The Biology of Calanoid Copepods
... In Bay of La Paz, 24 taxonomic groups have been reported, and copepods are the second most abundant group (Mojica-Ramírez 2008). The genus Centropages belongs to the order Calanoida, family Centropagidae, and inhabits most oceans (Mauchline 1998). Their diet depends on the stage of their life cycle, which consists of egg, 6 nauplius stages, and 6 copepodite stages; the sixth copepodite stage corresponds to the adult stage where females and males ...
... En la bahía de La Paz, se han reportado 24 grupos taxonómicos, y los copépodos son el segundo grupo más abundante (Mojica-Ramírez 2008). El género Centropages pertenece al orden Calanoida, familia Centropagidae, y habita en la mayoría de los océanos (Mauchline 1998). Su alimentación depende de la etapa de su ciclo de vida, el cual consta de Batimetría (isolíneas, m) de la bahía de La Paz, estaciones hidrográficas para los registros de CTD (+), estaciones PNF-300 para la determinación de clorofila a (○) y sitios de muestreo de zooplancton (). ...
... Su alimentación depende de la etapa de su ciclo de vida, el cual consta de Batimetría (isolíneas, m) de la bahía de La Paz, estaciones hidrográficas para los registros de CTD (+), estaciones PNF-300 para la determinación de clorofila a (○) y sitios de muestreo de zooplancton (). Las líneas sólidas oscuras muestran los transectos A-B y C-D. can be differentiated (Mauchline 1998). Regarding its diet, during the first copepodite stages, it feeds mainly on phytoplankton and other protists, whereas in the following stages, its feeding regime is more omnivorous and even carnivorous (Conover andCorner 1968, Gaudy andThibault-Botha 2007). ...
Se analizó la estructura poblacional de Centropages furcatus asociada a estructuras hidrográficas a finales de la primavera de 2004. La distribución de los diferentes estadios de copepoditos de C. furcatus fue analizada a partir de las muestras de zooplancton obtenidas con una red bongo. En la bahía de La Paz, la hidrografía y la velocidad geostrófica relativa al fondo revelaron la presencia de un giro ciclónico en la cuenca Alfonso y un frente termohalino cerca de Boca Grande. La distribución de la concentración de clorofila a integrada verticalmente mostró valores máximos en el centro del giro y en la región del frente, lo que evidenció que ambas estructuras hidrográficas favorecen la productividad biológica debido al flujo de nutrientes hacia la capa eufótica en el giro y a la acumulación de nutrientes en el frente termohalino. Los resultados mostraron que la variación espacial de C. furcatus estuvo influenciada por ambas estructuras hidrográficas. En el giro ciclónico se observó una distribución diferencial por etapa de desarrollo, con mayor densidad poblacional de los primeros estadios de copepoditos en el centro del giro, como consecuencia de la alta concentración de clorofila a por el enriquecimiento de nutrientes en la capa eufótica, debido al bombeo de Ekman. La densidad poblacional de copépodos fue mayor en el frente termohalino que en el interior del giro ciclónico, debido a que el frente actúa como una zona reproductiva de la especie que mantiene una densidad poblacional estable para los adultos de la bahía y del golfo de California.
... The cryptic Acartia tonsa is a typical species of subtropical and warm-temperate regions (Mauchline, 1998;Albaina et al., 2016;Figueroa et al., 2020). It has a cosmopolitan distribution and is characterized by having great phenotypic plasticity with a versatility to changes in temperature, salinity, and feeding (Cervetto et al., 1999;Tester and Turner 1991;Belmonte and Potenza, 2001;Marcus and Wilcox, 2007;Calliari et al., 2009;Jensen, 2010). ...
... The growth and reproduction of copepods are highly conditioned by the quality and quantity of available food, temperature and salinity, among other factors (Mauchline, 1998;Kiørboe et al., 1985;Runge and Roff, 2000;Holste and Peck, 2006;Calliari et al., 2006;Carotenuto et al., 2011). Eurytemora americana is well adapted to low temperature regimes (Avent, 1998;Sage and Herman, 1972;Berasategui et al., 2021) and in the BBE peaks during the coldest period of the year. ...
... An inverse relationship between female size and temperature is a common pattern to several copepod species, including congeneric E. affinis (Mauchline, 1998;Devreker et al., 2009). In this sense, our REML results showed the same pattern added to a negative relation with the DSi (which in turn is positively correlated with the Chl a and with SmThal), ultimately with the food available. ...
Climatic variability and anthropogenic pressures impact the structure and dynamics of pelagic ecosystems and copepods are good indicators of such changes. This investigation aims to explore the interannual pattern of the mesozooplankton community, in relation to environmental variables in the Bahía Blanca Estuary during winter-spring from last two decades focusing on the dominant species Eurytemora americana. Main changes recorded include increased temperature, alteration of the nutrient balance, a decrease in chlorophyll-a, modifications in the abundance-structure of the phytoplankton assemblages, and changes in the abundance-structure of the mesozooplankton community. A significant decrease was observed in species richness of the mesozooplankton over time. Alterations in abundance and reproductive traits of E. americana, were also found. The population of E. americana dropped from mean relative abundance of 47% in first years to 20-12% in lasts one, accompanied with an increase of copepod species characterized by higher trophic plasticity in eutrophic conditions, like Acartia tonsa and Euterpina acutifrons.
... The role of food selectivity in controlling zooplankton communities in pelagic ecosystems has been well documented (Frost 1972;Dahms and Qian 2005). Selectivity in feeding plays a crucial role in interspecies competition for food resources and influences adaptive strategies, making it an important trophic pathway for the transfer of energy and material from lower to higher trophic levels (Mauchline 1998;Bamstedt et al. 2000). ...
... The accurate measurement of zooplankton feeding and grazing rates is essential. Numerous methods have been developed to measure these rates, but none has been fully effective, and their uncritical use can lead to misinterpretation of results (Peters 1984;Mauchline 1998). The incubation method used in this study has several limitations (crowding of grazers, algae growth due to excrement, and differences in turbulence) because of bottle effects (Roman and Rublee 1981;Sautour 1994). ...
The grazing impacts of two Acartia species (Acartia omorii and A. steueri) on size-fractionated phytoplankton biomass were measured in Jangmok Bay, Korea (34°59′37.8" N, 128°40′28.2'' E) from January to May 2015. Total chlorophyll (Chl-a) concentrations ranged from 0.66 to 5.18 µg L⁻¹, and micro-phytoplankton (> 20 µm) comprised up to 66% (range, 10.5–65.6%) of the total pigment. The total abundance of Acartia species ranged from 267 to 5931 ind. m⁻³, and these copepods accounted for 20.8 to 88.0% of the total copepod abundance. The ingestion rates of A. steueri (r² = 0.904, P = 0.013) and A. omorii (r² = 0.239, P = 0.046) showed a high correlation with micro-phytoplankton. The average grazing impact of Acartia species on phytoplankton biomass was approximately 6.8 ± 11.8% (range, 0.1–69.0%). Temperature–salinity (T–S) diagram analysis revealed distinct environmental preferences for each species; A. omorii preferred a broader temperature range of 6.2 to 17.1 °C and a salinity range of 31.8 to 33.5, whereas A. steueri was more restricted, preferring temperatures between 6.5 and 12.8 °C and a salinity range of 32.2 to 33.5. These findings not only contribute to our understanding of the ecological roles of these copepod species in marine ecosystems but also highlight the importance of continuous research regarding the mechanisms driving their coexistence and interaction with the coastal food web.
... This species, and copepods generally, are useful models to test mechanisms and costs of adaptation because of their short generation time, large extant genetic variation and established culturing methods [45]. As arguably the ocean's most abundant metazoans [46,47], copepods dominate the zooplankton, comprise the most important link between primary producers and upper trophic level consumers [48], and are major modulators of biogeochemical cycles [49,50]. Acartia hudsonica, which is present in estuaries during winter and spring, experiences cooler temperatures and higher pH levels relative to its warm season congener, A. tonsa [51]. ...
