Dynamics of planktivory in a coastal area of the northern Baltic Sea

Rudstam, Lars G.; Hansson, Sture; Johansson, Sofia; Larsson, Ulf

doi:10.3354/meps080159

Cited by 115 publications

(98 citation statements)

References 32 publications

(34 reference statements)

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“…This is in agreement with previous studies on sprat from the North Sea (De Silva 1973;Last 1987), Oslofjorden (Brun 2007;Kaartvedt et al 2009) and the Baltic (Coombs et al 1992;Rudstam et al 1992Rudstam et al , 1994Arrhenius 1996;Casini et al 2004;Mö llmann et al 2004;Bernreuther 2007). Similar to studies from the North Sea, fjord sprat had a diverse diet including copepods, cladocerans, appendicularians, eggs and meroplanktonic larvae.…”

Section: Diet Compositionsupporting

confidence: 82%

Diet composition and food selectivity of sprat (Sprattus sprattus) in Hardangerfjord, Norway

Falkenhaug

Dalpadado

2013

Marine Biology Research

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The diet composition and prey selection of sprat (Sprattus sprattus) was studied in the Hardangerfjord, western Norway during four cruises in spring and autumn of 2009 and 2010. Feeding activity, indicated by stomach fullness, varied with sprat size, season and time of day. Small-sized sprat were found to feed both in spring and autumn, while the larger individuals had lower feeding activity late in the season. Diurnal variation in stomach fullness was observed in the autumn but not in spring. Sprat fed on a broad diversity of prey types, including copepods, phytoplankton and meroplankton. Multivariate statistical analysis suggested that the dietary composition of sprat differed significantly between years, seasons and among areas within the fjord. During spring, phytoplankton and invertebrate eggs dominated the diet, while copepods were most important in the autumn. Positive selection was found for Microsetella norvegica and euphausiid eggs, which were the most frequently occurring prey in stomachs, followed by Oithona and Acartia spp. Interannual variability in zooplankton abundance in the fjord, related to physical processes, may have a large impact on the feeding conditions for fjord populations of sprat.

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Section: Diet Compositionsupporting

confidence: 82%

Diet composition and food selectivity of sprat (Sprattus sprattus) in Hardangerfjord, Norway

Falkenhaug

Dalpadado

2013

Marine Biology Research

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“…Investigations on the food consumption by planktivores in a coastal area of the Baltic have revealed a simultaneous increase in planktivory and decrease in zooplankton biomass in late summer (Rudstam et al, 1992). Rudstam et al (1994) inferred that planktivory by clupeids contributes to the decline in zooplankton in late summer, thus acting as a seasonal top-down force.…”

Section: Discussionmentioning

confidence: 99%

Food consumption by clupeids in the Central Baltic: evidence for top-down control?

Möllmann¹

1999

ICES Journal of Marine Science

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Considerable changes have taken place in the pelagic ecosystem of the Central Baltic Sea during the last decade. Owing to a combination of high fishing pressure and unfavourable hydrographic conditions, the cod (Gadus morhua) stock as the top predator in the system was reduced from a high level in the early 1980s to its lowest size on record in the early 1990s. The preferred prey species sprat (Sprattus sprattus) showed a significant increase in population size since the late 1980s to the highest level on record in recent years, while the herring (Clupea harengus), another important planktivore in the system, did not show such a response. We investigate whether fluctuations in clupeid stock size cascade down to the trophic level of mesozooplankton, based on stomach content data and daily ration estimates in combination with stock sizes estimated from Multispecies Virtual Population Analysis. Estimates of daily consumption by the populations of the two species for 1978–1990 were compared with standing stocks of mesozooplankton species. No evidence was found for food limitation as might be expected if clupeids exert a strong top-down control on mesozooplankton. Also no influence on interannual variability of mesozooplankton abundance was detected. However, predation did contribute to the seasonal development of two copepod species (Pseudocalanus elongatus and Temora longicornis).

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“…This also implies that herring populations are able to control zooplankton biomass. However, although ca 70 % of the annual zooplankton production is estimated to be consumed by herring in the northern Baltic (Hansson et al 1990, Rudstam et al 1992, Arrhenius 1995, there is no evidence that Baltic zooplankton biomass are affected by interannual variations in herring stocks (Rudstam et al 1994). This apparent discrepancy can be explained by our findings, which suggest that herring feeding is not Limited by the total amount of zooplankton, but by the availability of suitably sized plankters.…”

Section: Top-down or Bottom-up Control Of Herring Growth?mentioning

confidence: 99%

Changes in northern Baltic zooplankton and herring nutrition from 1980s to 1990s:top-down and bottom-up processes at work

Flinkman¹,

Aro²,

Vuorinen³

et al. 1998

Mar. Ecol. Prog. Ser.

138

116

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During the stagnation period of the Baltic Sea the mean weight-at-age of Baltic herring decreased by 50% (between 1977 and 1992). This has usually been attributed to a top-down process, i.e. to the simultaneous collapse of cod stocks and their predation. We present long-term data for 1980 to 1993 showing that bottom-up effects may also have played a role: along with the decline of salinity. the biomass proportion of zooplankton taxa preferred by herring (larger than 20 pg ind:' in wet welght) significantly declined. To support our hypothesis we present a study in which Baltic herring feeding and selective predation were investigated during 1985, a time of good growth and high weightat-age, and 1991, when herring growth and weight-at-age were poor. In this study, herring ston~achs and simultaneously taken plankton samples were analysed from trawl surveys conducted in the northern Baltic proper d'uring the peak of the herring feeding season in late summer. During both 1985 and 1991, herring selectively preyed on the larger zooplankton categones, especially neritic copepods. However, in 1991, a smaller proportion of the prey in herring stomachs consisted of neritic copepods, apparently because their share in plankton had decreased. Consequently, and despite an increase in total zooplankton biomass, the estimated carbon content of the food eaten by herring was lower, and the average stomach fullness index (on a scale of 0 to 5) decreased from 3.9 in 1985 to 1.9 in 1991. Also, the amount of mesenteric fat on herring stomachs declined from 4.2 to 3.2 (scale 0 to 5), indicating a longer-term failure in feeding success. We suggest that, in addition to possible top-down effects (a release of cod predation), bottom-up processes mediated via changes in mesozooplankton species composition have also influenced hernng growth and that both of these processes are affected by the same environmental factor-the Baltic salinity level.

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Dynamics of planktivory in a coastal area of the northern Baltic Sea

Cited by 115 publications

References 32 publications

Diet composition and food selectivity of sprat (Sprattus sprattus) in Hardangerfjord, Norway

Diet composition and food selectivity of sprat (Sprattus sprattus) in Hardangerfjord, Norway

Food consumption by clupeids in the Central Baltic: evidence for top-down control?

Changes in northern Baltic zooplankton and herring nutrition from 1980s to 1990s:top-down and bottom-up processes at work

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