Vertical Distribution Of Copepods Research Articles

Dark plumes of glacial meltwater affect vertical distribution of zooplankton in the Arctic

In polar regions, the release of glacial meltwater resulting in turbid plumes is expected to transform coastal waters with numerous consequences on the marine ecosystem. This study aimed to determine the influence of turbidity regimes on the vertical distribution of copepods together with their potential food (chlorophyll a fluorescence) and non-visual predators (gelatinous zooplankton). Hydrography, turbidity, suspended particulate matter and chlorophyll a were studied in July and August 2019 in West Spitsbergen waters (European Arctic). Fine-scale vertical distribution patterns of zooplankton were assessed by an optical counter (LOPC) and underwater camera (UVP) and verified by plankton nets. In waters with the shallow impact of dark plumes, Calanus spp. and gelatinous zooplankton were concentrated in the upper water layers, whereas in areas with a thick turbid layer, they were distributed evenly in the water column. However, chlorophyll a peaks were found to be restricted to the surface in the turbid waters and there were subsurface maxima in the shallow turbidity regime. Regardless of the region, the turbidity regime was a significant factor shaping the vertical distribution of Calanus spp. We speculate that similar trends might be observed in other rapidly emerging turbid ecosystems and urge that future plankton research should also include relatively simple turbidity measurements.

Species richness, abundance and vertical distribution of Copepods in Banda Sea, Indonesia

The aims of this research were to investigate the species richness and abundance of Copepods. Copepods were sampled using rosette sampler (surface, 25 m and 75 m) on November 21st – 30th, 2013, from the Banda Sea. A total of 21 taxa of Copepods belonging to three orders were identified. Calanoid was identified as the most richness order, followed by Cyclopoid and Harpacticoid. The highest value of total abundance in the surface water is 121 ind/6L, in the 25 m of depth is 221 ind/6 L, and in the 75 m of depth is 96 ind/6L. Acrocalanus longicornis is the most abundant taxa of Copepods, followed by Acartia bispinosa, and Subeucalanus mucronatus. The most predominant taxa of Acartia bispinosa, and Subeucalanus mucronatus showed a remarkable peak at 25 m layers.

Synergistic effects of seasonal deoxygenation and temperature truncate copepod vertical migration and distribution

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 575:57-68 (2017) - DOI: https://doi.org/10.3354/meps12205 Synergistic effects of seasonal deoxygenation and temperature truncate copepod vertical migration and distribution James J. Pierson*, Wen-Cheng L. Slater, David Elliott, Michael R. Roman Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD 21613, USA *Corresponding author: jpierson@umces.edu ABSTRACT: The vertical distribution of copepods in coastal and estuarine systems is altered by the concentration of dissolved oxygen in the water column. We studied the combined effects of temperature and dissolved oxygen on vertical distribution and migration behavior of the copepod Acartia tonsa in the Chesapeake Bay throughout the period of seasonal deoxygenation in 2010 and 2011. Vertically stratified net tows and hydrographic casts were conducted at 2 stations over diel cycles in spring, summer, and autumn. The partial pressure of dissolved oxygen ( pO2) was used as a metric for the condition of copepod habitat during each cruise instead of oxygen concentration, because partial pressure incorporates the temperature dependence of dissolved oxygen solubility, making it a more useful indication of available oxygen supply than concentration. Habitat conditions were described as having pO2 above limiting conditions, below the maximum respiratory demand but above potentially lethal conditions, or below the minimum basal respiratory demand. In general, adult males were found deeper in the water than females in most oxygen conditions. Regression tree analysis supported these findings and showed that pO2 was a key predictor of the fraction of copepodites, adult females, and adult males above the pycnocline, and for copepodites and adult females below the pycnocline. Temperature was a strong predictor of the fraction of adult males below the pycnocline, with a smaller fraction found there at higher temperatures. These findings suggest sex-specific responses to deoxygenation, potentially as a result of different oxygen demands or behavior. KEY WORDS: Copepod · Hypoxia · Diel vertical migration · Vertical distribution · Acartia tonsa · Chesapeake Bay · Estuarine Full text in pdf format Supplementary material PreviousNextCite this article as: Pierson JJ, Slater WCL, Elliott D, Roman MR (2017) Synergistic effects of seasonal deoxygenation and temperature truncate copepod vertical migration and distribution. Mar Ecol Prog Ser 575:57-68. https://doi.org/10.3354/meps12205 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 575. Online publication date: July 20, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