... The OWA lineage shows phenotypic plasticity at F11 in two ways: fitness is maintained when the environment changes from food replete to food limited, and when the environment changes from OWA to AM. Results for the former suggest that A. hudsonica requires few resources to maintain homeostasis and population fitness is less susceptible to food limitation than A. tonsa [24]. Indeed, A. hudsonica is smaller in size than A. tonsa [48], which could lead to lower nutritional requirements. Thus, adaptation to OWA is not resource dependent for this species, at least for the temperature, CO 2 and food conditions evaluated here. ...
Phenotypic plasticity and evolutionary adaptation allow populations to cope with global change, but limits and costs to adaptation under multiple stressors are insufficiently understood. We reared a foundational copepod species, Acartia hudsonica, under ambient (AM), ocean warming (OW), ocean acidification (OA), and combined ocean warming and acidification (OWA) conditions for 11 generations (approx. 1 year) and measured population fitness (net reproductive rate) derived from six life-history traits (egg production, hatching success, survival, development time, body size and sex ratio). Copepods under OW and OWA exhibited an initial approximately 40% fitness decline relative to AM, but fully recovered within four generations, consistent with an adaptive response and demonstrating synergy between stressors. At generation 11, however, fitness was approximately 24% lower for OWA compared with the AM lineage, consistent with the cost of producing OWA-adapted phenotypes. Fitness of the OWA lineage was not affected by reversal to AM or low food environments, indicating sustained phenotypic plasticity. These results mimic those of a congener, Acartia tonsa, while additionally suggesting that synergistic effects of simultaneous stressors exert costs that limit fitness recovery but can sustain plasticity. Thus, even when closely related species experience similar stressors, species-specific costs shape their unique adaptive responses.
... Calanoid copepods are an important part of the zooplankton in aquatic food webs and constitute a major link between primary production and higher trophic levels (Mauchline, 1998). Members of the family Diaptomidae represent over 80 % of the freshwater calanoid species of the Palaearctic zoogeographic region (Boxshall and Defaye, 2008). ...
... The total length (L tot , mm) and the length and width of the prosoma (l pr and d pr , mm) were measured of anesthetized copepods after the conclusion of the experiments using a microscope (MBS-10 Lomo USSR; magnification: x 48), and the body volume (V b , mm 3 ) was calculated using equation V b = 0.47 L tot 0.21 l pr 0.93 d pr 1.86 with an accuracy of 9.8% for females and 13.5% for males (Svetlichny et al. 2012, supplement). Wet weights (WW, mg) were calculated using equation (Mauchline, 1998) and dry weight (DW) was determined as DW = 0.2WW. ...
The appearance of invasive species threatens the integrity of aquatic ecosystems. Much is known about dispersal and introduction mechanisms while little is known on the biological properties of invasive species, such as behavior and energy efficiency, allowing them to successfully colonize new environments and compete with native species. This study examines the functional features of the Asian invasive copepod Sinodiaptomus sarsi (Rylov, 1923) that has invaded Europe since 2016. We focused on the energy metabolism and kinematic parameters of the main swimming types (i.e., gliding, hovering, small relocation jumps, and the escape reaction) of females and males of S. sarsi. Based on the above parameters, the mechanical energy for swimming and the respiration energy needed for movement were calculated. Females and males spend up to 95% of time hovering and slowly gliding at a speed of up to 0.5 cm s-1. During the remaining time, the average swimming speed was 8 cm s-1 by small jumps. In contrast, the average speed was 42 cm s-1 during escape swimming. Non-ovigerous females moved faster than ovigerous females during all relocation swimming types except for upward gliding. While performing small jumps with a frequency of 0.79 Hz, the respiration rate of active non-ovigerous females (0.32 ± 0.03 µg O2 ind-1 h-1) was 2.1 times higher than that of anesthetized individuals. The respiration energy associated with movement was 2.6 * 10-3 J h-1, while the total mechanical energy was only 4.2% of this value. The low energy cost of feeding along with the high speed of locomotion may explain the success of this Asian invader in European waters.
... To assess daily rations on all food resources, the carbon to chlorophyll ratio of faecal pellets egested by L. macrurus at older stages (CIV-CVI) of 61 [51] was used for back-calculating this ratio in the ingested food. Assuming assimilation efficiency of 70%, typical of the mixed diet [52], the carbon to ...
... To assess daily rations on all food resources, the carbon to chlorophyll ratio of faecal pellets egested by L. macrurus at older stages (CIV-CVI) of 61 [51] was used for back-calculating this ratio in the ingested food. Assuming assimilation efficiency of 70%, typical of the mixed diet [52], the carbon to chlorophyll ratio of the food was 203, and daily ingestion of L. macrurus CIV to adults increased to 11-22% of body carbon, which considerably exceeded metabolic needs. These results indicate that at least older stages of L. macrurus used carnivory and were well provided with food in both 2016 and 2019. ...
In the estuaries of large Siberian rivers, ice coverage and the timing of ice retreat have varied in recent decades under the ongoing climate change. The seasonal development and functioning of the mesozooplankton community depend to a great extent on the timing of ice retreat. In the Arctic estuaries, the response of zooplankton to the timing of ice melt remains unclear. An earlier ice retreat was suggested to result in an advanced seasonal development of zooplankton, and higher biomass and feeding rates. Zooplankton composition, biomass, demography and grazing (assessed with the gut fluorescent approach) were studied in the Ob Estuary in July 2019 (“typical” ice retreat time). The obtained results were compared with the published data for July 2016 (ice retreat three weeks earlier). Zooplankton biomass in 2019 was considerably lower than in 2016, while species composition was similar; dominant populations were at an earlier stage of development. Herbivorous feeding of the dominant copepod, Limnocalanus macrurus, was also lower in 2019. The consequences of an earlier ice melt and increased temperature on seasonal population dynamics of the dominant brackish-water species are discussed. Our findings demonstrate that zooplankton communities in the Arctic estuaries are highly sensitive to the environmental changes associated with early sea-ice reduction.
... Copepods are probably the most abundant multicellular organisms on Earth (Mauchline et al. 1998, Kiørboe 2011 and in marine ecosystems, where they are of prime importance due to the position they occupy in the trophic web (Brierley 2017). Copepods are indiscriminate or suspension particle feeders (Boltovskoy 1999). ...
... Los copépodos son probablemente los organismos multicelulares más abundantes en la Tierra (Mauchline et al. 1998, Kiørboe 2011, y en los ecosistemas marinos son de suma importancia debido a la posición que ocupan en la red trófica (Brierley 2017). Los copépodos son organismos que se alimentan de manera indiscriminada de partículas en suspensión (Boltovskoy 1999). ...
As one of the main groups comprising marine zooplankton, copepods play an important role due to their position in the trophic web. We assessed the copepod biomass in a cyclonic eddy during 2 contrasting seasons in the Bay of La Paz, southern Gulf of California, which is characterized by high biological productivity. Two oceanographic expeditions took place in the winter of 2006 and the summer of 2009; a CTD probe was used to determine the physical structure of the water column, and oblique zooplankton hauls collected zooplankton samples. Satellite data were used to visualize the chlorophyll a (Chla) distribution patterns. The results showed a well-defined cyclonic eddy in both seasons, with a diameter of ~25 km and geostrophic velocities >50 cm·s–1 in its periphery. At the edges of the eddy, Chla was high, reaching ~3 mg·m–3 in winter. The maximum calanoid copepod biomass occurred in winter, reaching 6.6 mg·100 m–3 in the western bay close to the coast; moreover, their distribution corresponded well with the Chla and circulation patterns, forming a belt shape following the periphery of the eddy, with a second peak close to the connection with the gulf. The mean values of copepod biomass exhibited a pattern with alternating calanoids-cyclopoids between winter and summer within the cyclonic eddy, with calanoid biomass higher than cyclopoid biomass in winter, which was the opposite of summer. The results highlight the impacts of the eddy on the planktonic ecosystem through its influence on the hydrographic conditions in the water column. Other factors, such as ecological interactions, population dynamics, and feeding habits, may also play a role. Feeding behavior is affected by the high concentrations of Chla, which represent a source of food for copepods observed around the eddy.
