Top-down and bottom-up regulation of phytoplankton assemblages in tidepools

Meta×as, Anna; Scheibling, Robert Eric

doi:10.3354/meps145161

Cited by 27 publications

(14 citation statements)

References 24 publications

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“…Blooms of noxious blue‐green algae under sustained strong grazing pressure are a familiar example from lakes (Leibold et al 1997). Similar dominance by unpalatable prey under strong grazing pressure has been documented in marine phytoplankton (Metaxas and Scheibling 1996) and especially in benthic seaweeds (Hay 1984b, Thacker et al 2001). For probably similar reasons, cascading trophic interactions have weaker average effects on plants in diverse grasslands and woodlands than in low‐diversity agroecosystems (Halaj and Wise 2001).…”

Section: Two‐level Modules: Prey Diversity Effectssupporting

confidence: 76%

Biodiversity and ecosystem function: the consumer connection

Duffy¹

2002

Oikos

548

503

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Minireviews provides an opportunity to summarize existing knowledge of selected ecological areas, with special emphasis on current topics where rapid and significant advances are occurring. Reviews should be concise and not too wide-ranging. All key references should be cited. A summary is required. Proposed links between biodiversity and ecosystem processes have generated intense interest and controversy in recent years. With few exceptions, however, empirical studies have focused on grassland plants and laboratory aquatic microbial systems, whereas there has been little attention to how changing animal diversity may influence ecosystem processes. Meanwhile, a separate research tradition has demonstrated strong top-down forcing in many systems, but has considered the role of diversity in these processes only tangentially. Integration of these research directions is necessary for more complete understanding in both areas. Several considerations suggest that changing diversity in multi-level food webs can have important ecosystem effects that can be qualitatively different than those mediated by plants. First, extinctions tend to be biased by trophic level: higher-level consumers are less diverse, less abundant, and under stronger anthropogenic pressure on average than wild plants, and thus face greater risk of extinction. Second, unlike plants, consumers often have impacts on ecosystems disproportionate to their abundance. Thus, an early consequence of declining diversity will often be skewed trophic structure, potentially reducing top-down influence. Third, where predators remain abundant, declining diversity at lower trophic levels may change effectiveness of predation and penetrance of trophic cascades by reducing trait diversity and the potential for compensation among species within a level. The mostly indirect evidence available provides some support for this prediction. Yet effects of changing animal diversity on functional processes have rarely been tested experimentally. Evaluating impacts of biodiversity loss on ecosystem function requires expanding the scope of current experimental research to multi-level food webs. A central challenge to doing so, and to evaluating the importance of trophic cascades specifically, is understanding the distribution of interaction strengths within natural communities and how they change with community composition. Although topology of most real food webs is extremely complex, it is not at all clear how much of this complexity translates to strong dynamic linkages that influence aggregate biomass and community composition. Finally, there is a need for more detailed data on patterns of species loss from real ecosystems (community ''disassembly'' rules). MINI-REVIEW

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Section: Two‐level Modules: Prey Diversity Effectssupporting

confidence: 76%

Biodiversity and ecosystem function: the consumer connection

Duffy¹

2002

Oikos

548

503

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“…From these studies we have learned that increasing zooplankton grazing pressure decreases autotrophic biomass and increases dissolved nutrient concentrations. In addition, a shift in the phytoplankton community towards grazing-resistant species is commonly observed (Kerfoot et al 1988;Strong 1992;Metaxas and Scheibling 1996).…”

Section: Introductionmentioning

confidence: 99%

Resource-niche complementarity and autotrophic compensation determines ecosystem-level responses to increased cladoceran species richness

Norberg¹

2000

Oecologia

105

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This study examines the relationship between cladoceran species richness and ecosystem functioning. I conducted an experiment in which four cladocerans, Daphnia. magna, D. longispina, D. pulex and Chydorus sphaericus, were cultured in microcosms using different species combinations and levels of species richness. The results demonstrate that even within this closely related group of organisms the effects on ecosystem-level variables, such as total algae and zooplankton biomass, per capita productivity, and nutrient concentrations, as well as phytoplankton community structure, were highly variable between different combinations of these species. Since only four species where involved in this study, species-specific effects dominated the general relationship between species richness and ecosystem functioning. Particular combinations of species resulted in effects that indicated more efficient grazing. These effects, which were most pronounced in combinations including both D. magna and C. sphaericus, were manifested as an indirect effect as the prey community shifted towards grazing-resistant species. As a result, the productivity of the prey community decreased, because phytoplankton species with lower per capita productivity became more dominant. I suggest that the primary mechanism that caused this significant effect was complementarity in prey-size use of D. magna and C. sphaericus. In terms of prey-size range, D. pulex and D. longispina were redundant when D. magna was present and were quickly out-competed by the latter despite higher per capita filtering efficiency. The results show that different mechanisms are important for different combinations of species. Furthermore, the ability of the prey community to respond to changes of consumer species composition is an important factor in experiments in which consumer species richness is experimentally manipulated.

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“…coastal phytoplankton assemblages (Kivi et al 1993;Metaxas and Scheibling 1996) and seagrass-epiphyte assemblages (Neckles et al 1993;Williams and Ruckelshaus 1993) indicates generally strong nutrient and grazing effects on plant species composition and biomass, together with pronounced seasonal variability. Macroalgal assemblages that dominate biomass and productivity of most of the worlds rocky shores (Mann 1973) have been studied intensively for consumer effects (Lubchenco and Gaines 1981;Menge and Farrell 1989;Worm and Chapman 1998), but these were rarely weighed against the effects of nutrients (Menge et al 1997).…”

Section: Acknowledgmentsmentioning

confidence: 99%

Coastal food web structure, carbon storage, and nitrogen retention regulated by consumer pressure and nutrient loading

Worm¹,

Lotze²,

Sommer³

2000

Limnology & Oceanography

152

118

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By factorial field experiments we analyzed the relative effects of increased nutrient (NϩP) loading and natural grazing pressure on species composition, carbon storage, and nitrogen retention in the Baltic Sea littoral food web, composed of macroalgae, grazers (snails, isopods, amphipods), and predators (shrimps, crabs, fish). Nitrogen was depleted relative to phosphorus throughout most of the year. Increasing nitrogen (6-200% over ambient concentrations) enhanced algal productivity and cover of fast-growing annual algae, grazer, and predator densities, suggesting a three-level bottom-up effect. With increasing nitrogen loading, annual algae increasingly blocked perennial algal recruitment (65-98% decrease) and growth. Grazers counteracted the effects of nutrient enrichment on algal species composition through selective consumption of annual algae. Grazer exclusion had equivalent negative effects on perennial recruitment as a 85% increase in nitrogen loading. Nutrient enrichment increased algal nitrogen content and decreased tissue C : N ratios in spring and summer but not in fall. Carbon storage and nitrogen retention, measured as C and N retained in plant biomass at the end of the growth season, were increased by grazers (C: 39%, N: 24%) but decreased with increasing nitrogen loading (C: Ϫ71%, N: Ϫ74%). Our results emphasize the important role of grazers in buffering moderate eutrophication effects and illustrate how food web interactions and shifts in species composition are tightly linked to coastal ecosystem function.

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Top-down and bottom-up regulation of phytoplankton assemblages in tidepools

Cited by 27 publications

References 24 publications

Biodiversity and ecosystem function: the consumer connection

Biodiversity and ecosystem function: the consumer connection

Resource-niche complementarity and autotrophic compensation determines ecosystem-level responses to increased cladoceran species richness

Coastal food web structure, carbon storage, and nitrogen retention regulated by consumer pressure and nutrient loading

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