Differences in top-down and bottom-up regulation of macroalgal communities between a reef crest and back reef habitat in Zanzibar

Sjöö, Gustaf Lilliesköld; Mörk, Erik; Melander, Inger

doi:10.1016/j.ecss.2010.12.003

Cited by 10 publications

(2 citation statements)

References 52 publications

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“…Water motion directly dictates algal growth and composition by imposing physical stress (D'Amours & Scheibling 2007) and varying nutrient delivery depending on the hydrodynamic forces acting on the area (Hurd 2000, Thomas & Cornelisen 2003. For example, studies have shown that even when nutrient delivery is greatest at a reef crest, macroalgal growth is minimal due to wave action (Hurd 2000, Lilliesköld Sjöö et al 2011). The physical structure (i.e.…”

Section: Introductionmentioning

confidence: 99%

Macroalgal biomass, growth rates, and diversity are influenced by submarine groundwater discharge and local hydrodynamics in tropical reefs

Valle¹,

Thomas²,

Nelson³

2019

Mar. Ecol. Prog. Ser.

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It is critical to evaluate the in situ effects of multiple stressors on coastal community dynamics, especially those communities harboring high diversity such as coral reefs, in order to understand the resilience of these ecosystems, prepare coastal management for future scenarios, and aid in prioritizing restoration efforts. In this in situ study, at 2 sites with gradients of submarine groundwater discharge (SGD), a suite of physical parameters (wave exposure index, wind exposure index, and depth) and an all-encompassing SGD chemical parameter (average nitrate + nitrite daily load) were measured along spatially cohesive and temporally relevant scales and used to model macroalgal growth, biomass, and diversity in Maunalua Bay, Hawai'i. We showed that (1) speciesspecific macroalgal biomass is significantly related to SGD and one of the 2 exposure indices (i.e. wind exposure or wave exposure), (2) SGD and wave exposure play key roles in species-specific growth rates, and (3) SGD supports low diversity and increased biomass of species that can tolerate the biogeochemistry associated with SGD. Our work suggests that SGD and local hydrodynamics predict local variation in macroalgal growth, biomass, and diversity in tropical reefs.

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Section: Introductionmentioning

confidence: 99%

Macroalgal biomass, growth rates, and diversity are influenced by submarine groundwater discharge and local hydrodynamics in tropical reefs

Valle¹,

Thomas²,

Nelson³

2019

Mar. Ecol. Prog. Ser.

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“…Such information is likely to become increasingly important for management of reefs, especially in the Caribbean, as D. antillarum recovers and potentially becomes the dominant grazer (Idjadi et al 2010). While several studies have looked at the combined and differential effects of grazers on (1) removal of algae (McClanahan 1997), (2) benthic composition of reefs , Sjöö et al 2011, and (3) erosion of reefs (Peyrot-Clausade et al 2000, Carreiro-Silva & McClanahan 2001, few empirical investigations have distinguished between the effects of fish and sea urchin grazing on early coral recruitment (Mapstone et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Fish and sea urchin grazing opens settlement space equally but urchins reduce survival of coral recruits

O’Leary¹,

Potts²,

Schoenrock³

et al. 2013

Mar. Ecol. Prog. Ser.

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Grazing fishes and invertebrates are influential in marine ecosystems because they open space for benthic recruits, alter post-settlement recruit survival, and can often determine benthic community composition. On tropical reefs, grazing fishes and sea urchins can play key roles in limiting growth of fleshy macro-algae, thereby facilitating coral recruitment and maintaining coral-dominated communities. However, as grazer abundance increases, grazer influence on corals (or other settlers) may shift from being positive and indirect by reducing space competitors, to being negative and direct by damage or removal of coral recruits. Fishing can alter both the abundances and types of dominant grazers, with potential cascading effects on coral recruitment and subsequent community organization. In Kenya, sea urchins dominate grazing on heavily fished reefs, while herbivorous and omnivorous fishes dominate grazing within fisheries closures (marine protected areas). We used reefs under these 2 fishery management systems to investigate the effects of fish versus sea urchin grazing on the availability of settlement substrate for corals, subsequent coral settlement, and mortality of coral recruits. Fish and sea urchin grazers were equally effective at clearing benthic space for coral settlement. However, grazing associated with high densities of sea urchins on fished reefs removed many coral recruits after settlement. In contrast, fish grazing within fisheries closures enhanced coral survival compared to non-grazed treatments. We conclude that the effects of reduced abundance of grazing fishes (on available space for coral settlement) may be initially offset by increased sea urchin grazing, but that higher urchin abundances may ultimately reduce coral cover by their negative influence on post-settlement survival.

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Recruit/algal interaction prevents recovery of overexploited mussel beds: Indirect evidence that post-settlement mortality structures mussel populations

Erlandsson¹,

McQuaid²,

Stanczak³

2011

Estuarine, Coastal and Shelf Science

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Differences in top-down and bottom-up regulation of macroalgal communities between a reef crest and back reef habitat in Zanzibar

Cited by 10 publications

References 52 publications

Macroalgal biomass, growth rates, and diversity are influenced by submarine groundwater discharge and local hydrodynamics in tropical reefs

Macroalgal biomass, growth rates, and diversity are influenced by submarine groundwater discharge and local hydrodynamics in tropical reefs

Fish and sea urchin grazing opens settlement space equally but urchins reduce survival of coral recruits

Recruit/algal interaction prevents recovery of overexploited mussel beds: Indirect evidence that post-settlement mortality structures mussel populations

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