... The most compelling evidence for a link between respiration and swimming rates was shown for the small marine cyclopoid copepod Dioithona ocula: a 5-times increase in the swimming speed in a spot of light led to a 3.3-times increase of the respiration rate (Buskey, 1998). The exposure to strong natural light is harmful to most copepods (Mauchline, 1998), but some species living in shallow marine waters congregate in small globular swarms (Ueda et al., 1983), induced by bright light (Hirche, 1987;Leising and Yen, 1997;Ambler, 2002;Sun et al., 2013). Remarkably, the in-situ swarm's abundance of cyclopoids can reach 90 individuals ml − 1 . ...
... were calculated (Mauchline, 1998 ...
Little is known on the swimming activity and respiration rate of the cyclopoid copepod Cyclops vicinus. Here, the swimming speed and respiration rate of C. vicinus were measured at different temperatures using a high speed (up to 1200 frames per second) camera and a closed-system respirometry, respectively. For cruise and escape swimming, log-linear relationships were found between temperature (range 1–22 °C) and duration, speed, and frequency of locomotor acts, respectively. The respiration rate of immobilized and active individuals showed log-linear relationships with temperature (range of 2–20 °C) and a thermal coefficient Q10 ≈ 2 was found. The maximum respiration rate of swimming females was 7.8 and 6.4 times higher than that of immobilized individuals at 2 and 20 °C, respectively. To better understand how temperature affects the energy efficiency of copepod swimming, the mechanical energy of movement was estimated from sswimming speed and the metabolic energy was estimated from the amount of oxygen consumed during swimming. Linear relationships between swimming speed and mechanical and metabolic energy, respectively, were found at all experimental temperatures. At 20 °C, the maximum mechanical and metabolic energy costs for movement was 15.2 × 10⁻⁵ and 37.7 × 10⁻⁴ J h⁻¹, respectively. In the range of 2–20 °C, the mechanical energy attributed to swimming represented only a small portion (4.0–8.2%) of the total metabolic energy. Cold-water specialization probably limited the increase of the swimming speed of C. vicinus at high temperatures compared to that of warm-water adapted species.
... In L. macrurus, the length and width of the posterior oil sac and diameters of anterior sacs were also determined, by which their volume (V os ) was determined using the formulas of an ellipsoid and a sphere, respectively ( Figure 1). Body wet weights (WW, mg) were determined according to the equation (Mauchline, 1998). ...
... Total carbon body weight (CW tot , μg) of copepods (Table 1) was calculated as CW tot = (1000 × WW × 0.2) 0.45, taking into account that for most calanoid copepods, which do not have large fat reserves, average dry weight (DW, mg) is equal to 20% of WW and CW tot averages 45% of DW (Mauchline, 1998). ...
Calanoid copepods with different life cycle strategies demonstrate varied velocity in the utilization of energy resources during
starvation. Tis study analyzes the influence of multiday starvation on the rate of total, basal and active energy metabolism in adult
females of two Marmara Sea and one Baltic Sea species of copepods; epiplanktonic Acartia clausi unable to accumulate lipid reserves
and mesoplanktonic Calanus helgolandicus with minor lipid reserves in the oil sac (approximately 7% of body volume) and the Baltic Sea
copepod Limnocalanus macrurus in quasi-diapausing state with large lipid reserves in the oil sac (approximately 19% of body volume).
Initially, total weight specifc respiration rates were about 0.12 μg C per µg C body weight per day (d–1) for both Marmara Sea species at
20 °C and 0.079 d–1 in the Baltic L. macrurus at 14 °C, decreasing signifcantly by 1.6–2.5 times with starvation, while basal metabolic
rates, measured in the same anesthetized individuals, was nearly constant during starvation. In this regard, the active metabolic rates,
defned as the difference between the respiration rate of active and anesthetized individuals, decreased during starvation by 1.7 times in
C. helgolandicus and by 4.7 and 6 times in A. clausi and L. macrurus, respectively. In A. clausi and C. helgolandicus with minimal lipid
reserves, total daily energy expenditure (5.1% of initial body carbon content) was twice as high as in L. macrurus (2.2% of initial body
carbon content daily), which has a large oil sac. Overall, the trend demonstrates that despite different energy reserves, a decrease in the
total energy metabolism in copepods occurs due to a reduction in energy expenditure for locomotor activity.
... Significant expression differences across development were found for eleven out of twelve transcripts encoding enzymes involved in the folic cycle and for all transcripts in the methionine cycle. Within its life cycle, C. finmarchicus undergoes multiple molts characterized by intense cellular and tissue proliferation, signaling, and lipid synthesis [15,16,20,[40][41][42]. Thus, since folate is an essential requirement for growth and development, it is therefore not surprising that high expression was reported for many of the transcripts in the early nauplius and the early copepodite (C1) stages. ...
Folate, also known as vitamin B9, plays a crucial role in the one-carbon (1C) metabolism, a conserved pathway from microbes to humans. The 1C metabolism, consisting of the folate and methionine cycles, is essential in many biological processes such as nucleotide and protein biosynthesis, cell proliferation, and embryonic development. Despite its functional role, little is known about the 1C metabolism in crustaceans. As part of an ongoing effort to characterize important pathways in Calanus finmarchicus, the biomass-dominant zooplankton in much of the North Atlantic Ocean, we identified transcripts encoding the 1C metabolism enzymes. Using an in silico workflow consisting of a transcriptome mining, reciprocal blasts, and structural analyses of the deduced proteins, we identified the entire set of enzymes in both cycles. The majority encoded for full-length proteins and clustered with homologs from other species. Stage-specific expression was reported, with several transcripts showing high expression in the naupliar stage (e.g., 10-FTHFD, SHMT2) while some methyltransferases (e.g., BHMT, SHMT, DNMT) were more expressed in adults. Overall, this study provides a set of genes which can be used as potential biomarkers of development and reproduction and can be tested in other zooplankters to assess ocean health status monitoring.
... The overall average microplastic ingestion rate by A. tonsa in Tampa Bay was 0.015 particles per individual, which was lower than estimates from estuarine studies conducted in the Hudson-Raritan Estuary, USA (0.56 particles per individual; Sipps et al., 2022), Kochi backwaters, India (0.41 particles per individual; Rashid et al., 2022), and Jiaozhou Bay, China (0.21 particles per individual; Zheng et al., 2021), but on par with estimates from studies in Terengganu Estuary, Malaysia (0.02 particles per individual; Taha et al., 2021) and Charleston Harbor, USA (0.009 particles per individual; Payton et al., 2020). Prey ingestion rates vary by copepod species, as well as prey concentration and nutritional quality (reviewed in Mauchline, 1998). For example, without the presence of infochemicals or biofilms on microplastic particles copepods could be deterred from ingesting microplastics (Vroom et al., 2017;Borrelle et al., 2020). ...
Microplastics have been recognized as an emerging contaminant. Copepods are abundant primary consumers in marine food webs. Interactions between copepods and microplastics can lead to negative health effects to the individual and may have implications for populations and ecosystems through biomagnification. Laboratory and field studies have observed various species of zooplankton ingesting microplastics, however, this is the first study to observe microplastic-copepod interactions in Tampa Bay. Over 2 years (November 2017-January 2020), 14 sampling cruises were conducted with seven stations throughout Tampa Bay. At each station copepods were collected by towing a 200 μm mesh ring net (0.5 m diameter) for 3 min. 1,000 individual Acartia tonsa copepods were picked from each sample and digested to release gut contents. Gut contents were stained in a Nile Red solution and then visualized using epifluorescent microscopy, quantified, photographed and sized using image analysis. In Tampa Bay, A. tonsa consumed fragments over fibers, ranging from 0.018 to 0.642 mm, with an average particle size of 0.076 mm. An overall average of 15.38 particles were ingested per 1,000 copepods, or 6.48 particles m–3 when normalized for environmental copepod concentrations. While significant differences were detected between stations and months, no clear spatial (from head to mouth of estuary) or temporal (between wet and dry seasons) trends in ingestion rate or ingested particle size were evident. These results show that A. tonsa ingested microplastics throughout Tampa Bay. These robust baseline data, for a copepod species that dominates estuarine zooplankton communities around the world, set the stage for valuable comparisons between estuaries with different physical mechanisms and levels of anthropogenic impact, allowing for exploration of how the environmental conditions impact ecological interactions.
