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Rapid biogeographical plankton shifts in the North Atlantic Ocean

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Abstract

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.

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... Calanus abundance (Munk and Nielsen, 1994;Arnott and Ruxton, 2002;Heath and Lough, 2007;Heath, 2007;Beaugrand et al., 2009;van Deurs et al., 2009). ...
... Zooplankton communities characterized by warm-water species tend to be smaller, exhibit less biomass and are less energy-rich than polar and boreal species (Kattner et al., 2007). A reduction in lipid rich species may reduce growth and survival, and in turn affect recruitment in fish or seabirds Beaugrand et al., 2009). ...
... Zooplankton communities characterized by warm-water species tend to be smaller, exhibit less biomass and are less energy-rich than polar and boreal species (Kattner et al., 2007). A reduction in lipid rich species may reduce growth, survival and in turn affect recruitment in fish or seabirds Beaugrand et al., 2009). Communities dominated by warm-water species are expected to have longer food chains, reduced trophic efficiency and represent unfavorable fish feeding conditions and less efficient utilization of primary production. ...
... an has been absorbing a large part of the surplus heat added to the climate system (Figure 1.8). This gradual uptake of heat could translate into sudden and stepwise shifts in marine ecosystems instead of gradual change over the years, due to the thermal thresholds in the marine environment that often manifest themselves as abrupt ecosystem shifts (Beaugrand et. al., 2009). Over 99 % of all organisms on Earth are ectothermic, making them susceptible to fluctuations of temperature, and hence, to global warming (Atkinson, 1994). Temperature is assumed to be a basic factor, ruling the physical environment (e.g. viscosity), limiting physiological processes (e.g. oxygen delivery within the organism) and bioche ...
... physiological processes (e.g. oxygen delivery within the organism) and biochemical reactions (e.g. enzyme activity), and finally determining growth and developmental rates of living organisms (Richardson, 2008). Temperature also has a substantial impact, directly and indirectly, on species interactions such as competition, predation and mutualism (Beaugrand et. al., 2009;Kordas et. al., 2011). A shift in temperature, either on a latitudinal or a seasonal scale, can modify these interactions between species and result in a changed ecosystem composition (Halsband-Lenk et. al., 2002). From a food web point of view, primary production by the smallest plankton is expected to increase in the warmer waters, but ...
... As a consequence, temperature often has striking impacts on virtually all life processes from a molecular scale to the entire pelagic ecosystem scale and from plankton to higher trophic levels (Beaugrand and Kirby, 2010;Beaugrand et al., 2009). ...
Thesis
Oceans and seas are often perceived as the last wilderness on the planet. However, anthropogenic actions are already impacting these ecosystems, ranging from the coasts and the sea surface to the open ocean and the deep sea floor. Marine ecosystems are currently affected by multiple human activities, such as eutrophication, overfishing, the introduction of non-indigenous species, the contamination by hazardous chemicals and (micro)plastics, etc., in addition to climate change, leading to impaired environmental conditions. Evidence is growing that these changing environmental conditions have negative effects on the biodiversity and functioning of marine food webs. Due to their rapid responses to environmental variation, planktonic organisms are used as bio-indicators of ecosystem changes. With the need for better understanding the impact of a changing environment on zooplankton communities, zooplankton monitoring programs have been carried out in the marine environment globally since the early 20th century. Most zooplankton monitoring studies focus mainly on variability in biodiversity and biomass. However, this approach is hindered by challenges in the identification, which is time-consuming, complicated and requires biological expertise. A combination of new technologies and techniques, together with classical in situ and laboratory studies, could improve our understanding of such biodiversity patterns by assessing the health and physiology of marine plankton. In this thesis, we aimed to apply molecular methods to investigate spatiotemporal patterns in zooplankton dynamics, as well as to investigate the influence of environmental variation and stressors on these dynamics.
... It is now widely acknowledged that there was a period of hydroclimatic change during the twentieth century, manifested in significantly higher sea surface temperatures, which dramatically altered planktonic ecosystems in the Northeast Atlantic (Beaugrand, 2004;Edwards et al., 2006;Philippart et al., 2011;Nohe et al., 2020). This warming of the oceans has continued, and in only 40 years, there has been a significant shift in plankton and fish communities (Beaugrand et al., 2002(Beaugrand et al., , 2009Choquet et al., 2017;Nohe et al., 2020). By the end of the twenty-first century, the Intergovernmental Panel on Climate Change (IPCC) climate projections indicate a mean increase in the sea surface temperature of between 0.73 °C to 2.58 °C (IPCC, 2019). ...
... Temperature has been linked to the abundance and geographical distribution of Calanus spp in the North Atlantic (Barnard et al., 2004;Bonnett et al., 2005;Choquet et al., 2017). Thus, as regions warm or cool, we can expect dramatic changes in the abundance and dominance of different copepod species (Beaugrand et al., 2002(Beaugrand et al., , 2009Richardson & Schoeman 2004;Choquet et al., 2017;. ...
... (Dutz, 1998;Collumb & Buskey, 2004;Prince et al., 2006;Costa et al., 2008). Therefore, in Chapter 4, adult female A. tonsa were exposed to (Beaugrand et al., 2002(Beaugrand et al., , 2009Beaugrand, 2012;Chivers et al., 2017;Murphy et al., 2020), and evidence of how climate change affects planktonic species is growing, particularly in terms of increased ocean temperature and ocean acidification (George & Harris, 1985;Costello et al., 2006;Edwards et al., 2006;Mayor et al., 2007Mayor et al., , 2012Cripps et al., 2014). Direct effects of warming and acidification to copepods include changes in physiology and behavior that can alter growth (McFeeters & Frost, 2011;Doan et al., 2019), body size (Escribano & Mclaren, 1992;Garzke et al., 2015;Sommer et al., 2016), reproductive output Mayor et al., 2012;Weydmann et al., 2012), naupliar development , and survival (Sommer et al., 2007;Kroeker et al., 2010;Cripps et al., 2015). ...
Thesis
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Copepods form an important link between phytoplankton and higher trophic levels. Several species of phytoplankton, including dinoflagellates of the genus Alexandrium, produce neurotoxins commonly known as paralytic shellfish toxins (PSTs). The toxins from harmful algae (HA) may impact copepod survival, eeding, and fitness by acting as a feeding deterrent and/or by causing physical incapacitation. However, copepods may be able to overcome these toxic effects and/or become tolerant to toxicity by partial metabolism. Published information on how HA affect survival, feeding and other physiological processes in opepods are difficult to compare due to the different concentrations of HA used as food, the level of toxins in the food, and the various responses measured on different copepod species from different locations. Very few experiments have examined how HA toxins influence the survival, feeding and fecundity of copepods within UK waters. This thesis aims to address this knowledge gap whilst also choosing organisms of wider geographical relevance. This study examined the effects of a toxin-producing dinoflagellate, Alexandrium catenella, on two physiologically different copepods: Acartia tonsa, a pelagic coastal copepod that is found in the UK and other coastal waters including Northern & Southern America and Australia, and Calanus helgolandicus, which is spread across the North East Atlantic with high numbers on the European shelf and in oceanic waters. In Chapter 3, short-term (24 h) survival and feeding experiments revealed that adult female A. tonsa can survive exposure to field-recorded bloom concentrations of toxic A. catenella. Survival only decreased when exposure levels exceed reported environmental concentrations by two orders of magnitude. The lethal median concentration (LC50) was 12.45 ng STX eq L−1. Ingestion rates were higher when offered A. catenella in the absence of alternative prey, potentially suggesting compensatory feeding. A. tonsa actively selected non-toxic Rhodomonas sp. over toxic A. catenella when offered a mixed diet. Chapter 4 demonstrated that the survival of female A. tonsa is not affected by prolonged (10 days) exposure to toxic A. catenella. However, additional feeding and egg production experiments suggested that whilst A. tonsa can obtain enough energy from ingesting toxic A. catenella to survive, it suffers reproductive impairment when feeding on this prey alone. In Chapter 5, C. helgolandicus showed a decrease in feeding rate when feeding on toxic A. catenella compared to when feeding on the non-toxic congener, Alexandrium tamarense. On the other hand, the egg production and hatching success rates were not affected by the relative abundance of toxic A. catenella and non-toxic A. tamarense in diet, suggesting they may have used biomass reserves to sustain egg production. Body toxin analysis of C. helgolandicus showed they may bioaccumulate toxins in their bodies; however, the retention efficiency was very low. Full toxin profiles for A. catenella, including 8 to 12 PSTs, are presented in all experiments. This study furthers our understanding of PST-producing HA-copepod interactions, and how they may be affected by the increased frequency and magnitude of HA blooms.
... Because these conditions vary with latitude, the corresponding variations in plankton distribution are well-known: higher diversity towards low latitudes [188,343,348,402] and higher biomass towards higher latitudes [190]. They are sensitive to environmental conditions: planktonic organisms are also global change sentinels [20,22,172]. Studying plankton biography is relevant to understand anthropocene pelagic ecosystems. ...
