Man’s impact on the Earth is constantly increasing due to ever progressing technological developments. One of our major impacts is the transportation of organisms to new habitats, leading to alterations of existing ecosystems. Mechanisms responsible for the transportation of marine organisms are mainly associated with the shipping industry e.g. hull fouling, sea chests and ballast water. Ballast water has long been recognised as one of the major mechanisms by which aquatic organisms are transported to new environments. In 2004 the International Convention for the Control and Management of Ships’ Ballast Water and Sediments was adopted and measures were implemented to reduce and control the number of future invasions. This thesis has addressed aspects relevant to the future prevention of organism transport via ballast water. Firstly, during ballast water uptake organisms are exposed to potential damage whilst passing through a centrifugal pump. Upon reaching the ballast tanks they are stored in dark, confined conditions. These processes are not intended to damage individuals, but both could potentially kill organisms and reduce the discharge of live individuals. Both processes were examined in isolation to determine their effect on plankton survival. To manage ballast water introductions water treatment technologies have been investigated to determine their ability to kill plankton. This study assessed three technologies: a stainless steel 40μm screen filter, a UV light and a chlorine based chemical, for their potential in ballast water treatments. A further challenge facing researchers involved in developing ballast water treatment systems is accurately assessing the resulting mortality in plankton from treatments. Five common viability assessment methods were investigated and their application on test organisms and natural populations examined. This thesis concludes that no significant mortality was caused to plankton by a centrifugal pump, and phytoplankton are able to survive long periods in dark confined conditions. Thus these processes will not prevent viable organisms reaching new destinations. The three treatments assessed were all effective on two iii test species and could be utilised in large scale treatment systems on board vessels to minimise introductions. Finally, while viability is difficult to assess in plankton using viability stains it is possible to obtain accurate information if the methods used are properly optimised prior to use.

As a result of interaction with the surrounding environment, shipping has become one of the vectors of bio-invasion across the globe. Ballast water is one of the means of bio-invasion from shipping through which microorganisms break through natural barriers and establish in a new location. Shipboard treatment systems are predominately considered as mitigating measures for bio-invasion via a ballast water system. Currently shipboard performance monitoring of ballast water treatment systems, and thus assessment of discharge quality of ballast water as required by the Convention, depends on off-line laboratory assays with long delay analysis. Lack of online measurement sensors to assess the viability of microorganisms after treatment has made monitoring and thus control of ballast water treatment systems difficult. In this study, a methodology was developed, through a mathematical algorithm, to provide an inferential model-based measurement system in order to monitor and thus control non-observable ballast water systems. In the developed inferential measurement the primary output of the treatment system is inferred by using easy to measure secondary output variables and a model relating these two outputs. Data-driven modeling techniques, including Artificial Neural Networks (ANN), were used to develop an estimator for the small scale UV treatment system based on the data obtained from conducted experiments. The results from ANN showed more accuracy in term of Root Mean Squared Error (RMSE) and Linear Correlation Coefficient (LCC) when compared to the other techniques. The same methodology was implemented to a larger scale treatment system comprising micro-filter and UV reactor. A software-based inferential measurement for online monitoring of the treatment system was then developed. Following monitoring, inferential control of the treatment setup was also accomplished using direct inverse control strategy. A software-based “Decision Making Tool” consisted of two intelligent inverse models, which were used to control treatment flow rate and maintain the effective average UV dose. The results from this study showed that software-based estimation of treatment technologies can provide online measurement and control for ballast water system.

Harmonia axyridis is a ladybird native to Asia, but introduced widely as a biocontrol agent. It is invasive and detrimental to native species in North America, which meant its arrival in Britain was met with concern. Establishment was seen as an opportunity to track the spread of an invasive alien species (IAS) whilst also monitoring impacts on native species. The aims of this thesis were to examine the responses of native British ladybirds to the arrival of H. axyridis, to establish the effect of the IAS on native ladybirds when compared to other drivers, and to investigate the possible facilitation of the H. axyridis invasion by natural enemy release. Modelling ladybird distributions with life-history and resource-use traits found that species predatory on a wide range of prey families had larger range sizes than those which ate fewer prey types. This suggests that the wide diet breadth of the IAS is likely to have played a critical role in the species’ rapid spread. Dietary niche overlap between H. axyridis and native ladybirds showed positive correlation with declines of native ladybirds. This indicates that the IAS is playing an important role, but the significance of urbanisation suggests habitat destruction is also significant. Abundance of H. axyridis was influenced by habitat type and aphid abundance, but not by the native ladybird community, suggesting the spread of the IAS will not be slowed by biotic resistance. Harmonia axyridis is attacked by native parasitoids, but at a much lower rate than is the native Coccinella septempunctata, in line with natural-enemy release theory. There was no evidence of attack rate increasing with time since arrival in an area. Overall, H. axyridis is an extremely successful IAS, with detrimental effects on native ladybirds which are likely to continue.