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Climate change: impacts on our vision for a healthy and biologically diverse marine ecosystem

SealAs the marine ecosystem is highly interconnected through predator-prey relations, the direct impacts of ocean climate change have 'knock-on' effects up the food-chain. For example, recent warmer conditions and associated changes in plankton abundance and geographical distribution have led to reduced availability of prey fish for some seabirds, which has been strongly linked to recent poor breeding success and reduced survival rates.

Where headline messages under each topic are new for 2010-2011, they are highlighted in bold text. Arrows show change in confidence since the 2007-2008 MCCIP Annual Report Card. Where a topic is referred to in the 'regional snapshot' map, a map symbol appears.

  WHAT IS ALREADY HAPPENINGWHAT COULD HAPPEN

Plankton

SAHFOS; Strathclyde University

More confidence High Confidence   Regional SnapshotSame confidence Low Confidence  
  • In the North Sea, the population of the previously dominant and important cold-water zooplankton species Calanus finmarchicus has declined in biomass by 70% since the 1960s.
  • There has been a northward shift in the distribution of many plankton species by more than 10º latitude over the past 50 years.
  • The seasonal timing of plankton production has altered with some species appearing up to four to six weeks earlier than 20 years ago, which is having an effect on predators.
  • The effects of an abrupt ecosystem shift in the late 1990s were most pronounced in regions of the north-eastern Atlantic near the 9-10°C sea surface temperature isotherm, a critical thermal boundary between 'warm' and 'cold' water ecosystems. As waters warm this boundary has moved northwards.
  • Future warming is likely to alter the geographical distribution of phytoplankton and zooplankton, affecting ecosystem services such as oxygen production, carbon sequestration and biogeochemical cycling.

Fish

Cefas; Strathclyde Univsersity

Same confidence Medium Confidence   More confidence Medium Confidence  
  • Some fish distributions have moved northwards over the past 30 years by between 50 to 400km, with coldwater species such as monkfish and snake blenny moving the furthest. At the same time, some have moved into deeper waters at an average rate of about 3.5 metres per decade.
  • Warmer temperatures around the UK are correlated with poor conditions for survival of cod larvae and cod growth, but enhanced growth rates in sole (a warm-water species). 
  • Diadromous species (which spend some of their life in both fresh and marine waters) such as salmon and eel have been shown to be particularly vulnerable to climate change (water temperature and river flow) with impacts on both the freshwater and marine phases.
  • By 2050, climate change may lead to pelagic species (such as herring and anchovy) moving northward by an average of 600km and demersal species (such as cod and haddock) by 220km. 
  • Changes to currents may have an impact on the dispersal of fish eggs and larvae. It is anticipated that winter and early spring spawners (such as cod and plaice) will experience poor larval survival, whereas warmer-water species (such as sprat) may benefit.

Seabirds

JNCC; CEH

Same confidence Medium Confidence   Regional SnapshotSame confidence Low Confidence  
  • Between 2000 and 2008, the total number of seabirds breeding in the UK decreased by approximately 9%. Breeding success also declined. Climate change is partly responsible.
  • Major changes in plankton abundance in the North Sea have contributed to the reduction in quality and abundance of prey species such as sandeels.
  • The greatest reductions in breeding success of species most sensitive to food shortages, such as Arctic skua, black-legged kittiwake and shag are seen in the Northern North Sea and Scottish Continental Shelf.
  • Models predict that by 2100, UK climate will no longer be suitable for great skua and Arctic skua. The same models predict that the geographic range of black guillemot, common gull and Arctic tern will shrink so that only Shetland and the most northerly tips of mainland Scotland will hold breeding colonies.
  • Any increased storminess would reduce the amount of safe breeding habitat for shoreline-nesting species (e.g. terns) and create unfavourable foraging conditions at sea, which may lead to starvation of adults and chicks of some species.

Marine Mammals

SWF; SMRU; University of Aberdeen

Same confidence Low Confidence   Same confidence Low Confidence  
  • Evidence of impacts from climate change are difficult to distinguish from the impacts of human activities such as those that cause prey depletion, incidental capture in fishing gear, pollution and disturbance.
  • In the temperate zone, some species of toothed whales and dolphins are showing shifts in distribution, which may be linked to increasing sea temperatures.
  • The most likely impacts will be from changes in prey distribution and abundance.
  • Species that have relatively narrow habitat requirements are the most likely to be affected (e.g. shelf sea species like harbour porpoise, white-beaked dolphin and minke whale).
  • Reduced plankton availability may directly affect some baleen whale species that feed at least in part upon zooplankton.
  • Increased coastal flood risk could affect seal haul-out and breeding sites in low-lying areas and caves.