... Tropical and temperate copepods' concentrations were likely underestimated but (see above) in various situations, conclusions on community composition are little affected, since all taxa concentrations are similarly underestimated near UVP target size range limits. Large changes in the biogeography, community composition and diversity of calanoid copepods in the North Atlantic Ocean are detected, as a result of global warming [20,21]. As copepods act as a trophic link between primary producers and higher trophic levels [343], these changes might prove detrimental to marine resources, like exploited fish stocks [21]. ...
Thesis
Full-text available
As the basis of oceanic food webs and a key component of the biological carbon pump, planktonic organisms play major roles in the oceans. However, their small-scale distribution − governed by biotic interactions between organisms and interactions with the physico-chemical properties of the water masses in their immediate environment − are poorly described in situ due to the lack of suitable observation tools. New instruments performing high resolution imaging in situ in combination with machine learning algorithms to process the large amount of collected data now allows us to address these scales. The first part of this work focuses on the methodological development of two automated pipelines based on artificial intelligence. These pipelines allowed to efficiently detect planktonic organisms within raw images, and classify them into taxonomical or morphological categories. Then, in a second part, numerical ecology tools have been applied to study plankton distribution at different scales, using three different in situ imaging datasets. First, we investigated the link between plankton community and environmental conditions at the global scale. Then, we resolved plankton and particle distribution across a mesoscale front, and highlighted contrasted periods during the spring bloom. Finally, using high frequency in situ imaging data, we investigated the fine-scale distribution and preferential position of Rhizaria, a group of understudied, fragile protists, some of which are mixotrophic. Overall, these studies demonstrate the effectiveness of in situ imaging combined with artificial intelligence to understand biophysical interactions in plankton and distribution patterns at small-scale.
... This is due to the key part it plays in the process of energy flow and material circulation in the marine ecosystem (Schmidt and Hutchins, 1999;Buitenhuis et al., 2006). Zooplankton can serve as sensitive indicators since they may reflect the current impact of climate warming on ecosystems more quickly than terrestrial organisms (Beaugrand et al., 2009). The hydrological environment has a direct impact on zooplankton distribution. ...
... The horizontal distribution of plankton in the epipelagic ocean (euphotic layer) is typically the main research topic of the geographical distribution of plankton since the biomass drops rapidly with increasing depth (Stefanoudis et al., 2019). The large-scale geographic distribution of zooplankton in the Atlantic and eastern Pacific has been extensively documented and discussed, beginning with the Challenger ocean expedition and continuing with more focused continuous observations in recent years (Beaugrand et al., 2009;Dexter et al., 2020). ...
Article
The northwestern Pacific (NWP) is a hotspot of marine biodiversity study, and zooplankton is a crucial secondary producer in the marine ecosystem. It is of utmost importance to do extensive study on the distribution of zooplankton community in the NWP. The distribution of epipelagic zooplankton community in the 143-146°E section between the equator and 36°N in winter was examined in this study. The findings indicated that the Kuroshio extension, the North Pacific Subtropical Gyre, the North Equatorial Current and the North Equatorial Countercurrent were the four main ocean currents in the NWP that regulated the latitudinal transition of epipelagic mesozooplankton and split the sample section into four station groups. The key factors influencing zooplankton's geographic distribution were temperature, primary productivity, and current movement. In general, as latitude increased, zooplankton abundance and biomass first decreased and subsequently flourished in the NWP. Diversity indexes and indicator species also revealed the difference across the communities in four station groups. The body length of zooplankton declined gradually from north to south under the combined influence of temperature and primary production, with the minimum in the oligotrophic subtropical zone and a sub-peak in the high primary production area near the equator. Additionally, the abundance of zooplankton was higher in the winter than in the summer due to seasonal fluctuations in the properties of the ocean currents. This study elucidated the control effects of ocean currents on the latitudinal distribution of zooplankton, supplemented records of the geographic distribution and body length characteristics of zooplankton communities in the NWP, and provided the basis for further research on the ecological role of zooplankton communities and the global changes of marine ecosystems.
... In other words, they are nowadays inhabiting warmer surface temperatures than they were 80 years ago. This is an important result as it is the exception to the general expectations of range shifts (generally polewards to cooler waters) under warming scenarios (Beaugrand et al., 2009). Indeed, Antarctic range shifts have been found in the Atlantic sector, both for E. superba and salps (Pakhomov et al., 2002;Atkinson et al., 2004Atkinson et al., , 2019, in keeping with those found for aquatic and terrestrial ectotherms more generally (Parmesan and Yohe, 2003). ...
... Three "universal" responses to rapid warming have been described for ecototherms. Copepods may shift (1) in geographical range (i.e., polewards range shifts Beaugrand et al., 2009), (2) in phenology (i.e., earlier when warmer , and (3) in body size (i.e., smaller species' , life stages or adult sizes in warmer environments Daufresne et al., 2009;Horne et al., 2016). The relative degree of expression of these responses is poorly known for zooplankton generally; it is certainly not known for Antarctic copepods. ...
Article
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In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary and secondary producers, and are prey for fishes, cephalopods, seabirds, and marine mammals. In providing the link between microbes, primary production, and higher trophic levels these taxa influence energy flows, biological production and biomass, biogeochemical cycles, carbon flux and food web interactions thereby modulating the structure and functioning of ecosystems. Additionally, Antarctic krill (Euphausia superba) and various fish species are harvested by international fisheries. Global and local drivers of change are expected to affect the dynamics of key zooplankton species, which may have potentially profound and wide-ranging implications for Southern Ocean ecosystems and the services they provide. Here we assess the current understanding of the dominant metazoan zooplankton within the Southern Ocean, including Antarctic krill and other key euphausiid, copepod, salp and pteropod species. We provide a systematic overview of observed and potential future responses of these taxa to a changing Southern Ocean and the functional relationships by which drivers may impact them. To support future ecosystem assessments and conservation and management strategies, we also identify priorities for Southern Ocean zooplankton research.
... Rapid changes to marine ecosystems will occur as tropical species-diversity drops regionally as thermal tolerances are exceeded, as warm-water species migrate to higher latitudes, and as higher latitude species become extinct as their physiological tolerances are undermined (Payne et al., 2023). Changes in geographical distribution, including local extinctions of marine zooplankton communities in the North Atlantic may cause cascade effects through the structure of food webs (Harris et al., 2015;Villarino et al., 2015), that have already disrupted patterns of cod abundance (Richardson, 2008;Beaugrand et al., 2009). In the southern hemisphere, reduced sea ice cover will affect krill abundance with potentially widespread impacts on whales, birds, seals and fish (Richardson, 2008). ...
Article
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The "Great Acceleration" beginning in the mid-20th century provides the causal mechanism of the Anthro-pocene, which has been proposed as a new epoch of geological time beginning in 1952 CE. Here we identify key parameters and their diagnostic palaeontological signals of the Anthropocene, including the rapid breakdown of discrete biogeographical ranges for marine and terrestrial species, rapid changes to ecologies resulting from climate change and ecological degradation, the spread of exotic foodstuffs beyond their ecological range, and the accumulation of reconfigured forest materials such as medium density fibreboard (MDF) all being symptoms of the Great Acceleration. We show: 1) how Anthropocene successions in North America, South America, Africa, Oceania, Europe, and Asia can be correlated using palaeontological signatures of highly invasive species and changes to ecologies that demonstrate the growing interconnectivity of human systems; 2) how the unique depositional settings of landfills may concentrate the remains of organisms far beyond their geographical range of environmental tolerance; and 3) how a range of settings may preserve a long-lived, unique palaeontological 2 record within post-mid-20th century deposits. Collectively these changes provide a global palaeontological signature that is distinct from all past records of deep-time biotic change, including those of the Holocene.
... equatorial Pacific vs North Atlantic) to aid classification but rather the relative location of two objects to each other. Such an approach should be sufficiently sensitive to capture geographical changes in plankton distribution caused by, e.g., climate change [75], [76], without enforcing strict location constraints that could conceal distribution changes. Finally, depth information greatly improved classification accuracy likely because plankton of the same species often swarm, co-locating in relatively narrow depth bands of just a few meters (e.g. ...
Article
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Automated camera-based sensors are widely used in vessel-based research to monitor plankton and marine particles. However, current methods suffer from the costly and time-consuming requirement of annotating data for fully supervised learning, especially in plankton grouping tasks characterized by long-tailed datasets. In response, we propose a novel self-supervised learning (SSL) framework that significantly reduces reliance on expensive human annotations by leveraging crucial metadata such as water depth and location. The method comprises three major steps: self-supervised training, innovative sampling, and final classification. It identifies key sample subsets from an unlabelled dataset using hierarchical clustering approach and incorporates an innovative balancing representative subsampling strategy that addresses the challenge of dataset imbalance and enhances generalisability across diverse plankton classes. Our approach prioritises discerning representation features observed in images that exhibit correlations with the patterns found in their associated metadata. Furthermore, our method introduce a novel grouping based on visual perspective selection method, enabling the identification of balanced subset views that depart from traditional class-based categorisation. Our experimental results showcase a significant enhancement in image classification accuracy, with a 23% improvement over methods that do not utilise metadata, and attains a macro F1-score of 54% for 10 populated species from a severely long-tailed dataset. This is achieved with a mere 0.3% of the entire dataset used for annotation.