... Body volume (V b , cm 3 ) was calculated using equation V b = 0.47 * 10 −3 * L tot 0.21 * l pr 0.93 * d pr 1.86 with an accuracy of 9.8% for female cyclopoid species (Svetlichny et al., 2012a, supplement). Wet mass (M, g) was calculated using equation M = V b ρ b , with body density ρ b ≈ 1.05 g cm −3 (Mauchline, 1998). The volume and weight of egg sacs were calculated from the diameter and number of eggs in both sacs of EC females. ...
Female cyclopoid copepods carry their embryos in egg sacs that impact swimming performance until nauplii hatch. We studied kinematic parameters and mechanical energy of small routine jumps and large escape jumps of non-egg-carrying (NEC) and egg-carrying (EC) females of Mesocyclops leuckarti and Macrocyclops albidus. The drag and body acceleration costs for EC females of M. leuckarti and M. albidus during routine jumps were 28 and 40%, respectively, higher than those for NEC females moving at the same speed. Maintaining position in the water column by small jumps was more costly for EC females, requiring 2.2–2.3 times more jumps and energy. Consequently, the persistence of EC females was limited in the open water. In M. leuckarti and M. albidus, the average speed and distances of jumps were 5–6 and 1.5–2.2 times higher, respectively, and the duration of jumps was 2.2–2.5 times shorter during escape than routine swimming. The maximum jumping speeds of NEC females, 40.6 and 50.5 cm s−1, respectively, were 12–14% higher than those of EC females, whereas their power and cost of transport were 16 and 23% lower, respectively. These results clearly indicated that egg sacs impair swimming and increase energetic costs of movement.
... Copepods are the most abundant animals in the ocean (Humes, 1994) and a main link between primary producers and higher trophic levels in the marine food webs (Mauchline, 1998;Yang et al., 2022). Copepods typically dominate the zooplankton biomass and contribute to the global biochemical processes in the ocean like nutrient recycling and carbon sequestration by the biological pump (Verity & Smetacek, 1996). ...
... Illustration by Justine Courboulès. (Nassogne 1972;Uye 1982;Martinussen and Båmstedt 1995;Mauchline 1998;Loret et al. 2000;Ara 2001;Torniainen and Lehtiniemi 2008;Wukovits et al. 2018). For Foraminifera, Ciliates, Bivalvia veliger and fish eggs, a mean value of C per specimen was used. ...
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 sex ratio of copepods also changes seasonally. When the number of females or the abundance of the population is low, the proportion of males tends to be high [57]. ...
We measured the monthly egg production rate (EPR) of Paracalanus parvus s. l. (P. parvus) at a fixed station in Busan Harbor from January 2020 to December 2021 to elucidate the seasonal variation in the EPR and the factors involved. Over the 2 years, the monthly EPR ranged from 0.5 to 47.0 eggs female−1 d−1 (average 13.3 eggs female−1 d−1). The seasonal mean EPR was high in spring (April to June) and summer (July to September) and low in autumn (October to December) in both years. Egg hatching success was high (average 94%). Monthly nauplii production in the P. parvus population ranged from 9 to 37,123 ind. m−3 d−1 (average 4605 ind. m−3 d−1), with a peak in March and May in 2020 and in April in 2021. The monthly EPR of P. parvus was more dependent on chlorophyll-a concentration than on water temperature. Nauplii production was dependent on the abundance of adult females, while the chlorophyll-a concentration had a positive effect on nauplii production. In this study, while there was no clear seasonal variation in the abundance of adult females, the EPR showed a clear pattern of seasonal variation. These results imply that for monitoring potential environmental changes in Busan Harbor, measuring the EPR of copepods may be a better indicator than copepod abundance.
... Within the zooplankton size-fractions, δ 15 N values increased with size, up to the 1000-2000 μm fraction, underlining an enhancement of the predation with size (Fry and Quiñones, 1994;Rolff, 2000;Bȃnaru et al., 2014;Espinasse et al., 2014;Hunt et al., 2017). The δ 15 N values increased with the size-fractions, which may be due to the succession of the different life stages of copepods, coinciding with the pattern observed in their biochemical composition (Espinasse et al., 2014;Chen et al., 2019) related to metabolic changes during the lifespan (Guisande, 2006), adaptative foraging (Kozak et al., 2020), ontogenetics (Mauchline, 1998;Im et al., 2015) or all these processes combined. Fierro-González et al. (2023) reported an increase in the proportion of carnivores with size. ...
Plankton represents the main source of carbon in marine ecosystems and is consequently an important gateway for contaminants into the marine food webs. During the MERITE- HIPPOCAMPE campaign in the Mediterranean Sea (April-May 2019), plankton was sampled from pumping and net tows at 10 from the French coast to the Gulf of Gabès (Tunisia) to obtain different size fractions in contrasted regions. This study combines various approaches, including biochemical analyses, analyses of stable isotope ratios (δ13C, δ15N), cytometry analyses and mixing models (MixSiar) on size-fractions of phyto- and zooplankton from 0.7 to >2000 μm. Pico- and nanoplankton represented a large energetic resource at the base of pelagic food webs. Proteins, lipids, and stable isotope ratios increased with size in zooplankton and were higher than in phytoplankton. Stable isotope ratios suggest different sources of carbon and nutrients at the base of the planktonic food webs depending on the coast and the offshore area. In addition, a link between productivity and trophic pathways was shown, with high trophic levels and low zooplankton biomass recorded in the offshore area. The results of our study highlight spatial variations of the trophic structure within the plankton size-fractions and will contribute to assess the role of the plankton as a biological pump of contaminants.
... The cycling of north east and south west monsoonal wind systems reverses the atmospheric circulation and the surface currents of the Bay of Bengal and the Andaman Sea from December to April, and June to October with intervening transitional period (Murthy et al., 1981). The mesozooplankton community, a key component of the pelagic food chain, linking the primary producers with the secondary consumers is strongly controlled by the physical environment, which influence their growth, reproduction and distribution (Mauchline, 1998). The zooplankton biomass values obtained in the mixed layer were in general higher than those reported earlier during winter monsoon from the Andaman waters (Madhu et al., 2003;Madhupratap et al., 1981a). ...
... Marine zooplankton comprises a phylogenetically and functionally diverse assemblage of protistan and metazoan that occupy multiple trophic levels in pelagic food webs, serving both as trophic links between primary producers and higher trophic levels (Mauchline, 1988). ...
Zooplankton assemblage was studied during seasonal aggregation of the whale shark Rhincodon typus in Nosy Be Island, a hotspot area in the Mozambique Channel. Two different sampling sites were identified in the outer neritic zone: a Feeding area, where whale shark was commonly sighted, and a Control area, never frequented by R. typus. The aim was to investigate zooplankton variability, in terms of composition, biomass and size spectra, in the two areas.
Mesozooplankton was collected vertically form 10 m depth to the surface, in November–December 2018–2019 in Control and Feeding areas. A total of 36 zooplankton samples were collected during both campaigns; two different size classes, ≤2 mm and >2 mm and biomass (dry and wet weights) were analysed. Taxonomic composition was performed on 12 samples collected each year. In Feeding and Control areas mesozooplankton composition was similar and mainly represented by Copepoda. Wet and dry weights were higher in Control area compared to the Feeding, with a significant contribution of organisms >2 mm. A decrease of the total number of individuals was recorded in 2019, compared to 2018, characterized by a decrease in copepod abundance (−10%). Biomass decreased of 36.4% in 2019 with respect to 2018, mainly due to a decrease of organisms >2 mm. Similar mesozooplankton assemblage was recorded in the Control and Feeding areas of whale shark, whereas a significant increase in mesozooplankton size in Control area, evidenced by the highest biomass of organisms > 2 mm, could be due to the absence of predators. A decrease of biomass observed in 2019 needs to be further monitored, but the lack of significant differences between mesozooplankton assemblage in Control and Feeding areas suggests a possibility of multiple prey sources. Analysis of prey/predator interaction is recommended for understanding feeding habits and abundance of whale sharks in tropical regions.
... In fact, due to the benthic nature of Tisbe and Tigriopus, almost all of the nauplii, especially the first nauplii stages, were concentrated at the bottom of the chambers (diameter of chanber 4cm), and as a result their density increased even more. According to Mauchline [36], the bodies of most copepods are denser than the seawater they live in, regardless of salinity. For this reason, staying in the benthos requires less energy consumption than staying in the water column. ...