East-west differences in population structure and vertical distribution of copepods along 47^|^deg;N in the subarctic Pacific in June 2009

Stratified zooplankton sampling was conducted in the subarctic Pacific in June 2009 at four stations along 47°N from 0 to 3,000 m depth to evaluate longitudinal changes in population structure and vertical distribution of the dominant copepod species. At the westernmost station (160°E), the population structure of Eucalanus bungii and Me- tridia pacifica was dominated by early copepodid stages. In E. bungii, nauplii were abundant and adult females had developed ovaries at 160°E, while at the three stations to the east (167°E, 174°E and 179°W), no E. bungii nauplii were collected, and the resting stages were dominant. This suggests the species was reproducing near 160°E and in dia- pause in the east. In all three Neocalanus species analyzed (N. cristatus, N. flemingeri and N. plumchrus), late cope- podid stages were dominant at the eastern three stations. Lipid accumulation in the fifth copepodid stage of Neocala- nus spp. was greater in the west than in the east. This probably resulted from better food conditions and lower tem- peratures in the west, where copepods could consume more food during development than in the east.

Production and fate of copepod fecal pellets across the Southern Indian Ocean

The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 μg C m−3 day−1. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg m−2 day−1).

Diel and ontogenetic variations in vertical distributions of large grazing copepods during the spring phytoplankton bloom in the Oyashio region

Short-term changes in vertical distributions of copepods during the spring phytoplankton bloom were analyzed based on day and night vertically stratified sampling (9 strata between 0 and 1000 m) with a fine-mesh (60 μm) VMPS in the Oyashio region on five occasions: 8 March, 5, 11, 23 and 29 April 2007. Responses to the bloom were varied and species-specific. Eucalanus bungii C3–C6 were resting around 400 m on 8 March. They had aroused from rest by 5 April, more completely for C6F than for C3–C4. On 29 April, newly recruited C1–C4 stayed in near-surface layers (0–50 m). Both Metridia pacifica and Metridia okhotensis showed strong diel vertical migrations (DVM). When the amount of sinking flux was sufficient (23 and 29 April), juveniles ceased DVM and stayed close to 300 m throughout the day and night, while the C6F continued DVM. Continuous DVM behavior of Metridia spp. C6F is likely related to spawning in the surface layer at night. The growth phase of juvenile Neocalanus spp. occurred shallower than 250 m. Within this depth range, vertical partitioning was observed among the species: Neocalanus flemingeri and Neocalanus plumchrus occurred above 50 m, while Neocalanus cristatus was distributed from 75 to 250 m. The boundary between two patterns was around 50–75 m. These findings are comparable to those in the eastern subarctic Pacific.

Characterization of the zooplankton community, size composition, and distribution in relation to hydrography in the Japan/East Sea

Abstract The Japan/East Sea (JES) may be thought of as a model or microcosm of larger oceanic systems where biogeographic boundaries juxtapose at highly dynamic boundaries. The northern and southern portions of the JES are hydrographically and biologically distinct, with the southern portion being more tropical/oligotrophic and the northern portion being more boreal/eutrophic. Regional zooplankton taxonomic and size compositions and abundance and the high-resolution vertical distribution of plankton, fluorescence, and coincident hydrography were described using the Video Plankton Recorder (VPR), equipped with high- and low-magnification cameras and environmental sensors and mounted on a vertically profiling towed vehicle, in the upper 80 m of the JES during the summer of 1999. A survey was conducted over both the northern and southern regions, including the Subpolar Front (SPF), that spanned 10–12° of latitude and longitude and covered an along track distance of 7000 km. Plankton also were collected at 15 selected stations using a ring net for silhouette analysis of taxa and size. Distributional patterns in abundance (#/liter) of plankton taxa from the VPR were quantified at sea in real time, identifying plankton automatically using a neural network classifier. The most abundant taxa identified were copepods, Oithona spp., Calanus spp., copepod nauplii, protozoa, and diatoms, with copepods the dominant taxon. The northern JES, southern JES, and North Korean Cold Current were distinct based on based on temperature-salinity properties. The hydrography was complex and characterized by multiple mesoscale features including currents and the meandering of the SPF. Different taxonomic and size compositions were observed in the three hydrographic regions. The vertical distributions of copepods and fluorescence were associated with hydrographic structure, especially at fronts. Plankton abundances varied with regional hydrographic region and environmental conditions, although strong associations were not always observed. The extremely dynamic nature of the JES may effectively mix the plankton and obscure strong gradients or differences between regions.