... Range shift is documented in calanoid copepods of North Atlantic Ocean. They are shifting northward at a rate of 23.16 km/yr due to rising sea surface temperatures (Gregory et al., 2009). It is important to note that these shifts are not consistently observed, and they vary significantly in strength and direction, often being specific to a particular species. ...
Chapter
Zooplankton are often overlooked but are vital components of marine and freshwater ecosystems. Zooplankton are pivotal in nutrient cycling and ecosystem dynamics as they transfer energy between primary producers and higher trophic levels. However, unprecedented growth in human population and industrialization have exposed aquatic environments to various pollutants, threatening zooplankton communities worldwide. Nutrient over-enrichment, primarily from sewage discharge and agricultural runoff, has caused eutrophication in water bodies. It is altering species composition and favouring the proliferation of certain zooplankton groups while decimating others. As a byproduct of industrialization, heavy metals have infiltrated aquatic ecosystems, accumulating in zooplankton and propagating up the food chain. It poses grave risks to human and ecosystem health. Microplastics (MPs) infiltrating aquatic environments also threaten zooplankton, impairing feeding, growth, and reproduction and altering gene expression. The emergence of pharmaceuticals and antibiotics as environmental contaminants further compounds the plight of zooplankton, disrupting reproduction, survival, and ecological resilience. Pesticides, pervasive in agricultural runoff, harm zooplankton communities significantly, jeopardizing ecosystem stability. Climate change compounds the problem in zooplankton communities by inducing range shifts and phenological changes, altering community dynamics, and heightening vulnerability to other stressors. Regular monitoring of zooplankton has emerged as an invaluable indicator of ecosystem function. As researchers strive to unravel the complex interplay of stressors reshaping aquatic ecosystems, the status of zooplankton communities can signal the urgent need for
... p-value refers to significance of differences in trends between adjacent areas, based on a Mann-Kendall test. 502 interpretation is consistent with the warming-induced distribution shifts documented for plankton assemblages with different temperatures preferences throughout the north Atlantic (Beaugrand et al. 2009), which encompasses the study area considered here, and is further corroborated by the fact that populations at the warm ends of their thermal niches were more vulnerable than those at the cool ends of their thermal niches which often benefited from historical warming (Free et al. 2019). The cross-species synthesis also showed that, compared with species showing no trends in abundance, species with increasing abundance trends showed more increases and fewer decreases in spatial occurrence, while species with a decreasing abundance showed more decreases and less increases in spatial occurrence. ...
... Copepod biomass showed a step decrease in 1985, while phytoplankton showed a step increase in 1989 (Lynam et al., 2011). Across the entire North Atlantic region, calanoid copepod assemblages showed large-scale biogeographical shifts between 1958 and 2005, whereby assemblages generally shifted northwards following the movement of the 10°C isotherm (Beaugrand et al., 2009). Bayesian network analysis confirmed these zooplankton regime shifts in the Irish Sea (Mitchell et al., 2021). ...
Article
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Marine populations often show considerable variation in their productivity, including regime shifts. Of special interest are prolonged shifts to low recruitment and low abundance which occur in many fish populations despite reductions in fishing pressure. One of the possible causes for the lack of recovery has been suggested to be the Allee effect (depensation). Nonetheless, both regime shifts and the Allee effect are empirically emerging patterns but provide no explanation about the underlying mechanisms. Environmental forcing, on the other hand, is known to induce population fluctuations and has also been suggested as one of the primary challenges for recovery. In the present study, we build upon recently developed Bayesian change-point models to explore the contribution of food and climate as external drivers in recruitment regime shifts, while accounting for density-dependent mechanisms (compensation and depensation). Food availability is approximated by the copepod community. Temperature is included as a climatic driver. Three demersal fish populations in the Irish Sea are studied: Atlantic cod (Gadus morhua), whiting (Merlangius merlangus) and common sole (Solea solea). We demonstrate that, while spawning stock biomass undoubtedly impacts recruitment, abiotic and biotic drivers can have substantial additional impacts, which can explain regime shifts in recruitment dynamics or low recruitment at low population abundances. Our results stress the importance of environmental forcing to capture variability in fish recruitment.
... Numerous taxa have moved northward to places where they were previously absent or uncommon (Lenoir and Svenning 2015). For example, the distribution of calanoid copepods showed a northward displacement across the North Atlantic, following the expansion of warm waters (Beaugrand et al. 2009). A study on 360 marine taxa in North America also found that shifts on species' distribution follow the speed of climate change, with the consequent reorganization of marine communities (Pinsky et al. 2013). ...
Thesis
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Global changes have altered biogeography, phenology and abundance of marine populations, thereby promoting a reconfiguration of marine ecosystems’ functioning. Increasing jellyfish blooms warn of major changes not only in ecosystem structure but also in their services and ultimately in human welfare. Rhizostoma pulmo is a large native scyphomedusa of the southern European seas, and in the last decade has gained notoriety due to massive bloom events. Underlying factors driving this phenomenon remain so far elusive, mainly due to the lack of knowledge on the species’ ecology. The aim of this Ph.D. was to uncover drivers of the population dynamics and trophic ecology of R. pulmo through a multi-scale approach. To achieve it, three nested and complementary approaches were employed. The first one assessed, by means of data mining, environmental drivers shaping geographical patterns of bloom events on a long-term scale along the Mediterranean and Black Seas (7,359 records from 1875 to 2019). Secondly, the effect of biotic and abiotic factors on the dynamics of a R. pulmo population, and its trophic role along ontogeny were studied. To do so, an in-situ monitoring was performed during one year (2019) in Bages Sigean, a northwestern French Mediterranean lagoon. It is a natural mesocosm that offers the possibility to track the species on time, as all its life cycle occurs in the lagoon. For a deeper understanding of the processes behind the observed patterns, as a final step, these results were incorporated into a food web model. The 0D plankton food web model coupled low trophic level dynamics, based on a classical Nutrient Phytoplankton Zooplankton Detritus (NPZD) model, to copepods and a jellyfish model based on the pelagic life stages from ephyrae to large medusae.The study showed that R. pulmo blooms exhibited an enhanced magnitude and frequency in recent decades, concurrently with positive temperature anomalies. The biogeographical patterns of the species appear also to be shaped by latitudinal temperature gradients, as northern locations with colder waters showed less intense blooms than southern warmer locations, where the most intense bloom events were recorded. Results uncovered a significant effect of warmer springs on phenological changes, which boosted an earlier start and a longer duration of the medusae season. An intersite comparison revealed different environmental niches in three Mediterranean lagoons, suggesting the existence of a metapopulation. At a local scale, three cohorts were identified during one year, and mesozooplankton abundance appeared to drive the population dynamics in the lagoon, evidencing a bottom-up control. Results showed that the diet composition differs from the availability of prey in the environment with contrasting preferences along ontogeny. Calanoid and harpacticoid copepods were the most frequent prey and the major carbon contributors for young medusae (bell diameter <15 cm), whilst ciliates were the most frequent prey for large organisms (>15 cm). Model simulations emphasized a leading effect of temperature on the bloom timing, while bloom development was promoted by food availability. These results bring an integrated overview of how multiscale environmental signals shape the ecology and population dynamics of R. pulmo. With jellyfish's broad diversity of forms, life strategies and trophic roles, we encourage future research to apply similar strategies in other species, that will allow identifying which species will increase in the future, and where.
... The quantity of marine plankton is, to a large extent, determined by nutrient concentrations, climate, hydrodynamic drivers and food availability (e.g., Beaugrand et al., 2009). Total phytoplankton (as biomass using chlorophyll-a or Phytoplankton Colour Index as a proxy) and zooplankton (as abundance -using total copepods abundance) represent key components of the plankton community. ...
... Finally, changes in the predator community alter the predation risk and populations of species with the same predators in a manner consistent with the shared predator hypothesis. While this hypothesis needs to be tested, there is substantial support for its components, 1) fluctuations of numerically dominant prey are closely linked to climate-induced changes in resources (Lima et al., 1999;Ernest et al., 2000), 2) fluctuations of numerically dominate prey are tied to changes in populations and communities of their predators (Post and Forchhammer, 2002;Beaugrand et al., 2009;Turkia et al., 2020), and 3) changes in predator communities alter the population demographics of species with the same predators (Rooney et al., 2006;Stoessel et al., 2019;Queŕouéet al., 2021). This framework (Figure 7) is more consistent with many patterns of our data than existing constructs. ...
