Indicator Assessment

Distribution shifts of marine species

Indicator Assessment

Prod-ID: IND-102-en

Also known as: CLIM 015

Published 20 Dec 2016 Last modified 04 Nov 2021

14 min read

Topics: Climate change adaptation Water and marine environment

This page was archived on 04 Nov 2021 with reason: No more updates will be done

Increases in regional sea temperatures have triggered a major northwards expansion of warmer water plankton and a northwards retreat of colder water plankton in the North-east Atlantic. This northerly movement has amounted to about 10 ° latitude (1 100 km) over the past 40 years, and it seems to have accelerated since 2000.
Sub-tropical species are occurring with increasing frequency in Europe’s seas, and sub-Arctic species are receding northwards.
Wild fish stocks are responding to changing temperatures and food supply by changing their distribution. This can have impacts on those local communities that depend on those fish stocks.
Further changes in the distribution of marine species, including fish stocks, are expected with the projected climate change, but quantitative projections of these distribution changes are not widely available.

Calanus ratio in the North Sea

Note: Continuous Plankton Recorder data

Data source:

Downloads and more info

Observed change in the distribution of demersal fish in response to observed rise in sea surface temperatures

Note: Changes in abundance in response to observed temperature change are relative changes (unitless).

Data source:

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Past trends

Increases in regional sea temperatures have triggered a major northwards movement of species. As a result, sub-tropical species are occurring with increasing frequency in European waters, and sub-Arctic species are receding northwards. However, in areas with geographical constraints, i.e. where a coastline hinders northwards movement, some species shift into deeper and cooler waters [i]. Some examples are provided below.

Plankton in the Greater North Sea have shown a northerly movement of about 10 ° latitude over the past 40 years. This corresponds to a mean polewards movement of around 250 km per decade, which appears to have accelerated since 2000 [ii]. As a result, the ratio of the coldwater Calanus finmarchicus to the warmwater Calanus helgolandicus copepod species has changed considerably over time (Figure 1). While C. helgolandicus is becoming more abundant in the North Sea, the overall Calanus biomass has declined by 70 % since the 1960s [iii]. Such rapid shifts in distribution range can reorganise marine species communities and have an impact on human communities that depend on them. For example, it has been shown that occurrences of European sprat are positively correlated with C. finmarchicus, while species such as Atlantic horse mackerel are positively correlated with C. helgolandicus [iv].

Benthic invertebrates are also shifting their distribution range as temperatures change in the Greater North Sea, but their response lags behind the temperature increase. Unless the individual species are able to withstand a change in thermal regime, this mismatch could lead to a drop in benthic diversity [v]. Such reorganisation will have an impact upon human communities and challenge traditional approaches to management of, for example fisheries, which have to consider species responses to temperature when planning future fishing opportunities [vi].

Very fast rates of northwards movement were observed in the coastal waters of southern Norway from 1997 and 2010. About 1 600 benthic marine species were found, and of these 565 species had expanded their distribution northwards along the coast, at rates of 500–800 km per decade [vii]. Phytoplankton and highly mobile pelagic species are the fastest migrating organisms; their migration rate can be an order of magnitude faster than those of terrestrial species [viii].

Increases in the surface temperature of the North Sea in recent decades have triggered establishment of warmwater swimming crabs, which in turn has allowed establishment of colonies of lesser black-backed gulls in Belgium and northern France [ix]. There is also evidence that the overwintering distributions of many water birds have changed. In recent decades, in response to warming, their distributions have shifted northwards and eastwards out of the United Kingdom [x].

In the eastern Mediterranean Sea, the introduction of warmwater and tropical alien species from the Red Sea has been exacerbated by observed warming, leading to a 150 % increase in the annual mean rate of species entry after 1998 [xi].