The locally isolated harpacticoid copepods Tigriopus sp. and Tisbe holothuriae were subjected to salinity tolerance experimentation at salinities under and above of 40 ppt, and presented high halotolerances in Tigriopus LC50 (24 h) of 1 ± 4.43 ppt and 132 ± 5.35 ppt, respectively, and in Tisbe of 15 ± 2.41 ppt and 93 ± 3.23 ppt, respectively. Tetraselmis suecica, among other microalgal feeds (Asteromonas gracilis, Rhodomonas salina, Dunaliella salina and Isochrysis galbana), resulted in the higher production of nauplii in Tigriopus and R. salina and D. salina in Tisbe (also close to T. suecica in Tigriopus). The demographics (number of nauplii, egg sacs, completion of hatching) of both cope-pods, using combinations of salinities in the range of 22-60 ppt and D. salina and R. salina as feeds, exhibited almost the same preference for microalgae but were negatively affected by the salinity of 60 ppt. The present experiments showed that these local copepods that have extreme salinity tolerance and a wide preference for easily cultured microalgae can be used in ecological studies and for mass production as live feed in marine fish hatcheries.
... Copepoda is the most important group of zooplankton in the CS (Raeiji et al., 2019) and according to other studies, it is also the most abundant in seas and in estuaries (Mauchline, 1998;Muxagata et al., 2012). The results of this research are similar to other catchment basins of Volga and Ural could reduce man-made stressors and allow the north Caspian wetlands to adapt to the challenging speed of CSL fluctuations (Lagutov, 2008;Leummens, 2018). ...
The situation of Ramsar sites along the Caspian Sea coast has deteriorated over the past decades, and this is more noticeable in the narrow coastal strip of the south Caspian Sea. In this study we investigate how the Caspian Sea level changes affect the coastal Ramsar sites. Particularly, we focus on the Gorgan Bay in the southeast corner of the Caspian Sea, which is experiencing extensive water level decline, even desiccation. We used satellite images from three periods corresponding to periods of two sea level falls and one sea level rise, in order to decipher spatio-temporal changes of the wetlands. We conducted field campaign in the Gorgan Bay for sampling and measurement of physical, chemical and biological parameters. We simulated water circulation for the past, current and future conditions of the Gorgan Bay, which is essential to sustain better water exchange between the Bay and the Caspian Sea. We applied dust simulation in the case of a total desiccation of the Gorgan Bay. The result shows that the total area of the Caspian coastal Ramsar sites during the two periods of the sea level fall is almost the same; however, the aerial changes in the southern wetlands are more visible. Nutrient and plankton analysis of the Gorgan Bay display mainly mesotrophic conditions, in some areas close to eutrophic ones. The average current velocity in the main inlet is 2.5 cms⁻¹. Dust simulation indicates that in case of the Gorgan Bay desiccation, it will become a dust source for the surrounding area up to 60 km. Simulation of the water circulation with dredging of inlets (future scenario), indicates that the water exchange velocity doubles compared to the current scenario. A recommended inlet maintenance would accelerate water circulation and reduce residence time, which will lead to better trophy and prevent bay desiccation.
... In the present study, the variability in cell/particle density was larger than at the Skagerrak reef and in earlier Rockall Bank measurements (van Duyl et al., 2008;Maier et al., 2011;Weinbauer et al., 2012). As zooplankton mostly feed on phytoplankton (Mauchline, 1998), their spatial distribution at the surface was closely linked to the chl-a concentration, with higher zooplankton biomass at Bank than at Oreo. We found decreasing zooplankton biomass with depth, consistent with observations on other North Atlantic zooplankton communities during spring (Gislason, 2018;Krumhansl et al., 2018). ...
Cold-water corals (CWCs) are important ecosystem engineers in the deep sea that provide habitat for numerous species and can form large coral mounds. These mounds influence surrounding currents and induce distinct hydrodynamic features, such as internal waves and episodic downwelling events that accelerate transport of organic matter towards the mounds, supplying the corals with food. To date, research on organic matter distribution at coral mounds has focussed either on seasonal timescales or has provided single point snapshots. Data on food distribution at the timescale of a diurnal tidal cycle is currently limited. Here, we integrate physical, biogeochemical, and biological data throughout the water column and along a transect on the south-eastern slope of Rockall Bank, Northeast Atlantic Ocean. This transect consisted of 24-hour sampling stations at four locations: Bank, Upper slope, Lower slope, and the Oreo coral mound. We investigated how the organic matter distribution in the water column along the transect is affected by tidal activity. Repeated CTD casts indicated that the water column above Oreo mound was more dynamic than above other stations in multiple ways. First, the bottom water showed high variability in physical parameters and nutrient concentrations, possibly due to the interaction of the tide with the mound topography. Second, in the surface water a diurnal tidal wave replenished nutrients in the photic zone, supporting new primary production. Third, above the coral mound an internal wave (200 m amplitude) was recorded at 400 m depth after the turning of the barotropic tide. After this wave passed, high quality organic matter was recorded in bottom waters on the mound coinciding with shallow water physical characteristics such as high oxygen concentration and high temperature. Trophic markers in the benthic community suggest feeding on a variety of food sources, including phytodetritus and zooplankton. We suggest that there are three transport mechanisms that supply food to the CWC ecosystem. First, small phytodetritus particles are transported downwards to the seafloor by advection from internal waves, supplying high quality organic matter to the CWC reef community. Second, the shoaling of deeper nutrient-rich water into the surface water layer above the coral mound could stimulate diatom growth, which form fast-sinking aggregates. Third, evidence from lipid analysis indicates that zooplankton faecal pellets also enhance supply of organic matter to the reef communities. This study is the first to report organic matter quality and composition over a tidal cycle at a coral mound and provides evidence that fresh high-quality organic matter is transported towards a coral reef during a tidal cycle.
... The timing of the collection of the copepods used in the two experiments from the field was different and might have caused the differences in fecundity. It was also suggested that the EPR of copepods decreases with age in the adult stage (Mauchline, 1998). Previous research demonstrated remarkable energy accumulation ability and starvation tolerance of A. steueri, and reported that EPR measured in the laboratory is influenced by the food environment in the field when the copepods were collected (Hirahara & Toda, 2018;Hirahara et al., 2018). ...
Adult females of the calanoid copepod Acartia steueri were individually reared for eight days with different microalgal diets to determine the optimal microalgal diet for their survival and reproduction. Five mono-microalgal diets (Thalassiosira weissflogii, Rhodomonas salina, Tetraselmis suecica, Phaeodactylum tricornutum, and Isochrysis galbana) and one mixed microalgal diet (Tetraselmis suecica + Thalassiosira weissflogii) were tested. The survival rate of the females, egg production rate, and hatching success were measured every day for eight days. A. steueri fed with R. salina, P. tricornutum, and I. galbana, showed a decreasing rate of egg production with time which eventually ceased. This phenomenon indicate that these microalgae are unfavorable diets for the adults of A. steueri. The cumulative number of eggs produced for eight days was 24.8 ± 4.2 eggs female-1 when fed with T. suecica, which was the highest value among the mono-microalgal diet treatments. The viable egg production was maximized under the mixed diet condition of T. suecica and T. weissflogii, and this mixed diet can be considered a suitable diet for A. steueri adults.
... The individual observations from were not available so we used the means for each prey species. Copepod volume was estimated as Log V (mm 3 ) = 3.164 × log PL (prosome length, µm) −10.690 (Mauchline 1998). Diatom chain volume was calculated assuming a cylindrical shape. ...
... Copepods are common live feed found in marine, freshwater and brackish water, representing up to 80% of the zooplankton biomass in the natural environment (Mauchline, 1998;Piasecki et al., 2004;Kimmerer et al., 2018). Cyclopoid copepod, Oithona rigida has been reported to contain high content of HUFAs, comparable to Artemia and rotifer. ...