Seasonal Patterns of Vertical Distribution between Meiofaunal Groups in Relation to Phytodetritus Deposition in the Bathyal Sagami Bay, Central Japan

Temporal changes in the vertical distribution of metazoan meiofaunal groups were examined at a bathyal site (depth 1450 m) in Sagami Bay from December 1996 to August 1998. Among major meiofaunal groups, the vertical distributions of copepods (adults and copepodites), and kinorhynchs changed seasonally and they concentrated in the shallower part in the sediment profile when CPE concentrations were higher. Seasonal changes in the vertical distributions of ovigerous females and nauplii of copepods were not related to CPE concentrations, but related to that of total copepods. On the other hand, nematodes, ostracods, and polychaetes did not show seasonal migrations. These results suggest that there is a difference in the response to the sedimentation of organic matter between metazoan meiofaunal taxa.

Mesozooplankton community characteristics in the NE subarctic Pacific

Mesozooplankton biomass, species composition, abundance, and vertical distribution were determined along a transect from the continental slope off the west coast of Canada to Ocean Station Papa (OSP) in the open-ocean waters of the NE subarctic Pacific as part of the Canadian Joint Global Ocean Flux Study of this area. All of these measurements had distinct seasonal patterns. At OSP biomass peaked in spring, coincident with the annual biomass maximum of large copepods of the genus Neocalanus. Early copepodites of these copepods were present in surface waters at all stations along the transect in winter, but N. plumchrus and N. flemingeri copepodites were only at the offshore stations in spring. This indicated that these large copepods had completed the growth phase of their life cycle slower in the open ocean than closer to shore where they had already descended to deep water by May or June. Summer biomass was low compared to the spring peak. The summer mesozooplankton abundance was similar to the springtime abundance, but the composition had changed from large-bodied copepods in the spring to small copepods and fewer non-copepod taxa in the summer, which accounts for the reduction in total biomass. Winter biomass was the lowest of the year. Winter species composition was similar to summer except for the appearance of juvenile stages of the genera Neocalanus and Calanus. Diel changes in biomass in the upper 150 m were found in summer but not in winter or spring. Vertical distributions of copepods were often distinct, with closely related species occupying different depth strata. Measurements of wet weight at OSP were higher than the long-term mean wet weight during winter and spring, and lower during summer.

Effect of vertical mixing on the vertical distribution of copepods in coastal waters

Effect of vertical mixing on the vertical distribution of copepods in coastal waters

Diel variations in the vertical distribution of copepods off the north coast of Spain

Diel variations in the vertical distribution of copepods were studied in the north coast of Spain and related to the physical and biological structure of the water column. Zooplankton samples were taken at three different stations during a 24 h period, in the proximity of a drogue buoy using a Longhurst Hardy Plankton Recorder (LHPR) sampling net, so that it is assumed that the same water mass was sampled continuously. Physical and other biological parameters were monitored by Conductivity Temperature Depth Recorder (CTD) profiles and vertical Undulating Oceanographic Recorder (UNDULATOR) dips for temperature, salinity, and chlorophyll a. Copepods were counted and classified into seven categories according to their size, and their distribution in the vertical plane was analysed using univariate and multivariate statistical techniques.Vertical distribution of copepods and their developmental stages were mainly determined by chlorophyll distribution and, when a subsurface chlorophyll maximum was present, small copepods and copepodite stages appeared aggregated in this layer. Nocturnal upward movements of the population and an ontogenetic component in the position and behaviour of the community were also important features that characterised the distribution of the community. Those patterns may explain a part of the observed variability of the abundances and distribution of the copepods in the water column. However, the water mass displacement in the 24 h period of study must also be considered as a main variability factor in the spatial and temporal distribution of the zooplankton populations.

