Aquaculture-derived trophic subsidy boosts populations of an ecosystem engineer

White, Camille A.; Bannister, Raymond; Dworjanyn, Symon A.; Husa, Vivian; Nichols, Peter D.; Dempster, Tim

doi:10.3354/aei00270

Cited by 14 publications

(12 citation statements)

References 59 publications

(72 reference statements)

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“…In a laboratory experiment, White et al (2016) found no differences in lipid profiles in gonads or eggs in the sea urchin Heliocidaris erythrogramma fed a natural (mixed), current feed (n3-n6 ratios currently used by the industry), and future feed diets (very low n3-n6 ratios that could be used if the proportion of terrestrial fatty acids keep increasing in feed used by the industry); current feed did not influence reproductive processes, but future feed had serious consequences on egg diameter, fertilization, and larval development and survival. Finally, in the sea urchin Echinus acutus, a laboratory diet of fish feed increased gonad size, gonad, and egg terrestrial fatty acid content when compared to a natural diet (White et al, 2017b), resulting in reduced egg and larval quality (White et al, 2018). While we observed negative impacts of feeding rock crabs solely with salmonid feed, it is important to remember that the experiment was designed to investigate the 'worst-case scenarios' where individuals are obliged to feed on a single item.…”

Section: Discussionmentioning

confidence: 82%

“…Even if individuals spend significant time under farms and consume predominantly finfish feed, the effects at the individual level will translate into changes at the population level based on the proportion of a population that frequents farms (White et al, 2018). In turn, this value will depend on the overall proportion of the habitat where farms are present and farm attraction.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Aquaculture-Related Diets on the Long-Term Performance and Condition of the Rock Crab, Cancer irroratus

et al. 2022

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Shellfish and salmonid aquaculture operations in Eastern Canada attract several mobile epibenthic species as a result of added structural complexity and increased food availability (bivalve fall-off and waste salmonid feed). It is not clear whether the aggregation of predators and scavengers below coastal farms contributes positively or negatively to their population dynamics, due to concerns about the quality of food items found under farms. We conducted an 18-month laboratory study to investigate the effect of diets composed of 1) mixed items, 2) mussels (Mytilus edulis), and 3) salmonid feed on the performance and condition of the rock crab, Cancer irroratus. Diet had no impact on crab survival but several negative consequences were observed in crabs fed the salmonid feed diet when compared to the mixed diet: reduced 1) moulting rates during the second growing season, 2) inter-molt growth, 3) gonad and hepatopancreas indices, 4) hemolymph dissolved compounds, 5) hepatopancreatic glycogen, and 6) shell hardness. Crabs fed the mussel diet had similar performance and condition when compared to the mixed diet. Fatty acid composition of muscle, gonad, and hepatopancreas tissues revealed that a salmonid feed diet decreased n3/n6 ratio when compared to a mixed or a mussel diet; those differences were mostly due to increases in the proportions of terrestrial (18:1n9 and 18:2n6) and decreases in proportions of marine essential (20:5n3 and 22:6n3) fatty acids. Together, these results point to a minimal impact of a mussel-only diet on crabs, whereas the salmonid feed diet resulted in negative impacts on condition. Our experimental results explored the consequences of a ‘worst-case scenario’ in which crabs were forced to feed on a single item for a long period of time; the realized impact in field settings will depend on other factors such as consumption of alternate food items underneath a farm, proportion of time spent in farms, and level of overlap between crab habitat and aquaculture facilities.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Effect of Aquaculture-Related Diets on the Long-Term Performance and Condition of the Rock Crab, Cancer irroratus

et al. 2022

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“…An example is the case of the urchin Echinus acutus , where increases in terrestrial fatty acid markers in both field and lab conditions indicated that fish waste was assimilated and incorporated into the gonads and eggs 27 . Subsequent work on the same species demonstrated that a diet with high proportions of terrestrial ingredients resulted in lower fertilisation and larval survival rates compared to individuals feeding on natural diets, 14 and thus a generally lower reproductive output. However, despite lower reproductive outcomes at the individual level, when the reproductive output estimates were combined with higher species abundance estimates from the farming area, the overall reproductive output of the population was higher compared to control areas, where urchins were less abundant 14 .…”

