The vulnerability to pollution and hydrochemical variation of eleven springs (catchments) in the karst lowlands of the west of Ireland

The vulnerability to pollution and hydrochemical variation of groundwater in the mid-west karstic lowlands of Ireland were investigated from October 1992 to September 1993, as part of an EU STRIDE project at Sligo Regional Technical College. Eleven springs were studied in the three local authority areas of Co. Galway, Co. Mayo, and Co. Roscommon. Nine of the springs drain locally or regionally important karstic aquifers and two drain locally important sand and gravel aquifers. The maximum average daily discharge of any of the springs was 16,000 m3/day. Determination of the vulnerability of groundwater to pollution relies heavily on an examination of subsoil deposits in an area since they can act as a protecting or filtering layer over groundwater. Within aquifers/spring catchments, chemical reactions such as adsorption, solution-precipitation or acid-base reactions occur and modify the hydrochemistry of groundwater (Lloyd and Heathcote, 1985). The hydrochemical processes) that predominate depend cm the mineralogy of the aquifer, the hydrogeological environment, the overlying subsoils, and the history of groundwater movement. The aim of this MSc research thesis was to investigate the hydrochemical variation of spring outflow and to assess the relationship between these variations and the intrinsic vulnerability of the springs and their catchments. If such a relationship can be quantified, then it is hoped that the hydrochemical variation of a spring may indicate the vulnerability of a spring catchment without the need for determining it by field mapping. Such a method would be invaluable to any of the three local authorities since they would be able to prioritise sources that are most at risk from pollution, using simple techniques of chemical sampling, and statistical analysis. For each spring a detailed geological, hydrogeological and hydrochemical study was carried out. Individual catchment areas were determined with a water balance/budget and groundwater tracing. The subsoils geology for each spring catchment were mapped at the 1:10,560 scale and digitised to the 1:25,000 scale with AutoCad™ and Arclnfo™. The vulnerability of each spring was determined using the Geological Survey's vulnerability guidelines. Field measurements and laboratory based chemistry analyses of the springs were undertaken by personnel from both the EPA Regional Laboratory in Castlebar, Co. Mayo, and the Environment Section of Roscommon Co. Council. Electrical conductivity and temperature (°C) were sampled fortnightly, in the field, using a WTW microprocessor conductivity meter. A percentage (%) vulnerability was applied to each spring in order to indicate the areal extent of the four main classes of vulnerability (Extreme, High, Moderate, and Low) which occurred within the confines of each spring catchment. Hydrochemical variation for the springs were presented as the coefficient of variation of electrical conductivity. The results of this study show that a clear relationship exists between the degree of vulnerability of each catchment area as defined by the subsoil cover and the coefficient of variation of EC, with the coefficient of variation increasing as the vulnerability increases. The coefficient of variation of electrical conductivity is considered to be a parameter that gives a good general reflection of the degree of vulnerability occurring in a spring catchment in Ireland's karstic lowlands.

Defining habitat characteristics influencing the distribution, density and growth of Plaice (Pleuronectes Platessa) and Dab (Limanda Limanda) on west of Ireland nursery grounds