Article
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Our understanding of synchrony between populations from different taxonomic groups has been centered on predator–prey dynamics in simple systems but has rarely been examined in complex predator–prey systems. In addition to trophic interactions such as predator–prey dynamics, there is some evidence that exogenous factor such as climatic variation may facilitate synchrony between different taxonomic groups. Using three longitudinal datasets on quail (Colinus virginianus) and cotton rats (Sigmodon hispidus) we examined 1) the consistency of synchrony across time and space, 2) the relative influence of trophic interactions vs. exogenous factors on synchrony and 3) if trophic interactions were positively associated with synchrony between populations. We found evidence of consistent synchrony in cotton rat and bobwhite populations at both the site and regional levels. We found that trophic interactions between cotton rats and bobwhite were associated with relative synchrony between these populations, but these interactions appeared to weaken in years of greater synchrony. We did not find evidence that exogenous factors influenced relative synchrony at the regional level. Given the lack of a clear mechanistic explanation of the patterns observed in our data, we propose an alternative climate-mediated predation framework to explain synchrony in complex predator–prey systems. This framework includes both classic bottom-up theories of regulation while integrating trophic interactions via components of the shared predator hypothesis.
... Marine planktonic protists (microscopic eukaryotes living in surface waters) are one of the first group of organisms to respond to changes in physical conditions and useful indicator organisms of such change (Hays et al., 2005). Rising sea surface and air temperatures have already been found to have profound consequences (potentially) affecting species' distributional ranges (Beaugrand et al., 2009) and favouring species invasions (Sorte et al., 2010). Increases in sea surface temperatures have been linked to increases in some marine pathogens such as Vibrio spp. ...
... Increasing temperature strengthens the stratification of the upper ocean, which hinders the nutrient supply from the subsurface to the upper layer, thereby limiting phytoplankton growth and decreasing Chla (Behrenfeld et al., 2006;Irwin and Oliver, 2009;Behrenfeld et al., 2016). However, the increasing temperature in the middle to high latitudes could promote phytoplankton growth by becoming closer to the optimum growing temperature for some phytoplankton species (Thomas et al., 2012) and causing poleward shifts of phytoplankton communities at mid to low latitudes (Toggweiler and Russell, 2008;Gregory et al., 2009), thus leading to the increase in Chla here. Moreover, the generally positive trend of Chla in the Southern Ocean is also consistent with the widely reported conclusion that carbon sinks have increased significantly since 2000 (Lavender et al., 2015;DeVries et al., 2019;Gruber et al., 2019;Zhang et al., 2022). ...
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Chlorophyll-a concentration (Chla) is recognized as an essential climate variable and is one of the primary parameters of ocean-color satellite products. Ocean-color missions have accumulated continuous Chla data for over two decades since the launch of SeaWiFS (Sea-viewing Wide Field-of-view Sensor) in 1997. However, the on-orbit life of a single mission is about five to ten years. To build a dataset with a time span long enough to serve climate change related studies, it is necessary to merge the Chla data from multiple sensors. The European Space Agency has developed two sets of merged Chla products, namely GlobColour and OC-CCI (Ocean Colour Climate Change Initiative), which have been widely used. Nonetheless, issues remain in the long-term trend analysis of these two datasets because the inter-mission differences in Chla have not been completely corrected. To obtain more accurate Chla trends in the global and various oceans, we produced a new dataset by merging Chla records from the SeaWiFS, MODIS (Medium-spectral Resolution Imaging Spectrometer), MERIS (Moderate Resolution Imaging Spectroradiometer), VIIRS (Visible Infrared Imaging Radiometer Suite), and OLCI (Ocean and Land Colour Instrument) with inter-mission differences corrected in this work. The fitness of the dataset on long-term Chla trend study was validated by using in situ Chla and comparing the trend estimates to the multi-annual variability of different satellite Chla records. The results suggest that our dataset can be used for long-term series analysis and trend detection. We also provide the global trend map in Chla over 23 years (1998–2020) and present a significant positive global trend with 0.67% ± 0.37%/yr.
... Barnard et al., 2004;Beaugrand et al., 2002), (iii) document distributional, phenological and physiological responses of marine species to climate change (e.g. Beaugrand et al., 2009;Helaouët and Beaugrand, 2009;Thackeray et al., 2016) and (iv) anticipate the consequences of global warming in the pelagic realm (e.g. Reid et al., 1998). ...
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The spatial arrangement of biodiversity and annual plankton succession are key phenomena influencing ocean biogeochemistry (e.g. the biological pump) and the life cycle of many species. Biodiversity and phenological shifts induced by climate change might alter species succession and lead to trophic desynchronization and community reorganisation in space and time. The aim of this PhD is to improve our understanding of plankton biodiversity and phenology by identifying factors and processes that control them and by modelling the annual plankton succession in the context of global climate change. To do so, we used an approach based on the MacroEcological Theory on the Arrangement of Life (METAL) and observations collected by the Continuous Plankton Recorder (CPR) survey. To understand how annual plankton succession and species phenology will be altered in the context of global warming, it is important to identify what parameters and processes control these phenomena. Therefore, in the first part of this PhD, we describe the seasonal variations of major phytoplanktonic taxa in the North Sea and demonstrate that species' phenology results from the interaction between species' niche and the environment. We also show that diatoms with similar cell shape have also similar phenology and niches, i.e. that oblates (flattened cells) dominate the spring and autumn periods whereas prolates (elongated cells) dominate the summer period. We therefore establish a salient link between functional traits, the niche and the phenology. In the second part, we examine the spatio-temporal organisation of plankton biodiversity in the North Atlantic Ocean and show that this region is characterised by large spatial coenoclines (i.e. gradient of biocoenosis or community) induced by the niche-environment interaction. We also develop a new method, called a "species chromatogram", that gives a graphical summary of the niche by representing together abundance gradients along various environmental dimensions. This method can be used to characterise and display the multidimensional ecological niches of different species and also to compare the niches of different species by means of an index that quantify the degree of niche overlapping. We use this index to demonstrate that the plankton belonging to the same trophic guildshave sufficiently distinct niches to coexist is an impermanent and heterogeneous environment in space and time. Finally, we apply a model based on METAL and the projections of six Earth Systems Mdels involved in the Coupled Model Intercomparison Project Phase 6 (CMIP6) to project the past, present and future phenological changes of three phytoplanktonic groups, i.e. oblate and prolate diatoms and dinoflagellates, in three keys areas of the North Atlantic Ocean. We show that the phenology of oblates is likely to continue to shrink and their abundance to decline whereas the phenology of prolates and dinoflagellates will expand and their abundance rise. Our results suggest a climate-induced reorganisation of the phytoplanktonic community in space and time that will affect the rhythm of generation of endosomatic energy, which may have strong consequences on ecosystem functioning and services.
... From a conservation perspective, this intra-population variation in habitat use, foraging dive depth and diet would be beneficial for coping with changes in the quality and quantity of prey in the context of climate change. The high mobility of the EC-WG bowhead whales that perform long seasonal migrations throughout the year would also allow them to track the distribution shifts of their prey (Beaugrand et al. 2002(Beaugrand et al. , 2009) as the conditions in sub-arctic waters become more temperate. However, the results also suggest that some individuals in the population may experience unequal impacts from climate induced shifts in prey. ...
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Shifts in zooplankton quantity and quality caused by climate change could challenge the ability of bowhead whales to meet their energetic requirements. When facing such selection pressure, intra-population variation dampens the negative effects and provides population-level resilience. Previous studies observed inter-individual diet variation in bowhead whales, but the mechanism responsible for the variation was undetermined. We investigated foraging variability in Eastern Canada-West Greenland bowhead whales using dietary biomarkers (stable isotopes, fatty acids) and movement data (satellite telemetry with time-depth recorders) from the same individuals. We found that bowhead whale individuals using distinct summer and fall foraging habitats displayed differences in horizontal movements, foraging dive depth, and diet. For individuals using the Canadian Arctic Archipelago habitat (Foxe Basin, Gulf of Boothia, Prince Regent Inlet, Lancaster Sound and Admiralty Inlet, Nunavut), they performed long distance movements across regions, and their foraging dive depth was generally shallow, but increased from July to November. These whales displayed higher δ ¹³ C and δ ¹⁵ N values and ratios of C16:1n7/C16:0. Individuals using the West Baffin Bay habitat (Cumberland Sound, Baffin Bay, Davis Strait) were more localized in their horizontal movements and consistent over time in their foraging dive depth, which was generally deeper. These whales displayed lower δ ¹³ C and δ ¹⁵ N values and ratios of C16:1n7/C16:0. Overall, this inter-individual variation in diet and foraging behaviour could indicate some niche variation which would be beneficial for the population under changing habitats and prey availability.
... According to climate models [136,[169][170][171][172], the continued warming of the climate, the retreat of glaciers, and a decrease in the area and thickness of the ice cover can have irreversible consequences for the succession of plankton in the ecosystems of the Southern Ocean. Any recorded trend relates only to the analyzed time period, and additional evidence is needed to distinguish it from the variability acting on longer time scales [22]. ...
