Microphytobenthos in the Elbe estuary: Biomass, species composition and primary production measurements with oxygen microelectrodes

1990 ◽  
pp. 399-402
Author(s):  
C. Gätje ◽  
L. Kies
Keyword(s):  
Species Composition ◽  
Primary Production ◽  
Elbe Estuary ◽  
Oxygen Microelectrodes

scholarly journals Cambios y Evolución de las Pesquerías en al Atlántico Centro-Oriental

1973 ◽  
Vol 30 (12) ◽  
pp. 2301-2307
Author(s):  
C. Bas
Keyword(s):  
Species Composition ◽  
Primary Production ◽  
Continental Shelf ◽  
West African ◽  
Biological Characteristics ◽  
Marine Fisheries ◽  
The West ◽  
West African Coast ◽  
African Coast ◽  
Very High

This paper deals with the marine fisheries off the West African coast, between the Straits of Gibraltar and Mauritania, an area which is characterized by its relatively narrow continental shelf, the presence of the Canary Current, and intensive upwelling resulting in very high primary production and rich bottom fauna.The main fisheries (for sardines, sardinellas, hakes, sparids, cephalopods, and demersal crustaceans) are analyzed with regard to their evolution, species composition, fishing areas and seasons, the biological characteristics of the exploited stocks, and the effect of fishing on them.The criteria to be considered when planning the control and regulation of these fisheries are also analysed.

scholarly journals Primary production during nutrient-induced blooms at elevated CO<sub>2</sub> concentrations

2007 ◽  
Vol 4 (6) ◽  
pp. 4385-4410 ◽  
Author(s):  
J. K. Egge ◽  
T. F. Thingstad ◽  
A. Engel ◽  
R. G. J. Bellerby ◽  
U. Riebesell
Keyword(s):  
Species Composition ◽  
Primary Production ◽  
Experimental Period ◽  
Mineral Nutrient ◽  
Substantial Part ◽  
Phytoplankton Species ◽  
Net Community Production ◽  
Phytoplankton Species Composition ◽  
Alternative Hypotheses

Abstract. Mesocosms experiments (PeECE II and PeECE III) were carried out in 9 transparent mesocosms. Prior to the experimental period, the seawater carbonate system was manipulated to achieve three different levels of CO2. At the onset of the experimental period, nutrients were added to all mesocosms in order to initiate phytoplankton blooms. Rates of primary production were measured by in-situ incubations using 14C-incorporation and oxygen production/consumption. Particulate primary production by 14C was also size fractionated and compared with phytoplankton species composition. Nutrient supply increased the primary production rates, and a net autotrophic phase with 14C-fixation rates up to 4 times higher than initial was observed midway through the 24 days experiment before net community production returned to near-zero and 14C-fixation rates relaxed back to lower than initial. We found a trend in the 14C-based measurements towards higher cumulative primary production at higher pCO2, consistent with recently published results for DIC removal (Riebesell et al., 2007). There where found differences to the size fractionated primary production response to CO2 treatments. The plankton composition changes throughout the bloom, however, resulted in no significant response until the final phase of the experiment where phytoplankton growth became nutrient limited, and phytoplankton community changed from diatom to flagellate dominance. This opens for the two alternative hypotheses that such an effect is associated with mineral nutrient limited growth, and/or with phytoplankton species composition. The lack of a clear net heterotrophic phase in the last part of the experiment supports the idea that a substantial part of production in the upper layer was not degraded locally, but either accumulated there or was exported vertically.

Carbon cycling along a gradient of beech bark disease impact in the Catskill Mountains, New York

2008 ◽  
Vol 38 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
Jessica E. Hancock ◽  
Mary A. Arthur ◽  
Kathleen C. Weathers ◽  
Gary M. Lovett
Keyword(s):  
New York ◽  
Species Composition ◽  
Primary Production ◽  
Forest Structure ◽  
Sugar Maple ◽  
Net Primary Production ◽  
Catskill Mountains ◽  
Beech Bark Disease ◽  
Aboveground Net Primary Production ◽  
Northern Hardwood

Exotic pests and pathogens, through direct and indirect effects on forest structure and species composition, have the potential to significantly alter forest ecosystem processes, including C cycling. Throughout the northern hardwood forest, beech bark disease (BBD) is causing widespread disruption in forest structure and composition. In the Catskill Mountains of New York, some forests formerly codominated by American beech ( Fagus grandifolia Ehrh.) and sugar maple ( Acer saccharum Marsh.) are shifting to sugar maple dominance. The effects of BBD and a subsequent shift in species composition on annual aboveground net primary production and soil CO2 efflux were examined in eight forest plots selected to represent a gradient of BBD impact. There were no significant trends in aboveground net primary production across this gradient. However, growing season soil CO2 efflux decreased linearly along the BBD gradient, declining by 40%. Although the mechanism controlling this decline is uncertain, the decrease in soil CO2 efflux with BBD impact and a shift to greater composition of sugar maple in litterfall could significantly alter C cycling in northern hardwood stands in the Catskill Mountains.

Summer Plankton Distributions Associated with the Physical and Nutrient Properties of the Northwestern Gulf of St. Lawrence

1979 ◽  
Vol 36 (2) ◽  
pp. 187-203 ◽  
Author(s):  
J.-M. Sevigny ◽  
M. Sinclair ◽  
M. I. El-Sabh ◽  
Serge Poulet ◽  
A. Coote
Keyword(s):  
Species Composition ◽  
Primary Production ◽  
Physical Properties ◽  
Nutrient Limitation ◽  
Physiological State ◽  
Copepod Species ◽  
Total Biomass ◽  
Surface Mixed Layer ◽  
North Shore ◽  
The North

Two transects, north–south and east–west, through the Anticosti gyre and the Gaspé current were sampled for physical properties, nutrient and plankton concentrations over a 5-d period during July 1976. Temperature, salinity, σt and nutrient isolines formed a dome characteristic of cyclonic circulation with the apex within the Anticosti gyre, but a strong shallow thermocline prevented nutrient enrichment of the surface mixed layer. Surface nitrate and silicate concentrations were very low, except for two anomalies, throughout the region sampled, with phosphate concentrations higher. Phytoplankton biomass was uniformly low and dominated by nannoplankton (< 15 μm) at all stations except that in the Gaspé current at which netplankton (15–202 μm) was important and the total biomass considerably higher. The higher biomass and importance of larger celled species suggest higher nutrient turnover in the Gaspé current. Nitzschia delicatissima dominated the species composition in the Gaspé current, dinoflagellates and microflagellates being of more importance within the gyre and along the north shore. Zooplankton biomass was distributed fairly uniformly over the entire region but species composition at the shallower stations was characterized by small copepod species (Pseudocalanus sp., Acartia sp.) and fish larvae, the gyre stations being characterized by larger copepod species (Calanus sp.), euphausids, and decapod larvae. Physical properties, nutrients, and plankton were distributed quite uniformly except for the marked variability in the measurements made in the strongly advective Gaspé current station. Distributions of derived parameters that were estimated at 5 m depth suggest nutrient limitation at most stations within the gyre, with the exception of the two stations at which surface nutrient anomalies were detected, while at the nearshore stations, in the Gaspé current and along the north shore, better physiological state and lack of nutrient limitation were observed. Short-term variability in these parameters complicate geographic interpretation, but trends were discernable. Estimated daily primary production was an order of magnitude less than that reported previously. Key words: Anticosti gyre, Gaspé current, primary production, nutrient limited growth

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