A comparative study of microalgal production in a marine versus a river-dominated temporarily open/closed estuary, South Africa     

Akash Anandraj  Renzo Perissinotto  Christian Nozais   《Estuarine, Coastal and Shelf Science》2007,73(3-4):768-780

Temporarily open/closed estuaries (TOCEs) account for almost 71% of the total number of South African estuarine systems. To date the dynamics of microalgal production and biomass in TOCEs is poorly understood. A survey was therefore conducted in two TOCEs along the KwaZulu-Natal coast: the river-dominated Mdloti and the marine-dominated Mpenjati. The aims of this investigation were: (1) to compare the variability of benthic and pelagic microalgal production and biomass in these two contrasting systems; (2) to determine the key environmental parameters influencing primary production in these TOCEs. Results show a similar pattern of primary production and biomass in both estuaries. High benthic microalgal biomass with low primary production and low phytoplankton biomass with high rates of pelagic primary production were observed in both estuaries. Possible explanations for this include: (a) optimum light conditions in the water column, compared to the sediment surface; (b) high impact of grazing by zooplankton in the water column; and (c) settling of phytoplankton. Significant correlations were observed between primary production and environmental parameters (K_d, PAR, temperature, DIN and DIP), during the open and closed phases of both estuaries. A BIOENV (PRIMER) analysis showed that patterns of primary production in both estuaries were influenced primarily by interactions of multiple independent parameters. Comparisons between measured hourly pelagic primary production rates at the Mpenjati and Mdloti and the composite parameter (P_c) of Cole and Cloern (1987) revealed highly significant relationships (r² = 0.8; p < 0.001) between these differently derived variables.  相似文献   

The Influence of Primary Production Rate on the Population Dynamics of Patella granulans, an Intertidal Limpet     

A. L. Bosnian  P. A. R. Hockey 《Marine Ecology》1988,9(3):181-198

Abstract. The production rates of intertidal algae at seven study sites in the Saklanha Bay area. South Africa, were measured monthly for 15 months. Algae grew rapidly and formed extensive, permanent mats on shores that were enriched with nutrients from the dissolved guano of seabirds. The most significant correlate of limpet (Patella granulans) growth was the rate of algal production; more rapid limpet growth on nutrient-rich shores, combined with the effects of predation by African Black Oystercatchers Haematopus moquini on limpets, led to differences in the size structures and life-history patterns of populations of limpets on enriched and unenricheci shores. The rate of primary production affected relationships between intertidal organisms at all trophic levels and influenced patterns of organization within the community.  相似文献   

Carbon and nitrogen primary productivity in three North Carolina estuaries     

T. R. Fisher  P. R. Carlson  R. T. Barber 《Estuarine, Coastal and Shelf Science》1982,15(6)

Uptake of inorganic carbon and ammonium by the plankton community of three North Carolina estuaries was measured using ¹⁴C and ¹⁵N isotope methods. At 0% light, C appeared to be lost via respiration, and at increasing light levels uptake of inorganic carbon increased linearly, saturated (mean I_k = 358±30 μEin m⁻² s⁻¹), and frequently showed inhibition at the highest light intensities. At 0% light NH₄⁺ uptake was significantly greater than zero and was frequently equivalent to uptake in the light (light independent); at increasing light levels NH₄⁺ uptake saturated (mean I_k = 172±44 μEin m⁻² s⁻¹) and frequently indicated strong inhibition. Light-saturated uptake rates of inorganic carbon and NH₄⁺ were a function of chlorophyll a (r² = 0·7−0·9); average assimilation numbers were 625 nmol CO₂ (μg chl. a)⁻¹ h⁻¹ and 12·9 nmol NH₄⁺ (μg chl. a)⁻¹ h⁻¹ and were positively correlated with temperature (r² = 0·3−0·7). The ratio of dark to light-saturated NH₄⁺ uptake tended to be near 1·0 for large algal populations at low NH₄⁺ concentrations, indicating near light independence of uptake; whereas the ratio was lower for the opposite conditions. These data are interpreted as indicative of nitrogen stress, and it is suggested that uptake of NH₄⁺ deep in the euphotic zone and at night are mechanisms for balancing the C:N of cellular pools. A 24-h study using summed short-term incubations confirmed this; the cumulative C:N of CO₂ and NH₄⁺ uptake during the daylight period was 10–20, whereas over the 24-h period the ratio was 6 due to dark NH₄⁺ uptake. Annual carbon and nitrogen primary productivity were respectively estimated as 24 and 4·0 mol m⁻² year⁻¹ for the South River estuary, 42 and 7·3 mol m⁻² year⁻¹ for the Neuse River estuary, and 9·6 and 1·6 mol m⁻² year⁻¹ for the Newport River estuary.  相似文献   

Standing crop and primary production of benthic microalgae on tidal flats in the Sanggou and Jiaozhou Bays, China     

Ning Xiuren  Cai Yuming  Liu Zilin  Hu Xigang  Liu Chenggang 《海洋学报(英文版)》2003,22(1):75-87

The standing crop and primary production of benthic microalgae on tidal flats have seasonally been observed in the Sanggou and Jiaozhou Bays of the northern China coast during 1999 - 2000. The results show that the annual primary productions of benthic microalgae on tidal flats in the two bays are 2 532 and 7 542 tons carbon, which would be able to support 3.1 x 103 and 9.2 x 103 tons shellfish meat, respectively. The nature of sediment is essential for governing the biomass and primary production of benthic microalgae on tidal flats. The biomass and primary production of benthic microalgae on tidal flats with muddy sediments are higher than those with sandy sediments, which resulted from higher nutrient concentration and lower grazing pressure. That is the reason why in comparison with Xiangshan Bay the standing crop and production of benthic microalgae on tidal flats of the Sanggou and Jiaozhou Bays are low. Light was a key factor controlling vertical distribution of biomass and production of benthic  相似文献   

