The condition at settlement of the western rock lobster pueruli presumably reflects both their energetic condition in reaching the near shore and subsequent recruitment into adult populations. In recruiting to the near shore the pueruli swim across the continental shelf where oceanographic conditions are complex and likely influence the success of recruitment. The results from the biochemical studies are interpreted in light of the oceanography off the coast of Western Australia. I investigated the nutritional condition of larval phyllosomata, post-larval puerulus and first instar post-pueruli juveniles of the spiny lobster, Panulirus cygnus, to determine energy use during the non-feeding transitional puerulus stage. Biochemical analyses of lipid, fatty acid (FA) and protein revealed that lipid, in particular phospholipids, is primarily used for energy during the nonfeeding puerulus stage. Monounsaturated FA showed the greatest decline with development, whereas the polyunsaturated FA showed a high degree of sparing, suggesting these FA are not used as a substrate for energy production. The knowledge gained on the biochemistry of energy use in P. cygnus was then used to investigate the spatial and temporal variability in the nutritional condition, in particular lipid condition, of puerulus collected at three near shore locations (Alkimos, Jurien Bay and Dongara) along the Western Australia coast, and one offshore location (Houtman Abrolhos Islands). The one offshore location was chosen as I hypothesised that arriving pueruli are likely to be in a better state of nutrition than those arriving at more coastal locations where the potential journey from offshore larval feeding grounds to the near shore is considerably greater. This element of my research showed lipid levels to be inversely related, generally, to shelf width but were variable, suggesting pueruli may travel complex trajectories to reach nearshore settlement. The lipid and FA composition of pueruli was also consistent with spatial and seasonal variation in Leeuwin Current and coastal productivity regimes.

No description available.

Pacific lamprey is a culturally valuable species to indigenous people, and has significant ecological importance in freshwater and marine ecosystems. Over the past several decades, constrictions in range and reductions in Pacific lamprey abundance have been observed in Western North America, and may be indicators of range-wide declines. In the face of declining populations, the U.S. Fish and Wildlife Service has partnered with tribal, state, federal, and local entities to implement a regional Pacific lamprey conservation agreement aimed at reducing threats to Pacific lamprey and improving their habitats and population status. Research needs identified in the conservation agreement include assessing larval Pacific lamprey occupancy and distribution, habitat requirements, and the limiting factors of larval distribution in the freshwater ecosystem. As part of the effort to address these knowledge gaps, we investigated the potential for larval lampreys to occur in tidally-influenced estuarine environments. Research of this type may be valuable for future conservation, management or recovery efforts of Pacific lamprey throughout its range. We employed a two-phased approach, consisting of laboratory and field components to address our aims. We first conducted a series of controlled laboratory experiments to evaluate osmotic stress tolerance and osmoregulatory status of larval Pacific lamprey exposed to a range of (1) fixed salinity in various dilutions of saltwater and (2) oscillating salinity treatments designed to simulate tidal activity. Tolerance was assessed by monitoring and comparing survival of larvae in various treatments through 96 h. Osmoregulatory status was assessed by quantifying and comparing total body water content, plasma osmolality, and plasma cation (i.e., sodium) concentrations among larvae surviving various treatments. In fixed salinity experiments, 100% survival was observed in 0‰, 6‰, 8‰ and 10‰ through 96 h, while 0% survival was observed through 48 h in 12‰, 30 h in 15‰, and 12 h in 25‰ and 35‰. In oscillating salinity experiments, on the other hand, a significant increase in survival (100%) was observed through 96 h in treatments that oscillated between 12‰ and 0‰ (freshwater) at about 6 h intervals versus fixed 12‰ salinity experiments. A significant increase in survival also occurred in oscillating 15‰ treatments (60%) versus fixed 15‰ through 96 h. Linear regression analysis indicated higher environmental salinity in laboratory experiments was significantly related to increases in plasma osmolality and plasma sodium (the most abundant osmotically active plasma cation) concentrations, and concurrent decreases in total body water content among larvae that survived various treatments. Tidal oscillations in salinity appeared to temper the desiccating effects of salinity, as changes in body water content and sodium ion concentration were less abrupt than fixed salinity treatments. These results suggest larvae cannot osmoregulate in hyperosmotic environments, but are able to tolerate some fixed and oscillating hyperosmotic salinity exposure. Consequently, larvae may be able to occur in certain areas of estuaries, such as oligohaline habitats that are characterized by low levels of salinity. Experimental results were used, in part, to guide larval sampling in a tidally-influenced habitat. Occurrence of larval Pacific lamprey and Lampetra spp. (western brook and river lampreys) was subsequently investigated across a gradient of salinity in Ellsworth Creek (Pacific County, Washington) by electrofishing. Larval Pacific and Lampetra spp. were detected within an approximately 300 m long tidally-influenced segment of the study area. Salinity monitoring was conducted in six tidally-influenced reaches where larvae were detected for up to 14 d following electrofishing. Maximum tidal cycle salinity exceeded 15 ppt during 52% to 80% of tidal cycles within tidally-influenced reaches where larvae were detected. These results suggest potential for larval lamprey to occur in certain portions of tidal estuaries. However, long-term residence of larvae in tidally-influenced habitats and whether larvae are able to subsequently survive, grow, transform, and out-migrate is not known and requires further study. Given the potential for tidally-influenced habitats to be occupied by larvae, assessments of larval occurrence in other areas, such as the lower Columbia River, may be warranted. Knowledge of larval lamprey distribution in estuarine environments may be valuable for habitat restoration, and mitigating potential impacts from dredging and other human disturbances.