Section: Advances In Knowledgementioning

confidence: 99%

“…Although mostly localised at the farm, enrichment effects may arise further afield, for example, cumulative fish waste deposition from multiple farms, or from accumulation of fish waste deposits in naturally depositional areas outside the primary footprint. Broader ecosystem changes may also occur through trophic shifts or interaction of fish wastes with high‐value habitats, or in habitats that are more sensitive to organic waste deposits 9,13,14 . To provide more context to potential environmental risks and broader consequences of farming activities, there is thus a clear need to understand how solid fish farm waste is dispersed and assimilated in any given environment.…”

Section: Introductionmentioning

confidence: 99%

Fate and effects of fish farm organic waste in marine systems: Advances in understanding using biochemical approaches with implications for environmental management

Elvines

MacLeod

Ross

et al. 2023

Reviews in Aquaculture

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Particulate waste from open‐cage fish farms in marine systems can cause organic enrichment of seabed habitats and enter the food web through consumption by wild organisms, with potential for broader ecosystem changes. Effects on biogeochemistry and benthic ecology are reasonably well understood in inshore, sheltered and soft sediment systems. However, food web effects and interactions with epifauna and larger consumers is less well understood, as is the fate of these discharges in more dynamic coastal areas with complex hydrodynamic regimes. Expected expansion of the aquaculture industry globally includes farming new areas that are more environmentally dynamic and biodiverse, with potentially sensitive habitats. Therefore, the aim of this review was to examine how biochemical tools can assist in identifying and managing impacts. Biochemical tools such as bulk stable isotopes and fatty acids can reliably trace the fate of fish waste in the environment and the food web, and have advanced our understanding of waste dispersal, as well as providing greater insights into biological interactions with fish wastes. This includes elucidating trophic subsidies to wild organisms, candidate species for co‐culture and waste assimilation mechanisms in native communities. Ultimately, biochemical tools can support improved environmental management, by helping to identify the zone of influence for spatial planning, providing additional ‘forensic’ evidence for farm‐related change, and by identifying potential risks to high‐value species and habitats. In this way, they can inform targeted research to link fish waste inputs meaningfully to potential ecosystem changes to better understand the consequences to support sustainable industry expansion.

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“…Yet, some species of urchin (e.g. Gracilechinus acutus ) can regulate the omega‐3: omega‐6 ratio in their gonads, despite being fed an aquaculture feed high in terrestrial omega‐6 polyunsaturated fatty acids (White et al, 2018). To date, most studies investigating the effect of dietary lipid content in formulated urchin feeds found that lipid source or concentration had little effect in improving urchin gonad size after roe enhancement (Gibbs et al, 2013; Kennedy et al, 2007; Pantazis et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

The balancing act: Protein, lipid and seaweed dietary levels to maximize gonad quantity in a wild‐caught sea urchin

et al. 2021

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Sea urchin gonads (roe) are a prized global sea food commodity, with growing demand driving the need for urchin roe enhancement aquaculture. Effective roe enhancement of urchins using formulated feeds require species‐specific optimization and an understanding of the interactions between key dietary components (e.g. protein, lipid, carbohydrate, energy and/or algal supplements). Here, we tested 18 formulated feeds on the sea urchin Heliocidaris erythrogramma, collected from barrens. The 18 iso‐energetic (~20 MJ/kg) feed combinations contained one of three protein levels (250, 375 or 500 g/kg), three lipid levels (73, 101 or 131 g/kg) combined with a single (45 g/kg Sargassum spp.) or multiple (45 g/kg Sargassum spp., 25 g/kg Solieria robusta, 25 g/kg Ulva lactuca) dried algal supplement. From two consecutive 12‐week enhancement trials, the most optimal feed type contained 375 g/kg protein, 73 g/kg lipid and a 45 g/kg algal supplement (Sargassum spp.) and produced gonad indices of 18.5 ± 0.4% (Trial 1) and 21.7 ± 1.2% (Trial 2). Across feed types, there was no significant difference in the proportion of marketable quality (A and B grade) roe produced (56%–85% Trial 1, 65%–85% Trial 2). We conclude that roe enhancement of H. erythrogramma collected from barrens is highly feasible.

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Aquaculture-derived trophic subsidy boosts populations of an ecosystem engineer

Cited by 14 publications

References 59 publications

Effect of Aquaculture-Related Diets on the Long-Term Performance and Condition of the Rock Crab, Cancer irroratus

Effect of Aquaculture-Related Diets on the Long-Term Performance and Condition of the Rock Crab, Cancer irroratus

Fate and effects of fish farm organic waste in marine systems: Advances in understanding using biochemical approaches with implications for environmental management

The balancing act: Protein, lipid and seaweed dietary levels to maximize gonad quantity in a wild‐caught sea urchin

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