Impacts on fisheries

Climate change is also affecting fish stocks of commercial interest. Wild fish stocks seem to be responding to changing temperatures and food supply by changing their geographical distribution and their phenology. Mackerel and horse mackerel are spawning earlier in the English Channel, and both earlier and further north on the Porcupine Bank (off the west coast of Ireland). International commercial landings from the North-east Atlantic Ocean of fish species identified as ‘warm-adapted’ (e.g. grey gurnard, red mullet and hake) have increased by 250 % since the 1980s, while landings of cold-adapted species (e.g. cod, haddock and whiting) have halved [xii]. A striking example for the potentially large economic consequences of the northwards movement of marine species is the recent establishment of the Northeast Atlantic mackerel in Greenlandic waters. This temperature-sensitive epipelagic fish was first observed in Greenlandic waters in 2011, following record-high summer temperatures. Following the rapid development of a large-scale fishery, mackerel already contributed 23 % to the export value of all goods from Greenland in 2014 [xiii].

In the North-east Atlantic Ocean, 72 % of commonly observed fish species have responded to warming waters by changing their abundance and/or distribution (Figure 2). Traditionally exploited fish species have moved further northwards in the region, while new species have moved in, most likely as a result of a shift in the thermal regime. While warming can lead to an increase in fish biodiversity in a region, there is often a concurrent decrease in the size structure of the fish population. For example, in the Greater North Sea, the relatively small species sprat, anchovy and horse mackerel have increased in recent decades, whereas the larger species cod and plaice have decreased at their southern distribution limit [xiv]. This change may have important socio-economic consequences, as the stocks moving out tend to have a higher value than the stocks moving in. Pronounced changes in community structures and species interactions of demersal fish are projected over the next 50 years, as fish will experience constraints in the availability of suitable habitat [xv].

Global projections of changes in total catch of marine fish and invertebrates in response to ocean warming suggest a large-scale redistribution of global catch potential, with an increase in high-latitude regions and a decline in the tropics. In Europe, a considerable increase in catch potential is expected in the Arctic [xvi].

Projections

As sea surface temperatures increase, marine species will continue to seek out the most optimal temperature regime for their metabolic demands, thus leading to further northwards movement of marine species. However, quantitative projections are not widely available. Furthermore, non-indigenous species might become invasive if conditions favour their metabolic demands, while native species are weakened [xvii].

[i] Nicholas K. Dulvy et al., ‘Climate Change and Deepening of the North Sea Fish Assemblage: A Biotic Indicator of Warming Seas’,Journal of Applied Ecology 45, no. 4 (August 2008): 1029–39, doi:10.1111/j.1365-2664.2008.01488.x; T. Brattegard, ‘Endringer i norsk marin bunnfauna 1997-2010’, DN-utredning 8-2011 (Trondheim: Direktoratet for naturforvaltning, 2011), http://www.dirnat.no/content/500042260/Endringer-i-norsk-marin-bunnfauna-1997-2010; M. L. Pinsky et al., ‘Marine Taxa Track Local Climate Velocities’,Science 341, no. 6151 (13 September 2013): 1239–42, doi:10.1126/science.1239352.

[ii] Grégory Beaugrand, ‘Decadal Changes in Climate and Ecosystems in the North Atlantic Ocean and Adjacent Seas’,Deep Sea Research Part II: Topical Studies in Oceanography 56, no. 8–10 (April 2009): 656–73, doi:10.1016/j.dsr2.2008.12.022.

[iii] M. Edwards et al., ‘Global Marine Ecological Status Report: Results from the Global CPR Survey 2014/2015’, SAHFOS Technical Report (Plymouth, UK: SAHFOS Technical Report, 2016), https://www.sahfos.ac.uk/media/1289/gacs-status-11-high-res.pdf.

[iv] Ignasi Montero-Serra, Martin Edwards, and Martin J. Genner, ‘Warming Shelf Seas Drive the Subtropicalization of European Pelagic Fish Communities’,Global Change Biology 21, no. 1 (January 2015): 144–53, doi:10.1111/gcb.12747.

