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Proportion of the large copepod community comprised of species that diapause for the northern North Atlantic CPR data (a), and data from Saito & Kubota (1995) (b).
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... the northern North Atlantic and in the Falkland Current, we correlated the model output with measured distribution patterns (Fig. 4). In both cases, Model I demonstrated the strongest correlation, with notably high correlation coefficients (r 2 = 0.71 and 0.42 respectively, p < 0.001, Table 2, Fig. 5). Models II and III had statistically significant correlations with very low r 2 values in the North Atlantic, and Model IV had no significant correlation in either ...
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... In this study, the generally low number of larvae surviving to 10 dph indicates potential for improved rearing that may still corroborate or falsify these conclusions. Overall, the northwest Atlantic shelf is rapidly warming (Kavanaugh et al. 2017) in addition to changes in Gulf Stream dynamics (Gangopadhyay et al. 2019), which are altering primary productivity, species compositions, and zooplankton prey items (Kleisner et al. 2017;Record et al. 2018;Suca et al. 2021;Benedetti et al. 2021;Balch et al. 2022). This could result in adverse effects for C. striata -independent of ocean acidification -perhaps via match/mismatch of larvae and their prey (Laurel et al. 2021) and/or a decrease in zooplankton nutritional quality (Rossoll et al. 2012). ...
Ocean acidification is a symptom of marine climate change resulting from the uptake of anthropogenic carbon dioxide (CO2) into the world’s ocean, thereby potentially affecting survival, growth, and numerous other traits in fish early life stages. But some fish species are clearly more CO2-resilient than others, perhaps because they reside in more CO2-variable, inshore habitats as opposed to more CO2-stable offshore waters. Here we studied the early life CO2 sensitivity of an ecologically and economically important fish species (Black Sea Bass, Centropristis striata) that seasonally migrates between offshore overwintering and inshore feeding and nursery grounds. We produced embryos from wild spawners and reared them until 10 days post-hatch (dph) at three contrasting pCO2 levels (~400, ~2200, ~3000 µatm), finding no statistical effects of pCO2 on hatching success (~28%) or survival to 10 dph (~23%). At the extreme pCO2 level, surviving larvae were 1.2× larger and grew 55% faster compared to control pCO2 conditions. These results extend pioneering work by Meseck et al. (2022; https://doi.org/10.1002/mcf2.10200) to confirm a surprising CO2 tolerance of C. striata early life stages. This suggests existing adaptation to high CO2 conditions either because of seasonal exposures at productive inshore environments or at offshore depths during overwintering.
... reproductive cycles. With the exception of Butterfish, these high-energy forage species are planktivores, feeding to some degree on lipid-rich copepods, including Calanus finmarchicus, which has fluctuated in abundance and generally declined over the past few decades in the coastal ocean of the U.S. Northeast (Record et al. 2018;Sorochan et al. 2019). The scarcity of lipid-rich Calanus spp. ...
Abstract
Objective: Energy density (ED) estimates for marine forage species have been limited, impeding our understanding of this important trophic level. We studied the EDs of eight key forage species: Alewife Alosa pseudoharengus, Atlantic Herring Clupea harengus, Silver Hake Merluccius bilinearis, Northern Sand Lance Ammodytes dubius, Atlantic Mackerel Scomber scombrus, Butterfish Peprilus triacanthus, northern shortfin squid Illex illecebrosus, and longfin inshore squid Doryteuthis pealeii (also known as Loligo pealeii).
Methods: Samples were obtained during spring and fall bottom trawl surveys across five regions (Gulf of Maine, Georges Bank, southern New England, northern Middle Atlantic Bight, and southern Middle Atlantic Bight) from 2017 to 2019. In the lab-oratory, we developed predictive relations between the percent dry weight (%DW) and ED (kJ/g wet weight) determined by proximate composition analysis (n= 606; r2= 0.76–0.98) to estimate the ED of additional samples (n= 4583). For each species, we modeled ED as a function of size, depth, season, and year (as factors) as well as location (latitude, longitude) using generalized additive models (GAMs).
Result: Alewife, Atlantic Herring, Northern Sand Lance, Atlantic Mackerel, and Butterfish were classified as high- quality prey (ED > 6 kJ/g), although Atlantic Herring ED was nearly half the values reported in earlier studies. Silver Hake, northern shortfin squid, and longfin inshore squid were classified as moderate- quality prey (4 kJ/g < ED < 6 kJ/g). Most species had higher EDs in the fall following summer feeding than in the spring after spawning and/or reduced winter feeding. The best-fitting GAMs included weight, depth (by season), season, and year effects for most species. Location (by season) explained significant amounts of variation.
