The decrease in wild fish stocks has led to a search for novel feed sources to supply the aquaculture industry. Polychaetes have recently been identified as suitable feed ingredients due to their favourable nutritional composition, especially their lipid profile which is high in unsaturated fatty acids. As ragworm farms have started to develop, there has been a need to understand and improve rearing techniques, in particular the dietary requirements and nutritional profile of the ragworm. In this thesis, research was focused on the king ragworm. Nereis virens. The protein and energy requirements were identified by increasing inclusion levels of nutrients in the diet as well as manipulating feed rations from starvation to satiation. Weight gain, survival, ingested feed as well as protein and energy retention efficiencies were evaluated. Results demonstrated that N. virens gained a proportional amount of nutrient in relation to the amount ingested up to a critical amount when gain either stagnated or decreased. A pattern of nutrient retention and maintenance requirements for different weight classes were calculated. This data was then used for bioenergetic modelling to calculate nutrient requirements using the equation: Requirement: a x BW (g) + c x growth The energy maintenance requirement was found to be 18 J g-1 worm day-1; for protein, the requirement was 0.19 mg g-1 worm day-1. The predicted weight gain (g) for a worm of any given size (g) was y = 0.015g1.106. The total nutrient requirement is the sum of maintenance and growth, including the constant c which is the cost of nutrient deposition. Alternative feed sources were also investigated to observe the extent at which N. virens can utilize novel sources and their abilities to preserve or convert highly unsaturated fatty acids such as EPA and DHA. Results showed a high adaptability to terrestrial animal or vegetable based feed sources but an inability to convert shorter chain or n-6 fatty acids when fed non-marine based feeds. There may however be potential for N. virens to utilize other feed sources from its natural environment to supplement n-3 HUFA content.

Made available in DSpace on 2014-06-12T15:07:16Z (GMT). No. of bitstreams: 2 arquivo3018_1.pdf: 1893063 bytes, checksum: 85f3900d7bc96891b2e542ad501df2ff (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O objetivo deste trabalho foi conhecer a estrutura de comunidade da meiofauna de substrato inconsolidado em ambiente recifal, suas interações com fatores ambientais e relacionála com a proteção ambiental e a influência do recife sobre a mesma. Foram feitas coletas nos meses de abril e setembro de 2008, dentro e fora de uma área de proteção ambiental. As duas áreas são compostas por areia grossa, com baixo teor de matéria orgânica. Foram encontrados 15 táxons da meiofauna, 56 gêneros de Nematoda e 18 gêneros de Polychaeta. A meiofauna apresentou diversidade foi maior na área protegida e na área mais afastada do recife, sendo estes resultados significativos. Os Nematoda não apresentaram diferença significativa de diversidade entre as áreas, tanto em relação a proteção quanto em relação ao afastatamento do recife. Os Polychaeta também não apresentou diferença significativa na diversidade entre as áreas comparadas, apesar da riqueza ser significativamente maior na área mais afastada do recife. As diferenças encontradas em relação aos parâmetros sedimentológicos e em relação aos parâmetros de estrutura biológica foram pequenas, indicando que algum fator foi subestimado teria influencia maior que os parâmetros aferidos. Ainda assim a influencia do recife sobre a comunidade foi claramente constatada, existindo ainda a necessidade de mais estudos, tanto em termos de variabilidade espacial, como em relação aos estudos de comunidade e os efeitos de cadeia sobre elas

Magister Scientiae - MSc / This study examined the relationship between sediment structure and infaunal polychaete communities off the southern coast of Namibia from two separate sets of data, and a total of ninety-two samples. It also examined whether a selected group of organisms (polychaetes) could provide the same level of information regarding community structure, as the entire fauna, at a number of taxonomic resolutions. A total of 44 samples were collected by De Beers Marine (Pty) Ltd in 1999 off the southern coast of Luderitz from depths between 40 m and 90 m. The sediments varied from soft muds (45 μm) to gravel (> 710 μm). Forty-three morpho species of polychaetes were distinguished, of which only 28 known species of polychaetes could be positively identified, which suggests that more information on the diversity of polychaetes in the region is needed. The fauna was dominated by species in the Ampharetidae, Capitellidae, Maldanidae, Spionidae, Lumbrineridae, Flabilligeridae, Nephtyidae, Pectinariidae and Onuphidae. Multi-variate analyses using PRIMER indicated that communities were structured by mud (45 μm) and very fine sand (45 - 63 μm) and gravel (> 710 μm). Mud and gravel, although selected by the BIOENV procedure as accounting for some of the variation in the polychaete assemblage structure, explained no more of the data (in combination) than did mud on its own. As similar clustering of samples was observed when the data were analysed at both the family and species-level, suggesting that the same level of information was being gained at the two taxonomic levels. The results of the BIOENV analyses were also broadly similar for both taxonomic levels of analyses, in terms of both the proportion of the variation in assemblage structure explained by the selected environmental variables and the choice of selected variables. These results suggested the information gathered at the polychaete family-level were equally clear when they are collected at the family-level for the entire infauna. The use of polychaetes (to the family-level) as surrogates, using sediment structure and depth was independently investigated from a total of 48 samples that were collected by De Beers Marine (Pty) Ltd in 2001, from depths between 20 m and 110 m. The sediment varied from mud (< 63 μm) to gravel (> 710 μm). Twenty-two families of polychaetes were distinguished, the fauna showing an abundance of Capitellidae, Cirratulidae, Flabilligeridae, Lumbrineridae, Magelonidae, Nephtyidae, Paraonidae, Pilargiidae, Onuphidae, Syllidae and Spionidae. Striking differences were found in the amount of variation accounted for in the biological samples by the environmental data. Interestingly, depth in combination with a particular sediment size fraction featured very strongly in structuring both sets of communities. The biotic patterns in the family-level total infauna were not similar for the polychaetes (at the same taxonomic resolution). These results suggested that one group of organisms (polychaetes at the family-level) may not be useful as a proxy for the entire infauna (at the family-level). Because of the contrasting results that were obtained in 1999 and 2001, the biological data in 1999 were pooled and the environmental data (sediment size fractions) were adjusted accordingly (i.e. some of the differences in the results may reflect differences in the methods used to collect data). Consequently the results still did not adequately explain why there was a low level of similarity between the total infauna and polychaete family-level biotic patterns in 2001. It seemed that pooled data improved the taxonomic resolution (amount of variation obtained), but when the sediment size fraction data were adjusted, it lowered the amount of taxonomic resolution. The results suggest that comprehensive and standardized samples must be collected to fully understand the relationships between biotic patterns and environmental variables. This is potentially important given the costs involved and the potentially long lasting value of the material collected. These sediment and biological samples were collected by industry (for baseline biological monitoring in the mining industry, and not academic purposes). Proper protocols need to be established which allow industry-related monitoring programs to make a real contribution to our understanding of the biodiversity and ecology of the area. / South Africa

