Temporal variation in the coral reefs of the east coast of the inner gulf of Thailand

A series of permanent line transects established on fourteen reefs on the eastern seaboard of the Gulf of Thailand were monitored through a three-year period (1995- 1998) using a video transect method. Hierarchical cluster analysis shows three distinctive reef community types dominated by 1) Porites, 2) Acropora and 3) zoantharians. The reefs are developed under naturally turbid conditions and relatively low salinity due to the proximity of four major river outlets located in the uppermost area of the gulf. The number of Acroporid species on the reefs is positively correlated with distance from the major flver outlets. Eighty-seven species of scleractinian coral were found on the transects. Over the three-year period, the comparison of 1995-97-98 matched stations using Repeated Measures ANOV A reveals no significant time-dependent change in percent area cover of reef components except for an overall significant reduction in the faviid coral component. In the 1997-98 matched station comparison, statistical tests reveal significant increases in both Acropora and Porites components that translated into an overall increase in total living coral cover. These findings indicate that the overall environmental conditions have been favorable for coral growth. Outcompetition of massive corals by faster growing corals on several reefs also indicates conditions favorable for reef expansion. Growth of newlyformed Porites colonies over primary rock substrate and dead coral skeleton was presumably responsible for its rapid increase. Although these reefs are in an area of rapid industrialization and population growth, resultant anthropogenic effects have not yet stopped active coral accretion.

Flow injection analysis (FIA) determination of lead by hydride generation in banded coral skeletons /

A flow injection hydride generation direct current plasma atomic emission spectrometric (FI-HG-DCP-AES) method was developed for the determination of lead at ng.ml-l level. Potassium ferricyanide (K3Fe(CN)6) was used along with sodium tetrahydroborate(III) (NaBH4) to produce plumbane (PbH4) in an acid medium. The design of a gas-liquid separator (hydride generator) was tested and the parameters of the flow injection system were optimized to achieve a good detection limit and sample throughput. The technique developed gave a detection limit of 0.7 ng.ml-l(3ob). The precision at 20 ng.ml"* level was 1.6 % RSD with 1 1 measurements (n=l 1). Volume of sample loop was 500 |J.l. A sample throughput of 120 h"^ was achieved. The transition elements, Fe(II), FeOH), Cd(n), Co(II), Mn(n), Ni(II) and Zn(n) do not interfere in this method but 1 mg,l'l Cu(II) will suppress 50 % of the signal from a sample containing 20 ng.ml'l Pb. This method was successfully applied to determine lead in a calcium carbonate (CaC03) matrix of banded coral skeletons from Si-Chang Island in Thailand.

Characterizing Dynamic Optimization Benchmarks for the Comparison of Multi-Modal Tracking Algorithms

Population-based metaheuristics, such as particle swarm optimization (PSO), have been employed to solve many real-world optimization problems. Although it is of- ten sufficient to find a single solution to these problems, there does exist those cases where identifying multiple, diverse solutions can be beneficial or even required. Some of these problems are further complicated by a change in their objective function over time. This type of optimization is referred to as dynamic, multi-modal optimization. Algorithms which exploit multiple optima in a search space are identified as niching algorithms. Although numerous dynamic, niching algorithms have been developed, their performance is often measured solely on their ability to find a single, global optimum. Furthermore, the comparisons often use synthetic benchmarks whose landscape characteristics are generally limited and unknown. This thesis provides a landscape analysis of the dynamic benchmark functions commonly developed for multi-modal optimization. The benchmark analysis results reveal that the mechanisms responsible for dynamism in the current dynamic bench- marks do not significantly affect landscape features, thus suggesting a lack of representation for problems whose landscape features vary over time. This analysis is used in a comparison of current niching algorithms to identify the effects that specific landscape features have on niching performance. Two performance metrics are proposed to measure both the scalability and accuracy of the niching algorithms. The algorithm comparison results demonstrate the algorithms best suited for a variety of dynamic environments. This comparison also examines each of the algorithms in terms of their niching behaviours and analyzing the range and trade-off between scalability and accuracy when tuning the algorithms respective parameters. These results contribute to the understanding of current niching techniques as well as the problem features that ultimately dictate their success.