Conclusion: Observed variation in ED across regions, species, seasons, and years provides the empirical data necessary to consider hypotheses related to “upstream” regulation of ED (via environmental drivers and productivity) and “downstream” effects on recruitment for these forage species as well the species that prey on them.
... Temporary ponds are already well known as favorable habitats for copepods, including such typical species in northern Europe as Cyclops furcifer (Claus, 1857), C. heberti Einsle, 1996, and C. singularis Einsle, 1996 [10,11]. Diapause (dormancy) is well known in Copepoda, and it is crucial for their survival in temporary aquatic habitats, allowing them to endure harsh conditions and resume their life cycle when conditions become favorable [12]. Copepods fundamentally have a 13-stage life history, and diapause may occur in most of these stages, but in the freshwater Cyclopoida, it is most characteristic of late copepodite stages [13,14]. ...
The hyporheic (phreatic) zone connects groundwater and surface water and hosts a diverse community of organisms that are adapted to its unique conditions. In order to investigate the hitherto poorly understood biotic connections between the hyporheic zone and temporary ponds, we analyzed changes in the community of Copepoda in a small and shallow ephemeral puddle in a meadow for one year, with comparison to the groundwater fauna of the surrounding region in northeastern Poland. In the puddle, three species of Cyclopoida (Acanthocyclops vernalis, Diacyclops bisetosus, and Cyclops furcifer) were present in large numbers throughout the year. These species were also common components of the region's groundwater fauna, but in much lower densities in the groundwater than in the puddle. These results suggest that temporary puddles can be a convenient place for copepods to feed and reproduce, while groundwater may serve as an important corridor for their dispersal. This study contributes to a more comprehensive understanding of copepod ecology and the functioning of ephemeral aquatic habitats.
... These copepods can respond to seasonal conditions (temperature and food supply) by accumulating more lipids and fatty acid during spring and summer phytoplankton blooms, and then relying on their reserves during winter (Kattner and Krause, 1989). This variability in copepod lipid content plays a fundamental role in global marine food webs (Jónasdóttir et al., 2015;Record et al., 2018). ...
Seasonal variations in environmental conditions determine the success of decapod larval development, and females transmit more energy in sub-optimal conditions to maximise the fitness of their offspring. The objective of this study was to focus on the combined effects of temperature (14, 18 and 22 °C) and food quality on the performance of larvae produced by 5 young (0+) and 5 old (I+) Palaemon serratus females. We prepared 3 diets based on Artemia, in decreasing order of total fatty acid content: freshly hatched nauplii (N), unenriched met-anauplii (M) and metanauplii enriched with a mixture of microalgae (ME). At hatching, the larvae produced by I+ females had a higher biomass but a similar fatty acid concentration to those produced by 0+ females. Larvae survived better and developed relatively faster as temperature increased, and the longer they waited to meta-morphose, the greater their weight at metamorphosis. These performances were diet-dependent, with more survival and more growth in less time with diet N than with the other two. Larvae from I+ females performed better than those from 0+ females, especially under the most stressful conditions. The greater biomass of the larvae of I+ females seems to have enabled them to follow a shorter, and therefore faster, development path than those of 0+ females. The larvae's diet also had an impact on post-metamorphic composition: larvae eating a diet richer in fatty acids produced richer juveniles and those eating a poorer diet produced juveniles with slightly more essential fatty acids. This study supports the high plasticity of caridean shrimp larval development and the importance of maternal effects on the fitness of offspring.
... In Calanus finmarchicus, one of the most ubiquitous species of copepods in the North Atlantic (Head et al., 2013;Melle et al., 2014Melle et al., , 2015, the oil sac is at its largest in stage CV copepodites, which typically require large lipid stores to diapause at depth. This diapausing trait plays an essential role in the avail-ability of marine lipids by concentrating energy-rich lipids from short phytoplankton blooms into a biological "battery", which provides higher trophic levels with a source of energy over a longer period (Record et al., 2018). The combination of the energetic value and the buoyancy characteristics of stored lipids is thought to be essential in the success of this diapausing stage (Irigoien, 2004). ...
Copepod size and energy content are influenced by regional and seasonal variation in temperature and food conditions, with implications for planktivorous consumers such as the endangered North Atlantic right whale (Eubalaena glacialis). Historical data (1990–2020) on Calanus finmarchicus stage CV copepodite prosome length and oil sac metrics were analyzed to determine the extent of variation in individual body size and estimated lipid and energy content in five regions of the Northwest Atlantic continental shelves [Gulf of Maine (GoM), Scotian Shelf (SS), Gulf of St. Lawrence (GSL), St. Lawrence Estuary (SLE) and Newfoundland Shelf]. Large-scale spatial patterns in size and lipid content were related to latitude, indicating that C. finmarchicus CV in the GSL and SLE were historically larger in body size, and had significantly higher lipid content compared with those in the GoM and the SS. The observed patterns of C. finmarchicus CV size and lipid storage capacity suggest that regional variation in whale prey energy content can play a role in the suitability of current and future whale foraging habitats in the Northwest Atlantic, with the larger lipid-rich individuals in the GSL providing a high-quality diet compared with those in southern areas.