Plaice (Pleuronectes platessa, L.) and dab (Limanda limanda, L.) are among the most abundant flatfishes in the north-eastern Atlantic region and the dominant species in shallow coastal nursery grounds. With increasing pressures on commercial flatfish stocks in combination with changing coastal environments, better knowledge of population dynamics during all life stages is needed to evaluate variability in year-class strength and recruitment to the fishery. The aim of this research was to investigate the complex interplay of biotic and abiotic habitat components influencing the distribution, density and growth of plaice and dab during the vulnerable juvenile life stage and to gain insight in spatial and temporal differences in nursery habitat quality along the west coast of Ireland. Intraspecific variability in plaice diet was observed at different spatial scales and showed a link with condition, recent growth and morphology. This highlights the effect of food availability on habitat quality and the need to consider small scale variation when attempting to link habitat quality to feeding, growth and condition of juvenile flatfish. There was evidence of trophic, spatial and temporal resource partitioning between juvenile plaice and dab allowing the co-existence of morphologically similar species in nursery grounds. In the limited survey years there was no evidence that the carrying capacity of the studied nursery grounds was reached but spatial and interannual variations in fish growth indicated fluctuating environments in terms of food availability, predator densities, sediment features and physico-chemical conditions. Predation was the most important factor affecting habitat quality for juvenile plaice and dab with crab densities negatively correlated to fish condition whereas shrimp densities were negatively associated with densities of small-sized juveniles in spring. A comparison of proxies for fish growth showed the advantage of Fulton’s K for routine use whereas RNA:DNA ratios proved less powerful when short-term environmental fluctuations are lacking. This study illustrated how distinct sets of habitat features can drive spatial variation in density and condition of juvenile flatfish highlighting the value of studying both variables when modeling habitat requirements. The habitat models generated in this study also provide a powerful tool to predict potential climate and anthropogenic impacts on the distribution and condition of juveniles in flatfish nurseries. The need for effective coastal zone management was emphasized to ensure a sustainable use of coastal resources and successful flatfish recruitment to the fishery.

Population dynamics of O-group plaice, Pleuronectes platessa L., on sandy beach nursery grounds in Galway Bay, the West Coast of Ireland, 2002 to 2006.

The recruitment of 0-group plaice to sandy beach nursery grounds in Galway Bay was examined, using a Riley push-net, from February to June in 2005 and 2006. Sampling was carried out every two weeks on spring tides. Three beaches were sampled, Ballyloughan, Silverstrand and Glann na Ri. Archived 0-group plaice, for Ballyloughan and Silverstrand, from 2004, were processed. Results were compared to findings from a previous study carried out in 2002 and 2003 (Allen 2004). Otolith microstructure analysis was used to determine hatching dates, larval duration, settlement dates, post-larval age and daily growth rates of 0-group plaice in April and May 2005. Results were compared to a previous study (Allen 2004). Hatching dates in Galway Bay ranged from late January to early April in 2005. No significant difference in hatching dates was observed between years or between beaches sampled. Larval duration of 0-group plaice in Galway Bay ranged from 21 to 45 days for fish sampled in April and May 2005. No significant difference was observed in larval age between beaches sampled in Galway Bay or between years in April 2003 and 2005. A significant difference was observed between larval age and years in May 2003 and 2005, however no significant difference was observed between beaches. Settlement timing was calculated using push-net data and otolith microstructure analysis. Settlement of 0-group plaice in Galway Bay generally started in early March and finished in May. Settlement patterns, calculated using otolith microstructure analysis, in 2003 and 2005, were not significantly different to one another. There was also no difference in settlement patterns between the beaches sampled. Results from the present study showed no spatial difference in the pelagic life cycle stages of fish caught in April and May 2003 and 2005.

The design and development of heat extraction technologies for the utilisation of compost thermal energy