Production of live feed for larval development of aquatic species is crucial in the aquaculture industry. The cultivation of cyclopoid copepod, Oithona rigida can enhance the growth performance and nutritional quality of fish and crustacean larvae. Hence this study was conducted to evaluate the different dietary regimes containing swiftlet waste, soybean meal, rice bran and microalgae (Nannochloropsis sp.) on the growth and productivity of O. rigida. The results showed that rice bran and Nannochloropsis sp. additives produced the best outcomes in terms of specific growth rate (0.109±0.002 and 0.104±0.001 day-1) of O. rigida., protein content (66.83±2.25 and 72.08±2.02%), and lipid content (21.98±1.41 and 18.09±1.18%) respectively. A mixture of rice bran and Nannochloropsis sp. (41.62%) as dietary additives also improved the polyunsaturated fatty acids (PUFAs) content of O. rigida as compared with mono diet applied such as rice bran (28.16%) and Nannochloropsis sp. (31.35%). The use of rice bran as food additives for O. rigida has shown a comparable result with the Nannochloropsis sp., in terms of the growth, survival, reproduction and dietary value. Thus, rice bran and Nannochloropsis sp. was marked as the best feeding regime for the cyclopoid copepod, O. rigida as potential characteristics for mass culture in aquaculture hatcheries.
The analysis of the mesozooplankton community from the Romanian Black Sea waters revealed variations both from quantitative and qualitative point of view. A decrease in the number of identified taa according to the season was observed, with a maimum of 25 taa in the warm season and a minimum of 15 taa in the cold season. The nonfodder component represented by Noctiluca scintillans recorded the highest density and biomass values in the warm season, in the cold season being less represented, fact highlighted by Simper analysis. The mesozooplanktonic fodder component showed variations of density and biomass, copepods and the meroplanktonic component representing the bulk of the community in the warm season. In the warm season, the group of Cladocera’s recorded high density and biomass values, unlike in the cold season where they were very poorly represented. Other groups were better represented also in the warm season, showing a decrease in terms of abundance and biomass in the cold season.
Compiling trait information promotes discovery and innovation in using trait-based approaches in ecology. Various zooplankton trait datasets are stored in unlinked data repositories, in diverse data structures, and have varying levels of complexity. These require standardization and harmonization to allow interoperability and to limit the duplication of efforts in the time-consuming and error-prone task of trait compilation. This study aggregated and harmonized 33 zooplankton traits datasets and supplemented these with more than 150 references into a single zooplankton trait database with an initial set of 56 traits for 3535 marine zooplankton species. The database has a long data table structure using the entity-attribute-value format and includes taxonomic and ancillary metadata, and data source provenance preserving how the data were originally recorded. The database is stored both at the individual level (Level 1) and as species level means (Level 2). The Level 1 database has 57,615 rows of trait records and the Level 2 database has 14,977 unique trait-taxon records. We evaluated the coverage of trait data, taxonomic representation, and strategies in filling-in data gaps. Comparison of trait value estimation approaches identified allometric scaling to be more accurate than taxon-level generalization and imputation. This centralized and harmonized marine zooplankton trait database aims to be extendable and future-proof and to promote trait data sharing, FAIR (findable, accessible, interoperable, reus-able) data practices, and reproducibility.
The mesopelagic calanoid copepod Cephalophanes reflugens is characterized by its large eyes with semi-parabolic reflectors. It is hypothesized that the eyes aid in finding crustacean carcasses as food in poor deep-sea light and oligotrophic conditions. Here, the crustacean carcasses-associated luminous, chitin-degrading bacteria may play a vital role in detecting and digesting foods by the copepod. In this study, we collected adult female C. reflugens (n = 9) from the mesopelagic layers off southwestern Japan in the Pacific Ocean and obtained a total of 47 bacterial isolates from the gut contents. None of the isolates were luminescent, but almost half of the isolates were chitinolytic. Based on the 16S rRNA gene sequences, these chitinolytic bacteria were identified as members of the genus Vibrio, Photobacterium and Pseudoalteromonas. In culture experiments at 15°C, most of the chitinolytic isolates efficiently utilized colloidal chitin as the sole carbon source and degraded the carapace strip of shrimp (Litopenaeus vannamei). Some isolates showed these chitinoclastic activities even at low temperatures (<5°C), equivalent to that of the deep-sea waters. The present results imply that chitin-degrading bacteria significantly contribute to chitin digestion in the gut of C. reflugens, whereas the involvement of luminous bacteria in the feeding mechanism remains unidentified.
Many copepods display a swim-and-sink behaviour, which is not energetically efficient but probably aids in perceiving and capturing diatom chains. Here, computational fluid dynamics was employed to calculate the mechanical power required by a negatively buoyant, self-propelled copepod in swim-and-sink versus hovering. The results show that upward swim-and-sink about a fixed depth always demands more power than hovering. Subsequently, high-speed microscale imaging was employed to observe the copepod Centropages sp. in swim-and-sink, specifically its encounter and handling of diatom chains for capture, along with the measured alternating swimming and sinking currents imposed by the swim-and-sink copepod. The findings suggest that during upward swimming, the copepod uses its swimming current to scan the fluid for detecting embedded diatom chains, presumably through chemoreception. Once a diatom chain is perceived, the copepod sinks and uses its sinking current to manipulate the orientation of the diatom chain before swimming upward to capture it. Overall, these results propose a hypothesis that swim-and-sink is an innate behaviour that assists copepods in perceiving and manoeuvring diatom chains for capture. In contrast with near-spherical algae, diatom chains predominately exhibit a horizontal orientation in the ocean, necessitating vertically oriented copepods to possess a handling behaviour that manoeuvres diatom chains for capture.
This study presents eight new high-quality de novo transcriptomes from six co-occurring species of calanoid copepods, the first published for Neocalanus plumchrus, N. cristatus, Eucalanus bungii and Metridia pacifica and additional ones for N. flemingeri and Calanus marshallae. They are ecologically-important members of sub-arctic North Pacific marine zooplankton communities. ‘Omics data for this diverse and numerous taxonomic group are sparse and difficult to obtain. Total RNA from single individuals was used to construct gene libraries that were sequenced on an Illumina Next-Seq platform. Quality filtered reads were assembled with Trinity software and validated using multiple criteria. The study’s primary purpose is to provide a resource for gene expression studies. The integrated database can be used for quantitative inter- and intra-species comparisons of gene expression patterns across biological processes. An example of an additional use is provided for discovering novel and evolutionarily-significant proteins within the Calanoida. A workflow was designed to find and characterize unannotated transcripts with homologies across de novo assemblies that have also been shown to be eco-responsive.
Aetideid copepods dominate the mesopelagic layer of the Arctic Ocean and play an important role in the vertical material flux and biodiversity. However, little information about the lengths and weights of their copepodids is available. In this study, we collected five sympatric aetideid copepods, Chiridius obtusifrons Sars G.O., 1902, Gaetanus tenuispinus (Sars G.O., 1900), Gaetanus brevispinus (Sars G.O., 1900), Aetideopsis multiserrata (Wolfenden, 1904), and Aetideopsis rostrata Sars G.O., 1903, from the Arctic Ocean and examined their body lengths, dry and ash-free dry weights, and developmental growths at each copepodid stage. Highly significant length-weight relationships were obtained among copepodids for all species. Within genera, individuals of the same length were heavier at shallower depths. This may result from the greater nutritional availability to species within genera inhabiting shallower depths. Common to all species, the organic content (ash-free dry weight per dry weight) was high for the early copepodid stages. This may be due to the residual organic content of lipid-rich eggs retained in the non-feeding nauplii. The largest growth in females occurred at C5/C6, whereas the largest growth in males occurred at C4/C5, as determined by moult increment and proportion of growth in weight. These sex differences in weight growth could be due to the degeneration of the feeding appendage and cessation of feeding in C6 males of aetideid copepods.
