Sea urchin fecal production and accumulation in a rocky subtidal ecosystem

Sauchyn, Leah K.; Lauzon-Guay, Jean-Sébastien; Scheibling, Robert Eric

doi:10.3354/ab00359

Cited by 22 publications

(22 citation statements)

References 61 publications

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“…Along the Atlantic coast of Nova Scotia, sea urchins form dense grazing fronts that advance onshore consuming kelp at a rate of 454 to 530 g d −1 (dry mass) across 1 m of front. This translates to an estimated fecal production rate of 74 to 81 g yr −1 per linear meter of front, or 20720 kg d −1 across an estimated 280 km of coastline spanned by these grazing fronts in the mid to late 1990s (Sauchyn & Scheibling 2009a, Sauchyn et al 2011). The small (~2 mm diameter) fecal pellets are a highly nutritious food source relative to live kelp, and nitrogen, lipid, and available energy content increase rapidly during degradation (Sauchyn & Scheibling 2009b).…”

Section: Rocky Subtidal Habitatsmentioning

confidence: 99%

Production and fate of kelp detritus

Krumhansl

Scheibling²

2012

Mar. Ecol. Prog. Ser.

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378

341

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The flow of detritus between habitats is an important form of connectivity that affects regional productivity and the spatial organization of marine ecosystems. Kelps form highly productive beds or forests that produce detritus through incremental blade erosion, fragmentation of blades, and dislodgement of whole fronds and thalli. Rates of detrital production range from 8 to 2657 g C m −2 yr −1 for blade erosion and fragmentation, and from 22 to 839 g C m −2 yr −1 for loss of fronds and thalli. The estimated global average rate of detrital production by kelps is 706 g C m , accounting for 82% of annual kelp productivity. Detrital production rates are regulated by current and wave-driven hydrodynamic forces and are highest during severe storms and following blade weakening through damage by grazers and encrusting epibionts. Detritus settles within kelp beds or forests and is exported to neighboring or distant habitats, including sandy beaches, rocky intertidal shores, rocky and sedimentary subtidal areas, and the deep sea. Exported kelp detritus can provide a significant resource subsidy and enhance secondary production in these communities ranging from tens of meters to hundreds of kilometers from the source of production. Loss of kelp biomass is occurring worldwide through the combined effects of climate change, pollution, fishing, and harvesting of kelp, which can depress rates of detrital production and subsidy to adjacent communities, with large-scale consequences for productivity.KEY WORDS: Kelp bed · Kelp forest · Connectivity · Detritus · Resource subsidy · Local-regional productivity Resale or republication not permitted without written consent of the publisher

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Section: Rocky Subtidal Habitatsmentioning

confidence: 99%

Production and fate of kelp detritus

Krumhansl

Scheibling²

2012

Mar. Ecol. Prog. Ser.

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378

341

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“…In addition, urchins inefficiently digest drift algae, producing abundant fecal pellets consisting of drift algal‐derived particulate matter that may be available to a broader range of consumers than the drift algae itself (Mamelona & Pelletier ; Sauchyn & Schiebling ; Sauchyn et al . ). Below the macroalgal zone, animals rely on energy subsidies, as primary production is essentially non‐existent.…”

Section: Discussionmentioning

confidence: 97%

Sedentary urchins influence benthic community composition below the macroalgal zone

et al. 2014

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Sea urchins are important ecosystem engineers in subtidal ecosystems worldwide, providing biogenic structure and altering nutrient dynamics through intensive grazing and drift algal capture. The current work evaluates red urchin (Strongylocentrotus franciscanus) density on fixed transects through time, individual displacement, and urchin‐associated benthic community composition using a field‐based approach at multiple depths (in and outside of the macroalgal zone) and replicated across sites in the San Juan Archipelago, Washington. Urchins exhibited no large‐scale, temporal or directional changes in density among depths. Furthermore, 87% of individual urchins observed in repeated small‐scale surveys over 3 weeks exhibited no change in position. Individual displacement was negatively correlated to drift algal capture. Evidence of sedentary behavior from the displacement surveys was supported by the sessile and mobile community composition in areas directly under versus adjacent to (control) urchins. The benthos under urchins had a higher percentage of bare space, crustose coralline algae, and increased density of snails, crabs and shrimp relative to associated control plots. Abundance of mobile organisms associating with urchins increased relative to control plots at the deepest survey depth (30 m), indicating a greater strength of interaction with distance from macroalgal production. This work presents evidence of food availability‐related behavior in red urchins and indicates that even when sedentary, urchins have a strong influence on ecosystem structure through increasing availability of shelter and macroalgal detritus to the benthos.