A composting Heat Extraction Unit (HEU) was designed to utilise waste heat from decaying organic matter for a variety of heating application The aim was to construct an insulated small scale, sealed, organic matter filled container. In this vessel a process fluid within embedded pipes would absorb thermal energy from the hot compost and transport it to an external heat exchanger. Experiments were conducted on the constituent parts and the final design comprised of a 2046 litre container insulated with polyurethane foam and kingspan with two arrays of qualpex piping embedded in the compost to extract heat. The thermal energy was used in horticultural trials by heating polytunnels using a radiator system during a winter/spring period. The compost derived energy was compared with conventional and renewable energy in the form of an electric fan heater and solar panel. The compost derived energy was able to raise polytunnel temperatures to 2-3°C above the control, with the solar panel contributing no thermal energy during the winter trial and the electric heater the most efficient maintaining temperature at its preset temperature of 10°C. Plants that were cultivated as performance indicators showed no significant difference in growth rates between the heat sources. A follow on experiment conducted using special growing mats for distributing compost thermal energy directly under the plants (Radish, Cabbage, Spinach and Lettuce) displayed more successful growth patterns than those in the control. The compost HEU was also used for more traditional space heating and hot water heating applications. A test space was successfully heated over two trials with varying insulation levels. Maximum internal temperature increases of 7°C and 13°C were recorded for building U-values of 1.6 and 0.53 W/m2K respectively using the HEU. The HEU successfully heated a 60 litre hot water cylinder for 32 days with maximum water temperature increases of 36.5°C recorded. Total energy recovered from the 435 Kg of compost within the HEU during the polytunnel growth trial was 76 kWh which is 3 kWh/day for the 25 days when the HEU was activated. With a mean coefficient of performance level of 6.8 calculated for the HEU the technology is energy efficient. Therefore the compost HEU developed here could be a useful renewable energy technology particularly for small scale rural dwellers and growers with access to significant quantities of organic matter

Nutritional composition, quality and spoilage capacity of orange roughy (Hoplostethus atlanticus) from the North East Atlantic

The nutritional composition o f orange roughy (collected from the Northeast Atlantic near the Rockall Trough) was studied on a seasonal basis. In addition samples were aged and stability assessed. Protein levels (16.68-16.21% w/w) were found to be slightly higher than those recorded for the N ew Zealand species o f orange roughy and compared favourably with protein values for fish muscle in general. Statistically results show a significant seasonal variation with no variation from fish to fish or in the location within the fish. Lipid content (3.6-4.5% w/w) was found to be much lower than that recorded for New Zealand. As with protein statistically results show a significant seasonal variation and no variation from fish to fish or in the location within the fish. Moisture levels (77.3_79.6%w/w) compared favourably with values obtained from other studies. Again statistically results show a significant seasonal variation with no variation from fish to fish or within the fish. Iodine values (74.63-79.54) indicate the likely presence o f a high level o f mono unsaturated fatty acids. Statistically results show no significant seasonal variation and no sample variation or variation within fish. Thin layer chromatography o f the extracted fat showed the major type to be wax esters with a much lower amount o f triglycerides and smaller amounts of polar lipids, free sterols and free fatty acids. Total fatty acid composition was found to be very similar to that recorded from other studies and showed that most o f the oils extracted from the fish muscle contained a high percentage o f mono unsaturates namely 16:1,18:1, 20:1 and 22:1 (85.63 - 91.14% ) with 16:1 present in the smallest amounts and 18:1 the major one. The only saturated fatty M.Sc. in Biochemistry III Nutritional Composition, Quality and Spoilage Capacity of Specific Deep Sea Fish acids present in significant quantities were 14:0, 16:0 and 18:0, the total varied from a seasonal average high o f 4.05 % to an average low o f 2.27%. The polyunsaturated fatty acids linoleic and arachidonic acid were present in small quantities varying in total from 0.89% to 1.50%. Docosapentaenoic acid (D P A ) was found only in trace quantities in spring, autumn and winter samples and undetected in summer. Levels o f Eicosapentaenoic acid (EPA ) and Docosahexaenoic acid (D H A ) were also found in very low percentages and varied on a seasonal basis with average values ranging from 0.41% in summer to 1.03 % in autumn for EPA and from 1.44 % in summer to3.20 % in autumn for D H A . Again statistically results show a significant seasonal variation with no variation from fish to fish or location within the fish. Levels o f freshness were measured using the Thiobarbituric acid (T B A ), Total volatile base nitrogen (T V B -N ) and Trimethylamine (T M A ) techniques. The quality o f the fish upon arrival was excellent and well below legal/acceptable lim its.T V B -N values ranged from 6.88-8.91 mg/lOOg and T M A values from 4.82-6.46 mg/lOOg Values for T B A ranged from 0.18-0.35 mg Malonaldehyde/kg fish. The summer values were higher than the other seasons. Seasonal variation was significant for all methods with no variation from fish to fish or within the fish. Fish aged at +4°C in air did not exceed the T V B N lim it o f 35mg/100g until day 6 whereas the T V B N lim it was extended to 8 days for fish aged at +4°C in vacuum. However the T M A lim it o f 12mg/100g was reached on day 4 for fish stored at +4°C in air and on day 5 for vacuum packed samples stored at +4°C . Fish stored at -5°C in air and vacuum packed did not reach the T V B N lim it until day 61 but the T M A limit was reached on day 24 for fish stored at -5°C in air and was extended to 31 days for vacuum packed fish stored at-5°C. Prolonged storage at -18°C caused some deterioration o f the frozen fish muscle. Upon thawing the shelf life o f fish stored for 12 months was much shorter than that stored for 6 M.Sc. in Biochemistry IV Nutritional Composition, Quality and Spoilage Capacity of Specific Deep Sea Fish months. This in turn deteriorated faster than fresh fish held at refridgeration temperature in air. Orange roughy were found to be a good source of protein with moisture levels similar to that o f other fish. They were o f medium fat content but have a very poor content o f the essential omega 3 and omega 6 fatty acids. Orange roughy can be stored at -18°C but its subsequent refridgerated shelf life will be shorter than that o f unfrozen orange roughy stored at refridgeration temperature. Orange roughy are a very important part o f the ecosystem. Their composition is less nutritionally beneficial than more readily available fish for human consumption and therefore should not be fished at all