[v] Jan G. Hiddink, Michael T. Burrows, and Jorge García Molinos, ‘Temperature Tracking by North Sea Benthic Invertebrates in Response to Climate Change’,Global Change Biology 21, no. 1 (January 2015): 117–29, doi:10.1111/gcb.12726.

[vi] Louise A. Rutterford et al., ‘Future Fish Distributions Constrained by Depth in Warming Seas’,Nature Climate Change 5, no. 6 (13 April 2015): 569–73, doi:10.1038/nclimate2607.

[vii] Brattegard, ‘Endringer i norsk marin bunnfauna 1997-2010’.

[viii] Elvira S. Poloczanska et al., ‘Global Imprint of Climate Change on Marine Life’,Nature Climate Change 3, no. 10 (4 August 2013): 919–25, doi:10.1038/nclimate1958.

[ix] C. Luczak et al., ‘North Sea Ecosystem Change from Swimming Crabs to Seagulls’,Biology Letters 8 (4 July 2012): 821–24, doi:10.1098/rsbl.2012.0474.

[x] MCCIP,Marine Climate Change Impacts Report Card 2013, ed. M. Frost et al., Summary Report (Lovestoft: MCCIP, 2013), http://www.mccip.org.uk/media/1301/mccip-arc2013.pdf.

[xi] Dionysios E. Raitsos et al., ‘Global Climate Change Amplifies the Entry of Tropical Species into the Eastern Mediterranean Sea’,Limnology and Oceanography 55, no. 4 (2010): 1478–84, doi:10.4319/lo.2010.55.4.1478.

[xii] MCCIP,Marine Climate Change Impacts Report Card 2013.

[xiii] Teunis Jansen et al., ‘Ocean Warming Expands Habitat of a Rich Natural Resource and Benefits a National Economy’,Ecological Applications, 1 June 2016, n/a-n/a, doi:10.1002/eap.1384.

[xiv] A. L. Perry, ‘Climate Change and Distribution Shifts in Marine Fishes’,Science 308, no. 5730 (24 June 2005): 1912–15, doi:10.1126/science.1111322.

[xv] Rutterford et al., ‘Future Fish Distributions Constrained by Depth in Warming Seas’.

[xvi] William W.L. Cheung et al., ‘Projecting Global Marine Biodiversity Impacts under Climate Change Scenarios’,Fish and Fisheries 10, no. 3 (September 2009): 235–51, doi:10.1111/j.1467-2979.2008.00315.x; J.- P. Gattuso et al., ‘Contrasting Futures for Ocean and Society from Different Anthropogenic CO2 Emissions Scenarios’,Science 349, no. 6243 (3 July 2015): 4722, doi:10.1126/science.aac4722.

[xvii] Miranda C. Jones and William W. L. Cheung, ‘Multi-Model Ensemble Projections of Climate Change Effects on Global Marine Biodiversity’,ICES Journal of Marine Science: Journal Du Conseil 72, no. 3 (3 January 2015): 741–52, doi:10.1093/icesjms/fsu172.

Supporting information

Indicator definition

Ratio of Calanus species in the Greater North Sea
Observed change in the distribution of demersal fish in response to the observed rise in sea surface temperature

Units

Ratio (dimensionless)

Abundance response to temperature (dimensionless)

Rationale

Justification for indicator selection

Most marine organisms are ‘ectotherms’ that rely on the temperature of their environment to function optimally and are adapted to the temperature regime of their existing distribution range. Because of this relationship between the physical environment and species’ life requirements, the redistribution of species has emerged as one of the most significant and visible species responses to climate change.

Climate velocities (the rate and direction that isotherms shift through space) can be up to seven times higher in the ocean than on land. Combined with fewer dispersal barriers in the marine environment, this allows marine species to seek out optimal temperature regimes faster than most terrestrial species. Changes in species distribution can therefore be used as an indicator of climate change impacts in marine ecosystems, bridging the gap between observed changes in physical conditions of the sea and observed changes in biological parameters.