The time it takes copepods to handle prey can vary depending on the properties of the prey, but it is still largely unknown how handling times may affect copepod feeding efficiency. We compiled data on prey‐handling times derived from video observations in 10 species of calanoid and cyclopoid copepods consuming a large variety of prey. Prey‐handling times vary by five orders of magnitude, and the largest fraction of this variation is explained by relative prey size: larger prey takes longer to handle. When normalized by prey volume (volume of prey handled per unit time), however, larger prey are handled more efficiently than smaller prey. Within this overarching pattern there are distinct differences among species. Thus, large species handle a certain prey size much faster than small species. However, when further normalizing by predator size, the data for all species (except Mesocyclops spp.) collapse on a common relationship. Handling times are generally not limiting maximum consumption rates, and less so for large prey. This allows room for prey selectivity, and indeed copepods are known to be highly selective feeders. Our data predict that copepods can afford to be more selective when feeding on larger than on smaller prey and when consumption is not limited by prey encounter rate, and this is consistent with observations of copepod feeding behavior. We argue that the fast handling times allow copepods to optimize their diet through prey selectivity, and that this is one key to the evolutionary success of pelagic copepods.
We assessed the spatial variability in the size structure of phytoplankton, community composition, primary production and carbon fluxes through the planktonic food web of the Gulf of Gabès (GG; Southeastern Mediterranean Sea) in the fall of 2017 during the MERMEX-MERITE cruise. High concentrations in nutrients, chlorophyll a (~ 2–6 µg L−1) and primary production (1816–3674 mg C m−2 d−1) revealed an eutrophic status of the studied stations in the GG. In accordance with hydrodynamic features, inorganic nutrients showed increases in concentrations from North to South and from coast to offshore, these nutrient gradients impacting the spatial distribution of phytoplankton community. Size-fractioned phytoplankton biomass and production were the lowest in the northernmost zone where they were mainly sustained by pico-sized fraction. Concomitantly, in this area, small aloricate ciliates were dominant leading to a high microbivory. Conversely, higher biomass and production were measured towards the South and offshore with prevalence of larger phytoplankton (nano- and/or micro-sized fractions) supported by diatoms. The herbivorous protozooplankton and metazooplankton were more abundant in these zones, resulting in an increase of the herbivory. The vertical particulate organic carbon flux followed also a north–south and coast-offshore increasing gradient, with a higher contribution of phytoplankton, and zooplankton fecal pellets to the sinking organic matter in the southernmost area. Our results suggest that even in nutrient-rich and highly productive waters, a continuum of trophic pathways, ranging from microbial to multivorous and herbivorous food webs, may exist, which implies different efficiencies in carbon export and carrying capacity within the ecosystem.
Rivers are dynamic systems that respond to various physicochemical characteristics. In this review, we focused on the most important physicochemical parameters that influenced zooplankton composition and diversity in the rivers, including water temperature, dissolved oxygen, biochemical oxygen demand, hydrogen ion concentration, electrical conductivity, salinity, total dissolved solids, total suspended solids, turbidity, total hardness, calcium, magnesium, total alkalinity, bicarbonate, phosphate, nitrate, sulphate, and water velocity. As well as, we define these environmental factors and determined the minimum and maximum values for each factor. In general, we can be concluded that physicochemical factors that exceed standard values affected negatively on the zooplankton composition and diversity.
This study investigated the host-epibiont relationship between calanoid copepods and suctorian ciliates collected widely from the northern North Pacific Ocean. Mid- and deep-water adult female calanoids without dormant stages were found to be infested with suctorians, probably because of their larger size, longer intermolt duration and longevity in comparison to males and surface water species. A total of 259 calanoids belonging to sixteen species were infested with five suctorian species. Among them, Candacia columbiae, Gaetanus minutus, Lucicutia bicornuta, Metridia similis, Pleuromamma scutullata, and Racovitzanus antarcticus were reported to be infested with suctorians for the first time in the present study. Ephelota coronata infested only Metridia pacifica and displayed a strong host preference, whereas the other suctorians displayed a weaker host preference. Any suctorian species that infested Metridia pacifica and M. similis attached almost exclusively to their urosome. Suctorians might avoid or could not stay attached to the anterior parts of these fast-swimming copepods. The attachment sites of Actinocyathula pleuromammae and Paracineta gaetani extended to the anterior part of the copepod body as the number of attached suctorians increased, suggesting they were obliged to attach to suboptimal parts that were exposed to faster flow speed.
The upper Gulf of California is one of the most energetic regions owing to its tidal range and strong tidal currents, making the upper gulf and the archipelago zone highly turbulent regions; the abundance of zooplankton should be associated with mixing phenomena. We aimed to determine the latitudinal distribution of zooplanktonic organisms in this region and the influence of the islands on their distribution and abundance using historical data. Distribution of abundance followed the current patterns, the archipelago influences abundance favorably but does not affect diversity. Latitudinal zooplankton richness had a quasi-parabolic shape. A decrease in richness was observed at 27.5 °N, in the archipelago region, with maximum richness at 26.5 °N and 28.5 °N. The distribution of latitudinal ranges is consistent with geometric constraints models; taxa with wide ranges are in the central area, while those with narrow ranges are near the boundaries and the Upper Gulf. Zooplankton responds in some way to the existence of the southern boundary as shown by the decrease of richness in this region. At the whole scale of the Gulf, the distribution of richness followed geometric constraints model, while at smaller scales, distribution and abundance are conditioned by the hydrodynamics of the Gulf. We compared zooplankton spatial distribution with Sea Level Anomaly, Sea Surface Temperature, and Chlorophyll-a concentrations from Copernicus to establish relationships between these factors. We performed Cluster and Redundancy Analysis to characterize similarities between stations in terms of biomass and taxon composition and to assess the importance of environmental variables on the distribution of zooplankton.
The effect of severe drought on the functional groups that sustain the base of the mangrove food webs in semi-arid areas is largely unknown. We therefore analyzed the intra-annual variation in the assemblages and functional groups of copepods in a shallow, low-inflow estuary of the Brazilian semi-arid coast when the most severe drought ever occurred. The lowest density was found in April (upstream region) and the highest in August (downstream region). Three main functional groups were identified, sorted by spawning strategy, and further subdivided according to feeding strategy, trophic regime, and diel vertical migration behavior. The community was significantly influenced by the extreme drought period, presenting a temporal homogenization in terms of composition, and an expressive and unexpected increase in density in the dry period, possibly due to phytoplankton blooms resistant to hypersalinity and the occurrence of copepod species adapted to stressful conditions. The few stress-tolerant species sustaining the food webs with seasonal variations were observed simplifying the trophic variability. The results indicate that hypersalinity can induce changes in the zooplankton community, increasing copepod mortality risk and, so, promoting alteration in the trophic estuarine dynamic.
Written by a group of international experts in their field, this book is a review of Lagrangian observation, analysis and assimilation methods in physical and biological oceanography. This multidisciplinary text presents new results on nonlinear analysis of Lagrangian dynamics, the prediction of particle trajectories, and Lagrangian stochastic models. It includes historical information, up-to-date developments, and speculation on future developments in Lagrangian-based observations, analysis, and modeling of physical and biological systems. Containing contributions from experimentalists, theoreticians, and modellers in the fields of physical oceanography, marine biology, mathematics, and meteorology, this book will be of great interest to researchers and graduate students looking for both practical applications and information on the theory of transport and dispersion in physical systems, biological modelling, and data assimilation.
Calanoid copepods comprise around 90% of Arctic zooplankton biomass and are fundamental to the ecological and biogeochemical functioning of high-latitude pelagic ecosystems. They accumulate lipid reserves during the productive months and represent an energy-rich food source for higher trophic levels. Rapidly changing climate in the Arctic may alter the quantity and composition of the food environment for one of the key copepod species, Calanus finmarchicus, with as yet unquantified effects on its production. Here we present rates of feeding and egg production in female C. finmarchicus exposed to the range of feeding conditions encountered across the Fram Strait in May/June 2018. Carbon (C) budgets were constructed and used to examine the relationship between feeding and growth (= egg production) in these animals. C-specific ingestion rates (mean ± standard deviation) were highly variable, ranging from 0.015 ± 0.004 to 0.645 ± 0.017 day-1 (mean = 0.295 ± 0.223 day-1), and were positively correlated with food availability. C-specific egg production rates ranged from 0.00 to 0.049 day-1 (mean = 0.012 ± 0.011) and were not correlated with either food availability or ingestion rate. Calculated gross growth efficiencies (GGE: growth/ingestion) were low, 0.12 ± 0.13 (range = 0.01 to 0.39). The assembled C budgets indicate that the average fraction of ingested food that was surplus to the requirements for egg production, respiration and losses to faecal pellets was 0.17 ± 0.42. We suggest that this excess occurred, at least in part, because many of the incubated females were still undergoing the energetically (C-) expensive process of gonad maturation at the time of sampling, an assertion that is supported by the relatively high C:N (nitrogen) ratios of the incubated females, the typically low egg production rates, and gonad maturation status. Ontogenetic development may thus explain the large variability seen in the relationship between egg production and ingestion. The apparently excessive ingestion rates may additionally indicate that recently moulted females must acquire additional N via ingestion to complete the maturation process and begin spawning. Our results highlight the need for improved fundamental understanding of the physiology of high-latitude copepods and its response to environmental change.