Ostrea lurida Carpenter 1864 is the only native oyster on the western North American coast, but it is functionally extinct in most of its historic range. Knowledge of environmental tolerances during larval development of O. lurida is minimal, which limits recovery strategies for this listed “species of special concern” (Species At Risk Act). The effects of rearing temperature (13, 17, 21°C), salinity (11, 15, 21, 24, 30, 31 psu) and food concentration (5x103, 1x104 and 5x104 algal cells/ml) on larval growth and development were investigated. Larvae were obtained from laboratory conditioned adults from Ladysmith Harbour, and the Gorge Waterway on Vancouver Island BC. At low temperature (13°C), salinity (15 psu) and food concentration (5x103 algal cells/ml) larvae did not grow or develop. Higher temperature, salinity and food concentration increased growth and developmental rates. Larvae reared at higher food densities and salinities, but not higher temperature, were larger when eyespots differentiated. / Graduate

No description available.

published_or_final_version / Biological Sciences / Master / Master of Philosophy

The study of larvae, their behaviour & physiology has gathered momentum in recent years due to the development of improved techniques of rearing during the past decade. Many marine larvae have been successfully reared in the laboratory (Shelbourne, 1964; Schumann, 1967; Blaxter, 1968,1969; Houde & Palko, 1970; Futch & Detwyler, 1970; Lasker, Feder, Theilacker & May, 1970). Fish larvae, in particular those of most marine species form an important tool for research in that at hatching they only possess the rudiments of most organs. Thus they are ideal material for ontogenetical studies. Although the respiratory mechanisms of adult fish have been the subject of a great deal of investigation from the point of view of gas exchange (see Randall 1970) gill structure (Hughes, 1966; Hughes & Grimstone, 1965; Newstead, 1967; to name a few) and dimensions (see Muir, 1969) gill ventilation and perfusion (see Shelton, 1970) circulatory systems (see Randall, 1970) bioenergetics, (see Brett, 1970) the respiratory systems of larvae have not been investigated in any great detail. Apart from a few studies on oxygen uptake (see Blaxter, 1969) and Harder (1954) on the development of branchial elements, no detailed study of the development of respiratory mechanisms have been made in marine fish larvae. The purpose of this study was to investigate the development of respiration in two species of marine larvae viz. the herring (Clupea harengus L.) and the plaice (Pleuronectes plates sa L.) These two species are well separated taxonomically and both adults and young have very different life histories. Herring lay demersal eggs, the plaice pelagic ones. The yolk-sac larvae of both species are planktonic, later feeding on diatoms and copepod nauplii and much later copepods. Adult herring are pelagic, living in mid water as juveniles and moving into deeper water with age, ranging from offshore to about 200m. They perform migrations partly caused by the distribution and density of food organisms. In contrast to this plaice at metamorphosis show an interesting asymmetry in that one eye migrates over the head and comes to lie against its opposite number. At this stage pelagic life ceases and the young fish assumes a bottom-living existence. Other features associated with asymmetry are secondary to the migration of the eye and follow on from the adoption of the benthic mode of life. They range from the shoreline when young to lOOOm feeding on bottom living organisms. During development the mechanism of respiration changes from a cutaneous one to gill respiration typical of the adult form. There is apparently no respiratory pigment in the early stages but the blood becomes pink at metamorphosis. The problem was approached from a morphological and a physiological viewpoint. The main parts of the study are as follows. (1) The survival times in water of low oxygen concentrations. (2) The oxygen uptake at normal oxygen concentrations. (3) The oxygen uptake at low oxygen concentrations. (4) Measurement of the body surface area as well as the gill area available for respiration. (5) The appearance of haemoglobin and its quantitative measurement.

