Predation on Euphausia pacifica by demersal fishes: predation impact and influence of physical variability

Yamamura, Orio; Inada, Tadashi; Shimazaki, Kazunori

doi:10.1007/s002270050386

Cited by 32 publications

(40 citation statements)

References 23 publications

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“…pacifica is the dominant euphausiid species in the subarctic northwestern North Pacific, 11) and plays an important role in transferring energy from lower to higher tropic levels in the sea because many predators depend on this species for food. 12,13) It was reported that the water-soluble extract of E. pacifica prevented triglyceride accumulation in adipocytes by suppression of two master regulators of adipocyte differentiation. 14) Obesity is a major health problem and a cause of metabolic syndrome.…”

Section: Discussionmentioning

confidence: 99%

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Beneficial Effects by Intake of <i>Euphausiacea pacifica</i> on High-Fat Diet-Induced Obesity

Sadzuka

Sugiyama

Miyashita

et al. 2012

Biological & Pharmaceutical Bulletin

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Obesity is a major health problem showing increased incidence in developed and developing countries. We examined the effect of Euphausia pacifica (E. pacifica) (Pacific Krill) on high-fat diet (HFD)-induced obesity in C57BL/6 mice. No significant differences were observed in average food intake between the HFD and HFD with E. pacifica group, or the low-fat diet (LFD) and LFD with E. pacifica group for 18 weeks. The increased ratio of body weight in the HFD containing E. pacifica group was significantly reduced, being 10% lower than that with HFD group in the 18th week (HFD, 298.6 18.8% vs. HFD with E. pacifica, 267.8 16.2%; p<0.05), while the ratio for the LFD containing E. pacifica group was reduced by 4% compared with LFD group (LFD, 244.2 11.6% vs. LFD with E. pacifica, 234.1 18.0%). There were no effects of E. pacifica on total cholesterol levels in serum and liver, whereas the supplement of E. pacifica tended to decrease triglyceride levels in the HFD groups. The leptin level in serum was significantly decreased in the HFD group (p<0.01) by E. pacifica. The adipocyte area (1926 1275 μm 2 ) in the HFD containing E. pacifica group was significantly reduced by 20% (p<0.001) compared with the HFD group. These results suggested that E. pacifica supplementation in the diet is beneficial for the prevention of HFD-induced obesity.Key words Euphausia pacifica; obesity prevention; leptin; triglyceride; high-fat diet Obesity is a major health problem, 1) and its incidence has increased by the over-intake of calorie-rich diets and exerciselacking lifestyles in developed and developing countries. 2),3) The prevalence varies from 12 to 41%. 4) Metabolic syndrome is a cluster of metabolic abnormalities consisting essentially of obesity, especially abdominal obesity. Furthermore, metabolic syndrome is a risk factor for type 2 diabetes, 5) cardiovascular, 6) dyslipidemia and hypertension. 7,8) Thus metabolic syndrome is a major health problem that must be resolved. Although it is important to improve physical activity and dietary habits to reduce obesity, it is really difficult to reduce body weight. Current anti-obesity drugs have safety issues, 9,10) so a safe anti-obesity drug is strongly required. On the other hand, if some foods show an anti-obesity effect, it is considered that they should be non-toxic and safe for humans.Euphausia pacifica (E. pacifica) (Pacific Krill) (Fig. 1) is the dominant euphausiid species in the subarctic North Pacific and also broadly distributes in far eastern sea area. 11) It plays an important role in the marine food chain and many predators depend on this species for food. 12,13) E. pacifica has been studied for morphology and ecology, 12) whereas there are few reports on the physiological and pharmacological effects. E. pacifica contains mineral (4.0%), lipid (1.8%), protein (19.1%), vitamin (0.8%) and so on and is used in some rice crackers, pasta relish, rice and some noodles and seasonings in Japan. However, most E. pacifica is not an effective use, because only feed for cultured fish...

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Section: Discussionmentioning

confidence: 99%

“…12,13) E. pacifica has been studied for morphology and ecology, 12) whereas there are few reports on the physiological and pharmacological effects. E. pacifica contains mineral (4.0%), lipid (1.8%), protein (19.1%), vitamin (0.8%) and so on and is used in some rice crackers, pasta relish, rice and some noodles and seasonings in Japan.…”

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confidence: 99%

Beneficial Effects by Intake of <i>Euphausiacea pacifica</i> on High-Fat Diet-Induced Obesity

Sadzuka

Sugiyama

Miyashita

et al. 2012

Biological & Pharmaceutical Bulletin

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“…As herbivores they can play a critical role as direct vectors of phytoplankton toxins to higher trophic levels in pelagic food webs. The principal predators of Pacific euphausiids are planktivorous fishes (Chess et al 1988, Starr et al 1998, Yamamura et al 1998, squid (Morejohn et al 1978), baleen whales (Ponomareva 1966, Schoenherr 1991, Fiedler et al 1998, and some seabirds such as Cassin's auklets (Ainley et al 1996). Previous studies have shown that krill feed on toxic Pseudo-nitzschia spp.…”

Section: Introductionmentioning

confidence: 99%

Effect of dissolved domoic acid on the grazing rate of krill Euphasia pacifica

Bargu¹,

Lefebvre²,

Silver³

2006

Mar. Ecol. Prog. Ser.

