The North Atlantic Oscillation affects landings of anchovy Engraulis encrasicolus in the Gulf of Cádiz (south of Spain)

The aim of this study was to explore the possible link between NAO (North Atlantic Oscillation) variations and the abundance of anchovy (Engraulis encrasicolus) stock in the Gulf of Cadiz. A significantly negative correlation was found between the NAO in the year previous to the anchovy landings. In the Gulf of Cadiz the mean anchovy landings after a negative NAO phase were significantly higher than after a positive NAO phase. A statistically significant negative relationship was obtained between the biennial NAO (estimated as the average monthly NAO values per two consecutive years starting with an odd‐numbered year) and the probability of having an anchovy landing value for a year higher than the average anchovy landings for the entire year. Results suggest that the NAO previous to the landing year is an ecological factor of European anchovy related to its abundance in the Gulf of Cádiz. This could have important applications for conservation strategies and species management.     

Reassessing the impact of North Atlantic Oscillation on the sub-Saharan vegetation productivity

The Northern Atlantic Oscillation (NAO) has been shown to have a significant impact on the terrestrial ecosystem in the Sahelian region of Africa during the 1980s, and it has been strongly suggested that NAO may be a reliable predictor for the response of the Sahelian ecosystem to global climate variability. Using data from an extended period, we provide a reassessment for the impact of NAO on the Sahelian climate and ecosystem, and show that there is no consistent relationship between NAO and the ecosystem over Sahel. Statistical analysis on the NAO, vegetation, and precipitation data indicates that NAO influences the Sahelian vegetation productivity exclusively through its impact on precipitation. However, the relationship between the NAO index and Sahelian precipitation varies substantially with time. The correlation coefficient fluctuates between positive and negative values, and does not pass the 5% significance test during most of the twentieth century. The NAO system, although documented to govern the ecosystem dynamics over many other regions, does not have a consistent impact on the ecosystem over the Sahel. Therefore, the NAO index cannot produce a useful prediction on the ecosystem variability and changes in this region. This study provides an example that correlations based on short climate and ecological records (less than 20 years in this case) can be spurious and potentially misleading.     

Warmer,deeper, and greener mixed layers in the North Atlantic subpolar gyre over the last 50 years

Shifts in global climate resonate in plankton dynamics, biogeochemical cycles, and marine food webs. We studied these linkages in the North Atlantic subpolar gyre (NASG), which hosts extensive phytoplankton blooms. We show that phytoplankton abundance increased since the 1960s in parallel to a deepening of the mixed layer and a strengthening of winds and heat losses from the ocean, as driven by the low frequency of the North Atlantic Oscillation (NAO). In parallel to these bottom‐up processes, the top‐down control of phytoplankton by copepods decreased over the same time period in the western NASG, following sea surface temperature changes typical of the Atlantic Multi‐decadal Oscillation (AMO). While previous studies have hypothesized that climate‐driven warming would facilitate seasonal stratification of surface waters and long‐term phytoplankton increase in subpolar regions, here we show that deeper mixed layers in the NASG can be warmer and host a higher phytoplankton biomass. These results emphasize that different modes of climate variability regulate bottom‐up (NAO control) and top‐down (AMO control) forcing on phytoplankton at decadal timescales. As a consequence, different relationships between phytoplankton, zooplankton, and their physical environment appear subject to the disparate temporal scale of the observations (seasonal, interannual, or decadal). The prediction of phytoplankton response to climate change should be built upon what is learnt from observations at the longest timescales.     