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In recent decades, the waters off the Antarctic Peninsula and surrounding region have undergone a significant transformation due to global climate change affecting the structure and distribution of pelagic fauna. Here, we present the results of our study on the taxonomic composition and quantitative distribution of plankton communities in Bransfield Strait, Antarctic Sound, the Powell Basin of the Weddell Sea, and the waters off the Antarctic Peninsula and South Orkney Islands during the austral summer of 2022. A slight warming of the Transitional Zonal Water with Weddell Sea influence (TWW) and an increase in its distribution area was detected. Among the pelagic communities, three groups were found to be the most abundant: copepods Calanoides acutus, Metridia gerlachei, and Oithona spp., salpa Salpa thompsoni, and Antarctic krill Euphausia superba. Eu-phausiids were found in cases of low abundance, species diversity, and biomass. In the studied region, an increase in the amount of the salpa S. thompsoni and the euphausiid Thysanoessa macrura and the expansion of their distribution area were observed. Significant structural shifts in phyto-plankton communities manifested themselves in changes in the structure of the Antarctic krill forage base. The composition and distribution of pelagic fauna is affected by a combination of environmental abiotic factors, of which water temperature is the main one. The obtained results have allowed us to assume that a further increase in ocean temperature may lead to a reduction in the number and size of the Antarctic krill population and its successive replacement by salps and other euphausiids that are more resistant to temperature fluctuations and water desalination.
... Long-term time series in Long Island Sound have shown a significant decrease in the size of resident copepod species with warming waters associated with climate change (Rice et al., 2015). In the same geographic areas, changes in water masses due to large-scale climate patterns (i.e., North Atlantic Oscillation [NAO], El Niño-Southern Oscillation [ENSO]) have similarly resulted in shifts in the copepod community to smaller species in warmer water masses (Beaugrand et al., 2009;Lilly and Ohman, 2018). Thus, the inverse relationship between temperature and size is manifest at both individual species and community scales for copepods. ...
Article
The copepods of coastal seas are experiencing warming water temperatures, which increase their oxygen demand. In addition, many coastal seas are also losing oxygen because of deoxygenation due to cultural eutrophication. Warming coastal seas have changed copepod species' composition and biogeographic boundaries and, in many cases, resulted in copepod communities that have shifted in size distribution to smaller species. While increases in ambient water temperatures can explain some of these changes, deoxygenation has also been shown to result in reduced copepod growth rates, reduced size at adulthood, and altered species composition. In this review we focus on the interactive effects of temperature and dissolved oxygen on pelagic copepods, which dominate coastal zooplankton communities. The uniformity in ellipsoidal shape, the lack of external oxygen uptake organs, and the pathway of oxygen uptake through the copepod's integument make calanoid copepods ideal candidates for testing the use of an allometric approach to predict copepod size with increasing water temperatures and decreasing oxygen in coastal seas. Considering oxygen and temperature as a combined and interactive driver in coastal ecosystems will provide a unifying approach for future predictions of coastal copepod communities and their impact on fisheries and biogeochemical cycles. Given the prospect of increased oxygen limitation of copepods in warming seas, increased knowledge of the physiological ecology of present-day copepods in coastal deoxygenated zones can provide insights into the copepod communities that will inhabit a future warmer ocean.
... The Atlantic sector of the Southern Ocean straddles the largest environmental gradients in the world oceans and, therefore, provides a robust research location for environmental variability and biodiversity studies. The current phenomenon of environmental stress observed in the Southern Ocean, which is caused by climate fluctuations and human pressures may modify the structures, life cycles and reproduction of marine zooplankton (Beaugrand et al. 2009(Beaugrand et al. , 2015Burrows et al. 2011Burrows et al. , 2014Gutt et al. 2015). In view of the above, studying the population structures of keystone Antarctic species is crucial for providing geospatial knowledge regarding biodiversity in the Southern Ocean. ...
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Numerous studies have revealed that large numbers of gelatinous invertebrates, Salpa thompsoni , are reported more often in high-latitude Antarctic waters (> 60°S) than were reported in data obtained from the early twentieth century. Previously published studies also suggested that this tunicate may form a small subpopulation in cold shelf Antarctic waters. However, many researchers claim that harsh environmental conditions inhibit the reproduction and development of this species. Therefore, the aim of this study was to examine S. thompsoni blastozooids and the development ability of their embryos within different zones of the eastern and western parts of the Southern Ocean. The samples used in this study were collected from two transects, (I) between the Weddell Sea and coastal waters of South Africa and (II) between South America and the South Shetland Islands (Drake Passage) during the summer season of 2009/2010. The presented results showed that the highest likelihood for the presence of mature salps is observed under both in the conditions considered favorable that are characterized for mid-latitude areas as well as those observed at higher latitudes in the Antarctic zone (60°S) of the Southern Ocean. This work indicated that the prevailing environmental conditions in the Antarctic zone were distinguished by the highest diversity of embryo development stages and the densest salp aggregations. Our work revealed evidence for dualistic environmental preferences, while blastozooid development and embryo fertilization were equally successful at lower temperatures and low chl -a concentrations as well as when these variables reached higher values. This study expands the knowledge about environmental preferences and provides evidence for flexibility of salp reproduction, which allows it to adapt to various environmental conditions of the Southern Ocean.
... cate that no morphological criterion can reliably distinguish between C. glacialis and C. finmarchicus (Choquet et al., 2018). Yet, accurate species identification is crucial considering the increasing northward shift of boreal species due to climate change (Beaugrand et al., 2009;Weydmann, Carstensen, et al., 2014), with a recent study indicating the successful recruitment of C. finmarchicus in Fram Strait (Tarling et al., 2022). A shift from generally larger and lipid-richer Arctic C. ...
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Species identification is pivotal in biodiversity assessments and proteomic fingerprinting by MALDI‐TOF mass spectrometry has already been shown to reliably identify calanoid copepods to species level. However, MALDI‐TOF data may contain more information beyond mere species identification. In this study, we investigated different ontogenetic stages (copepodids C1‐C6 females) of three co‐occurring Calanus species from the Arctic Fram Strait, which cannot be identified to species level based on morphological characters alone. Differentiation of the three species based on mass spectrometry data was without any error. In addition, a clear stage‐specific signal was detected in all species, supported by clustering approaches as well as machine learning using Random Forest. More complex mass spectra in later ontogenetic stages as well as relative intensities of certain mass peaks were found as the main drivers of stage distinction in these species. Through a dilution series, we were able to show that this did not result from the higher amount of biomass that was used in tissue processing of the larger stages. Finally, the data were tested in a simulation for application in a real biodiversity assessment by using Random Forest for stage classification of specimens absent from the training data. This resulted in a successful stage‐identification rate of almost 90%, making proteomic fingerprinting a promising tool to investigate polewards shifts of Atlantic Calanus species and, in general, to assess stage compositions in biodiversity assessments of Calanoida, which can be notoriously difficult using conventional identification methods.
... The increasing northward inflow of warm and saline Atlantic waters is referred to as 'Atlantification' or 'Borealization' of the Arctic (Polyakov et al., 2017). Associated with Atlantic water masses are boreal-Atlantic species, which are rapidly expanding their ranges poleward (Beaugrand et al., 2009). For instance, copepods (Beaugrand et al., 2002;Weydmann et al., 2014), gelatinous zooplankton (Mańko et al., 2020) and fishes (Fossheim et al., 2015;Vihtakari et al., 2018) are shifting northward in their biogeographic distribution. ...
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The Arctic Ocean is rapidly changing. Air temperature is rising two to four times faster in the Arctic than the global average, with dramatic consequences for the ecosystems. Polar zooplankton species have to cope with those increasing temperatures, whilst simultaneously facing increasing competition by boreal-Atlantic sister species advected into the Arctic Ocean via a stronger Atlantic inflow. To assess the sensitivity of Arctic and Atlantic zooplankton to rising temperatures, respiration rates of dominant Arctic species (Calanus hyperboreus, Calanus glacialis, Paraeuchaeta glacialis, Themisto libellula) and their co-occurring Atlantic congeners (Calanus finmarchicus, Paraeuchaeta norvegica, Themisto abyssorum) were measured at ambient temperatures and simulated conditions of ocean warming from 0 to 10°C during three expeditions with RV Polarstern to the Arctic Fram Strait. Arctic zooplankton showed only slowly increasing respiration rates with increasing temperatures, also indicated by low Q10 ratios. In contrast, boreal-Atlantic representatives responded to higher temperatures by a rapid and steeper increase in their respiration rates (higher Q10), suggesting higher metabolic activity. These results imply that Arctic species are physiologically more tolerant to ocean warming than expected but might be outcompeted by their Atlantic congeners beyond a certain temperature threshold in areas of strong distribution overlap. Thus, the ‘Atlantification’ of the Arctic zooplankton community seems to be driven rather by ecological interactions than by physiological limitations. Changes in zooplankton community composition and biodiversity will have major consequences for trophodynamics and energy flux in Arctic ecosystems, since polar species tend to be larger than their southern counterparts and have a higher lipid content, providing more energy-rich food for higher trophic levels.
... Dovekies are diving seabirds that feed on a variety of zooplankton, including fish larvae, euphausids and their primary prey, copepods (Fort et al., 2010). Given that the ranges of their preferred prey, Calanus glacialis, Calanus finmarchicus and Calanus hyperboreus, are shifting northward as a result of climate change (Beaugrand et al., 2009), dovekies will likely have to switch to a less nutritious species or increase foraging effort, both of which may increase daily energy expenditure (DEE) (Amélineau et al., 2016;Grémillet et al., 2012). So far, dovekies have shown a remarkable resilience to the shift, but their ability to buffer its effects may be reaching its limit (Amélineau et al., 2019;Grémillet et al., 2012;Harding et al., 2009b). ...