Station Papa Time Series: Insights into Ecosystem Dynamics     

Paul J. Harrison 《Journal of Oceanography》2002,58(2):259-264

The Northeast Pacific has one of the longest time series of any open ocean station, primarily as a result of the weathership station at Station P from the 1950s to 1981. This review summarizes our understanding of the plankton ecosystem for this station and examines interannual variability for the primary producers. The weathership era characterized a period of high temporal sampling resolution with a limited number of parameters being measured. In contrast, the post-weathership period focussed on seasonal sampling (usually three times per year), but a wider range of parameters were measured and sediment traps were deployed to estimate carbon and opal flux rates. The mixed layer depth is shallow compared to the Atlantic Ocean, ranging from 40 to 120 m in late summer and winter respectively. Nitrate, silicate and phosphate are saturating year round with only a few exceptions in the 1970s. Winter and summer Si:N ratios are the same (1.5:1). Ammonium and urea are 0.5 uM in winter and near detection limits (∼0.1 uM) in late summer. Iron is limiting (∼0.05 nM) in late spring and summer for the growth of large diatoms, but iron is co-limiting with irradiance in winter. Chlorophyll and primary productivity are low and show little seasonal variation (about 2 times). Summer chl is about 20 mg m⁻² while primary productivity ranges from 400–850 mg C m⁻²d⁻¹. The f-ratio of 0.25 does not vary with seasons and indicates that primary productivity is fueled by regenerated nitrogen (e.g. NH₄ and urea). Small cells (<5 um) are normally abundant and they utilize regenerated nitrogen produced by the micrograzers; they do not appear to be Fe-limited, but rather controlled by the micrograzers. Shipboard carboy experiments indicate that large diatoms become dominant when iron is added. Therefore top down control is exerted by the micrograzers on the small cells, while there is bottom up control of the large phytoplankton due to low Fe concentrations. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Capelin in Faroese waters-a messenger of harsh times?     

Jakupsstovu  Stein Hjalti i; Reinert  Jakup 《ICES Journal of Marine Science》2002,59(5):884-889

  相似文献   

Influence of Energy Directional Spread on Wave Spectral Refraction     

Li Yucheng Professor  Dept. of Civil Engineering  Dalian University of Technology  Dalian 《中国海洋工程》1992,(2)

Pierson- Moskowitz Spectrum, JONSWAP Spectrum as well as Bretschneider- Mitsuyasu Spectrum are used in this paper for analyzing the influence of wave energy directional spread on refraction of wave spectrum due to both current and topography of sea bed. The author's calculation indicates that such kind influence on the characteristic value of wave height as well as the average direction of wave energy propagation can not be ignored.  相似文献   

贝类育苗中几种水处理新方法应用的探讨     

于瑞海  王如才 《海洋科学进展》1997,(2)

本文主要叙述磁化水、泡沫处理水、臭氧处理水、高分子重金属离子吸附剂在贝类育苗上的应用，介绍其使用方法、优点和不足，从而为贝类人工育苗创造出一个良好的水环境，使贝类育苗稳产高产。  相似文献   

Size-fractionated phytoplankton standing stock and primary production in the Bohai Sea during late spring     

Ning Xiuren  Cai Yuming  Liu Zilin  Chai Fei 《海洋学报(英文版)》2002,21(3):423-435

During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-fractionated chlorophyll a (Chl a) and primary production, photosynthet-ically available radiation (PAR), as well as the related physico-oceanographic and zooplanktonic parameters were measured at five time-series observation stations representing sub-areas of the sea. Results obtained show that there were the marked features of spatial zonation of Chl a and primary production in the Bohai Sea. The values in the Laizhou Bay, the Liaodong Gulf and the Bohai Gulf were high and showed close relation with tidal fluctuations, i.e. high Chl a concentration occurred during high tide in the Laizhou Bay, and during low tide in the Liaodong Gulf and the Bohai Gulf. In the strait and the central region of the Bohai Sea, the values were relatively low and no relationship with tidal fluctuation could be foun  相似文献   

Influence of Coupled Rossby Waves on Primary Productivity and Tuna Abundance in the Indian Ocean     

Warren B. White  Kathryn A. Gloersen  Francis Marsac  Yves M. Tourre 《Journal of Oceanography》2004,60(3):531-541

Interannual coupled Rossby waves in the extratropical Indian Ocean propagate westward in covarying pycnocline depth, sea surface temperature, and meridional surface wind anomalies from the west coast of Australia between 15°S and 35°S, taking 3–4 years to transit the interior ocean to Madagascar. In the interior subtropical gyre, where the tuna longline catch (TLC) mainly concerns two species (albacore and bigeye), these waves have been observed to affect year-to-year changes in catch, with wave crests (troughs) in the main pycnocline associated with high (low) TLC anomalies. This suggested that tuna longline catch is associated with the entrainment of nutrient-rich pycnocline water into the photic zone and a subsequent increase in primary productivity there. Here, this hypothesis is examined within the context of SeaWiFS chlorophyll concentration (CC). We find the situation the opposite of that expected, with wave crests (troughs) in the main pycnocline associated with low (high) CC anomalies averaged over the photic zone. These results are shown to be consistent with a model relating the anomalous CC tendency to upper-layer divergence in the wave, not unlike that relating surface slicks to upper-layer divergence in internal gravity waves. Thus, the connection between interannual coupled Rossby waves and TLC in the interior subtropical gyre does not appear to derive from wave-induced modulation of the pelagic food web. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献