Factors controlling long-term changes of the eutrophicated ecosystem of Pärnu Bay,Gulf of Riga

Phytoplankton, mesozooplankton, mysids and fish larvae were studied during 15–29 annual cycles measured weekly to monthly in Pärnu Bay, the Gulf of Riga. The monthly variability of the biological data was related to temperature, ice conditions, salinity, influx of nutrients, the North Atlantic Oscillation (NAO) index, cloudiness and solar activity. Phytoplankton development was mainly a function of the NAO index. For the whole study period the abundance of zooplankton increased with increasing water temperature and solar activity. Significant correlations between phytoplankton and zooplankton densities were found until 1990. After the invasion of the predatory cladoceran Cercopagis pengoi in 1991, the zooplankton community was likely to be regulated by the introduced species rather than phytoplankton dynamics. The increased abundances of rotifers and copepods triggered the increase in mysid densities. The development of herring larvae was positively affected by the high density of copepods and rotifers but also by increased eutrophication. Until 1990 there was no significant relationship between the density of zooplankton and herring larvae. A negative relationship between the density of zooplankton and herring larvae in the 1990s suggests that the major shift in zooplankton community resulted in food limitation for herring larvae. The results indicated that (1) atmospheric processes in the northern Atlantic explain a large part of the interannual variation of the local phytoplankton stock, (2) trophic interactions control the development of pelagic communities at higher trophic levels, and (3) the introduction of an effective intermediate predator has repercussions for the whole pelagic food web in Pärnu Bay.     

Biomass changes and trophic amplification of plankton in a warmer ocean

Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3‐D coupled physical‐biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate‐change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom‐up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and regional models, imply the need for caution when extending these considerations into higher trophic levels.     

The effects of climate change on harp seals (Pagophilus groenlandicus)

Harp seals (Pagophilus groenlandicus) have evolved life history strategies to exploit seasonal sea ice as a breeding platform. As such, individuals are prepared to deal with fluctuations in the quantity and quality of ice in their breeding areas. It remains unclear, however, how shifts in climate may affect seal populations. The present study assesses the effects of climate change on harp seals through three linked analyses. First, we tested the effects of short-term climate variability on young-of-the year harp seal mortality using a linear regression of sea ice cover in the Gulf of St. Lawrence against stranding rates of dead harp seals in the region during 1992 to 2010. A similar regression of stranding rates and North Atlantic Oscillation (NAO) index values was also conducted. These analyses revealed negative correlations between both ice cover and NAO conditions and seal mortality, indicating that lighter ice cover and lower NAO values result in higher mortality. A retrospective cross-correlation analysis of NAO conditions and sea ice cover from 1978 to 2011 revealed that NAO-related changes in sea ice may have contributed to the depletion of seals on the east coast of Canada during 1950 to 1972, and to their recovery during 1973 to 2000. This historical retrospective also reveals opposite links between neonatal mortality in harp seals in the Northeast Atlantic and NAO phase. Finally, an assessment of the long-term trends in sea ice cover in the breeding regions of harp seals across the entire North Atlantic during 1979 through 2011 using multiple linear regression models and mixed effects linear regression models revealed that sea ice cover in all harp seal breeding regions has been declining by as much as 6 percent per decade over the time series of available satellite data.     

The effects of fluctuations in North Sea flows on zooplankton abundance

Time series of annual mean zooplankton abundance observed bythe Continuous Plankton Recorder Survey in the North Sea duringthe last three decades are compared with transports from a depth-averagedstorm-surge model by means of multiple regression analysis.In the northern areas, more than half the variance of Calanusfinmarchicus can be accounted for by the winter flows. Thereare no statistically significant relationships in other NorthSea areas or by using the flows from other seasons. This isconsistent with the accepted view that this copepod overwintersin the North Atlantic and enters the North Sea in the earlyspring. The model flows are strongly related to the strengthof the North Atlantic Oscillation (NAO). which may explain therecently reported association of C.finmarchicus with the NAO.Other species do not exhibit statistically significant relationshipswith any of the model flows.     

Timing of spring migration in birds: long-term trends, North Atlantic Oscillation and the significance of different migration routes

