| 1. |
- Carroll, J. M., et al.
(författare)
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Scaredy-Oysters: In Situ Documentation of an Oyster Behavioral Response to Predators
- 2019
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Ingår i: Southeastern Naturalist. - : Humboldt Field Research Institute. - 1528-7092. ; 18:3
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Tidskriftsartikel (refereegranskat)abstract
- Non-consumptive effects of predators on prey populations have received increased interest in recent years. For Crassostrea virginica (Eastern Oyster), much of the focus has been on induced morphological defenses (e.g., shell thickening). Here, we provide in situ documentation of a behavioral response of Eastern Oysters (valve closure) to the threat of predation on a natural reef. This behavioral response, while intuitive, has been largely ignored in the literature despite potential impacts on individual oyster health by affecting feeding and subsequently energy assimilation, reproductive condition, and growth. In situ photographs revealed that, under natural conditions, Eastern Oysters closed during the passive presence of a crab mate-guarding pair and took similar to 5 minutes to reopen to pre-predator gapes. Given that multiple oysters in our photos reacted similarly, this behavioral response may scale up to have effects on the population and the ecosystem services that Eastern Oysters provide. Ultimately, our observations open the door to a number of testable hypotheses regarding a predator's non-consumptive effects on oyster reefs.
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| 2. |
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| 3. |
- Clements, Jeff C., et al.
(författare)
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Nitrogen removal potential of shellfish aquaculture harvests in eastern Canada: A comparison of culture methods
- 2019
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Bivalve farming can contribute to nutrient removal in coastal and estuarine systems, as bivalves directly incorporate nutrients into their tissues and shells. We conducted a meta-analysis to compare the nitrogen removal potential (NRP; i.e., percentage of nitrogen in tissues and shells) of mussels, Mytilus edulis, and oysters, Crassostrea virginica. We then used species-specific NRPs to determine and compare the total and per-hectare NRPs for four shellfish aquaculture methods used in two Atlantic Canadian provinces – New Brunswick (NB) and Prince Edward Island (PEI) – based on current harvest biomasses. Finally, we determined the contribution of current shellfish farming to nitrogen load mitigation for a subset of bays in NB and PEI. Results revealed that on a per-weight basis, NRP was similar for the tissues of mussels and oysters, while mussel shells had a significantly higher percentage of nitrogen than oyster shells. Collectively, shellfish harvesting has the capacity to remove a mean annual total of 99088 kg and 204571 kg of nitrogen from NB and PEI, respectively. Given current harvesting practices for four culture methods employed in the region, suspended mussel culture provides the greatest NRP per hectare of farm area, followed in sequence by suspended mussel and oyster mixed culture, suspended oyster culture, and bottom oyster culture. Preliminary analysis suggested that harvests in the region typically remove <10% of the total nitrogen load on the bay scale, with the exception of bays where nitrogen loads are low and farming intensity is high (where shellfish harvesting can remove higher percentages of nitrogen loads). Ultimately, harvests from shellfish farming in NB and PEI have the capacity to remove substantial amounts of nitrogen from local bays. Future studies assessing the influence of shellfish farming on full nutrient budgets across bays with varying physicochemical conditions will enhance our understanding the role of shellfish farms in nearshore nutrient dynamics, both regionally and globally. © 2019
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| 4. |
- Clements, Jeff C., et al.
(författare)
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Ocean acidification and molluscan shell taphonomy: Can elevated seawater pCO(2) influence taphonomy in a naticid predator-prey system?
- 2018
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Ingår i: Palaeogeography Palaeoclimatology Palaeoecology. - : Elsevier BV. - 0031-0182. ; 507, s. 145-154
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Tidskriftsartikel (refereegranskat)abstract
- The size and frequency of gastropod drill holes in shells of their prey are common indicators of predator-prey ecology in the fossil record. Taphonomic processes occurring after predation, however, can influence the preservation of shells in a given fossil assemblage and can thus influence ecological inferences based on preserved shells. To determine if ocean acidification (OA) has the capacity to influence prey shell taphonomy in a gastropod drilling predation system, we tested for effects of elevated pCO(2) on dissolution rates, breakage force, and drill hole diameters in non-fragmented shells of two prey species of the cannibalistic naticid gastropod, Euspira heros. Drilled and non-drilled shells of Littorina littorea and E. heros were exposed to control (similar to 300 mu atm) and elevated (similar to 800 and 4000 mu atm) pCO(2) treatments for five weeks. Dry shell weight and drill hole diameter (outer and inner) were recorded for individual shells before and after exposure; the force required for shell breakage was recorded at the end of the exposure period. Shell mass loss in 800 and 4000 mu atm, respectively, were similar to 1 and 7% for E. heros, and similar to 0 and 4% for L. littorea, compared to similar to 0% in the control for both species. Shell breakage force was unaffected by elevated pCO(2), but was affected by species and drill hole presence, with E. heros shells requiring a force of similar to 220 and 269 Newtons in drilled and non-drilled shells, respectively, compared to similar to 294 and 415 Newtons in L. littorea. At 4000 mu atm, outer drill hole diameter significantly increased by similar to 12% for E. heros, while inner drill hole diameter significantly increased by similar to 13% in E. heros and similar to 10% in L. littorea. Ultimately, this study provides the first documentation of molluscan shell taphonomy in the context of OA for a gastropod drilling predation system and sets the stage for future research.
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