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Some amino acids released from phytoplankton into the water are known to be feeding stimulants to zooplankton. However, domoic acid (DA), a neuroexcitatory amino acid released by some species of the diatom genus Pseudo-nitzschia, has the potential to be a feeding deterrent due to its neurotoxicity. Euphausiids (krill) are important members of the zooplankton grazer community and key prey items for many high level carnivores in the world's oceans. Although it is known that krill do consume toxic Pseudo-nitzschia spp. during blooms, there is currently no information concerning the effect of dissolved DA on the rate of feeding or the grazing behavior of krill. Therefore, we conducted experiments in which Euphausia pacifica were fed non-toxic P. pungens along with different added levels of either dissolved DA or glutamic acid (GA), an amino acid with a similar structure to DA. Krill grazing rates did not change significantly with added GA, but decreased significantly in the presence of DA. The rapid response of krill to dissolved DA suggests that either direct toxic action on the filtering apparatus or a chemoreceptor-like mechanism may suppress grazing in the krill. We suggest that these dissolved DA concentrations are relevant, given the DA concentrations found in Pseudo-nitzschia spp. populations in Monterey Bay and the feeding biology of krill. In either case, the suppression of feeding by dissolved DA suggests that high dissolved DA concentrations, should they occur in the field, may be a mechanism whereby blooms are perpetuated due to reduced losses to grazers such as krill.

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“…They are a common prey for many marine organisms ranging from fish to whales. Pelagic fishes such as Pacific herring, salmon and the Pacific hake (Yamamura et al 1998), and seabirds such as Cassin's auklet and ashy storm petrel (Ainley et al 1996) can feed heavily on krill in Monterey Bay. In addition to pelagic predators, demersal fish such as Pacific cod and rockfish feed directly on E. pacifica, which is found normally at greater depths during the day (Chess et al 1988).…”

Section: Introductionmentioning

confidence: 99%

Krill: a potential vector for domoic acid in marine food webs

Bargu¹,

Powell²,

Coale³

et al. 2002

Mar. Ecol. Prog. Ser.

100

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Over the past decade, blooms of the domoic acid (DA) producing diatom Pseudonitzschia have been responsible for numerous deaths of marine mammals and birds in Monterey Bay, California. Euphausiids (krill) are important members of the local zooplankton grazer community and comprise the primary diet of squid, baleen whales, and many seabirds. Krill are thus a key potential vector for the transfer of DA to higher trophic level organisms in Monterey Bay. A better understanding of the quantitative trophic interactions and body burden of DA in krill is required to predict whether they can act as an effective vector for this neurotoxin. Here we report results of toxin analyses and gut content examinations of krill Euphausia pacifica collected from Monterey Bay in 2000. Corresponding counts of toxic Pseudo-nitzschia species in the water and their cellular DA concentrations were also obtained at the collection sites. Toxin analysis by receptor binding assay demonstrated that DA in krill tissue varied between 0.1 to 44 µg DA equiv. g -1 tissue (confirmed by tandem mass spectrometry), with levels corresponding to the abundance of toxic Pseudo-nitzschia species present in the water. The occurrence of Pseudo-nitzschia australis frustules in the digestive tract of E. pacifica verified that a toxic species of this diatom was an important part of their diet and thus implicated this phytoplankter as the source of DA. These findings provide compelling evidence for the role of krill as a potential transfer agent of the phycotoxin DA to higher trophic levels in marine food web. 237: 209-216, 2002 toxigenic species of the diatom Pseudo-nitzschia to sea lions and seabirds. The first major event occurred in 1991, when more than 200 brown pelicans and Brandt's cormorants were found dead on the beaches of Monterey Bay (Fritz et al. 1992, Work et al. 1993. Similarly, Monterey Bay was the site of another major DA poisoning incident in 1998, when sea lions were observed dying on the beaches suffering from neurological symptoms (Lefebvre et al. 1999, Scholin et al. 2000. In all DA poisoning events in this region, Pseudo-nitzschia australis was determined to be the primary source of the toxin, and filter-feeding anchovies Engraulis mordax the apparent vector. Anchovies are not the only potential filter-feeding vectors of DA in the Monterey Bay system. For example, zooplankton are generally key consumers of phytoplankton. Nonetheless, while the link between zooplankton and toxic dinoflagellates has been confirmed (e.g. White 1981, Huntley et al. 1986, Ives 1987, McClatchie 1988, Uye & Takamatsu 1990, Turriff et al. 1995, Bagoien et al. 1996, Teegarden & Cembella 1996, Shaw et al. 1997, Turner & Tester 1997, Tester et al. 2000, there has been less attention focused on toxin transfer between toxic diatoms and zooplankton grazers (Windust 1992, Tester et al. 2001, Lincoln et al. 2001. KEY WORDS: Krill · Pseudo-nitzschia · Domoic acid · Harmful algal blooms · Toxic algae · Trophic transfer · Food webs Resale or republication not p...

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Predation on Euphausia pacifica by demersal fishes: predation impact and influence of physical variability

Cited by 32 publications

References 23 publications

Beneficial Effects by Intake of <i>Euphausiacea pacifica</i> on High-Fat Diet-Induced Obesity

Beneficial Effects by Intake of <i>Euphausiacea pacifica</i> on High-Fat Diet-Induced Obesity

Effect of dissolved domoic acid on the grazing rate of krill Euphasia pacifica

Krill: a potential vector for domoic acid in marine food webs

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