Disturbance and gap formation in a marine benthic mosaic:influence of shifting macroalgal patches on seagrass structure and mobile invertebrates

Holmquist, Jeff G.

doi:10.3354/meps158121

Cited by 92 publications

(80 citation statements)

References 46 publications

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“…This variability likely resulted from patchiness associated with the bloom deposition in our mesocosms or heterogeneity in the sediment microbial communities. Similar patchiness has been observed in field studies (Holmquist 1997, Sfriso & Marcomini 1999. Despite the observed variability, our statistical analyses confirmed that bulk isotopic enrichments at the end of the experiment (Days 7 & 14) were higher than at the beginning of the experiment (Days 1 & 2) for both lagoons, demonstrating accumulation and retention of macroalgal 13 C and 15 N in the sediments following the simulated die-off.…”

Section: Label Incorporation Into Bulk Sedimentssupporting

confidence: 71%

Fate of macroalgae in benthic systems: carbon and nitrogen cycling within the microbial community

Hardison

Canuel

Anderson

et al. 2010

Mar. Ecol. Prog. Ser.

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High nutrient loading to coastal bays is often accompanied by the presence of bloomforming macroalgae, which take up and sequester large amounts of C and N while growing. This pool is temporary, however, as nuisance macroalgae exhibit a bloom and die-off cycle, influencing the biogeochemical functioning of these systems in unknown ways. The objective of this study was to trace the C and N from senescing macroalgae into relevant sediment pools. A macroalgal die-off event was simulated by the addition of freeze-dried macroalgae (Gracilaria spp.), pre-labeled with stable isotopes ( 13 C and 15 N), to sediment mesocosms. The isotopes were traced into bulk sediments and partitioned into benthic microalgal (BMA) and bacterial biomass using microbial biomarkers to quantify the uptake and retention of macroalgal C and N. Bulk sediments took up label immediately following the die-off, and macroalgal C and N were retained in the sediments for at least 2 wk. Approximately 6 to 50% and 2 to 9% of macroalgal N and C, respectively, were incorporated into the sediments. Label from the macroalgae appeared in both bacterial and BMA biomarkers, suggesting that efficient shuttling of macroalgal C and N between these communities may serve as a mechanism for retention of macroalgal nutrients within the sediments. KEY WORDS: Stable isotopes · Macroalgae · Benthic microalgae · Bacteria · Biomarker · Coastal eutrophication Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 414: [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] 2010 Studies of macroalgal bloom decay have demonstrated rapid breakdown of biomass, resulting in release of both inorganic and organic nutrients to the water column (Buchsbaum et al. 1991, Castaldelli et al. 2003, García-Robledo et al. 2008, supporting phytoplankton and bacterial metabolism , Nedergaard et al. 2002. Fewer studies have focused on macroalgal decay within the sediments (Nedergaard et al. 2002, Lomstein et al. 2006, Rossi 2007, García-Robledo et al. 2008, where heterotrophic bacterial densities are significantly higher than in the water column (Deming & Baross 1993, Schmidt et al. 1998, Ducklow 2000. In addition, most of the sediment studies have been conducted in low or no light environments, even though light is typically available to shallow sediments where macroalgal die-offs occur and sediment biogeochemistry is largely affected by benthic microalgal (BMA) activity (Underwood & Kromkamp 1999). While nutrients associated with senescent macroalgal blooms are recycled and can have a positive feedback on phytoplankton production in the water column, nutrients released during macroalgal decay in the sediments may support BMA and bacterial production, which could intercept the return of nutrients to the overlying water column. Thus if shallow-water sediments behave as a nutrient filter, the response by phytoplankton may be reduced, and benthic production could effectively buffer the system from further eutrophication. In order to be...

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Section: Label Incorporation Into Bulk Sedimentssupporting

confidence: 71%

Fate of macroalgae in benthic systems: carbon and nitrogen cycling within the microbial community

Hardison

Canuel

Anderson

et al. 2010

Mar. Ecol. Prog. Ser.

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“…Decreased grass-shrimp abundances in response to trampling, particularly for Thor manningi, were probably the result of the decrease in seagrass physical complexity. As trampling slowly thinned the seagrass, shrimps probably emigrated to denser seagrass outside the trampling lanes, or failed to immigrate into the trampling lanes rather than suffering direct mortality (see also Holmquist 1997, Keough & Quinn 1998, Brown & Taylor 1999. Conversely, shrimps of the family Processidae are often associated with bare patches in seagrass meadows (Holmquist pers.…”

Section: Discussionmentioning

confidence: 99%

Trampling in a seagrass assemblage: direct effects, response of associated fauna, and the role of substrate characteristics

Eckrich¹,

Holmquist²

2000

Mar. Ecol. Prog. Ser.