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Animal-borne telemetry devices provide essential insights into the life-history strategies of far-ranging species and allow us to understand how they interact with their environment. Many species in the seabird family Alcidae undergo a synchronous moult of all primary flight feathers during the non-breeding season, making them flightless and more susceptible to environmental stressors, including severe storms and prey shortages. However, the timing and location of moult remains largely unknown, with most information coming from studies on birds killed by storms or shot at sea. Using light-level geolocators with saltwater immersion loggers, we develop a method for determining flightless periods in the context of the annual cycle. Four Atlantic puffins (Fratercula arctica) were equipped with geolocator/immersion loggers on each leg to attempt to overcome issues of leg-tucking in plumage while sitting on the water, which confounds the interpretation of logger data. Light level and saltwater immersion time-series data were combined to correct for this issue. This approach was adapted and applied to 40 puffins equipped with the standard practice deployments of geolocators on one leg only. Flightless periods consistent with moult were identified in the dual-equipped birds, whereas moult identification in single-equipped birds was less definitive and should be treated with caution. Within the dual-equipped sample, we present evidence for two flightless moult periods per non-breeding season in two puffins that undertook more extensive migrations (> 2000km), and were flightless for up to 76 days in a single non-breeding season. A biannual flight feather moult is highly unusual among non-passerine birds, and may be unique to birds that undergo catastrophic moult, i.e. become flightless when moulting. Though our conclusions are based on a small sample, we have established a freely available methodological framework for future investigation of the moult patterns of this and other seabird species.
... Dovekies are diving seabirds that feed on a variety of zooplankton, including fish larvae, euphausids and their primary prey, copepods (Fort et al., 2010). Given that the ranges of their preferred prey, Calanus glacialis, Calanus finmarchicus and Calanus hyperboreus, are shifting northward as a result of climate change (Beaugrand et al., 2009), dovekies will likely have to switch to a less nutritious species or increase foraging effort, both of which may increase daily energy expenditure (DEE) (Amélineau et al., 2016;Grémillet et al., 2012). So far, dovekies have shown a remarkable resilience to the shift, but their ability to buffer its effects may be reaching its limit (Amélineau et al., 2019;Grémillet et al., 2012;Harding et al., 2009b). ...
Article
Accelerometry has been widely used to estimate energy expenditure in a broad array of terrestrial and aquatic species. However, a recent reappraisal of the method showed that relationships between dynamic body acceleration (DBA) and energy expenditure weaken as the proportion of non-mechanical costs increase. Aquatic air breathing species often exemplify this pattern, as buoyancy, thermoregulation and other physiological mechanisms disproportionately affect oxygen consumption during dives. Combining biologging with the doubly-labelled water method, we simultaneously recorded daily energy expenditure (DEE) and triaxial acceleration in one of the world's smallest wing-propelled breath-hold divers, the dovekie (Alle alle). These data were used to estimate the activity-specific costs of flying and diving and to test whether overall dynamic body acceleration (ODBA) is a reliable predictor of DEE in this abundant seabird. Average DEE for chick-rearing dovekies was 604±119 kJ/d across both sampling years. Despite recording lower stroke frequencies for diving than for flying (in line with allometric predictions for auks), dive costs were estimated to surpass flight costs in our sample of birds (flying: 7.24, diving: 9.37 X BMR). As expected, ODBA was not an effective predictor of DEE in this species. However, accelerometer-derived time budgets did accurately estimate DEE in dovekies. This work represents an empirical example of how the apparent energetic costs of buoyancy and thermoregulation limit the effectiveness of ODBA as the sole predictor of overall energy expenditure in small shallow-diving endotherms.
... Changes in species composition have been reported in various marine ecosystems, and these changes are driven mainly by climate change and fishing (Holbrook et al., 1997;Gregory et al., 2009;Möllmann and Diekmann, 2012;Wernberg et al., 2016;Kleisner et al., 2017). Climate change has been proposed to strongly affect the distribution and abundance of populations (Rose, 2005;Perry et al., 2005;Rijnsdorp et al., 2009), and fishing directly changes not only species abundance but also predator-prey interactions and community structure (Pauly et al., 1998;Bianchi et al., 2000;Frank et al., 2005). ...
Article
Climate change and intensive fishing have affected not only population abundance, but also species composition. Cephalopods have been increasing in abundance in the world ocean under climate change due to their flexible life-history traits, including the over-exploited China Seas. Despite the increasing importance of coastal cephalopods in the China Seas, there have been no reports of changes in either species composition, nor the ecological roles of species with different life-history traits. Thus, this study first presents the changes in species composition of coastal cephalopods throughout the China Seas as summarized from fishery-independent survey reports over the last six decades. This is followed by an investigation of species composition of cephalopods in Haizhou Bay in the Yellow Sea. The ecological roles of two currently targeted cephalopods, Amphioctopus fangsiao and Loliolus spp. (Loliolus beka and Loliolus japonicus), are evaluated using an ecosystem model. The species composition of coastal cephalopods in the China Seas has changed since the 1960s, from species of large size and high value to small-size, low-value species. Cephalopod species composition in Haizhou Bay shows great seasonality, which is probably due largely to the characteristics of their life cycle. The population abundance of A. fangsiao and Loliolus spp. appear to be affected by ambient water temperature, and population distribution of Loliolus spp. seems to correlate with water depth. Occupying the highest trophic level in this ecosystem, A. fangsiao potentially displays strong top-down control over other organisms. Loliolus spp. are keystone species showing higher keystoneness in the autumn, owing to a low abundance of fish species which normally prey on them. The species-specific life-history traits and ecological roles of cephalopods are therefore important factors to consider in order to manage them effectively.
... This may partially explain the selective foraging of herring on copepods in late 2018 and 2019, when we observed increased densities of small-bodied copepods in Trinity Bay. Distribution shifts and decline of large-bodied copepods in high latitude systems have been reported throughout the North Atlantic and Pacific (Beaugrand et al., 2009) and are attributed to higher temperatures and reduced sea ice ( (Pitois and Fox, 2006;Coyle and Gibson, 2017). Given the importance of large copepods to forage fish diets, including herring, throughout the North Atlantic (Darbyson et al., 2003;Dommasnes et al., 2004;Prokopchuk and Sentyabov, 2006;Raab et al., 2012; this study), a shift in dominance from Calanus spp. to smaller, less-nutritious copepods could trigger bottom-up effects and alter forage fish energy budgets. ...
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Atlantic herring (Clupea harengus; hereafter herring) is a forage fish that transfers energy from lower to higher trophic levels and sustains high-volume fisheries in the North Atlantic. This study aims to improve our understanding of the ecology of Newfoundland herring and its vulnerability to climate change by identifying key prey items and describing adult herring feeding strategies. We compared plankton assemblages to stomach content and stable isotope analyses from herring collected in Trinity Bay, Newfoundland, in late summer and autumn 2017-2019. Six distinct zooplankton communities were identified across all years, with a shift in community structure in September 2018. This shift coincided with a change from fresher, warmer waters (12-17 • C) to more saline, cooler waters (10.5 • C). The most frequently consumed prey items were amphipods (Themisto spp.) and calanoid copepods (primarily Calanus and Temora spp.). Fish eggs, larvae, and juveniles, primarily identified as capelin, were observed in stomach contents in all years. Fish contributed most to diets in 2017, which corresponded with the peak year for larval densities in Trinity Bay, suggesting that piscivory may increase at higher larval densities. Herring were opportunistic feeders, although some individuals exhibited selective feeding on copepods, amphipods, euphausiids, and the early life stages of fishes. Stable isotope analyses supported the finding that herring piscivory is prevalent in eastern Newfoundland. Given its adaptive feeding strategy and wide range of consumed prey, we conclude that adult Newfoundland herring is resilient to bottom-up changes observed in the environment.
... Shelf seas contain diverse and productive ecosystems (Lauria et al. 2012) that have undergone profound changes in recent times as a result of both natural and anthropogenic modes of climate variability (Southward et al. 1995;Beaugrand and Reid 2003;Schmidt et al. 2020). Marine zooplankton are possibly the most sensitive animals to changes in environmental conditions and monitoring their long term abundance and diversity has facilitated the detection of ecosystem-wide changes in several shelf basins (Southward et al. 1995;Beaugrand et al. 2009;Conversi et al. 2010). In fact, the fourth descriptor of the European Union's Marine Strategy Framework Directive includes zooplankton as an important factor influencing the state of a food web due to pelagic-benthic coupling (EU, 2017). ...