Ireland’s understudied flatfish: reproduction, age and growth of the dab Limanda limanda (L.) in Irish coastal waters

In Ireland, although flatfish form a valuable fishery, little is known about the smallest, the dab Limanda limanda. In this study, a variety of parameters of reproductive development, including ovarian phase description, gonadosomatic index (GSI), hepatosomatic index (HSI), relative condition (Kn) and oocyte size were analysed to provide information on the dab’s reproductive cycle and spawning periods. Sampling were collected monthly over an 18-month period using bottom trawls of the Irish coastline. A six phase macroscopic guide was developed for both sexes of dab, and verified using histology. In comparisons of macroscopic and microscopic phases, there was high agreement in the proposed female guide (86%), with males demonstratively lower (62%). No significant bias was observed between the the two reproductive methods. When the male macroscopic guide was examined, misclassification was high in phase 5 and phase 5 (41%), with 96% of misclassification occurring in adjacent phases. The sampled population was primarily composed of females, with ratios of females to males 1:0.6, although the predominance of females was less noticeable during the reproductive season. Oocyte growth in dab follows asynchronous development, and spawn over a protracted period indicating a batch spawning strategy. Spawning occurred mainly in early spring, with total regeneration of gonads by May. The length at which 50% of the population was reproductively mature was identified as 14cm and 17cm, for male and female dab, respectively. Precision and bias in age determinations using whole otoliths to age dab was investigated using six age readers from various institutions. Low levels of precision were obtained (CV: 10-23%) inferring the need for an alternative methodology. Precision and bias was influence by the level of experience of the reader, with ageing error attributed to interpretative differences and difficulty in edge determination. Sectioned otolith age determinations were subsequently compared to whole otolith age determinations using two age readers experienced in dab ageing. Although increased precision was observed in whole otoliths from previous estimates (CV=0%, 0% APE), sectioned otoliths were used for growth models. This was based on multinominal logistic regression on age length keys developed using both ageing methods. Biological data (length and age) for both sexes was applied to four growth models, where the Akaike criterion and Multi model Inference indicated the logistic model as having the best fit to the collected data. In general, female dab attained a longer length then males, with growth rates significantly different between the two sexes. Length weight relationships between the two sexes were also significantly different.