We studied long-term trends and the yearly variation in mean spring passage time in 36 passerine bird species trapped at Ottenby Bird Observatory in south-eastern Sweden. Between the years 1952–2002, data were available for 22–45 years depending on species. Most long-distance migrant species passed progressively earlier over the study period (range: 2.5 days earlier to 0.7 days later per 10 years, with an average of 0.9 days earlier per 10 years). The annual variation in timing of migration in most species, regardless of migration distance, correlated negatively with the winter index of the North Atlantic Oscillation (NAO), a large-scale climate phenomenon influencing the climate in the North Atlantic region. Birds passed earlier after mild and humid winters, corresponding to the high phase of the NAO. This corroborates the pattern found at a nearby migration site with a comparable dataset (Helgoland, 600 km WSW of Ottenby). However, short/medium-distance migrant species at Ottenby, in contrast to the situation at Helgoland, have shown no general trend of earlier passage in recent years. This was probably a consequence of the shorter study period at Ottenby, which included only the last 22–32 years (41 years at Helgoland), when the NAO showed no significant trend. At the species-specific level, the long-term trends in passage time were similar at the two sites, and there was some congruence to the extent that a given species was affected by NAO. Long-distance migrants wintering south and south-east of the breeding grounds showed some of the strongest changes in long-term trends (passing progressively earlier) at Ottenby, and for some of these species passage time varied negatively with NAO. Obviously, and contrary to previous suggestions, variations in NAO also influence birds migrating through eastern Europe, although the direct or indirect mechanisms through which this is achieved are unknown.     

Influences of the atmospheric patterns on unstable climate-growth associations of western Mediterranean forests

Quantifying climate-growth associations is needed to evaluate how forest productivity will respond to climate change. Year-to-year fluctuations in forest productivity and radial growth are partly explained by local climatic conditions driven by large-scale atmospheric patterns. This is illustrated by Iberian forests in the western Mediterranean Basin, which are subjected to complex climatic and atmospheric influences such as Atlantic and Mediterranean cyclogenesis. The North Atlantic Oscillation (NAO) is one of the major atmospheric circulation patterns affecting Iberian forests since positive winter NAO phases lead to dry and warm conditions. The Western Mediterranean Oscillation (WeMO) may also explain Iberian forest growth in some areas since this index captures Mediterranean cyclogenesis and WeMO negative phases are linked to warm and wet spring to summer conditions. Here, we analyze the associations between atmospheric patterns, climate and tree growth and we determine if they are changing through time. We use dendrochronology to relate radial growth of four tree species (Pyrenean oak, Sweet chestnut, Maritime pine and Scots pine) growing in western Spain to climate conditions and the NAO and WeMO indices. Winter and early spring temperatures increased since the 1950s in the area whereas the negative association between winter precipitation and the NAO strengthened since then. However, mean temperature rise was particularly evident since the 1970s. Growth was reduced by dry conditions during the growing season (spring and summer), but also by cold and dry conditions during the previous autumn and winter. This explains why the NAO January and the WeMo April indices were negative to growth of three species excluding Pyrenean oak. The early 1970s reflected an inflection point in the instability of climate-growth associations in the study area. We conclude that the winter NAO is a relevant driver of forest growth in the western Iberian Peninsula forests but additional atmospheric patterns (WeMO) also affect, albeit to a minor extent, these forests.     

Climate,body condition and spleen size in birds

Climatic conditions may impact on the body condition of animals and thereby affect their survival prospects. However, climate may also impact directly on the survival prospects of animals by affecting the size of immune defence organs that are used for defence against parasites. We used a large long-term database on body condition and size of the spleen in birds to test for immediate and delayed relationships between climatic conditions as indexed by the North Atlantic Oscillation (NAO) and body condition and spleen mass, respectively. Across 14 species of birds, spleen mass was significantly positively correlated with the NAO index, while the delayed effect of NAO on spleen mass was not significant. Spleen mass was positively related to body condition, but body condition did not depend significantly on NAO or delayed NAO effects. Bird species with a strong positive effect of NAO on spleen mass tended to have small spleens for their body size, while species with a strong negative effect of NAO on spleen mass tended to have relatively large spleens. Since bird species with relatively large spleen have been shown to suffer more from the negative effects of parasites, we can infer that the effects of climate as indexed by NAO on the size of the spleen depends on the importance of parasite-mediated natural selection.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.     

Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

We explored the possible effects of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) on interannual sea surface temperature (SST) variations in the Alborán Sea, both separately and combined. The probability of observing mean annual SST values higher than average was related to NAO and AO values of the previous year. The effect of NAO on SST was negative, while that of AO was positive. The pure effects of NAO and AO on SST are obscuring each other, due to the positive correlation between them. When decomposing SST, NAO and AO in seasonal values, we found that variation in mean annual SST and mean winter SST was significantly related to the mean autumn NAO of the previous year, while mean summer SST was related to mean autumn AO of the previous year. The one year delay in the effect of the NAO and AO on the SST could be partially related to the amount of accumulated snow, as we found a significant correlation between the total snow in the North Alborán watershed for a year with the annual average SST of the subsequent year. A positive AO implies a colder atmosphere in the Polar Regions, which could favour occasional cold waves over the Iberian Peninsula which, when coupled with precipitations favoured by a negative NAO, may result in snow precipitation. This snow may be accumulated in the high peaks and melt down in spring-summer of the following year, which consequently increases the runoff of freshwater to the sea, which in turn causes a diminution of sea surface salinity and density, and blocks the local upwelling of colder water, resulting in a higher SST.     

Common growth signal and spatial synchrony of the chronologies of tree-rings from pines in the Baltic Sea region over the last nine centuries

The common growth signal and spatial synchrony of nine chronologies of tree rings (Pinus sylvestris L.) from the Baltic Sea region were studied using moving correlations with time windows of 50 and 100 years. Drifts from synchrony to asynchrony and again back to synchrony across several centuries were observed. The chronologies showed higher (or lower) coefficients of correlations and correspondingly gentler (or steeper) declines in spatial synchrony in certain periods. In accordance with research into other ecological phenomena, the origin of the spatial synchrony was found to relate to the intensity of the westerly circulation over the Atlantic and Europe as described by the North Atlantic Oscillation (NAO) index. The tree rings from all of the analysed subregions were found to be wider, identifying faster periods of growth, when there was a positive NAO during the extended winter season from December to March that preceded the period of growth. Previous studies showed that the NAO index can be linked with the growth of tree rings because of factors in the local climate that affect growth, such as temperature and precipitation. Moreover, the spatial synchrony showed multidecadal fluctuations that were correlated with variations of a similar scale in the reconstructed NAO index. However, a high degree of spatial synchrony was observed during the 20^th century in the presence of values of NAO index that were strongly negative. A more detailed view was provided by maps of the correlations in which spatial changes were demonstrated in the growth of pines between the 12^th and the 20^th century. These results could be used as background information in the development of improved proxy-based reconstructions of the NAO index (or other similar meteorological variables), which could also be inferred from tree ring data relating to earlier centuries.     

The influence of the North Atlantic Oscillation on the physical, chemical and biological characteristics of four lakes in the English Lake District

1. Thirty‐six years of winter meteorological and limnological measurements from four lakes in the English Lake District are analysed and related to variations in the North Atlantic Oscillation (NAO). Winter weather conditions were strongly influenced by the NAO with mild, wet winters being associated with strongly positive values of the NAO index (NAOI). 2. Lake surface and bottom temperatures were strongly positively correlated with the NAOI, with the highest correlations being recorded in the shallower lakes. 3. Variations in the NAOI also had a significant effect on the winter concentration of nitrate. In all the lakes, there was a significant negative correlation between the NAOI and the detrended winter concentration of nitrate. The key driving variable was the local air temperature, which appeared to limit the quantity of nitrate reaching the lake by increasing the amount assimilated in the surrounding catchment in mild winters. 4. Dissolved reactive phosphorus (DRP) concentrations were not significantly correlated with the NAOI in the two larger basins but significant positive correlations were recorded in the two smaller lakes. The key driving variable was the local rainfall with higher DRP concentrations being recorded after heavy rain in the lakes with a short retention time. 5. The NAOI‐related changes in rainfall also influenced the phytoplankton. In wet winters the concentration of chlorophyll in the two smaller lakes with the shortest retention time was lower and the spring growth of Asterionella formosa was delayed in the smallest lake. 6. These differential responses demonstrate how the large‐scale effects associated with the NAO can be ‘filtered’ by the physical characteristics of a particular site.     