Thesis
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Gelatinous zooplankton are a natural and globally important group of marine organisms, as they provide regulating, provisioning and supporting services to ecosystems. However, gelatinous zooplankton are still a major issue for human activities in several parts of the world, and there is concern that in these regions, the abundance of gelatinous zooplankton may be increasing over time. Added uncertainty comes from the lack of information for the abundance of gelatinous zooplankton at a regional level, particularly in offshore waters, and for gelatinous mesozooplankton that are < 2 cm in size. This thesis sought to improve these knowledge gaps by generating two decade-long datasets for the abundance and diversity of two poorly represented groups of gelatinous zooplankton in the Celtic Seas region of the North East Atlantic (NEA), using fisheries surveys as a research platform. To generate baseline information for gelatinous mesozooplankton species in the Celtic Seas, we identified two fisheries research surveys that were actively collecting zooplankton samples in the region, that could be re-analysed for gelatinous mesozooplankton. However, the net methods used to sample zooplankton on the two types of fisheries survey were different. To evaluate whether each net type (i.e. a Gulf VII sampler and a ring net) estimated the abundance and diversity of gelatinous mesozooplankton similarly, simultaneous deployments of the Gulf VII and ring net were made at 15 sites in July 2017 in Irish and UK shelf waters, and their gelatinous catches were compared. The difference in the estimates of gelatinous mesozooplankton abundance and taxon richness of the Gulf VII and the ring net samples were not significant. This confirmed that zooplankton samples from these two fisheries surveys could be re-analysed to generate a novel long-term data set for gelatinous mesozooplankton in the Celtic Seas. Using zooplankton samples from the two aforementioned fisheries surveys, species abundance data was generated for gelatinous mesozooplankton in the Celtic Sea for seven summers over a 13-year period (2007 – 2019). Total abundance was highly variable each summer, but did not increase or decrease linearly over time. However, subtle compositional changes occurred interannually, including a gradual shift in the abundance ratio of two siphonophore species Muggiaea atlantica and Agalma elegans. Holoplanktonic species dominated the abundance of the gelatinous mesozooplankton community (93.27%) and their abundance was negatively associated with sea surface temperature in July (represented by the position of the 16°C isotherm), and this was underpinned by natural climate variability (represented by the Eastern Atlantic Pattern index). Importantly, these findings suggest that gelatinous mesozooplankton abundance in the Celtic Sea may be lower as a consequence of future ocean warming. The aggregations of one oceanic jellyfish, Pelagia noctiluca, have negatively affected the aquaculture industry in the NEA, especially in Ireland and Scotland. Despite this, there is very little long-term information for their abundance and distribution in the NEA. To investigate the frequency and scale of P. noctiluca aggregations in this region, we collected semi-quantitative data for this species from an autumn-winter fisheries survey, which deployed 1,948 trawls over 11 years (2008 – 2018) covering most of the Celtic Seas. P. noctiluca was present on the Irish shelf in every year of the study (which is much higher than the historical record), and large aggregations of this warm-temperate species occurred in 5 of 11 years, as isolated events. When aggregations occurred, the highest by-catch density was recorded in the northern Irish shelf (maximum catch of P. noctiluca was 195 kg in 2009). P. noctiluca occurrence and abundance was related to wind patterns and two modes of hydroclimatic variability (the North Atlantic Oscillation index and the Eastern Atlantic Pattern index), which could reflect changes in advective processes that transport offshore populations onto the Irish shelf. A recent increase in the occurrence of P. noctiluca detected in the present work may pose a rising threat to coastal enterprise in the North East Atlantic, namely the aquaculture industry. Together, the present work revealed that different groups of gelatinous zooplankton species displayed different trends in abundance over time in the NEA, and this was likely a result of differences in specific biological traits such as life history type, geographical distribution and temperature preference. The diversity of trends (and associated mechanisms) described here further emphasises the complexity and diversity of gelatinous zooplankton, and the need to study this group of organisms at a high taxonomic resolution and over regional or sub-regional scales.
... These important changes in the composition and biomass of species are likely to influence whole ecosystems(Scheffer et al. 2001, Hoegh-Guldberg and Bruno 2010, Doney et al. 2012). The alteration of ecosystem structure and functioning is indirectly influencing lower trophic levels, especially planktivorous organisms through top-down trophic propagation (e.g.Beaugrand et al. 2009, Chust et al. 2014). However, ecosystem consequences of climate change remains poorly understood(Payne et al. 2016a), with only few studies concerning marine systems (e.g.Albouy et al. 2013, Woodworth-Jefcoats et al. 2017, Lotze et al. 2019). ...
Thesis
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Environmental conditions are shaping the spatial distribution of marine species worldwide. However, climate change may alter their future distribution, impacting marine resources exploitation and ecosystems balance. In this context, this PhD identifies climate induced impacts in species and geographical areas, by focusing on some species, indigenous or non-indigenous, of commercial interest in the Mediterranean.Based on the ecological niche concept, that defines the potential distribution of a species according to the environmental conditions in which it is observed, we developed a contemporary and future distribution modelling procedure for marine species. This procedure includes an ensemble of statistical algorithms, future climate models and scenarios while accounting for common ecological niche modelling limitations. Applied to small pelagic fish and cephalopods, we projected major climate induced impacts in the Mediterranean Sea by 2100, including local extinctions in its south-eastern basin. Conversely, we projected a distributional range expansion of most of the studied species towards the North, Norwegian and Baltic seas. In the Gulf of Lion, the small pelagic fish distributional range shifts may indirectly impact their harvesting capacity as well as the productivity of low trophic levels. The combined effects of climate warming and the opening of the Suez Canal induced biological invasions, especially in the South-East Mediterranean. These non-indigenous Mediterranean species may be of commercial interest subject to future harvesting. After quantifying the invasive potential of several non-native Mediterranean marine species, according to their functional and ecological traits, we applied our modelling procedure to estimate their future distributional range expansion. We projected a major distributional range expansion of non-native species in the whole Mediterranean Sea by 2100, especially for warming exceeding 2°C.This work highlights the sensitivity of the Mediterranean Sea to climate change while proposing adaptation and conservation perspective of species and ecosystems facing the upcoming climate trends of the 21st century.
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ABSTRACT FRENCH-Chapitre 1: Il existe des interactions étroites entre le climat terrestre et le vivant et ceci depuis les origines. En étudiant l’histoire de la vie sur Terre, on comprend que l’atmosphère l’a probablement créée et que le vivant n’a pas cessé de modifier cette atmosphère en réaction aux pressions de sélection issues des grandes transitions qu’a subie la Terre. Le vivant s’est adapté aux perturbations en se stabilisant grâce à la spécialisation et à l’organisation. FRENCH-BOOK: En plus d’un hymne à la biodiversité marine, cet ouvrage a pour objectif d’aider les décideurs à mieux comprendre le rôle de la planète bleue dans le climat et l’importance de la prendre en considération dans chacune des décisions politiques de ce XXIème siècle. ENGLISH-Chapter-1: There are close interactions between the Earth's climate and life, and this has been the case since the beginning. By studying the history of life on Earth, we understand that the atmosphere probably created it and that life has not stopped modifying this atmosphere in response to the selection pressures resulting from the major transitions that the Earth has undergone. Life has adapted to perturbations by stabilizing itself through specialization and organization. ENGLISH-BOOK: In addition to being a hymn to marine biodiversity, this book aims to help decision-makers to better understand the role of the blue planet in the climate and the importance of taking it into consideration in each of the political decisions of this 21st century.
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This review highlights diatoms and their production of fatty acids at Arctic ice edges and temperate estuaries as strategic in initiating high spring productivity. As important as their energy production is their synthesis de novo of omega-3 long-chain polyunsaturated fatty acids (LCPUFAs), which are bioactive molecules fundamental to maintaining ecosystem processes, and are necessary for reproduction and growth for the entire marine food web. Without these fatty acids, consumers can suffer poor reproduction and growth even with sufficient energy intake, and shorebirds may need LCPUFAs for nonstop long-hop migration. Timing of high energy fatty acid and LCPUFA production by diatoms coincides with growth and reproduction of consumer populations, with the arrival of seabirds in the Arctic and staging of shorebirds in estuaries. The switch from diatom production of carbohydrates to fatty acids is triggered by changes in chemical and physical environmental factors, which can be muted by factors such as climate change or habitat modification. Higher ocean temperatures and lower pH from climate change alters the ability of diatoms to make LCPUFAs, and habitat degradation reduces the numbers of diatoms in the area, subsequently reducing the amounts of LCPUFA produced. Changes in LCPUFA output could impact functionality of ice-edge and estuarine ecosystems, impacting shorebird migration and consumer productivity. Research is scarce on marine consumer reproduction and growth comparing quantity vs. quality of ingested saturated, monounsaturated, and omega-3 LCPUFAs, and nonexistent for seabirds and shorebirds. Future studies of marine food webs should include the role of diatoms and their contribution of not just energy, but also LCPUFAs to the food web.