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Human wading in shallow coastal waters is a common activity that inherently involves trampling of the substrate. An experiment was conducted in Thalassia testudinum seagrass beds in Puerto Rico to determine how seagrass and associated mobile fauna respond to this anthropogenic disturbance. Three trampling intensities were applied to replicate seagrass beds throughout a 4 mo period. Seagrass biomass was inversely related to trampling intensity and duration. There was moderate recovery in the trampled areas 7 mo after the last trampling event. Intense levels of trampling resulted in decreased shrimp abundances, especially for Thor manningi. Fish abundances and composition of shrimp and fish assemblages did not change significantly after 4 mo of trampling. T. testudinum beds with softer substrates lost more seagrass biomass as a result of trampling than seagrass beds with firm substrates, suggesting that substrate firmness can modify disturbance effects. Educators and resource managers should limit trampling by large groups, or confine it to small areas with firm substrates, and researchers should be mindful of artifacts arising from trampling in and around sampling areas.

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“…Algal epiphytes can increase the complexity of aquatic macrophytes, resulting in greater diversity of the associated mobile species (Holmquist, 1997;Jernakoff and Nielsen, 1998). Similarly, the presence of colonial organisms such as sponges, hydrozoans, and bryozoans can increase macrophytic complexity (Hall and Bell, 1988).…”

Section: Introductionmentioning

confidence: 99%

Structural variation in the brown alga Sargassum cymosum and its effects on associated amphipod assemblages

2007

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The presence of diverse biological substrates adds complexity to coastal landscapes and increases the number of ecological niches that can be used by the mobile epifauna. Studies on the influence of structural complexity have focused mainly on algal host species, but there is little information about the influence of intraspecific structural variation on the associated mobile epifauna. In this work, we examined whether intraspecific variation in the brown alga Sargassum cymosum influenced the structure of amphipod assemblages on two shores with different wave exposure. At least 15 fronds were randomly sampled at Fortaleza and Perequê-Mirim beaches, on the Atlantic coast of São Paulo state, southeastern Brazil, and 12 variables were measured for each alga. The amphipods were identified and counted. The greatest structural variation in S. cymosum occurred within shores, whereas the differences between shores were mainly related to algal size. These characteristics influenced amphipod assemblages differently on each shore, with the greatest effects being associated with variables related to morphological complexity, such as holdfast size, the number and size of branches, and the extent of cover by sessile colonial animals. These findings show that monospecific algal banks are not homogeneous, and that morphological differences and interactions with other biological substrates can influence the mobile epifaunal assemblages.Keywords: Sargassum cymosum, amphipods, structural variation, morphology.Variação estrutural da alga parda Sargassum cymosum e seu efeito sobre as assembléias dos anfípodes associados Resumo A presença de substratos biológicos aumenta a complexidade dos ambientes costeiros, proporcionando maior número de nichos ecológicos para a epifauna vágil. Estudos sobre os efeitos da complexidade estrutural das algas têm enfocado principalmente as espécies presentes entre os seus ramos, porém há poucos dados sobre a influência da variação estrutural intra-específica sobre essa fauna. Neste trabalho, foi analisada a influência da variação da alga parda Sargassum cymosum sobre a estrutura da assembléia de anfípodes entre duas praias com diferentes graus de exposição às ondas, e em cada uma delas, no SE do Brasil. Pelo menos 15 frondes foram individualmente coletadas aleatoriamente nos costões das praias de Fortaleza e Perequê-Mirim, e diversas variáveis (12) foram medidas para cada fronde de alga. Os anfípodes foram identificados e contados. As maiores variações nas características de S. cymosum foram obtidas em cada praia, enquanto que diferenças entre as praias foram principalmente relacionadas ao tamanho das algas. Estas características influenciaram as assembléias de anfípodes de maneira diferente em cada praia, sendo que os maiores efeitos foram atribuídos a variáveis relacionadas com a morfologia das algas como o tamanho do apressório, o número e tamanho dos ramos e a cobertura por organismos coloniais sésseis. Portanto, bancos monoespecíficos de algas não são homogêneos e tanto as diferenças morf...

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Disturbance and gap formation in a marine benthic mosaic:influence of shifting macroalgal patches on seagrass structure and mobile invertebrates

Cited by 92 publications

References 46 publications

Fate of macroalgae in benthic systems: carbon and nitrogen cycling within the microbial community

Fate of macroalgae in benthic systems: carbon and nitrogen cycling within the microbial community

Trampling in a seagrass assemblage: direct effects, response of associated fauna, and the role of substrate characteristics

Structural variation in the brown alga Sargassum cymosum and its effects on associated amphipod assemblages

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