Calanus sinicus is one of the most dominant planktonic copepods and plays a key role as a secondary producer in the mid-latitude coastal shelf areas of the Northwestern Pacific. In this study, we investigated seasonal changes in in situ egg production rate (EPR) of C. sinicus collected from March 2014 to February 2015 in Sagami Bay, Japan. Simultaneously, we collected formalin-preserved samples to measure reproductive index (RI), which was calculated as the proportion of individuals with matured gonad to total females in each sample. Monthly averages of EPR and RI varied from 2.4 to 44.9 eggs female⁻¹ day⁻¹ and 0% to 75.9%, respectively. RI showed a significant positive effect on EPR. Moreover, EPR decreased with increasing temperature, which was the inverse of the effect of temperature on EPR reported in a previous study in the Seto Inland Sea. The difference between the studies suggests that the local population may adapt to different temperature environments in each location. Using a stepwise multiple regression model, EPR estimates for C. sinicus in Sagami Bay were explained by the average water temperature and RI with high probability (R²=0.71). Although local water temperature ranges must be considered before applying our model to other areas, the model would be useful to reconstruct past secondary production of C. sinicus from preserved samples collected in other neighboring coastal areas.
Aetideidae is a calanoid copepod family dominant in the mesopelagic layer of the Arctic Ocean for which little ecological information is available because species identification, especially of early copepodite stages, is difficult. In this study, we developed a species identification flow for the whole copepodite stages of five sympatric aetideid copepods ( Chiridius obtusifrons , Gaetanus tenuispinus , G. brevispinus , Aetideopsis multiserrata , and A. rostrata ). Vertical distributions and seasonal population structures of these species were evaluated using a year-round sample time-series collected at the drifting ice station (SHEBA) in the western Arctic Ocean. Combinations of morphological characteristics (prosome length, cephalosome, and prosome widths) were used to identify the early copepodite stages to species. Aetideopsis rostrata was distributed in deep waters (1,032–1,065 m) throughout the year. The other species all were found at 600–700 m during the midnight sun. However, during the polar night, the vertical distributions of each species were distinct, resulting from ascent, descent, or depth maintenance, indicating seasonal vertical migration which may function to reduce inter-specific competition during the polar night when food resources are scarce. Reproduction timing varied among four aetideid copepods: C.obtusifrons and G. tenuispinus showed polar night ascent and reproduction at the end of the polar night, whereas G. brevispinus and A. multiserrata showed descent or depth maintenance during the polar night and reproduction at the beginning of the polar night. There was not sufficient data to examine reproduction timing of A. rostrata . Common for all aetideid species, δ ¹⁵ N values of the adult females indicate more carnivorous feeding modes during the polar night than those in the midnight sun. Such vertical distribution and timing of reproduction variation among these five aetideid copepods may function to reduce species competition in the mesopelagic layer of the Arctic Ocean.
Climate change-induced salinity decrease is currently occurring in many estuarine coastal zones, due to increased outflow of freshwater. This freshening can be a problem for brackish-water animals, already living on the edge of their salinity tolerance. We measured oxygen consumption of common copepod Eurytemora affinis along a natural salinity gradient in the western Gulf of Finland. The salinity varied between 3 in the inner bay and 7 in the offshore area along the gradient, pH varied between 7.05 and 7.86. Our results show that respiration increased with decreasing salinity, as expected for a genus more commonly found in estuarine/saline waters, even if it has colonised brackish waters. Our results suggest that future decreasing salinity could enhance respiration rate, and so energy requirements, of large-bodied zooplankton in estuarine areas such as the Baltic Sea and could lead to lower food quality availability for coastal planktivorous fish, such as herring and sprat.
Cyclopoid and calanoid copepods differ in how they move. Cyclopoid copepods use the thoracic legs for cruise and escape swimming while most calanoid copepods use the cephalic appendages for cruise swimming and the thoracic legs for escape reactions. Apart from this gross difference, little is known on the comparative aspects of the locomotor function of copepod appendages. This study investigated the main kinematic patterns of cruise and escape swimming of two small cyclopoid copepods, Thermocyclops oithonoides and Oithona davisae, and a small calanoid copepod, Paracalanus parvus, by video filming at a frame rate of up to 1200 frames/s. During escape swimming, O. davisae and the twice as large P. parvus showed similar movement, jumping at a frequency of 150 Hz and moving at 12 cm s-1 ; however, at a lower jump frequency (∼100 Hz), the cyclopoid T. oithonoides showed an almost two times faster escape swimming than that of P. parvus which has the same body size. This higher speed can be linked to the greater role of the longer abdomen for the flopping strokes in T. oithonoides. In accordance with the Arrhenius law, the kinematic parameters of cruise and escape swimming of T. oithonoides showed temperature dependence in the range of 6.5-27°С. At a temperature of about 20°C, the respiration rate of O. davisae and P. parvus was 1.6 times higher (i.e., ∼1.5 µg O2 mg-1 h-1 ) than in T. oithonoides during normal swimming; however, in the swarming state, the respiration rate of T. oithonoides increased 3.4 times to 3.0 µg O2 mg-1 h-1 , which was nine times higher than the respiratory rate of anesthetized individuals of this species. Based on the speed and duration of locomotor acts, the cyclopoid T. oithonoides consumed about the same amount of respiratory energy as the calanoid P. parvus, but the mechanical energy required for movement in jumps mode was 1.5 times higher.
The Arabian Sea and the Bay of Bengal are cul-de-sacs of the northern Indian Ocean, and they contain more than half of the world's Oxygen Minimum Zones (OMZs). The current study reviews the vast and advancing literature on the oceanographic settings that lead to distinct OMZs in the Arabian Sea and the Bay of Bengal and links them with the copepods thriving there, their status, and likely adaptations. The Arabian Sea has a thicker perennial subsurface OMZ (∼1000 m) than the Bay of Bengal (∼500 m), which is linked to high plankton production via upwelling and winter convection in the former and river influx and mesoscale eddies in the latter. Studies world over show that OMZs adversely affect the zooplankton community as their core always sustains reduced zooplankton biomass. Exclusive studies on copepods in the perennial OMZ in the northern Indian Ocean have been limited to the Arabian Sea so far, which showed that the calanoid copepod Lucicutia grandis is an indicator species of the OMZ lower boundary, whereas Calanoides natalis is a diapausing species in the OMZ. Studies also evidenced that many calanoids (Pleuromamma indica, Lucicutia longicornis, Rhincalanus nasutus, Paracalanus aculeatus, Eucalanus attenuatus, Euchaeta rimana, Subeucalanus subcrassus), cyclopoids (Oithona nana, Oncaea conifera, Oncaea subtilis, Saphirina), Harpacticoids (Microsetella sp., Aegisthus mucronatus) and Mormonilloids (Mormonilla minor) living in the perennial OMZ are either vertical migrators or having a patchy distribution between the epipelagic to the deeper OMZ stratum. These OMZ copepods are believed to have distinctive growth and reproductive traits that allow them to exist in the OMZs. Their high enzyme activity allows them to carry out vertical migration, their high lipid reserves allow them to stay alive in starving conditions, and their slow lifestyle reduces their energy consumption in deeper OMZs. Unlike the perennial OMZs in the Arabian Sea, copepods in the seasonal OMZs in the coastal upwelling zones are almost unexplored, except for a recent attempt that demonstrated that cyclopoids have better survival strategies there. The Arabian Sea and the Bay of Bengal around India have a strong seasonal exchange of their water masses, but how they influence and shape the copepod communities in these regions and the OMZs they harbour is completely unknown.
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