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Two forms of spatial interpolation, the interpolation of point and areal data, are distinguished. For point interpolation, the numerous methods may further be classified into exact and approximate. Exact methods include most distance-weighting methods, Kriging, spline interpolation, interpolating polynomials, and finite-difference methods. Approximate methods include power- series trend models, Fourier models, distance-weighted least-squares, and least-squares fitting with splines. Areal interpolation methods, on the other hand, are classsified according to whether they preserve volume. Traditional areal interpolation methods which utilize point interpolation procedures are not volume-preserving, whereas the map overlay and pycnophylactic methods are. It is shown that methods possessing the volume-preserving property generally outperform those that do not. -Author
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The temperature of the upper 300 m of the North Atlantic increased by about 0.57°C between 1984 and 1999. but this underlying trend was overlain with substantial geographic and interannual variability. Northward shifts occurred in the distribution of many commercial and non-commercial fish species in the NE Atlantic during the 1990s. New records were established for a number of Mediterranean and NW African species on the south coast of Portugal. Red mullet (Mullus surmuletus) and bass (Dicentrarchus labrax) extended their ranges northward to western Norway and catches of the former increased throughout the 1990s in the North Sea. Abundance or relative abundance of warm-water commercial species of gadoids and flatfish generally increased during the 1990s, but like the warming trend the changes in distribution and abundance were by no means uniform and there was considerable interannual variability. There were also examples of southward shifts for some species, which can be related to local hydrographic conditions, such as upwelling. Information on distribution and abundance of Greenland cod (Gadus morhua L.) and Norwegian spring spawning herring (Clupea harengus) during a previous warming period in the late 1920s and 1930s is also presented and compared with changes in the 1990s.
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We show that the distributions of both exploited and nonexploited North Sea fishes have responded markedly to recent increases in sea temperature, with nearly two-thirds of species shifting in mean latitude or depth or both over 25 years. For species with northerly or southerly range margins in the North Sea, half have shown boundary shifts with warming, and all but one shifted northward. Species with shifting distributions have faster life cycles and smaller body sizes than nonshifting species. Further temperature rises are likely to have profound impacts on commercial fisheries through continued shifts in distribution and alterations in community interactions.
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Hutchinson's (1957; Cold Spring Harbour Symp Quant Biol 22:415-427) niche concept is being used increasingly in the context of global change, and is currently applied to many ecological issues including climate change, exotic species invasion and management of endangered species. For both the marine and terrestrial realms, there is a growing need to assess the breadth of the niches of individual species and to make comparisons among them to forecast the species' capabilities to adapt to global change. In this paper, we describe simple non-parametric multivariate procedures derived from a method originally used in climatology to (1) evaluate the breadth of the ecological niche of a species and (2) examine whether the niches are significantly separated. We first applied the statistical procedures to a simple fictive example of 3 species separated by 2 environmental factors in order to describe the technique. We then used it to quantify and compare the ecological niche of 2 key-structural marine zooplankton copepod species, Calanus finmarchicus and C. helgolandicus, in the northern part of the North Atlantic Ocean using 3 environmental factors. The test demonstrates that the niches of both species are significantly separated and that the coldwater species has a niche larger than that of its warmer-water congeneric species.
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Global climate change is expected to modify the spatial distribution of marine organisms. However, projections of future changes should be based on robust information on the ecological niche of species. This paper presents a macroecological study of the environmental tolerance and ecological niche (sensu Hutchinson 1957, i.e. the field of tolerance of a species to the principal factors of its environment) of Calanus finmarchicus and C. helgolandicus in the North Atlantic Ocean and adjacent seas. Biological data were collected by the Continuous Plankton Recorder (CPR) Survey, which samples plankton in the North Atlantic and adjacent seas at a standard depth of 7 m. Eleven parameters were chosen including bathymetry, temperature, salinity, nutrients, mixed-layer depth and an index of turbulence compiled from wind data and chlorophyll a concentrations (used herein as an index of available food). The environmental window and the optimum level were determined for both species and for each abiotic factor and chlorophyll concentration. The most important parameters that influenced abundance and spatial distribution were temperature and its correlates such as oxygen and nutrients. Bathymetry and other water-column-related parameters also played an important role. The ecological niche of C. finmarchicus was larger than that of C. helgolandicus and both niches were significantly separated. Our results have important implications in the context of global climate change. As temperature (and to some extent stratification) is predicted to continue to rise in the North Atlantic sector, changes in the spatial distribution of these 2 Calanus species can be expected. Application of this approach to the 1980s North Sea regime shift provides evidence that changes in sea temperature alone could have triggered the substantial and rapid changes identified in the dynamic regimes of these ecosystems. C. finmarchicus appears to be a good indicator of the Atlantic Polar Biome (mainly the Atlantic Subarctic and Arctic provinces) while C. helgolandicus is an indicator of more temperate waters (Atlantic Westerly Winds Biome) in regions characterised by more pronounced spatial changes in bathymetry.
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The filtration efficiency [volume filtered/(inlet aperture area × distance travelled through the water)] and retention of copepods by the Continuous Plankton Recorder (CPR) were measured in sea trials. Filtration efficiency was independent of tow speed (n = 14 trials, range of speeds 5–13 knots, F1.12 = 0.1, P = 0.73), but was influenced by the extent to which the body of the CPR was sealed. The retention of copepods on the silk filtering mesh routinely used in CPRs did not differ significantly from that predicted for a 270 μm nylon mesh and did not vary with tow speed.
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North Atlantic sea surface temperatures for 1856–1999 contain a 65–80 year cycle with a 0.4 °C range, referred to as the Atlantic Multidecadal Oscillation (AMO) by Kerr [2000]. AMO warm phases occurred during 1860–1880 and 1940–1960, and cool phases during 1905–1925 and 1970–1990. The signal is global in scope, with a positively correlated co-oscillation in parts of the North Pacific, but it is most intense in the North Atlantic and covers the entire basin there. During AMO warmings most of the United States sees less than normal rainfall, including Midwest droughts in the 1930s and 1950s. Between AMO warm and cool phases, Mississippi River outflow varies by 10% while the inflow to Lake Okeechobee, Florida varies by 40%. The geographical pattern of variability is influenced mainly by changes in summer rainfall. The winter patterns of interannual rainfall variability associated with El Niño-Southern Oscillation are also significantly changed between AMO phases.
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It has been assumed that the volume of seawater filtered by each sample remained constant and close to 3 m,. In this study, the volume filtered for each CPR sample was measured on two routes (SA and IN), monitored by the CPR survey, between 1995 and 2000.Although the filtered volume was near the theoretical value of 3 m, on the SA route (3.2 m,), it was significantly higher on the IN route (3.8 m,). A significant negative relationship was found between the volume filtered and the speed of the ships. This relationship indicates that the faster the speed of the ship, the lower the volume filtered. This could have implications for the CPR survey as the speed of the ships has increased continuously since the end of the 1950s. However, no significant correlation was found between the long-term changes in the speed of the ships and two commonly used indicators of plankton variability: the Phytoplankton Colour and the Total Copepods indices. This absence of relationship may indicate that the effect found is small in comparison with the influence of hydroclimatic forcing, although a more extensive study is needed to confirm these findings.
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Present-day patterns in pelagic biodiversity are the result of the interaction of many fac- tors acting at different scales. Developing an understanding of the processes that regulate the diver- sity of oceanic ecosystems is thus challenging. In this study, diversity of calanoid copepods was decomposed into species associations by means of the recent 'indicator value method' and multivari- ate analyses. For the first time, at an oceanic basin scale and with a spatial resolution approaching the mesoscale, species associations of calanoid copepods have been identified. Nine species associations were determined and have enabled us, (1) to improve the ecological partitioning of this region, and (2) to identify the main factors that regulate pelagic biodiversity in this area. It is shown that temper- ature, hydrodynamics, stratification and seasonal variability of the environment are likely to be the main factors contributing to the ecological regulation of diversity of calanoid copepods. The similar geographical pattern evident between currents/water masses and the species associations suggest that the species groups may be used as an environmental indicator to evaluate long-term changes in the marine environment related to climate change and other increasing human-induced influences.
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After 1987, Phytoplankton Colour (a visual estimate of chlorophyll) measured on samples taken by the continuous plankton recorder (CPR) in the North Sea increased substantially, both in level and seasonal extent, compared to earlier years since 1946. Many species of phytoplankton and zooplankton showed marked changes in abundance at about the same time. These events coincided with a large increase in catches of the western stock of the horse mackerel (Trachurus trachurus L.) in the northern North Sea reflecting a northerly expansion of the stock along the shelf edge from the Bay of Biscay to the North Sea after 1987. Using a 3D hydrodynamic model, with input from measured wind parameters, monthly transport of oceanic water into the North Sea has been calculated for the period 1976–1994, integrated for a section from Orkney to Shetland to Norway. A substantial increase in oceanic inflow occurred in the winter months, December to March, from 1988. Higher sea surface temperatures were also measured after 1987 especially in spring and summer months. These biological and physical events may be a response to observed changes in pressure distribution over the North Atlantic. From 1988 onwards, the North Atlantic Oscillation (NAO) index, the pressure difference between Iceland and the Azores, increased to the highest positive level observed in this century. Positive NAO anomalies are associated with stronger and more southerly tracks of the westerly winds and higher temperatures in western Europe. These changing wind distributions may have led to an increase in the northerly advection of water along the western edge of the European shelf and may have assisted the migration of the horse mackerel. This study is possibly a unique demonstration of a correlation between three different trophic levels of a marine ecosystem and hydrographic and atmospheric events at decadal and regional scales. The results emphasise the importance of maintaining into the future long term programmes such as the CPR.
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