Sex-dependent diel vertical migration in northern krill Meganyctiphanes norvegica and its consequences for population dynamics

Tarling, Geraint A.

doi:10.3354/meps260173

Cited by 41 publications

(44 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We are confident that both sexes are the same age, since they were the same size as in the population study of Boysen and Buchholz (1984) and in the Clyde Sea study of Tarling (2003) when cohorts were followed over a complete annual cycle. This means that growth increments (GIs) at moult must be different between sexes.…”

Section: The Body Length Of Males and Femalesmentioning

confidence: 95%

“…It may be through this means that they obtain enough food to avoid the allocation conflict between growth and reproduction that could affect the relative growth rates of males and females in crustaceans (Hartnoll 1985;Conan 1985). However, high feeding rates are achieved at the cost of greater exposure to predation risk (Tarling 2003). This may explain why, as a rule, numbers of females are smaller than those of males.…”

Section: The Body Length Of Males and Femalesmentioning

confidence: 96%

See 1 more Smart Citation

On the timing of moulting processes in reproductively active Northern krill Meganyctiphanes norvegica

2006

View full text Add to dashboard Cite

The interactions between moult phasing, growth and environmental cues in Northern krill (Meganyctiphanes norvegica) were examined through analysing populations at seasonal, weekly, and daily timescales. The analyses were carried out on resident populations of krill found in three different neritic locations that experience similar environmental signals (the Clyde Sea, Scotland; the Kattegat, Denmark; Gullmarsfjord, Sweden). Seasonal analyses were carried out on the Clyde Sea population and showed that moulting frequency increased significantly moving from winter to summer. The proportion of moulting females in summer samples was often more than double the proportion of moulting males, suggesting that females had a comparatively shorter intermoult period (IMP). Weekly samples taken from the Kattegat showed a similar pattern. However, although the difference between the proportion of female and male moulters was significant in one week, it was not another, mainly because of the variability in the proportion of female moulters. Such variability in females was equally evident in the daily samples taken at Gullmarsfjord. It suggests that females have a shorter IMP (12.5 days) than males (18.4 days) and are more likely to moult in synchrony. Nevertheless, the daily samples revealed that males are also capable of moult synchronisation, although less frequently than females. Shortened IMPs in females were not a result of the abbreviation of specific moult stages. Accordingly, reproductive activity did not alter the course of the normal moult cycle. There was no significant difference between the total body lengths of males and females indicating that females achieve the same levels of growth despite moulting more frequently and having to provision the energy-rich ovaries. This is in contrast to most other crustaceans where the energy costs of reproduction reduce female growth. The fact that females were less abundant than males, probably by suffering a greater level of mortality, suggests that different behavioural strategies, particularly vertical migration regimes, were adopted by each sex to maximise growth and reproduction.

show abstract

Section: The Body Length Of Males and Femalesmentioning

confidence: 95%

Section: The Body Length Of Males and Femalesmentioning

confidence: 96%

On the timing of moulting processes in reproductively active Northern krill Meganyctiphanes norvegica

2006

View full text Add to dashboard Cite

show abstract

“…In Antarctic krill, it was demonstrated that males grow faster but die younger than females (Kawaguchi et al 2007), and this pattern might also hold for tropical species under mixed column water conditions. Tarling (2003) mentioned that selective mortality, either through physiological differences between sexes or sex-specific predation, is the major factor responsible for the substantial sex ratio variability in Meganyctiphanes norvegica. Hill et al (1996) also found evidence that males of E. superba in the northwest of South Georgia evade nets and predators such as macaroni penguins Eudyptes chrysolophus more efficiently than females.…”

Section: Seasonal/interannual Variability Of Tropical Euphausiidsmentioning

confidence: 99%

“…Previous krill studies in the ETP have been realized from single oceanographic cruises (Brinton 1979, Färber-Lorda et al 1994, Gómez-Gutiérrez & Hernández-Trujillo 1994. Relatively more extensive studies about euphausiid biology and ecology have been performed on both sides of the Baja California peninsula (Brinton 1962, 1981, Brinton & Townsend 1980, 2003, Brinton et al 1986, Lavaniegos 1994). …”

Section: Introductionmentioning

confidence: 99%

Influence of coastal upwelling−downwelling variability on tropical euphausiid abundance and community structure in the inshore Mexican central Pacific

