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

Filbee‐Dexter, Karen; Scheibling, Robert Eric

doi:10.3354/ab00607

Cited by 39 publications

(18 citation statements)

References 67 publications

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“…Drift algal mats may subsidise the diet of urchins from unproductive habitats despite an absence of attached macroalgae (Chidgey & Edmunds 1997, Filbee-Dexter & Scheibling 2014a. A similar phenomenon has been documented off the coast of Nova Scotia, where the diet of urchins from barrens is supplemented by unattached macroalgae from neighbouring kelp beds (Kelly et al 2012).…”

Section: Spatio-temporal Variability In Gonad Indexmentioning

confidence: 78%

Barrens of gold: gonad conditioning of an overabundant sea urchin

Pert¹,

Swearer²,

Dworjanyn³

et al. 2018

Aquacult. Environ. Interact.

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Overgrazing by the overabundant native purple urchin Heliocidaris erythrogramma has caused kelp-dominated reefs to shift to urchin barrens throughout southeastern Australia. These areas are characterised by low kelp abundance, low biodiversity and high urchin densities. As purple urchin gonads are a delicacy in many countries, commercial harvest from barrens could aid kelp recovery. However, the lack of macroalgae in these habitats, driven by high urchin densities, results in urchins with small, poor-quality roe that is commercially undesirable. To overcome this, we assessed whether urchin gonad quantity and quality could be improved with access to high-quality feed and optimal environmental conditions, a process known as 'gonad conditioning'. Specifically, we (1) surveyed the quality of urchins from barrens and kelp sites in Port Phillip Bay, Australia, over 18 mo and (2) tested if gonad conditioning was effective on urchins from barrens during and after the harvest season. Field surveys revealed considerable variation in gonad size across sites, habitats and collection periods (mean gonad index range: 3 to 12%). Gonad conditioning with the best diet increased urchin gonad size by up to 2.8 times during the harvest season. Moreover, gonads of conditioned urchins from one barren were 3 times brighter in colour and contained lower concentrations of arsenic than wild urchins. In contrast, gonad conditioning at 22°C after the harvest season was ineffective. Our results show that targeted in-season harvest from barrens and subsequent gonad conditioning produces roe of commercial quality, promoting the use of urchin fisheries as a tool for managing urchin barrens.

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Section: Spatio-temporal Variability In Gonad Indexmentioning

confidence: 78%

Barrens of gold: gonad conditioning of an overabundant sea urchin

Pert¹,

Swearer²,

Dworjanyn³

et al. 2018

Aquacult. Environ. Interact.

View full text Add to dashboard Cite

show abstract

“…Through herbivory and wave disturbance, some carbon becomes particulate organic matter (Pessarrodona et al 2018), and as much as 14-26% of fixed carbon is excreted as DOC (Abdullah andFredriksen 2004, Reed et al 2015), consistent with our finding of higher DOC within the kelp bed. Export of kelp biomass to deeper areas is also demonstrated (Krumhansl andScheibling 2012, Filbee-Dexter andScheibling 2014). Further, large rafts of kelp decompose in situ and in nearby coastal areas (Harrold and Lisin 1989), likely resulting in the respiration of carbon and its return to seawater and the atmosphere.…”

Section: Kelp Forests Effects On the Seawater Carbonate Systemmentioning

confidence: 91%

“…S1). Export of kelp biomass to deeper areas is also demonstrated (Krumhansl andScheibling 2012, Filbee-Dexter andScheibling 2014). Diel cycles in the coastal carbonate cycle have been documented (Yates et al 2007, Wootton et al 2008, Frieder et al 2012 and are likely ubiquitous.…”

Section: Kelp Forests Effects On the Seawater Carbonate Systemmentioning

confidence: 95%

Kelp beds and their local effects on seawater chemistry, productivity, and microbial communities

Pfister

Altabet

Weigel

2019

Ecology

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Our research showed that kelp beds locally increased the pH, oxygen, and aragonite saturation state of the seawater, while seawater inorganic carbon content and total alkalinity were lowered. Kelp beds depleted nitrate and phosphorus concentrations, but enhanced ammonium and DOC concentrations. Kelp beds entrained distinct microbial communities, with higher taxonomic and phylogenetic diversity compared to seawater outside of the kelp bed, and kelp carbon fixation more than compensated for decreased phytoplankton production that occurred in their proximity. Thus, the diversity of pathways for carbon and nitrogen cycling is enhanced in proximity to kelp.Pfister, C. A., M. A.

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“…These regions have reduced flow compared to areas with positive BPI, and should retain drift algae and small detrital particles (e.g., phytodetritus) that are important food sources for deep‐living urchins (Campos‐Creasey et al. , Filbee‐Dexter and Scheibling ). Less suitable habitats included regions >3.4 km from the coast or at depths >85 m, flat areas >3.1 km 2 , and convexities of the seafloor.…”

Section: Discussionmentioning

confidence: 99%

The present is the key to the past: linking regime shifts in kelp beds to the distribution of deep‐living sea urchins

Filbee‐Dexter

Scheibling

2017

Ecology

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Understanding processes that drive sudden shifts in ecosystem structure and function has become an important research focus for coastal management. In kelp bed ecosystems, regime shifts occur when high densities of sea urchins destructively graze kelp and create coralline algal barrens. While the importance of predation and disease in mediating shifts between kelp beds and barrens on shallow rocky reefs has been well documented, little is known about the role of deep-living urchins in these alternative stable-state dynamics. In this study, we test the hypothesis that deep-living urchins along the central Atlantic coast of Nova Scotia move onshore and trigger shifts from kelp beds to barrens on shallow rocky reefs. We documented urchin distribution and abundance using tow-camera surveys down to 140 m depth and spanning 140 km of coast and created a predictive species-distribution model using these observations and spatial data on environmental factors that likely delineate suitable habitat for urchins. We used a random forest model to generate our predictions, which correctly classified 91% of observations into a positive or negative occurrence of urchins. Sea urchins predominantly occurred within 1.5 km of shore, in depressions and flat habitats between 40 and 85 m depth. We found that shallow regions where destructive grazing fronts have been documented over the past four decades were closer to deep-living sea urchin habitats compared to regions that remained in a kelp bed state during the same period. This supports our prediction that deep-living urchins play an important role in driving shallow regime shift dynamics, and indicates that their distribution can help identify areas of coast that are most vulnerable to a collapse to barrens.

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

Cited by 39 publications

References 67 publications

Barrens of gold: gonad conditioning of an overabundant sea urchin

Barrens of gold: gonad conditioning of an overabundant sea urchin

Kelp beds and their local effects on seawater chemistry, productivity, and microbial communities

The present is the key to the past: linking regime shifts in kelp beds to the distribution of deep‐living sea urchins

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