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81.
82.
83.
F. van Duyl G. Gast W. Steinhoff S. Kloff M. Veldhuis R. Bak 《Coral reefs (Online)》2002,21(3):293-306
The short-term temporal dynamics of phytoplankton composition was compared among coral reef waters, the adjacent ocean and polluted harbour water from July until October along the south-western coast of Curaçao, southern Caribbean. Temporal variations in phytoplankton pigment 'fingerprints' (zeaxanthin, chlorophyll b, 19'-hexanoyloxyfucoxanthin, fucoxanthin, 19'-butanoyloxyfucoxanthin, chlorophyll c2 and c3 relative to chlorophyll a) in the ocean were also observed in waters overlying the reef. However, with respect to specific pigments and algal-size distribution, the algal composition in reef waters was usually slightly different from that in the oceanic water. Phytoplankton biomass (chlorophyll a) was either higher or lower than in the oceanic water. The relative amount of fucoxanthin and peridinin was usually higher, and the relative and absolute amount of zeaxanthin was significantly lower than in oceanic water. Zeaxanthin-containing Synechococci were significantly reduced in reef water. Average algal cell size increased from the open water to the reef and the harbour entrance. Large centric diatoms (>20 m Ø) were better represented in reef than in oceanic water. In reef-overlying waters, the nitrate and nitrite concentrations were higher than in oceanic water. In front of the town, anthropogenic eutrophication (sewage discharge and ground water seepage) resulted in higher NH4, NO3 and PO4 concentrations than at other reef stations. This concurred with significantly enhanced phytoplankton biomass (chlorophyll a), chlorophyll c2 and peridinin amounts at Town Reef compared with the other reef stations. Polluted harbour water usually showed the highest phytoplankton biomass of all stations, dominated by diatoms and dinoflagellates. Conditions in reef waters and harbour water promoted the occurrence and the relative abundance of diatoms and dinoflagellates. Harbour water did not influence the phytoplankton composition and biomass at reef stations situated >5 km away from the harbour entrance. We conclude that phytoplankton undergoes a shift in algal composition during transit over the reef. The dominant processes appear to be selective removal of zeaxanthin-containing Synechococcus (by the reef benthos) and (relative) increase in diatoms and dinoflagellates. The difference in the phytoplankton composition between reef and oceanic waters tends to increase with decreasing dilution of reef water with ocean water. 相似文献
84.
Mertz Christoffer Krarup Sara Jensen Cecilie D. Lindholm Sandy E. H. Kjær Christina Pinborg Lars H. Bak Lasse K. 《Neurochemical research》2020,45(6):1247-1255
Neurochemical Research - Epilepsy is one of the most common chronic neurological conditions. Today, close to 30 different medications to prevent epileptic seizures are in use; yet, far from all... 相似文献
85.
Circular, repetitive DNA in yeast 总被引:8,自引:0,他引:8
86.
The dimensions of chromatids in vivo and in fixed preparations of human chromosomes from cultured lymphocytes were compared. The relative variation in diameter in relation to length was the same in both conditions, but the lengths of the fixed chromosomes were about twice that of the chromosomes in vivo. The last order of coiling was studied in fixed chromosomes and in prematurely condensed chromosomes. The pitch of the coils in the fixed chromosomes, 0.6 μm, was independent of haploid length in the interval 90–220 μm. A clear indication of a spiralization of an underlying fibre was found throughout the haploid length interval of the prematurely condensed chromosomes, which ranged from 130 μm to more than 350 μm. 相似文献
87.
88.
Experimental actinomycotic abscess in mice of several strains 总被引:2,自引:0,他引:2
89.
A small-scale, “no-use zone policy” has been implemented since 1992 at Eilat’s Coral Nature Reserve (Northern Red Sea). Six
years later, the status of this closed-to-the-public reef area was compared to two nearby open-to-the-public sites, by evaluating
populations of the scleractinian coral Stylophora pistillata in the strolling zone (0.5–1.5 m depth). Results from the open sites show that: (1) Live coral cover was three times lower
than at the closed site; (2) numbers of small colonies (recruits) were significantly higher than in the closed site, while
numbers of medium and large size colonies (geometric mean radius, rˉ>4.1 cm) per m2 were significantly lower; (3) maximum rˉ was almost half than that in the closed site (9.6 cm versus 16.7 cm); (4) average number of broken colonies was three times
higher than in the closed site; (5) significantly fewer colonies were partially dead. The latter result may reflect senescence
processes in the large colonies of the closed site. Although colony breakage is reduced, it appears that the “no-use zone”
policy is not sufficient for protecting small reef areas. The intense exploitation of Eilat’s coral reef by the tourist industry
requires’ in addition to the conventional protective measures, the initiation of novel management solutions such as reef restoration
by sexual and asexual recruits.
Accepted: 11 August 1999 相似文献
90.
Coral reef crisis in deep and shallow reefs: 30 years of constancy and change in reefs of Curacao and Bonaire 总被引:1,自引:0,他引:1
Coral reefs are thought to be in worldwide decline but available data are practically limited to reefs shallower than 25 m.
Zooxanthellate coral communities in deep reefs (30–40 m) are relatively unstudied. Our question is: what is happening in deep
reefs in terms of coral cover and coral mortality? We compare changes in species composition, coral mortality, and coral cover
at Caribbean (Curacao and Bonaire) deep (30–40 m) and shallow reefs (10–20 m) using long-term (1973–2002) data from permanent
photo quadrats. About 20 zooxanthellate coral species are common in the deep-reef communities, dominated by Agaricia sp., with coral cover up to 60%. In contrast with shallow reefs, there is no decrease in coral cover or number of coral colonies
in deep reefs over the last 30 years. In deep reefs, non-agaricid species are decreasing but agaricid domination will be interrupted
by natural catastrophic mortality such as deep coral bleaching and storms. Temperature is a vastly fluctuating variable in
the deep-reef environment with extremely low temperatures possibly related to deep-reef bleaching.
An erratum to this article can be found at 相似文献