As the distribution and abundance of a species changes, so will the role of that particular species in the local or regional marine community. Changes in species distribution can, in turn, change the overall productivity and stability of the local ecosystem, thereby ultimately affecting the food available to (other) fish, birds and marine mammals.

Changes in species distribution will also create challenges for local communities that depend on fish stocks and other marine resources. For example, the recent mackerel dispute between the EU and the Faroe Islands was caused by the fact that the mackerel stock had increased the time it spent in the waters of the Faroe Islands rather than in EU waters. This caused a heated discussion on stock allocation between countries. Ultimately, it led to an increase in the Faroe Islands’ total allowable catch from 5 to 13 %, with further increases planned. Such disputes will most likely occur again as coldwater species retreat northwards. New opportunities may arise as new species come in from the south, but it is uncertain whether these will be of a similar commercial value to the receding ones.

In addition to changes in species distribution, rising sea surface temperatures are also causing changes in the phenology of marine species.

Scientific references

No rationale references available

Policy context and targets

Context description

In April 2013, the European Commission (EC) presented the EU Adaptation Strategy Package. This package consists of the EU Strategy on adaptation to climate change (COM/2013/216 final) and a number of supporting documents. The overall aim of the EU Adaptation Strategy is to contribute to a more climate-resilient Europe.

One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which will be achieved by bridging the knowledge gap and further developing the European climate adaptation platform (Climate-ADAPT) as the ‘one-stop shop’ for adaptation information in Europe. Climate-ADAPT has been developed jointly by the EC and the EEA to share knowledge on (1) observed and projected climate change and its impacts on environmental and social systems and on human health, (2) relevant research, (3) EU, transnational, national and subnational adaptation strategies and plans, and (4) adaptation case studies.

Further objectives include Promoting adaptation in key vulnerablesectors through climate-proofing EU sector policies and Promoting action by Member States. Most EU Member States have already adopted national adaptation strategies and many have also prepared action plans on climate change adaptation. The EC also supports adaptation in cities through the Covenant of Mayors for Climate and Energy initiative.

In September 2016, the EC presented an indicative roadmap for the evaluation of the EU Adaptation Strategy by 2018.

In November 2013, the European Parliament and the European Council adopted the 7^th EU Environment Action Programme (7^th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7^th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7^th EAP refer to climate change adaptation.

Targets

No targets have been specified.

Methodology

Methodology for indicator calculation

Data from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) on Calanus abundance in the central North Sea since 1958 is used for the indicator. The Continuous Plankton Recorder (CPR) survey is the longest running, large-scale marine biological survey in the world. The CPR is a near-surface (10 m) plankton sampler voluntarily towed each month behind merchant ships on their normal routes of passage. Methods of analysis for 400 phyto and zooplankton taxa have remained almost unchanged since 1958.

The effects of temperature variability on abundance of demersal species within the European continental shelf ﬁsh assemblage has been investigated through compiling and analysing three decades of high-resolution data

Methodology for gap filling

Not applicable

Methodology references

No methodology references available.

Uncertainties

Methodology uncertainty

See under "Methodology".

Data sets uncertainty

In general, changes related to the physical and chemical marine environment are better documented than biological changes. For example, systematic observations of sea surface temperature began around 1880. In contrast, the longest available time series of plankton from the Continuous Plankton Recorder (CPR) is around 60 years. Sampling was started in the North Sea in the 1950s and today a network covering the entire North Atlantic Ocean has been established.

Our understanding is improving of how climate change, in combination with the synergistic impacts of other stressors, can cause regime shifts in marine ecosystems, but additional research is still needed to untangle the complex interactions and their effects upon biodiversity. Ecological thresholds for individual species are still only understood in hindsight, i.e. once a change has occurred.