Ambriz-Arreola

Gómez‐Gutiérrez

Franco-Gordo

et al. 2012

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The effect of wind-induced coastal upwellings on tropical euphausiid abundance and community structure was investigated in the Mexican central Pacific (19°N, 105°W) during a monthly time series (1996−1998). Eight species were identified, of which Euphausia distinguenda contributed between 88 and 90% of the total euphausiid abundance, and E. lamelligera con tributed ~7%. The hydrographic structure (< 200 m depth) and euphausiid species composition had strong seasonality patterns associated with the upwelling (February to May) and downwelling (July to November) periods. Redundancy analysis of euphausiid abundance and community structure as a function of the environmental variables revealed that coastal upwelling index, salinity at 10 m depth, and temperature explained most of the euphausiid abundance variability. Stations sampled during intense upwelling periods had the highest abundance of E. distinguenda and E. lamelligera juveniles and adults. Their abundance was strongly and positively correlated with salinity and abundance of nano-and microphytoplankton, but was negatively correlated with surface temperature. Larvae of E. distinguenda and the oceanic species Nematoscelis gracilis (downwelling ensemble) were strongly associated with warm waters of low phytoplankton abundance. The hepato-somatic index (ratio of hepatopancreas length to carapace length) of E. distinguenda and E. lamelligera adults was significantly larger during mixed and semi-mixed than during stratified periods, providing a useful proxy for euphausiid health and trophic condition. Wind-induced upwelling−downwelling are significant coastal processes that influenced seasonal euphausiid abundance and species composition in this tropical ecosystem, while the strong and brief El Niño event of 1997−98 had only a relatively moderate effect in comparison with that observed on euphausiids from transitional (northwest of Mexico) and temperate (Pacific USA) ecosystems.

show abstract

“…Comparison between summer distribution of large whale species in the Gulf (solid white circles) from the only systematic survey made (1995 and 1996 aerial survey by Kingsley & Reeves 1998) and averaged simulated abundance of zooplankton during July and August 1997. Whale species comprise blue, fin, and humpback (see Kingsley & Reeves 1998 for more details) 1993, Buchholz et al 1995, Bergström & Strömberg 1997, Onsrud & Kaartvedt 1998, Pearre 2003, Tarling 2003. Although krill cross the thermocline (Simard et al 1986b), their particular location in relation to this boundary (and particularly the exact duration of their stay above it, where mean currents are stronger and outflowing) are not well known and have not been considered in any model.…”

Section: Sensitivity To Biological Parametersmentioning

confidence: 99%

Krill aggregation in the St. Lawrence system, and supply of krill to the whale feeding grounds in the estuary from the gulf

Sourisseau¹,

Simard²,

Saucier³

2006

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Persistent high-density krill aggregations make the St. Lawrence Estuary and the Gulf of St. Lawrence important feeding-grounds for large marine mammals. To estimate the effects of the circulation on the seasonal krill distribution, a krill biomass-concentration equation with active vertical migration was coupled to a 3D regional sea ice-ocean circulation model. The results show recurrent spatial patterns of aggregation and advection controlled by the circulation and a high sensitivity to the parameters of the biological model. The time spent in the surface layer is crucial for the retention of organisms in the estuary. The simulated krill aggregation areas are associated with 3 processes (tidal interactions with bathymetry, wind-driven upwelling and mean circulation). Zooplankton generally aggregate near the edges of the Laurentian Channel and other secondary channels, at locations that are consistent with the sparse synoptic information on the distributions of large marine mammals in the gulf. The simulations also indicate that changes in the seasonal circulation significantly affect the krill distribution within the gulf through gyre intensities, the seasonal thermocline and the strength of the estuarine circulation. Finally, the variability of zooplankton transport to the estuary from the gulf appears to be controlled by processes acting on the circulation mode at the mouth of the estuary and estuarine pumping of the krill layer towards the head of the Laurentian Channel. The simulated krill biomass imported into the estuary changed by a factor of 2 over the 3 simulated years.

show abstract

Sex-dependent diel vertical migration in northern krill Meganyctiphanes norvegica and its consequences for population dynamics

Cited by 41 publications

References 36 publications

On the timing of moulting processes in reproductively active Northern krill Meganyctiphanes norvegica

On the timing of moulting processes in reproductively active Northern krill Meganyctiphanes norvegica

Influence of coastal upwelling−downwelling variability on tropical euphausiid abundance and community structure in the inshore Mexican central Pacific

Krill aggregation in the St. Lawrence system, and supply of krill to the whale feeding grounds in the estuary from the gulf

Contact Info

Product

Resources

About