Spring weather determines the relative importance of ciliates, rotifers and crustaceans for the initiation of the clear-water phase in a large, deep lake

Clear-water phase (CWP) is an important event in seasonal planktonsuccession. We examined the influence of all herbivorous zooplanktonon its initiation under different weather and climatic conditionsusing up to 19 years of observations from the large, deep LakeConstance (Europe) and estimates of relative clearance rates.A CWP occurred regularly, even if daphnid biomass was stillvery low. CWP was attributed to strong grazing either by a daphnid-dominatedzooplankton community or by a diverse assemblage consistingof micro- and meso-zooplankton. Both types of zooplankton communitiesoccurred with approximately the same frequency. The timing ofthe CWP was unrelated to the North Atlantic Oscillation (NAO)but correlated with the wind-dependent intensity of deep verticalmixing 3 months earlier, during early spring. Less mixing enabledearly growth of phytoplankton, ciliates and rotifers despitelow temperatures, which prevented daphnid development at thistime. This resulted in enhanced grazing of ciliates and rotifers,which increased the importance of phytoplankton less ediblefor most ciliates, rotifers and daphnids. Ciliates clearly dominatedthe grazing pressure on phytoplankton throughout spring, maintaininghigh biomasses together with the phytoplankton for up to 2 months.A CWP was observed when herbivores grazing on larger phytoplanktondeveloped in addition to ciliates.     

North Atlantic Oscillation influences on radial growth of Pinus pinea on the Italian mid-Tyrrhenian coast

The North Atlantic Oscillation (NAO) is the most important source of winter atmospheric variability in the northern hemisphere. NAO inversely reflects the precipitation regime, which plays a fundamental role in Mediterranean regions, e.g., by recharging the water table. As no attempt has been made thus far to analyze the relationship between NAO variability and tree radial growth in coastal Mediterranean conifers, this paper identifies the monthly, winter, annual, and decadal influence of NAO on tree-ring chronologies of six planted Pinus pinea L. populations distributed along the Tyrrhenian coasts of central Italy. Through multidimensional analyses, we identified tree-ring chronology associations in two main groups. The influence of NAO on the regional chronologies was identified with correlation functions for the comparison period between 1949 and 2003 at both annual and decadal timescales. Results indicate that winter NAO influence on radial tree growth at annual and decadal timescales may depend on geographical location, site characteristics, and the age structure of tree-ring chronologies. These results contribute to a better understanding of the P. pinea coastal forest ecology and provide evidence of large-scale climatic forcings that influence forest Mediterranean ecosystems.     

Winter North Atlantic oscillation effects on the tree rings of the Italian beech (Fagus sylvatica L.)

Climatic signals in beech tree-ring width series from Central Italy have been studied over different periods of time. Prewhitened tree-ring chronologies respond mainly to summer precipitation and they do not correlate in a significant manner with the winter North Atlantic oscillation (NAO) index. In this high-frequency pattern the NAO signs are only found on a small number of rings characterized by being very narrow or wide. By contrast, tree-ring width chronologies in which all the frequency components are conserved were significantly related to the NAO. The significant inverse correlation between actual measurements of ring width and NAO is a consequence of the availability of water in the soil at the beginning of the growing season. In fact, in the Mediterranean area the recharging of soil moisture depends on the amount of winter precipitation, which is inversely correlated with the NAO. Strong signals of winter precipitation and NAO are found in the low-frequency components of tree-ring growth. Received: 18 March 1999 / Revised: 29 February 2000 / Accepted: 1 March 2000     

Was high grouse hag in early 20th century Norway due to a program for extermination of small game predators?

