Limits...
Hydrostatic pressure and temperature effects on the membranes of a seasonally migrating marine copepod.

Pond DW, Tarling GA, Mayor DJ - PLoS ONE (2014)

Bottom Line: Temperature and/or pressure both had significant, additive effects on the overall composition of the membrane phospholipid fatty acids (PLFAs) in C. acutus.As copepods cannot synthesise DHA and do not feed during dormancy, sufficient DHA must be accumulated through ingestion before migration is initiated.Climate-driven changes in the timing and abundance of the flagellated microplankton that supply DHA to copepods have major implications for the capacity of these animals to undertake their seasonal life cycle successfully.

View Article: PubMed Central - PubMed

Affiliation: Scottish Association for Marine Science, Oban, Argyll, United Kingdom.

ABSTRACT
Marine planktonic copepods of the order Calanoida are central to the ecology and productivity of high latitude ecosystems, representing the interface between primary producers and fish. These animals typically undertake a seasonal vertical migration into the deep sea, where they remain dormant for periods of between three and nine months. Descending copepods are subject to low temperatures and increased hydrostatic pressures. Nothing is known about how these organisms adapt their membranes to these environmental stressors. We collected copepods (Calanoides acutus) from the Southern Ocean at depth horizons ranging from surface waters down to 1000 m. Temperature and/or pressure both had significant, additive effects on the overall composition of the membrane phospholipid fatty acids (PLFAs) in C. acutus. The most prominent constituent of the PLFAs, the polyunsaturated fatty acid docosahexanoic acid [DHA - 22:6(n-3)], was affected by a significant interaction between temperature and pressure. This moiety increased with pressure, with the rate of increase being greater at colder temperatures. We suggest that DHA is key to the physiological adaptations of vertically migrating zooplankton, most likely because the biophysical properties of this compound are suited to maintaining membrane order in the cold, high pressure conditions that persist in the deep sea. As copepods cannot synthesise DHA and do not feed during dormancy, sufficient DHA must be accumulated through ingestion before migration is initiated. Climate-driven changes in the timing and abundance of the flagellated microplankton that supply DHA to copepods have major implications for the capacity of these animals to undertake their seasonal life cycle successfully.

Show MeSH
Map indicating locations of the four study sites in the Southern Ocean.(APF = Antarctic Polar Front, SACCF = Southern Antarctic Circumpolar Current Front, SBACC = Southern Boundary of the Antarctic Circumpolar Current).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4206463&req=5

pone-0111043-g002: Map indicating locations of the four study sites in the Southern Ocean.(APF = Antarctic Polar Front, SACCF = Southern Antarctic Circumpolar Current Front, SBACC = Southern Boundary of the Antarctic Circumpolar Current).

Mentions: Copepods were collected from four stations during a cruise of the RRS James Clark Ross to the Scotia Sea in January and February 2008 (Fig. 2, Table S1, [15]–[16]). Vertical profiles of pressure are linear and effectively constant between stations whereas temperature profiles, determined at dawn using a SeaBird 911+CTD, differed between stations (Fig. 3). This sampling design enabled us to reliably distinguish between the effects of pressure and temperature; for any given pressure we had observations across a range of temperatures. Stratified samples were collected during the night from 375 m to 1000 m in 125 m depth horizons using a MOCNESS multi-net. Copepods from the photic zone water column were collected using Bongo nets deployed immediately after the CTD deployments and were hauled vertically at ∼0.22 ms−1 from 400 m to the surface [16]. A total of 85 individual C. acutus (pre-adult 5th copepodite stage) were collected over four stations and six depth horizons. Copepods were individually sorted onboard and stored in 500 µl of chloroform∶methanol (2∶1 v/v) in 1.1 ml tapered vials (Chromacol) at −80°C until analysis. All samples were analysed in laboratories in Cambridge <1 year after sample collection.


Hydrostatic pressure and temperature effects on the membranes of a seasonally migrating marine copepod.

Pond DW, Tarling GA, Mayor DJ - PLoS ONE (2014)

Map indicating locations of the four study sites in the Southern Ocean.(APF = Antarctic Polar Front, SACCF = Southern Antarctic Circumpolar Current Front, SBACC = Southern Boundary of the Antarctic Circumpolar Current).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206463&req=5

pone-0111043-g002: Map indicating locations of the four study sites in the Southern Ocean.(APF = Antarctic Polar Front, SACCF = Southern Antarctic Circumpolar Current Front, SBACC = Southern Boundary of the Antarctic Circumpolar Current).
Mentions: Copepods were collected from four stations during a cruise of the RRS James Clark Ross to the Scotia Sea in January and February 2008 (Fig. 2, Table S1, [15]–[16]). Vertical profiles of pressure are linear and effectively constant between stations whereas temperature profiles, determined at dawn using a SeaBird 911+CTD, differed between stations (Fig. 3). This sampling design enabled us to reliably distinguish between the effects of pressure and temperature; for any given pressure we had observations across a range of temperatures. Stratified samples were collected during the night from 375 m to 1000 m in 125 m depth horizons using a MOCNESS multi-net. Copepods from the photic zone water column were collected using Bongo nets deployed immediately after the CTD deployments and were hauled vertically at ∼0.22 ms−1 from 400 m to the surface [16]. A total of 85 individual C. acutus (pre-adult 5th copepodite stage) were collected over four stations and six depth horizons. Copepods were individually sorted onboard and stored in 500 µl of chloroform∶methanol (2∶1 v/v) in 1.1 ml tapered vials (Chromacol) at −80°C until analysis. All samples were analysed in laboratories in Cambridge <1 year after sample collection.

Bottom Line: Temperature and/or pressure both had significant, additive effects on the overall composition of the membrane phospholipid fatty acids (PLFAs) in C. acutus.As copepods cannot synthesise DHA and do not feed during dormancy, sufficient DHA must be accumulated through ingestion before migration is initiated.Climate-driven changes in the timing and abundance of the flagellated microplankton that supply DHA to copepods have major implications for the capacity of these animals to undertake their seasonal life cycle successfully.

View Article: PubMed Central - PubMed

Affiliation: Scottish Association for Marine Science, Oban, Argyll, United Kingdom.

ABSTRACT
Marine planktonic copepods of the order Calanoida are central to the ecology and productivity of high latitude ecosystems, representing the interface between primary producers and fish. These animals typically undertake a seasonal vertical migration into the deep sea, where they remain dormant for periods of between three and nine months. Descending copepods are subject to low temperatures and increased hydrostatic pressures. Nothing is known about how these organisms adapt their membranes to these environmental stressors. We collected copepods (Calanoides acutus) from the Southern Ocean at depth horizons ranging from surface waters down to 1000 m. Temperature and/or pressure both had significant, additive effects on the overall composition of the membrane phospholipid fatty acids (PLFAs) in C. acutus. The most prominent constituent of the PLFAs, the polyunsaturated fatty acid docosahexanoic acid [DHA - 22:6(n-3)], was affected by a significant interaction between temperature and pressure. This moiety increased with pressure, with the rate of increase being greater at colder temperatures. We suggest that DHA is key to the physiological adaptations of vertically migrating zooplankton, most likely because the biophysical properties of this compound are suited to maintaining membrane order in the cold, high pressure conditions that persist in the deep sea. As copepods cannot synthesise DHA and do not feed during dormancy, sufficient DHA must be accumulated through ingestion before migration is initiated. Climate-driven changes in the timing and abundance of the flagellated microplankton that supply DHA to copepods have major implications for the capacity of these animals to undertake their seasonal life cycle successfully.

Show MeSH