Contribution Of Copepods Research Articles

Temporal changes of abundance, biomass and production of copepod community in a shallow temperate estuary (Ria de Aveiro, Portugal)

The present study reports on temporal changes of abundance, biomass and secondary production of the copepod community of Ria de Aveiro (Portugal). Zooplankton sampling and hydrological measurements (salinity, temperature, chlorophyll a and nutrients concentrations) were conducted at four occasions (June 2000, September 2000, December 2000 and March 2001), at 6 sampling stations and during ebb and flood. The contribution of copepods (from nauplius to adults) to the total abundance and biomass of the zooplankton community of Ria de Aveiro (Portugal) was equal to 63.6% and 62.0%, respectively (annual average). The estimate of nauplius abundance given by two zooplankton nets with different meshes was significantly different ( P < 0.001) with the 64 μm net collecting 13.9 times more than the 125 μm one. No significant differences were found for copepodites and adults. The abundance of all development stages (except adults) was positively correlated ( P < 0.05) with salinity and temperature. The seasonal patterns of abundance and biomass were similar to those found in other temperate coastal waters. Mean daily secondary production rate (mean ± SE) estimated by the Huntley and Lopez growth model [Huntley, M.E., Lopez, M.D.G., 1992. Temperature-dependent production of marine copepods: a global synthesis. American Naturalist 140, 201–242] was 22% higher than the value given by the application of the Hirst and Bunker model [Hirst, A.G., Bunker, A.J., 2003. Growth of marine planktonic copepods: global rates and patterns in relation to chlorophyll a, temperature, and body weight. Limnology and Oceanography 48, 1988–2010]: 3.71 ± 0.540 and 2.90 ± 0.422 mg C m −3 d −1, respectively.

Contribution of copepods, cladocerans and cirripeds to phosphatase activity in mediterranean zooplankton

The hydrolysis of dissolved phosphoric esters by zooplankton was studied in Toulon seaport (N.W Mediterranean Sea, France). Zooplankton was collected on 90 μm filters. The enzyme reaction was studied using paranitrophenyl phosphate (p-NPP) dissolved in sea water. The particulate material activity was expressed as Vmax (reaction rate when the enzyme is saturated with substrate) using Eadie-Hofstee plots. The activity per L. was high in spring and decreased from summer to winter. Biomass and zooplankton abundance varied also widely during the year. There were significant correlations between activity per L. and the cirriped cyprid abundance. In contrast, during periods when cyprids were absent, positive correlations with copepod and cladoceran abundance were found. Specific activity varied also during the year, with high values in spring and low values in winter. This activity was positively correlated with cyprid abundance, but not with total zooplankton, copepod or cladoceran abundance. These results indicated that copepods and cladocerans contributed to the overall enzyme production, and that cirripeds could be responsible of high specific activities.

Composition and biomass of summer metazoan plankton in the 0?200 m layer of the Atlantic sector of the Antarctic

Composition of the metazoan plankton was studied during R.V. “Dmitry Mendeleev” cruise 43 (February to April, 1989) in the Atlantic sector of the Southern Ocean. Samples were collected from ten stations at six locations. Four of the locations were in open oceanic waters along the 15° W longitude. Two others were in the Bransfield Strait and in inshore waters near Elephant Island. At three locations at 15° W sampling was conducted twice or thrice. At all stations three different sampling gears were used to collect different size groups of Zooplankton: series of hauls were performed by 2001 water-bottle, mesoplankton net and macroplankton trawl for depths from 200 m to the surface. The average biomass of Zooplankton in open oceanic waters was 20.55 g · m−2 wet weight. Copepoda Calanoida dominated composing 54.8% of the total plankton, followed by Euphausiacea (19.8%), Ctenophora (9.7%) and Copepoda Cyclopoida (7.2%). Biomass of any other taxonomic group was less than 1g·m−2. The relative biomass of Calanoida had a tendency to decrease southward along 15°W from 86.1 to 68.1% in February and from 81.8 to 23.6% in March–April. The relative biomass of Euphausiacea increased in the same manner from 2.3 to 17.8% in February and from 3.7 to 41.6% in March–April. The average biomass of calanoids from February to March–April decreased from 77.3 to 31.2% and that of euphausiids increased from 6.2 to 33.8%. The contribution of copepods and euphausiids to the production of the plankton community in the Antarctic is discussed.

Midwater biomass profiles over the Madeira Abyssal Plain and the contribution of copepods

Midwater biomass profiles over the Madeira Abyssal Plain and the contribution of copepods