... Among the many individual properties measurable from images, the visual estimation of lipid stores is an obvious research target, owing to the important role energy-rich lipids play for the biological carbon pump (Record et al., 2018;Pinti et al., 2023) and for marine trophic networks up to humans (Belton and Thilsted, 2014). Productive, lipid-rich food webs in the ocean depend on a handful of large, lipid-rich pelagic mesozooplanktonic species that form a hub of matter and energy between the intense but often short-lived microbial primary production and upper trophic levels (Kattner and Hagen, 2009). ...
... Some long-chained fatty acids that are essential for all animals (e.g. docosahexaenoic acid-DHA-and eicosapentaenoic acid-EPA) must be obtained from planktonic primary producers via the hub of matter and energy formed by copepod communities toward higher trophic levels, including human population (Parrish, 2009;Record et al., 2018). More generally, lipid is the currency of productive marine trophic networks that rely on short-lived but intense periods of primary production (blooms), since it is the most efficient form of energy and carbon storage, easily transferable among the different actors of the network. ...
In Arctic marine ecosystems, large planktonic copepods form a crucial hub of matter and energy. Their energy-rich lipid stores play a central role in marine trophic networks and the biological carbon pump. Since the past ~15 years, in situ imaging devices provide images whose resolution allows us to estimate an individual copepod’s lipid sac volume, and this reveals many ecological information inaccessible otherwise. One such device is the Lightframe On-sight Keyspecies Investigation. However, when done manually, weeks of work are needed by trained personnel to obtain such information for only a handful of sampled images. We removed this hurdle by training a machine learning algorithm (a convolutional neural network) to estimate the lipid content of individual Arctic copepods from the in situ images. This algorithm obtains such information at a speed (a few minutes) and a resolution (individuals, over half a meter on the vertical), allowing us to revisit historical datasets of in situ images to better understand the dynamics of lipid production and distribution and to develop efficient monitoring protocols at a moment when marine ecosystems are facing rapid upheavals and increasing threats.
... Knowing how resource availability affects an individual's ability to accumulate lipid stores is key to understanding their resilience and ability to cope with non-optimal environmental conditions. The copepods' ability to store lipids allows them to transform a brief pulse in primary production into a long-term energy source (Conover and Corner, 1968;Kaartvedt, 2000;Kattner et al., 2007;Darnis et al., 2012;Jónasdóttir et al., 2015;Record et al., 2018). These lipid-rich calanoid copepods play a key role in high-latitude pelagic food webs as an important food source for higher trophic levels, so their persistence is critical to ecosystem health (Lee et al., 2006;Kattner and Hagen, 2009). ...
... Diatoms are an important food source for copepods and, being high in nutritious lipids (Jónasdóttir, 2019), are considered to be a primary food for lipid-rich copepods. Species in the genera Calanus and Neocalanus inhabiting high latitude environments synchronize growth, development and lipid accumulation to spring diatom blooms (Conover and Huntley, 1991;Mackas and Tsuda, 1999;Kaartvedt, 2000;Record et al., 2018). The selection of three diatom species for the current experiment was based on their occurrence in the Gulf of Alaska. ...
The high-latitude copepod Neocalanus flemingeri exploits the spring phytoplankton bloom to accumulate lipids for survival during food-limited periods and to fuel reproduction. At some point during development, lipid-accumulation ends and pre-adults molt into adults, descend to depth and enter a state of dormancy termed "diapause." How and when they determine to make this transition is still unresolved. According to one hypothesis, the trigger is their attaining a threshold amount of "lipid fullness." Alternatively, they might follow a genetic program, entering diapause within a narrow developmental window. To better understand the decision, a 5-week laboratory experiment was conducted to assess the effect of food quantity and type on lipid accumulation, biomass and gene expression in N. flemingeri copepodite stage CV. In fed individuals, the initial rate of lipid accumulation slowed by week 5, as a portion of CVs began to molt into adults. While changes in gene expression common to all fed individuals between weeks 1 and 3 were consistent with a developmental program, the duration of the CV stage was variable. Unfed individuals maintained lipid stores initially, suggesting physiological acclimatization to conserve energy. A comparison with gene expression profiles of field-collected individuals suggests similar responses to resources in the environment.