The family Maldanidae is a group of sedentary polychaetes having a cylindrical body with elongate, but relatively few segments. The prostomium has a dorsal pair of nuchal organs and may have eye-spots ventrally; true appendages are absent. The mouth opens ventrally on the peristomium and has an extrusible sacciform proboscis. The pygidium may be plate-shaped, funnel shaped with an internal cone, or simply cone-shaped. All maldanids inhabit tubes of sand or mud, and subject to the limitations and advantages of this habjtat.

Pygospio elegans Claparede (1863) is a relatively small, inconspicuous intertidal Spionid polychaete (10 to 15 mm in length) having approximately 50 to 60 body segments. The species occurs in high intertidal sand flats along the central California coast. Pygospio elegans is one of three species of the genus Pygospio, with the other being, P. california Hartman (1936) which is found only along the central California coast and P. dubia Munro (1930), from Antarctic seas. P. elegans is the most cosmopolitan of the three species (Clay, 1967; Light, 1978). The species has been recorded from both sides of the Atlantic Ocean; in the western part from Nova Scotia to Massachusetts and in Europe from the Mediterranean to the Baltic, Norwegian Archipelago and Barents Sea. It has been cited from South Africa, in the North Pacific Ocean, from the Sea of Okhotsk and Prudhoe Bay, Alaska. As a successful cosmopolitan species, P. elegans has demonstrated its ability to accomplish two objectives: (1) it has colonized new habitats and (2) it has been to withstand perturbations of its local habitat and become, in some cases numerically dominant. The purpose of this study was to investigate the ways and means by which P. elegans has been able to accomplish these objectives.

A dominant organism on intertidal Pacific Coast sandflats is the lophophorate Phoronopsis viridis Hilton. This suspension feeder builds a stiff, sandy tube, 3 mm wide and up to 20 cm long and usually lying within 6 cm of the surface (Johnson 1967a). Phoronopsis viridis is found over large areas and tidal ranges of sandflats in aggregate densities of over 21,000 phoronids per m2 (Ronan 1978). On Lawson's Flat, the location of the present study, the areas of highest density of P. viridis have been known to persist for over 20 years (Steven Obrebski, personal communication). The factors accounting for the persistence of these dense phoronid populations have not been studied although four hypotheses have been proposed (see Ronan 1975, 1978). These are: 1) dense clusters of adult phoronids increase the probability of successful gamete fertilization; 2) high densities of phoronids stablize the sediment, thus limiting the movement of large burrowing in fauna that are potentially destructive to phoronids (Ronan 1975); 3) a dense canopy of lophophores slows currents over the sediment surface, increasing the deposition of food items; and 4) clustering limits the effects of predation. The sudden retraction of a lophophore in response to a disturbance results in withdrawal of neighboring phoronids in the area of the disturbance (Ronan 1978). In order to evaluate the adaptive significance of population persistence it is crucial to understand the mechanism by which dense populations :persist. Therefore the purpose of this study is not to assess the adaptive significance of clustering, but rather to determine what mechanisms might explain the persistence of dense phoronid populations.. Consequently, this study is more applicable to an "ecological" time scale than an *evolutionary" one. In this study the population dynamics and recruitment pattern of P. viridis is described with reference to the mechanism which enables persistence of dense phoronid areas. In addition, the effects of food abundance and the reworking activity of the surface deposit feeder, Axiothella rubrocincta Johnson, a maldanid polychaete, on P. viridis density and recruitment are measured.

In the coves and crevices at Natural Bridges State Park, Santa Cruz, California, one can find large masses of worm tubes constructed of sand. These tube masses often cover areas of several square feet. The tubes are usually straight and packed together in large masses. The individual tubes are about one-fourth of an inch in diameter and may be up to two and one-half feet long. The worm responsible for these masses of tubes is a small polychaete, Phragmatopoma californica. Very little work has been done on the natural history of local sabellarlids. It is therefore the purpose of this paper to present data pertaining to the natural history of the sabellarlid polychaete, Phragmatopoma california. Such data will include notes of the reproduction, feeding, tube building habits, and associated biota of this polychaete as well as a description of its digestive system.

Chone mollis occurs in large numbers in Tomales Bay and is an ecologically important infaunal member of the bay community. As with most marine communities, very little work has been done with individual species of the community. The present study of C. mollis is a contribution towards an understanding of the community as an ecological unit. This study investigates the structure and function of the tube; tube-building habits; burrowing and locomotion; external anatomy; feeding; and internal anatomy of the muscular, skeletal, vascular, excretory, reproductive, and alimentary systems of C. mollis.

No description available.

No description available.