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“…In the present study, we demonstrated that even though there were no significant differences in the FA profiles between algae consumed and egested, the urchins increased the nutritive quality of egesta in the form of increased total lipid content. This has significant implications for marine food webs, because increased lipid content in a food source is likely to benefit consumers, and suggests a mechanism for why macrophyte-derived carbon (generally) and kelpderived carbon (more specifically) may be a valuable trophic subsidy (Sauchyn and Scheibling, 2009;Sauchyn et al, 2011;Britton-Simmons et al, 2012;Lowe et al, 2015) to benthic organisms that might not otherwise utilize these sources directly.…”

Section: Discussionmentioning

confidence: 99%

“…Urchins are known to transform significant amounts of kelp-derived biomass into particulate organic matter (e.g., Koike et al, 1987) through their fecal production (Sauchyn and Scheibling, 2009;Sauchyn et al, 2011), which enhances growth of associated microbes. Moreover, urchins are notoriously inefficient assimilators of their diet (Vadas, 1977), such that a large portion (e.g., 40-80%) of the macronutrients from Strongylocentrotus droebachiensis algal diets are left intact in the resulting feces (Mamelona and Pelletier, 2005).…”

Section: Introductionmentioning

confidence: 99%

Trophic Transfer of Macroalgal Fatty Acids in Two Urchin Species: Digestion, Egestion, and Tissue Building

et al. 2018

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Sea urchins are ecosystem engineers of nearshore benthic communities because of their influence on the abundance and distribution of macroalgal species. Urchins are notoriously inefficient in assimilation of their macroalgal diets, so their fecal production can provide a nutritional subsidy to benthic consumers that cannot capture and handle large macroalgae. We studied the assimilation of macroalgal diets by urchins by analyzing the profiles of trophic biomarkers such as fatty acids (FAs). We tracked macroalgal diet assimilation in both Strongylocentrotus droebachiensis and S. purpuratus. Juvenile S. droebachiensis and adult S. purpuratus were maintained for 180 and 70 days, respectively, on one of three monoculture diets from three algal phyla: Nereocystis luetkeana, Pyropia sp., or Ulva sp. We then analyzed FA profiles of the macroalgal tissue fed to urchins as well as urchin gonad, gut, digesta, and egesta (feces) to directly evaluate trophic modification and compare nutritional quality of urchin food sources, urchin tissues, and fecal subsidies. In the S. purpuratus assay, there were significantly more total lipids in the digesta and egesta than in the algae consumed. The FA profiles of urchin tissues differed among urchin species, all diets, and tissue types. Despite these differences, we observed similar patterns in the relationships between the urchin and macroalgal tissues for both species. Egesta produced by urchins fed each of the three diets were depleted with respect to the concentration of important long chain polyunsaturated fatty acids (LCPUFAs), but did not differ significantly from the source alga consumed. Both urchin species were shown to synthesize and selectively retain both the precursor and resulting LCPUFAs involved in the synthesis of the LCPUFAs 20:4ω6 and 20:5ω3. S. droebachiensis and S. purpuratus exhibited consistent patterns in the respective depletion and retention of precursor FAs and resulting LCPUFAs of Pyropia and Ulva tissues, suggesting species level control of macroalgal digestion or differential tissue processing by gut microbiota. For both S. droebachiensis and S. purpuratus, macroalgal diet was a surprisingly strong driver of urchin tissue fatty acids; this indicates the potential of fatty acids for future quantitative trophic estimates of urchin assimilation of algal phyla in natural settings.

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Sea urchin fecal production and accumulation in a rocky subtidal ecosystem

Cited by 22 publications

References 61 publications

Production and fate of kelp detritus

Production and fate of kelp detritus

Sedentary urchins influence benthic community composition below the macroalgal zone

Trophic Transfer of Macroalgal Fatty Acids in Two Urchin Species: Digestion, Egestion, and Tissue Building

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