... Cold-water zooplankton species tend to have different life histories than their warmer-water counterparts. They employ energy-storage strategies like storing wax esters, triacylglycerols, phospholipids, or diacylglycerol to facilitate overwintering, whereas warm-water species lack such strategies and are, therefore lower-quality food items due to lower concentrations of these nutritional compounds (Colombo et al., 2017;Hiltunen et al., 2021;Lee et al., 2006;Record et al., 2018). Overall, the predicted invasions, extirpations, and overall global re-distribution of species under climate warming (Cheung et al., 2009;Heneghan et al., 2023) are likely to have direct effects on energetic pathways in marine food webs via changes in fatty acid profiles of the prey community (Garzke et al., 2016;Sahota et al., 2022;Stevens et al., 2022) and an altered efficiency of energy and biomass transfer through food webs (Pontavice, 2019;Pontavice et al., 2020;Ullah et al., 2018). ...
Global climate change is projected to raise global temperatures by 3.3–5.7 ◦C by 2100, resulting in changes in species composition, abundance, and nutritional quality of organisms at the base of the marine food web. Predicted increases in prey availability and reductions in prey nutritional quality under climate warming in certain marine systems are expected to impact higher trophic levels, such as fish and humans. There is limited knowledge of the interplay between food quantity and quality under warming, specifically when food availability is high, but quality is low. Here, we conducted an experiment assessing the effects of food quality (fatty acid composition and ratios) on juvenile Chinook salmon’s (Oncorhynchus tshawytscha) body and nutritional condition,
specifically focusing on RNA:DNA ratio, Fulton’s K, growth, mortality and their fatty acid composition. Experimental diets represented three different climate change scenarios with 1) a present-day diet (Euphausia pacifica), 2) a control diet (commercial aquaculture diet), and 3) a predicted Intergovernmental Panel on Climate Change (IPCC) worst-case scenario diet with low essential fatty acid concentrations (IPCC SSP5-8.5). We tested how growth rates, RNA:DNA ratio, Fulton’s K index, fatty acid composition and mortality rates in juvenile Chinook salmon compared across diet treatments. Fatty acids were incorporated into the salmon muscle at varying rates but, on average, reflected dietary concentrations. High dietary concentrations of DHA, EPA and high DHA:EPA ratios, under the control and present-day diets, increased fish growth and condition. In contrast, low concentrations of DHA and EPA and low DHA:EPA ratios in the diets under climate change scenario were not compensated for by increased food quantity. This result highlights the importance of considering food quality when assessing fish response to changing ocean conditions.
... These planktonic crustaceans use specialized oil sacs to sequester lipids, allowing them to survive periods of low food availability and fueling future development and reproduction (Lee et al., 2006). Copepods in these families are among the most abundant zooplankton in temperate and polar oceans and their lipid reserves can take up more than 50% of their body volume (Miller et al., 2000), making them an energy-rich food source for higher trophic levels and a critical component of productive, lipid-rich marine food webs (Record et al., 2018). Despite their ecological significance, we do not yet understand the physiological responses of these taxa to food deprivation, or the molecular and evolutionary adaptations that facilitate lipid storage and starvation tolerance. ...
Large lipid-storing copepods dominate mesozooplankton biomass in the polar oceans and form a critical link between primary production and higher trophic levels. The ecological success of these species depends on their ability to survive periods of food deprivation in a highly seasonal environment, but the molecular changes that mediate starvation tolerance in these taxa are unknown. We conducted starvation experiments for two dominant Southern Ocean copepods, Calanoides acutus and Calanus propinquus, allowing us to compare the molecular starvation response between species. These species differ in life history, diet, and metabolic traits, and expressed overlapping but distinct transcriptomic responses to starvation. Most starvation-response genes were species-specific, but we identified a conserved core set of starvation-response genes related to RNA and protein metabolism. We used phylotranscriptomics to place these results in the context of copepod evolution and found that starvation-response genes are under strong purifying selection at the sequence level and stabilizing selection at the expression level, consistent with their role in mediating essential biological functions. Selection on starvation-response genes was especially strong in our focal lipid-storing lineage relative to other copepod taxa, underscoring the significance of starvation tolerance for these species. We also found that certain key lipid enzymes (elongases and desaturases) have experienced diversification and positive selection in lipid-storing lineages, reflecting the unique lipid storage needs of these animals. Our results shed light on the molecular adaptations of high-latitude zooplankton to variable food conditions, and suggest that starvation-response genes are under particularly strong sequence and expression constraints.
... As parametrized here, both C. glacialis and C. finmarchicus would develop faster under increasing temperatures and food availability characteristic of more temperate regions of the model domain. Since lipid content in copepods is related to body size (Record et al., 2018) and growth and development rates for zooplankton are thermally decoupled (Horne et al., 2019), faster development could lead to a smaller-sized and less lipid-rich Calanus spp. complex in a warmer Barents Sea (Renaud et al., 2018). ...