A Norwegian program for extermination of (small game) predators (NPEP) was run during 1900‐ 1914, This initiative is believed to have caused larger small game stocks and more regional synchrony in rodents. To investigate the effectiveness of the NPEP time series of predators bountied (1885–1914), rodent dynamics (1885–1914), ptarmigan hunting index (1885–1914 and 1900/1‐1914), and willow ptarmigan and berry export statistics (1885–1914) were analyzed for three different regions: south, east and central Norway. In south and east Norway there were higher ptarmigan export in the period 1907–1914 than the years before, but not in central Norway. There was not bountied higher number of red fox. eagle or goshawk in any of the three regions when comparing years a) before and after 1900. and b) when comparing the periods 1900–1906 and 1907–1914. This suggests that predator removal was not the cause of increased ptarmigan export. The ptarmigan hunting index and rodent index for south and east Norway were correlated in the period 1885 1914, while the ptarmigan export from east Norway was correlated with berry export from the year before. However, for central Norway the rodent index was not correlated with the hunting index. There were cross correlation between berry and ptarmigan export with lag from minus one to nine years for south and east Norway, The NAO (North Atlantic Oscillation) ‐ an indication of the winter weather variation ‐ had higher values during 1900–1914 than 1885–1899, indicating moister and warmer winters in the last period. This analysis indicates that NPEP generally did not increase predator removal. The results suggest, however, that it was a series of years with high rodent density, that caused the increase in ptarmigan populations In south and cast Norway, which, in turn, may have been caused by favourable weather conditions leading to among others good berry crops. Conclusions based on old data series must, however, be drawn with caution.     

Cumulative effect of the North Atlantic Oscillation on age‐class abundance of albacore (Thunnus alalunga)

The aim of this study was to look into possible relationships between climate and the inter‐annual variability of albacore (Thunnus alalunga) catch rates by age class observed during a recreational fishery tournament at the spawning grounds of S’Estanyol (Balearic Islands, Spain) in the years 2004–2009. The mean capture per unit effort (CPUE) was significantly higher when the mean of the North Atlantic Oscillation (NAO) experienced by the albacore in winter and spring of its life history (NAO_life) was negative than when the NAO_life was positive. A statistically significant negative relationship was obtained between NAO_life and the probability of a CPUE value for an age class and year being higher than the average CPUE for all the cohorts in that age class. The results suggest that local abundance of albacore in a spawning grounds could be related to environmental factors dependent on the NAO and that there may be a cohort‐age effect. It is hypothesized that factors dependent on the NAO, such as the abundance variation of small pelagic fishes as a response to the NAO variability, could have a cumulative effect over the good biological condition (fitness) of a long‐living fish predator such as the albacore.     

Rapid biogeographical plankton shifts in the North Atlantic Ocean

Large‐scale biogeographical changes in the biodiversity of a key zooplankton group (calanoid copepods) were detected in the north‐eastern part of the North Atlantic Ocean and its adjacent seas over the period 1960–1999. These findings provided key empirical evidence for climate change impacts on marine ecosystems at the regional to oceanic scale. Since 1999, global temperatures have continued to rise in the region. Here, we extend the analysis to the period 1958–2005 using all calanoid copepod species assemblages (nine species assemblages based on an analysis including a total of 108 calanoid species or taxa) and show that this phenomenon has been reinforced in all regions. Our study reveals that the biodiversity of calanoid copepods are responding quickly to sea surface temperature (SST) rise by moving geographically northward at a rapid rate up to about 23.16 km yr^?1. Our analysis suggests that nearly half of the increase in sea temperature in the northeast Atlantic and adjacent seas is related to global temperature rises (46.35% of the total variance of temperature) while changes in both natural modes of atmospheric and oceanic circulation explain 26.45% of the total variance of temperature. Although some SST isotherms have moved northwards by an average rate of up to 21.75 km yr^?1 (e.g. the North Sea), their movement cannot fully quantify all species assemblage shifts. Furthermore, the observed rates of biogeographical movements are far greater than those observed in the terrestrial realm. Here, we discuss the processes that may explain such a discrepancy and suggest that the differences are mainly explained by the fluid nature of the pelagic domain, the life cycle of the zooplankton and the lesser anthropogenic influence (e.g. exploitation, habitat fragmentation) on these organisms. We also hypothesize that despite changes in the path and intensity of the oceanic currents that may modify quickly and greatly pelagic zooplankton species, these organisms may reflect better the current impact of climate warming on ecosystems as terrestrial organisms are likely to significantly lag the current impact of climate change.