Pathways to Spatial Subsidies by Kelp in Seagrass Meadows

Cartraud, Audrey E.; Lavery, Paul; Rae, Caitlin; Hyndes, Glenn A.

doi:10.1007/s12237-020-00860-8

Cited by 6 publications

(6 citation statements)

References 58 publications

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“…In Australia, the kelp Ecklonia radiata made a notable contribution to the diets of two seagrass-dwelling gastropods ( Doropoulos et al., 2009 ), and gastropod species were found to assimilate isotopically-labeled δ 15 N kelp under both field and laboratory conditions ( Hyndes et al., 2012 ). Further, in-situ addition of kelp to Posidonia sinuosa seagrass plots increased the densities and biomass of the gastropod Strigosella lepidus and shrimp ( Cartraud et al., 2021 ). Finally, the trophic incorporation of kelp subsidies by seagrass dwelling species has been demonstrated at higher levels of the food web such as fish ( Wernberg et al., 2006 ; Olson et al., 2019 ).…”

Section: Discussionmentioning

confidence: 99%

“…Previous work has largely focused on the effect of cross-ecosystem subsidies on nutrient-poor recipient ecosystems such as desert islands ( Anderson and Polis, 1999 ) and sandy beaches ( Lastra et al., 2008 ; Liebowitz et al., 2016 ), as well as aquatic subsidies into riparian ecosystems ( Hocking and Reimchen, 2009 ; Lafage et al., 2019 ). Growing evidence suggests cross-ecosystem energy transfer may be important to highly productive recipient ecosystems, such as mangroves ( Slim et al., 1996 ), coral reefs ( Carreón-Palau et al., 2013 ) and seagrass meadows ( Hyndes et al., 2012 , Cartraud et al., 2021 ).…”

Section: Introductionmentioning

confidence: 99%

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Grazing preference and isotopic contributions of kelp to Zostera marina mesograzers

et al. 2022

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In seagrass food webs, small invertebrate mesograzers often exert top-down control on algal epiphytes growing on seagrass blades, which in turn releases the seagrass from competition for light and nutrients. Yet, nearshore habitat boundaries are permeable, and allochthonous subsidies can provide alternative food sources to in-situ production in seagrass meadows, which may in turn alter mesograzer-epiphyte interactions. We examined the contribution of allochthonous kelp (Nereocystis luetkeana), autochthonous epiphytic macroalgal (Smithora naiadum), Ulva lactuca, and seagrass production to mesograzer diets in a subtidal Zostera marina (eelgrass) meadow. In both choice feeding experiments and isotopic analysis, mesograzer diets revealed a preference for allochthonous N. luetkeana over Z. marina, S. naiadum, and U. lactuca. Notably, Idotea resecata showed an ~20x greater consumption rate for N. luetkeana in feeding experiments over other macrophytes. In the meadow, we found a positive relationship between epiphytic S. naiadum and gammarid amphipod biomass suggesting weak top-down control on the S. naiadum biomass. Epiphyte biomass may be driven by bottom-up factors such as environmental conditions, or the availability and preference of allochthonous kelp, though further work is needed to disentangle these interactions. Additionally, we found that gammarid and caprellid amphipod biomass were positively influenced by adjacency to kelp at seagrass meadow edges. Our findings suggest that N. luetkeana kelp subsidies are important to the diets of mesograzers in Z. marina meadows. Spatial planning and management of marine areas should consider trophic linkages between kelp and eelgrass habitats as a critical seascape feature if the goal is to conserve nearshore food web structure and function.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Grazing preference and isotopic contributions of kelp to Zostera marina mesograzers

et al. 2022

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“…Similar to shoreline systems, detrital kelp has been shown to accumulate and contribute to secondary production in other coastal systems, such as the kelp forests themselves (Vanderklift and Kendrick, 2005), adjacent seagrass meadows (Hyndes et al, 2012;Cartraud et al, 2021), and deep habitats (Dethier et al, 2014). Thus, kelp-associated bacteria could play a similar role in facilitating the transfer of nutrients into other coastal food webs.…”

