Drift algal subsidies to sea urchins in low-productivity habitats

Kelly, Jonathan; Krumhansl, Kira A.; Scheibling, Robert Eric

doi:10.3354/meps09628

Cited by 51 publications

(39 citation statements)

References 52 publications

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“…Changes in δ 15 N during degradation may obscure interpretation of the tro phic position of consumers in stable isotope analysis of benthic food webs. For example, δ 13 C values in sea urchins collected in barrens up to 240 m from kelp beds indicate that drift kelp is an important food source (Kelly et al 2012). However, these sea urchins have enriched δ 15 N values relative to sea urchins in kelp beds, suggesting either a higher trophic position (i.e.…”

Section: Discussionmentioning

confidence: 99%

Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Krumhansl¹,

Scheibling²

2012

Mar. Ecol. Prog. Ser.

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Invasive species have the potential to alter the dynamics of detrital subsidy from high to low productivity areas through changes in quantity and nutritional quality of detrital material. We examined the effect of the invasive alga Codium fragile ssp. fragile on the nature of detrital export from subtidal algal beds off Nova Scotia, Canada, by comparing changes in mass, nutritional quality (%C, %N, C/N ratio), concentration of dimethylsulfoniopropionate (DMSP, a secondary metabolite that deters grazers), and isotopic composition (δ C. We also compared macrofaunal communities associated with degrading thalli of each algal species and found significantly higher abundances of invertebrates (mainly capitellid polychaetes) on S. latissima after 8 wk of degradation, resulting in lower evenness (J') and diversity (H ') on S. latissima compared to C. fragile. Macrofaunal community composition became similar between algal species at 12 and 16 wk in concordance with decreases in C/N ratio in S. latissima and DMSP concentration in C. fragile. Our results indicate that differences in biochemical composition and the rate of degradation between C. fragile and native kelps result in community-level effects in areas linked to shallow algal beds via the transfer of detritus.

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Section: Discussionmentioning

confidence: 99%

Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Krumhansl¹,

Scheibling²

2012

Mar. Ecol. Prog. Ser.

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“…Patterns of detrital kelp production (Krumhansl & Scheibling 2011, Filbee-Dexter & Scheibling 2012 and degradation (Krumhansl & Scheibling 2012b) have been measured in Nova Scotia, however the seasonal variation and extent of detrital deposition to deep subtidal habitats have not been quantified. Kelly et al (2012) found that sea urchins in habitats beyond the kelp bed edge (25 to 30 m depth and 240 m offshore) with access to kelp detritus had higher gonad indices than those living in barrens, but sea urchins at greater depths have not been studied.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have recorded a decrease in gonad size and fecundity with increasing depth and distance from macroalgal beds for Strongylocentrotus droebachiensis (Keats et al 1984, Bertram & Strathmann 1998, Wahle & Peckham 1999, Brady & Scheibling 2006, Kelly et al 2012) and congeneric species (Rogers-Bennett et al 1995, Wahle & Peckham 1999, Konar & Estes 2003. In contrast, we found that sea urchins at 60 m depth in a sedimentary basin can have comparable or in some cases greater reproductive effort (mean GI at spring or autumn peak: 10 (2009) found that S. franciscanus feeding on macroalgal detritus at 24 m depth also a had similar GI compared to sea urchins in barrens at 6 m depth in the San Juan Islands, Washington, USA.…”

Section: Detrital Kelp Subsidy and Reproductive Condition Of Deep-livmentioning

confidence: 99%

“…We expected these sea urchins to have a higher reproductive capacity than populations remote from a source of attached or detrital kelp (BrittonSimmons et al 2009, Kelly et al 2012. Here, we describe the reproductive cycle of the deep-living population in St. Margarets Bay and compare it to a population in a shallow kelp bed.…”

Section: Introductionmentioning

confidence: 99%

“…Off wave-exposed headlands in Nova Scotia, where rocky substrata usually extend to greater depths before burial by sediments, deep-living sea urchins inhabit persistent barrens (Brady & Scheibling 2005, Kelly et al 2012. Sea urchins in deep barrens subsist mainly on microbial films and coralline algae (Johnson & Mann 1982).…”

Section: Introductionmentioning

confidence: 99%

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Detrital kelp subsidy supports high reproductive condition of deep-living sea urchins in a sedimentary basin

Filbee‐Dexter¹,

Scheibling²

2014

Aquat. Biol.