Coastal populations of perch (Perca fluviatilis) in the Baltic Sea has declined substantially the last decades while the populations of three-spined sticklebacks (Gasterosteus aculeatus) has increased rapidly during the same time period. Earlier studies have suggested that predation on perch larvae and or competition from sticklebacks are the causes behind the decline in perch. To test if predation from sticklebacks commonly occur on perch larvae as well as provide data on stickleback diets in general, diets of sticklebacks were examined by looking at the stomach content of collected samples of sticklebacks from different bays along the Swedish and Finnish coast. Results showed no evidence of stickleback predation on perch larvae as no perch larvae were found in any of the examined stomachs.  Three-spined sticklebacks generally had the same diet in all studied bays consisting mainly of Chironomidae and Asellus aquaticus. The diet results suggest that competition between perch larvae and sticklebacks is minor if any due to low proportions of zooplankton found in the stomachs of the sticklebacks while zooplankton is the main food source for perch larvae. In bays where three spined sticklebacks were found with nine-spined sticklebacks they generally had similar diets. Still, due to a larger size and gape size of three-spined sticklebacks they fed more on larger prey like Asellus aquaticus while nine-spined sticklebacks contained smaller prey such as benthic cladocerans. Due to few samples from bays where sticklebacks were found together with perch larvae, no conclusion regarding predation on larvae as the main the mechanism for declines in coastal perch population can be drawn from the results in this study.

Thesis (MTech (Oceanography))--Cape Peninsula University of Technology, 2016. / Similarities in marine fauna found off the coasts of southern Madagascar and KwaZulu-Natal (KZN, South Africa) led to the development of the “Suitcase Project”, with the aim of establishing whether eddies that form off southern Madagascar may package and transport biological material, as if in a suitcase, across the Mozambique Channel. In pursuit of this question, sampling was conducted on the southern Madagascan shelf and along a transect across a cyclonic eddy which originated off the southern tip of Madagascar, between the 15th and 23rd of July 2013. Bongo nets (300 and 500 μm-mesh) and a neuston net (900 μm-mesh) were used to collect zooplankton within the upper 200 m and at the surface, respectively. Samples were sorted for meroplankton (larval stages of fish and benthic invertebrates) under a stereo microscope, particularly seeking species known to be common to both the east coasts of Madagascar and South Africa and, thus potential indicators of connectivity between these regions. Larvae of crabs, rock lobster, and fish were used for DNA barcoding. Zooplankton biovolume and abundance were compared between the eddy core, eddy periphery and outer regions of the eddy, as well as stations from the Madagascan shelf. Mean neuston biovolume on the Madagascan (0.08 mL m-3) was not significantly higher than that in the eddy (0.06 mL m-3). Mean bongo biovolume in the upper 200 m was much higher on the Madagascan shelf (0.62 mL m-3) than in the eddy (0.16 mL m-3) although only 2 stations were sampled on the shelf. Highest biovolume in the eddy was recorded in the west eddy zone (0.25 mL m-3) and west outer zone (0.23 mL m-3), which was not statistically significantly higher than the eddy core (0.12 mL m-3) and east eddy zone (0.17 mL m-3). Meroplankton was comprised of coastal origin taxa and was most abundant on the shelf and in the eddy perimeters. Larval goat-fish, Parupeneus fraserorum was identified, a newly described mullid, and has been recorded on both the coasts of Madagascar and KZN, SA. Larvae of coastal invertebrate species identified, include the squat lobster Allogalathea elegans and camel shrimp Rhynchocinetes durbanensis. Other larval fish identified, but not found in high abundance include the families of reef associated fishes, for example: Apogonidae, Labridae, Pomacentridae, Priacanthidae, Serranidae and Sparidae. Higher zooplankton biovolumes, larval abundances and reef-associated larval assemblages found on the Madagascan shelf and in the periphery of the cyclonic eddy compared to the core in this study provide support for the suitcase hypothesis that planktonic organisms are entrained within eddies as they propagate south-westwards of the Madagascan shelf. However, further studies are required to determine whether planktonic larvae are able to cross the Mozambique Channel and reach the KZN coast in time to settle.

Typescript (photocopy). / Digitized by Kansas Correctional Industries