Overwintering strategies in Calanus finmarchicus

Hind, A.; Gurney, William; Heath, Michael R.; Bryant, Andrew

doi:10.3354/meps193095

Cited by 58 publications

(68 citation statements)

References 24 publications

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“…The central feature of the forecast model was a simple representation of diapause entry and duration, elaborated slightly from that of Hind et al (2000). Despite the vital importance of diapause in the life cycle of C. finmarchicus, understanding the regulating processes remains elusive.…”

Section: Forecast Modelmentioning

confidence: 99%

“…Egg production was then converted to estimated egg abundance by multiplying by the egg stage residence time. Hind et al (2000) derived a relationship between rate of egg production (adult 1 d 1 ) and chlorophyll concentration from data presented by Hirche et al (1998). However, this was a simplified relationship that ignored temperature dependency and did not recognize any threshold chlorophyll concentration for the onset of egg production.…”

Section: Egg Production Nowcast Modelmentioning

confidence: 99%

“…Hirche (1996) reviewed the information on diapause and identified a number of physiologically distinct phases, but was unable to identify the cues for entry or emergence. Hind et al (2000) summarized the main hypotheses on factors governing diapause, and showed by application of simple models that environmental cueing of emergence date is not a prerequisite for synchronization of the life cycle to seasonal cycles in the environment. Plausible seasonal patterns of reproduction can be obtained simply by assuming suppression of normal development rates while in diapause.…”

Section: Forecast Modelmentioning

confidence: 99%

“…In part, the field results may reflect the fact that Calanus is not exclusively herbivorous. Based on the data of Richardson et al (1999), a food threshold of 0.2 mg chlorophyll m 3 (8 mgC m 3 ) was incorporated into the functional relationship of Hind et al (2000), and the model refitted to the data presented by Hirche et al (1998).…”

Section: Egg Production Nowcast Modelmentioning

confidence: 99%

“…The forecast and hindcast models were based on the cohort model of Hind and Gurney (1998) and Hind et al (2000). The model represents the development and changes in abundance of a group of identical copepods having the same birthdate and experiencing the same conditions of temperature and food.…”

Section: Hindcast and Forecast Modelsmentioning

confidence: 99%

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Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

HEATH¹

2004

ICES Journal of Marine Science

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. 2000. Comparative analysis of Calanus finmarchicus demography at locations around the Northeast Atlantic.Standardized time-series sampling was carried out throughout 1997 at seven locations around the Northeast Atlantic to investigate regional variations in the seasonal demography of Calanus finmarchicus. Sites ranged from an inshore location in the North Sea, where C. finmarchicus formed only a small component of the zooplankton (<10 mgC m 2 during spring and early summer), to the shelf south of Iceland, and Weathership M in the Norwegian Sea, where the species dominated the zooplankton (>2000 mgC m 2 during spring and summer). The internal consistency of the demographic time series from each site was investigated by three partial models of life-cycle processes. In general, the demography of late copepodites could be accounted for by a relatively simple forecast model of stage development and diapause. However, there was a large discrepancy between nowcast estimates of egg production based on female abundance, temperature, and chlorophyll, and hindcast simulations of the egg production required to account for the observed abundance of early copepodite stages. The results point to a gap in our understanding of seasonal variations in rates of egg production and/or survival of nauplii. Overall, the population sampled at Weathership M appeared to be reasonably self-contained, but all other sites were reliant on invasion of overwintered stock in spring. At least two generations were observed at all but one site, but the extent to which these were generated by discrete bursts of egg production varied between sites and seemed to be partly dependent on the proximity to an overwintering location.

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Section: Forecast Modelmentioning

confidence: 99%

Section: Egg Production Nowcast Modelmentioning

confidence: 99%

Section: Forecast Modelmentioning

confidence: 99%

Section: Egg Production Nowcast Modelmentioning

confidence: 99%

Section: Hindcast and Forecast Modelsmentioning

confidence: 99%

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Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

HEATH¹

2004

ICES Journal of Marine Science

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Temporal Expression of the Clock Genes in the Water Flea Daphnia pulex (Crustacea: Cladocera)

et al. 2016

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The timekeeping mechanisms that operate at the core of circadian clocks (oscillators) are based on interacting molecular feedback loops consisting of clock and clock-associated genes. However, there is a lack of comprehensive studies on the expression of clock genes (particularly those forming its core) in single crustacean species at the mRNA and protein levels, and these studies could serve as a basis for constructing a model of the crustacean molecular oscillator. Studies on Daphnia pulex are well suited to fill this gap because this species is the only representative crustacean whose genome has been sequenced. We analyzed the abundance of 20 gene transcripts throughout the day in the whole bodies of D. pulex (single clone); we found that 15 of these genes were transcriptionally active, and most had daily expression level changes. According to the functional classification of their homologues in insects, these genes may represent elements of the Daphnia molecular oscillator core and its input and output pathways. Studies of PERIOD (PER) protein, one of the main clock components, revealed its rhythmic expression pattern in the epidermis, gut, and ovaries. Finally, the cycling levels of many of these clock components observed in animals reared in continuous light led to the conclusion that the Daphnia oscillator, even if it is structurally similar to the oscillators of other arthropods, can be considered a particularly important adaptive mechanism for living in environments with extreme photoperiods.

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Calanus finmarchicus seasonal cycle and diapause in relation to gene expression, physiology, and endogenous clocks

Häfker

Teschke

Last

et al. 2018

Limnology & Oceanography

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The copepod Calanus finmarchicus plays a crucial role in the north Atlantic food web. Its seasonal life cycle involves reproduction and development in surface waters before overwintering in diapause at depth. Although diapause has been studied for more than a century, the factors responsible for the initiation and termination of it are still unclear. Endogenous clocks have been identified as potent tools for photoperiod measurement and seasonal rhythmicity in many terrestrial species, but knowledge of these remains scarce in the marine realm. Focusing on the dominant CV copepodid stage, we sampled a population of C. finmarchicus from a Scottish sea loch to characterize population dynamics, several physiological parameters, and diel and seasonal expression rhythms of 35 genes representing different metabolic pathways, including the circadian clock machinery. This generated a detailed overview of the seasonal cycle of C. finmarchicus including the most extensive field dataset on circadian clock gene expression in a marine species to date. Gene expression patterns revealed distinct gene clusters upregulated at different phases of the copepod's seasonal cycle. While diel clock cycling was restricted to the active spring/summer phase, many clock genes exhibited the highest expression during diapause. Our results provide new insights into diapause on physiological and genetic levels. We suggest that photoperiod, in interaction with internal and external factors (lipid content, temperature, food availability) and the endogenous clock mechanism, plays an important role in the timing of diapause in C. finmarchicus.

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Overwintering strategies in Calanus finmarchicus

Cited by 58 publications

References 24 publications

Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

Temporal Expression of the Clock Genes in the Water Flea Daphnia pulex (Crustacea: Cladocera)

Calanus finmarchicus seasonal cycle and diapause in relation to gene expression, physiology, and endogenous clocks

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