The impact of climate change on the adaptation of marine fish in the Baltic Sea

Ojaveer, Evald; Kalejs, Margers

doi:10.1016/j.icesjms.2005.08.002

Cited by 51 publications

(46 citation statements)

References 15 publications

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“…Deep-water oxygen concentration and cod yearclass strength were clearly correlated during the period from 1958 to 1988 (Jansson, 2003). The expansion of oxygendeficient bottom water has caused strong shifts within the food web so that marine fishes (cod, sprat, herring) are impacted by both a loss in spawning area and a change of prey spectra in the Baltic Sea (Ojaveer and Kalejs, 2005). Commercial fisheries follow these changes, but normally with a phase-delay of a few years to adapt fishing gear and method.…”

Section: Baltic Seamentioning

confidence: 99%

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

et al. 2010

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Abstract. Dissolved oxygen (DO) concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species-and stagespecific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 mL O 2 L −1 through impacted growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 mL O 2 L −1 . A change in the average or the range of DO may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity.Evidence for the deleterious effects of oxygen depletion on pelagic species is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with variable DOs and exploit adaptive mechanisms, nektonic species may avoid areas of unfavourable DO and develop adapted migration strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ). In shallow areas only the surface layer can serve as a refuge, but in deep waters many organisms have developed vertical migration strategies to use, pass through and cope with the OMZ.Correspondence to: W. Ekau (wekau@zmt-bremen.de) This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity. We describe processes in two contrasting systems, the semi-enclosed Baltic Sea and the coastal upwelling system of the Benguela Current to demonstrate the consequences of increasing hypoxia on ecosystem functioning and services.

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Section: Baltic Seamentioning

confidence: 99%

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

et al. 2010

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“…The colonisation by marine species in the Baltic Sea is believed to have been achieved as a result of specific adaptations to life in a marginal environment (e.g. Ojaveer & Kalejs 2005). In the North Sea-Baltic Sea transition zone salinity levels are expected to exert a significant selective pressure on local populations although other environmental factors, such as temperature dynamics, are also expected to play a role.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, it has been shown that Baltic (Atlantic) cod Gadus morhua L. tolerate lower salinities during egg fertilisation and the egg phase compared with populations from the Skagerrak (Nissling & Westin 1997). Timing of spawning also seems to conform to spatial and temporal production peaks (Tomkiewicz et al 1998, Ojaveer & Kalejs 2005.…”

Section: Introductionmentioning

confidence: 99%

Genetic population structure of European sprat Sprattus sprattus: differentiation across a steep environmental gradient in a small pelagic fish

Limborg

Pedersen²,

Hemmer‐Hansen³

et al. 2009

Mar. Ecol. Prog. Ser.

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Factors such as oceanographic retention, isolation by distance and secondary contact zones have, among others, been suggested to explain the low, but statistically significant, neutral population structure observed in many marine fishes. European sprat Sprattus sprattus L. is not known to display philopatric spawning behaviour or to exhibit local retention of eggs and larvae. It thus constitutes a good model for studying population structure in a characteristic small pelagic fish with high dispersal potential and an opportunistic life history. We analysed 931 specimens of sprat from 9 spawning locations in and around the North Sea and Baltic Sea area and from a geographically distant population from the Adriatic Sea. Analyses of 9 microsatellite loci revealed a sharp genetic division separating samples from the northeastern Atlantic Ocean and the Baltic Sea (pairwise θ = 0.019 to 0.035), concurring with a steep salinity gradient. We found, at most, weak structure among samples within the northeastern Atlantic region and within the Baltic Sea (pairwise θ = 0.001 to 0.009). The Adriatic Sea population was highly differentiated from all northern samples (pairwise θ = 0.071 to 0.092). Overall, the observed population structure resembles that of most other marine fishes studied in the North and Baltic Sea areas. Nevertheless, spatially explicit differences are observed among species, probably reflecting specific life histories. Such fine-scale population structures should be taken into account when considering complex ecosystem functions, e.g. in multispecies stock management.

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“…KEY WORDS: Sprat · Overwintering · 'Rise and sink' swimming · Schooling · Ice cover 464: 245-256, 2012 Populations of sprat are also present in environments that may be covered with ice, e.g. the Baltic Sea and some Norwegian fjords (Ojaveer & Kalejs 2005, Casini et al 2006). Ice will affect not only light conditions, but also the ability for this physostome fish to ascend to the surface for gulping air in order to fill its swimbladder (Blaxter & Batty 1984).…”

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Continuous acoustic studies of overwintering sprat Sprattus sprattus reveal flexible behavior

Solberg

Klevjer²,

Kaartvedt³

2012

Mar. Ecol. Prog. Ser.

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The clupeid fish Sprattus sprattus was studied in a 150 m deep Norwegian fjord throughout an entire overwintering period during which the fjord froze over and a major water renewal occurred. A bottom-mounted (upward-facing) echosounder provided continuous highresolution data and enabled studies of swimming speed and behavior of individual sprat in addition to population behavior. The continuous acoustic studies were supplemented with intermittent field campaigns. The sprat displayed different behavioral modes with changing environmental conditions. During the first part of the winter, the majority of the population occurred in deep waters during both day and night, yet exhibited a shallower night-time distribution. Individual sprat swam alternately up and down, a 'rise and sink' behavior likely a compensation for negative buoyancy because of swim bladder compression. Because feeding was negligible in deep waters, the swimming pattern was not inferred as prey search behavior. Another part of the population schooled at shallower depths during the day and carried out vertical migration to upper waters at night. However, individuals were observed as they switched between these behavioral groups. A sudden change in both swimming behavior and vertical distribution occurred as the fjord became ice covered. Near-bottom 'rise and sink' swimming was replaced by schooling in midwater during the day, and the sprat aggregated in dense layers near the surface at night. We suggest that the ice made the sprat shift their antipredator strategy from hiding at depth to hiding in schools in the darker waters below the ice. This long-term acoustic study has shown that sprat have a flexible behavioral repertoire, displaying different overwintering strategies within a population, depending on environmental conditions. KEY WORDS: Sprat · Overwintering · 'Rise and sink' swimming · Schooling · Ice cover 464: 245-256, 2012 Populations of sprat are also present in environments that may be covered with ice, e.g. the Baltic Sea and some Norwegian fjords (Ojaveer & Kalejs 2005, Casini et al. 2006). Ice will affect not only light conditions, but also the ability for this physostome fish to ascend to the surface for gulping air in order to fill its swimbladder (Blaxter & Batty 1984). There are, however, no studies on how ice covering may affect the overwintering sprat. Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESSMar Ecol Prog SerThe inner part of the Oslofjord is easily accessible for long-term acoustic measurements. In the present study we took advantage of this to continuously monitor a population of sprat throughout a whole overwintering period. We deployed an echosounder, cabled to shore, at the bottom of the fjord during a winter where waters were hypoxic, yet sufficiently oxygenated for the sprat to inhabit the whole water column. Because the echosounder was situated at the bottom, it provided high-resolution data of acoustic targets in deep waters, enabling studies of ...

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The impact of climate change on the adaptation of marine fish in the Baltic Sea

Cited by 51 publications

References 15 publications

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

Genetic population structure of European sprat Sprattus sprattus: differentiation across a steep environmental gradient in a small pelagic fish

Continuous acoustic studies of overwintering sprat Sprattus sprattus reveal flexible behavior

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