In the field, a 12-month survey was conducted at 6 stations spanning a wide salinity range in the Forth estuary, to investigate the influence of geographical, seasonal, tidal and physical environmental variables on community structure. Pump samples, in two net fractions (69 urn and 250 um) were collected on spring and neap tides, at high and low water over 9 complete or partial lunar cycles. The use of two concentric nets of differing mesh size extended the size range of specimens caught, and permitted the observation and enumeration of small plankters such as rotifers, copepod nauplii and early polychaete larvae. In early 1982, a clear temporal succession of rotifers> freshwater crustacea> Haranzelleria larvae> Eurytemora was observed. The data acquired on field distribution and abundance were analysed in a variety of ways. The most effective approach was found to be a combination of polythetic, divisive classfication (Twinspan) of sepcies data, followed by Multiple Discriminant Analysis (MDA) of the classification using geographical, seasonal, tidal and environmental data as the discriminating variables. The effects of geographical, seasonal and tidal variation were removed by analysing subsets of the data restricted to one state of a variable at a time; comparison of these restricted analyses with those performed on larger data sets revealed, however, that the relative influence of variables on community structure could be readily discerned even when all variables were considered together. Salinity and geographical position of station were clearly the dominant factors in explaining the species associations defined by classification analysis; organic suspended particulate material was closely associated with these, and temperature also but to a lesser degree. The influences of season and primary production were linked, and were orthogonal to the influence of the dominant variables. Classification analysis identified three main assemblages: the freshwater community; a low-salinity group comprising Eurytemora affinis and Neomysis integer; A neritic assemblage dominated by Acartia spp., Pseudocalanus and Oithona but also including Temora, Centropages and meroplanktonic larvae. Pseudocalanus and Oithona were more persistent than the other neritic taxa, and were more often found in samples of lower salinity and in the autumn and winter. Predation and development rate are two biological factors which directly influence the abundance and distribution of individual taxa. In the laboratory, studies were conducted a) on the rate of predation of Neomysis on Eurytemora and b) the effects of temperature and food availability on the development rate of Eurytemora. Predation rates of adult mysids on adult Eurytemora were estimated to range up to 170 prey/day at 500 prey/litre, and the functional response was adequately modelled by a Type II curve. It was experimentally , demonstrated that predation rates were not reduced in the dark or in the presence of detritus, and it is inferred from this that Neomysis relies on random foraging rather than on visual predation. Estimated predation rates were sufficiently high to suggest that Neomysis predation may, at some times of the year, have a significant effect on Eurytemora population size. Development rates in Eurytemora were not affected by food level, but were quantitatively related to temperature. Development was approximately isochronal, but the duration of the second naupliar instar was consistently longer than that of other instars, especially at lower temperatures. Total estimated development times ranged from 39 days at 8 deg.C to 15.25 days at 20 deg.C, with the effect of temperature being more marked at low temperatures than at high temperatures. The results of the development study were applied to field observations of instar body lengths, in order to estimate daily length increment for 9 dates in 1982. Field observations had indicated that, in contrast to many other studies, body size did not bear a simple inverse relationship to water temperature; whilst the smallest animals were observed during the spring bloom .and midsummer, the largest specimens were collected in September when water temperatures were still high. Highest growth rates were estimated for August (small animals) and September (large animals) ; winter animals, although similar in size to September specimens, had low estimated growth rates. The large size of specimens encountered in September suggests, when considered in conjunction with the low abundance at that time, that a switch may have occurred from investment in reproduction to an investment in somatic growth.

Thesis (M.S.)--Ohio University, March, 1985. / Title from PDF t.p.

Abstract Not Provided. / Thesis / Master of Science (MSc)

The population of shrimps from five stations in the estuary and one station in Firth of Forth were sampled for two years from January 1992 to investigate their population dynamics, reproductive biology and feeding ecology. Sampling was carried out at high water and low water, six times a year, by towing an Agassiz trawl, with the Forth River Purification Boards' research vessel, the 'Forth Ranger'. Two residents, Crangon crangon and Pandalus montagui, and a migrant species, Crangon ailmanni, were identified as the main three species of shrimps in the estuary and Firth of Forth. C. crangon was found throughout the estuary while P. montagui was confined to the lower reaches of the estuary. C. alimanni appeared in the estuary in October and left by June. In the Firth of Forth, P. montagui and C. alimanni were the dominant species. The breeding cycle commenced in October, and berried females were found by December/January for all species. Berried females of P. montagui, and both male and female C. alimanni, migrated from the estuary to deeper areas, never to return. C. crangon females with eggs ready to hatch, spent females and larvae all occurred in the estuary. The larvae were present in the estuary from April to October. Larvae of the other two species were not found in the estuary. All species fed mainly on polychaetes, followed by bivalves and crustaceans, which indicated a benthophagous feeding habit. The choice of food depended on the local availability of prey items, and the range of the particular shrimp species within the area; shrimps fed on prey which was abundant in their area of residence rather than moving elsewhere. The Forth Estuary is well utilized by the three species with little competition between them. Although a slow growth rate was observed in C. crangon, the mean condition factor indicated that the conditions in the Forth estuary were close to those normally required for shrimps. The Forth estuary shelters three species of shrimps, with populations, varying between 1992 and 1993, of 1.6-7.7 x 107 for C. crangon, 1.6-2.5 x 107 for P. montagui and 0.7-1.0 x 107 for C. alimanni. These three species contributed to the total annual shrimp production, which ranged from 5.59-17.93 tons at low water in the ratio 40:14:1. Both resident and migratory fish species benefit from this production because shrimps play a key role in the food web, forming the major link between the lower benthic invertebrates and predatory fish.

Thesis (Ph. D.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 190-201).

Thesis (Ph.D.) - University of St Andrews, February 2010.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnologico / Made available in DSpace on 2016-01-08T21:04:45Z (GMT). No. of bitstreams: 1 106543.pdf: 2939708 bytes, checksum: 2ae3c6db787cc2471f76532d891c4a52 (MD5) Previous issue date: 1996 / É implementado um algoritmo de controle Difuso em um sistema FORTH em assembler 80X86 para sistemas dedicados. É abordado o ambiente de desenvolvimento criado, o desenvolvimento de sistemas dedicados, controle Difuso, e sugerido uma aplicação real. São listados a implementação FORTH, o algoritmo implementado, e a simulação com os respectivos resultados.

No description available.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.