Waterbirds

BTO

NEW
Low Confidence  
NEW
Low Confidence  
  • Overwintering wader distributions have shown an eastward and northward shift. In recent years numbers of some species have declined as birds have overwintered further east in Europe as conditions have improved there.
  • Overwintering wildfowl are showing similar distribution shifts.
  • Waders and wildfowl may be more susceptible to intermittent severe weather events in the future. 
  • Changes in the Arctic and sub-Arctic are expected to lead to reduced availability of suitable breeding grounds and increased predation pressure.

Non-natives

Queen's University, Belfast; Marine Scotland; MBA

Same confidence Medium Confidence   Regional SnapshotLess confidence Low Confidence  
  • The distribution and reproductive capabilities of many non-native marine species have been limited by water temperatures.
  • The introduced Pacific oyster (Crassostrea gigas) spread from oyster farms in the early 1990s, becoming established in southern England. Similarly new self-sustaining populations are now established in Northern Ireland with recruitment occurring in favourable years.
  • Rising water temperatures may have contributed to the expansion in range of a number of species such as the bryozoan Bugula neritina, previously restricted to warm water areas such as power station outlets, and the red seaweed Caulacanthus ustulatus which was introduced from Asia and spread rapidly to Devon in 2004, Cornwall in 2005 and Kent in 2009.
  • Changes in ocean physics and chemistry could favour some non-native species over native species.
  • Current sea temperature projections are thought likely to result in certain species such as Crassostrea gigas recruiting every year in Northern Ireland, Wales and south-west England by 2040.

Coastal Habitats

NE; CCW; National Coastal Consultants; SNH

Same confidence Medium Confidence   Same confidence Low Confidence  
  • Coastal habitats are being affected by changes to the amount of sediment being supplied and removed as a result of natural processes and human intervention.
  • Past human intervention and modification of coastal habitats means they have a reduced capacity to adapt naturally to climate change impacts.
  • Continued sea-level rise, and other climate change related factors are expected to have an impact on the extent, distribution and quality of various coastal habitats.

Intertidal Habitats

MBA

Same confidence Medium Confidence   Regional SnapshotSame confidence Medium Confidence  
  • Biodiversity is increasing in southern areas as warm water species extend their distributions faster than cold water species are retreating.
  • Changes in geographic distributions of rocky shore species have continued with the range limits of southern species moving up to 12km further north (e.g. Osilinus species) between surveys undertaken in July 2007 and July 2009.
  • Population abundances of the topshell Gibbula umbilicalis have increased throughout the UK and in warmer southern areas they have switched to having two periods of gonad maturation per year. This was observed for the first time in 2008/2009. Such a strategy is more characteristic of populations inhabiting warm waters and lower latitudes.
  • The further development of hard coastal defences to tackle sealevel rise could provide 'stepping stones', enabling some rocky shore species to further expand their range.
  • More information is required to quantify the impacts of climate change on seagrass beds, mudflats, and other soft sediment communities.

Shallow and Shelf Subtidal Habitats

Cefas; Oxford University; MBA; University of Wales, Bangor

Less confidence Low Confidence   Same confidence Low Confidence  
  • We lack information on ecosystem dynamics over the range of shallow and shelf subtidal habitats, which hinders our ability to identify and understand large-scale climate change effects.
  • There is no obvious signal of warming effects in sediments in southern and south-western areas where changes would be most expected. However, changes in crustacean abundance in some locations and the occurrence of previously undocumented species in others (e.g. brittle star Amphiura incana and shrimp Athanas nitescens) suggest some degree of climate-influence.
  • Increased seawater temperatures have been linked with disease outbreaks in seafans, changes in algae distribution and abundance, and the appearance and increased occurrence of a previously unrecorded warm-water barnacle Solidobalanus fallax in southern and south-western areas.
  • Changes already documented in soft-sediment communities are expected to continue, and probably escalate, in response to the cumulative effects of seawater warming and ocean acidification.
  • Cold-water coral species and maerl may experience shifts in distribution as a result of intolerance to raised seawater temperature and altered chemistry, with knock-on effects on community composition and function.

Deep-Sea Habitats

SAMS; NOC

NEW
Low Confidence  
NEW
Low Confidence  
  • A detailed assessment of climate change impacts on deep-sea ecosystems is difficult due to the scarcity of sustained observations. Climate driven changes in surface waters could already be having a direct impact through the quantity of food being delivered to the sea bed in any given year.
  • Predicting future changes is extremely difficult due to lack of baseline data and appropriate models at this time.