Section: Discussionmentioning

confidence: 99%

Kelp-Associated Microbes Facilitate Spatial Subsidy in a Detrital-Based Food Web in a Shoreline Ecosystem

et al. 2021

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Microbes are ubiquitous but our knowledge of their effects on consumers is limited in benthic marine systems. Shorelines often form hotspots of microbial and detritivore activity due to the large amounts of detrital macrophytes that are exported from other coastal ecosystems, such as kelp forests, and accumulate in these systems. Shoreline ecosystems therefore provide a useful model system to examine microbial-detritivore interactions. We experimentally test whether bacteria in the biofilm of kelp provide a bottom-up influence on growth and reproductive output of detritivores in shorelines where detrital kelp accumulates, by manipulating the bacterial abundances on kelp (Ecklonia radiata). The growth rates for both male and female amphipods (Allorchestes compressa) were greater in treatments containing bacteria than those in which bacteria were reduced through antibiotic treatment, and this effect was greater for males offered aged kelp. The proportions of ovigerous females were greater when reared on kelp with intact bacteria, indicating a more rapid reproductive development in the presence of more bacteria. Bacterial abundance had little to no influence on nutrient content and palatability of kelp, based on tissue toughness, nitrogen and carbon content and C:N ratio. Thus, the most likely pathway for a microbial effect on detritivores was through feeding on kelp-associated bacteria. Regardless of the pathway, kelp-associated microbes have a strong influence on the fitness of a highly abundant detritivore that feeds preferentially on E. radiata in shoreline systems, and therefore form a hidden trophic step in this “brown” food web and a hotspot of secondary production.

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“…2020, Cartraud et al. 2021). Seaweed beds are therefore termed “carbon donors,” and the export of carbon from a seaweed bed has been termed “carbon leakage” and “carbon out‐welling” (Hill et al.…”

Section: Natural Seaweed Beds: Carbon Fluxes and Fate In Food Websmentioning

confidence: 99%

“…A large proportion of seaweed DOC and POC is exported laterally out of seaweed beds via currents and can "subsidize" (add to) the carbon available for consumption by higher trophic levels in other coastal systems such as sandy beaches, seagrass beds, soft sediments, and offshore deep-water habitats (Hyndes et al 2014, Smale et al 2018, Cartraud et al 2021). Seaweed beds are therefore termed "carbon donors," and the export of carbon from a seaweed bed has been termed "carbon leakage" and "carbon out-welling" (Hill et al 2015, Queir os et al 2019, Santos et al 2021).…”

Section: Natural Seaweed Beds: Carbon Fluxes and Fate In Food Websmentioning

confidence: 99%

Forensic carbon accounting: Assessing the role of seaweeds for carbon sequestration

Hurd

Law

Bach

et al. 2022

Journal of Phycology

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Carbon sequestration is defined as the secure storage of carbon‐containing molecules for >100 years, and in the context of carbon dioxide removal for climate mitigation, the origin of this CO2 is from the atmosphere. On land, trees globally sequester substantial amounts of carbon in woody biomass, and an analogous role for seaweeds in ocean carbon sequestration has been suggested. The purposeful expansion of natural seaweed beds and aquaculture systems, including into the open ocean (ocean afforestation), has been proposed as a method of increasing carbon sequestration and use in carbon trading and offset schemes. However, to verify whether CO2 fixed by seaweeds through photosynthesis leads to carbon sequestration is extremely complex in the marine environment compared to terrestrial systems, because of the need to jointly consider: the comparatively rapid turnover of seaweed biomass, tracing the fate of carbon via particulate and dissolved organic carbon pathways in dynamic coastal waters, and the key role of atmosphere–ocean CO2 exchange. We propose a Forensic Carbon Accounting approach, in which a thorough analysis of carbon flows between the atmosphere and ocean, and into and out of seaweeds would be undertaken, for assessing the magnitude of CO2 removal and robust attribution of carbon sequestration to seaweeds.

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Pathways to Spatial Subsidies by Kelp in Seagrass Meadows

Cited by 6 publications

References 58 publications

Grazing preference and isotopic contributions of kelp to Zostera marina mesograzers

Grazing preference and isotopic contributions of kelp to Zostera marina mesograzers

Kelp-Associated Microbes Facilitate Spatial Subsidy in a Detrital-Based Food Web in a Shoreline Ecosystem

Forensic carbon accounting: Assessing the role of seaweeds for carbon sequestration

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