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Highly productive kelp beds off Nova Scotia, Canada export detrital material to adjacent sedimentary habitats in deeper waters. We evaluated the importance of this subsidy to sea urchins Strongylocentrotus droebachiensis in less productive habitats. Gonad index and gut content of urchins on sediments at 60 m depth were measured monthly from September 2010 to May 2013 in a large semi-protected bay, and compared to concurrent measurements of sea urchins at 8 m depth off a nearby headland. Detrital algal cover in the bay was measured using a towed camera system. Seasonal patterns in algal deposition and gut contents of deep-living urchins indicated that detritus was the predominant food source from March to October. We observed lower gonad indices in deep-living sea urchins compared to those at 8 m, but deep-living urchins spawned outside of the main spring season, suggesting periodic detrital subsidy enhances their reproductive condition. Food availability and temperature appear to control the timing of gametogenesis, and phytodetritus may cue gamete release in these deep habitats. To evaluate the response of deepliving urchins to detrital subsidy, and turnover time of this material, we deployed lines baited with kelp thalli at 45 and 60 m depth and measured rates of encounter and consumption of kelp detritus by sea urchins, using the towed camera. Sea urchins aggregated on kelp within hours of deployment, and consumed it after 3 to 5 mo. Our findings suggest kelp detritus represents an important energy source that can support a high reproductive capacity in deep-living urchins.

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Nearshore seascape connectivity enhances seagrass meadow nursery function

Olson

Hessing‐Lewis

Haggarty

et al. 2019

Ecological Applications

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Diverse habitats composing coastal seascapes occur in close proximity, connected by the flux of materials and fauna across habitat boundaries. Understanding how seascape connectivity alters important ecosystem functions for fish, however, is not well established. For a seagrass‐dominant seascape, we predicted that configuration and composition of adjacent habitats would alter habitat access for fauna and trophic subsidies, enhancing nursery function for juvenile fish. In an extensive Zostera marina seagrass meadow, we established sites adjacent to (1) highly complex and productive kelp forests (Nereocystis luetkeana), (2) unvegetated sand habitats, and (3) in the seagrass meadow interior. Using SCUBA, we conducted underwater observations of young‐of the‐year (YOY) rockfish (Sebastes spp.) recruitment across sites. Using generalized linear mixed effects models, we assessed the role of seascape adjacency relative to seagrass provisions (habitat complexity and prey) on YOY recruitment. YOY rockfish collections were used to trace sources of allochthonous vs. autochthonous primary production in the seagrass food web, via a δ13C and δ15N isotopic mixing model, and prey consumption using stomach contents. Overall, seagrass nursery function was strongly influenced by adjacent habitats and associated subsidies. Allochthonous N. luetkeana was the greatest source of energy assimilated by YOY rockfish within seagrass sites. In seagrass sites adjacent to N. luetkeana kelp forests, YOYs consumed higher quality prey, which corresponded with better body condition relative to sites adjacent to sand. Moreover, kelp forest adjacency enhanced YOY rockfish recruitment within the seagrass meadow, suggesting that habitat complexity is a key seascape feature influencing the nursery function of nearshore habitats. In general, to promote seascape connectivity, the conservation and restoration of nursery habitats should prioritize the inclusion of habitat mosaics of high structural complexity and productivity. We illustrate and emphasize the importance of using a seascape‐level approach that considers linkages among habitats for the management of important nearshore ecosystem functions.

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Drift algal subsidies to sea urchins in low-productivity habitats

Cited by 51 publications

References 52 publications

Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Detrital kelp subsidy supports high reproductive condition of deep-living sea urchins in a sedimentary basin

Nearshore seascape connectivity enhances seagrass meadow nursery function

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