Vertical distribution of copepods and the utilization of the chlorophyll a-rich layer within Concepcion Bay, Chile

The potential factors contributing to the development of vertical distribution patterns of two copepod species, Calanus chilensis and Calanoides patagoniensis, were studied in Concepcion Bay, Chile, during three 24-h cruises in late winter, mid-spring 1984 and early winter 1986. Results show that both species tend to aggregate at the depth of maximum chlorophyll a in the water column and that neither minimum oxygen concentrations (<1 ml O 2l −1) nor strong thermoclines play a determinant role in the depth of maximum copepod aggregation. Gut contents (chlorophyll a and phaeopigments) in copepods revealed that the peak in feeding activity occurred during the night for both C. chilensis in June and for C. patagoniensis in November. The C. chilensis and C. patagoniensis populations consumed about 70% and 50% of their total daily ingestion in the chlorophyll a-rich layers in June and November, respectively. In spite of the environmental and population abundance differences between June and November, both copepod populations presented similar values of food consumption: the C. chilensis population ingested up to 8·47 mg C m 2 day −1 in June while the C. patagoniensis population consumed 6·81 mg C m −2 day −1 in November. The daily ingestion carried out by each copepod species would represent less than 1% of the total daily primary productivity in both months. Our results suggest that a great amount of phytoplankton biomass is not directly utilized by zooplankton in Concepcion Bay.

Vertical migrations of herring, Clupea harengus, larvae in relation to light and prey distribution

The influence of light and prey abundance on the vertical distribution of herring larvae was evaluated by three investigations made under calm weather conditions in the North Sea off the Scottish coast. The investigations took place at different time after hatching and the vertical distributions of three size groups of larvae (mean sizes 8,15 and 19 mm) were related to time of day and the vertical distribution of copepods. No migratory behaviour of copepods was observed but their vertical distribution differed between investigations. In the investigation on intermediate sized larvae, copepod density peaked at the pycnocline (40 m). Larvae concentrated at this depth at noon. At dawn and dusk larvae migrated towards the surface and the vertical distributions fluctuated semidielly. In the two other investigations, copepods were homogeneously distributed in the water column and after migration towards the surface at dawn larvae stayed in the upper water column during the day. The observations suggest that the daytime vertical distribution of larvae in calm weather is mainly determined by feeding conditions: the larvae move to depths were light is sufficient for feeding, and refinement within that zone is made according to a compromise between optimal light conditions for feeding and optimal prey densities.

Vertical movements of zooplankton during a solar eclipse.

THE solar eclipse of March 7, 1970, provided an opportunity to examine the reactions of zooplankton. to rapid changes in light intensities. Diurnal changes in the vertical distribution of zooplankton are recognized behavioural phenomena1,2. Light is considered to be the principal stimulus to vertical movement in planktonic crustaceans3,4. The basic pattern of diurnal distribution is a rise to the surface in late afternoon in response to decreasing light intensity, followed by a sinking in the absence of a light gradient at night; as light increases at dawn the zooplankton moves upward to the source of light change, and then downward away from the increasing intensity of daylight2. The general pattern of movement can vary, however, under the influence of various exogenous and endogenous conditions5. Observations of the responses of zooplankton to solar eclipses are limited to the studies of Petipa6, Skud7 and Backus, Clark and Wing8; changes in the vertical distributions of copepods, meroplankton and scattering layer and bioluminescent organisms were attributed to the exogenous light effects of the eclipse.

DIURNAL MIGRATION OF PLANKTON IN THE GULF OF MAINE AND ITS CORRELATION WITH CHANGES IN SUBMARINE IRRADIATION

1. Observations on the vertical distribution of copepods and measurements of the submarine irradiation were made in the Gulf of Maine during 12- to 48-hour periods to procure information on the importance of light in controlling diurnal migration.2. Five closing nets were towed simultaneously at different depths from a single vertical cable. The method devised for allowing the nets to be open only during the 10-minute towing period is described.3. The sources of error involved in the work at sea and in the sampling of the catch in the laboratory are discussed. The methods used allow special dependence to be placed upon differences found among the hauls within each series.4. The general vertical distribution of the three species studied was as follows: Centropages typicus inhabited the stratum of water above the thermocline (10 to 20 meters), Calanus finmarchicus was irregularly distributed, and Metridia lucens occurred below the thermocline. In each case the individuals present in the upper part of the range were found to have a slightly smaller average length than those occurring at deeper levels.5. The adult females of Metridia exhibited the most marked diurnal migration, the level of maximum abundance rising in the afternoon and during the night and falling in the morning. These movements were found to coincide to a considerable extent with changes in submarine irradiation.6. The changes in the vertical distribution of the other groups of copepods were slight or quite irregular. In some cases, however, there was a definite tendency for the maximum to occur at greater depths at noon than at other times.7. This investigation confirms the idea that light is the most important factor controlling diurnal migration. In addition, the observations are shown to have a bearing on various of the theories regarding the manner in which light exerts its effect.