew 1970). In intertidal environments, many molluscan herbivores feed on micro-algae (e.g.…”

Section: Introductionmentioning

confidence: 99%

Unexpected patterns of facilitatory grazing revealed by quantitative imaging

Underwood¹,

Murphy

2008

Mar. Ecol. Prog. Ser.

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Micro-algae (the principal food of intertidal gastropods) were quantified in areas surrounding mid-shore refuges of the intertidal snail Nerita atramentosa to test the hypothesis that removal of important grazers would lead to more micro-algae. Digital colour-infrared imagery provided independent quantitative measurements of amounts of chlorophyll (as an index of amounts of micro-algae) over small areas through time. To determine the effect of grazing on micro-algal abundance, cages were used to exclude animals from refuges. Other refuges were left uncaged or had partial, control cages. Contrary to predictions, amounts of micro-algae in areas close to refuges from which N. atramentosa had been excluded were smaller than in controls, suggesting facilitatory effects of N. atramentosa on micro-algal growth or survivorship. Facilitation may occur because of decreased grazing by the limpet Cellana tramoserica where N. atramentosa (a competitive dominant) are present or to facilitatory effects of N. atramentosa directly on the micro-algae. To unravel complex ecological interactions involving grazing around refuges and the impact of grazing on ecological structure and function it is necessary to make repeated, independent measurements through time. Remote-sensing provided information on distribution of food that would be difficult or impossible to achieve using conventional methods. This research identified complexities and interactions that have implications for the study of grazing effects across many terrestrial, intertidal and marine habitats.

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Effects of habitat heterogeneity in seagrass beds on grazing patterns of parrotfishes

Cited by 28 publications

References 29 publications

Experimental dispersal of recovering Diadema antillarum increases grazing intensity and reduces macroalgal abundance on a coral reef

Experimental dispersal of recovering Diadema antillarum increases grazing intensity and reduces macroalgal abundance on a coral reef

Seagrass Meadows Provide 3D Habitat for Reef Fish

Unexpected patterns of facilitatory grazing revealed by quantitative imaging

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