Metapopulation Modelling and Spatial Analysis for HEG Technology in the Control of Malaria

The success of any vector control strategy can be enhanced by onsite analysis and investigation. Combatting malaria, a global disease carried by the vector Anopheles gambiae, has led to the development of novel genetic technologies such as the use of HEG; homing endonuclease genes. This thesis explored the age and stage elements of the vector, building upon current biological understanding and using fitting algorithms with metapopulation matrices to create cohort orientated survival and transition. The environmental forces were analysed alongside this with emphasis on sub-model creation and tool design, employing an array of methods from RBF to satellite classification to couple the local environment and vector. When added, the four potential genetic strategies all demonstrated the ability to suppress a wild type population and even eradicate it, although reinvasion and hotspot population phenomena were reoccurring observations. The movement of the vector was an important factor in control efficiency, which was investigated as a series of different assumptions using wind driven movement and host attraction. Lastly, practical factors such as monitoring and resource distribution within a control project were assessed, which required routing solutions and landscape trapping assessments. This was explored within a framework of Mark-Release-Recapture experiment design that could provide critical information for efficient HEG release strategies.Open Acces

A comparative analysis of population estimation methods for a burrow-nesting seabird: a novel ground-count method and closed population capture-recapture modelling

xii, 125 leaves : ill. (chiefly col.), maps ; 29 cm.Includes abstract and appendices.Includes bibliographical references (leaves 109-117).Spatial variation in nesting patterns can cause variation in population size estimates. This thesis research shows that more accurate estimates can be made of population sizes of breeding burrow-nesting seabirds by mapping Bonin Petrel (Pterodroma hypoleuca) nesting colonies into low, medium, and high burrow densities and then randomly conducting burrow density and occupancy surveys, as compared to more traditional censusing methods. Results from closed population modelling, using the Program MARK, indicate that capture-recapture studies may be useful in estimating the total population size of Bonin Petrels. Capture-recapture studies are more time/cost-effective than ground-count studies, are less harmful to the study species, and can estimate both breeding and total population sizes of any burrow-nesting seabird species worldwide. Support for distinguishing breeding females from breeding males and non-breeding individuals through cloacal size is provided, and the importance of habitat (and Verbesina encelioides, an invasive species) to Bonin Petrel nesting patterns is discussed

Distribution, social structure and habitat use of short-finned pilot whale, Globicephala macrorhynchus, in the Canary Islands

The Canary Archipelago is considered one of the planet’s biodiversity hotspots and the short-finned pilot whale is a key species in need of conservation measures. To address a lack of knowledge, almost 2,000 day-surveys were conducted (1999-2012) resulting in 1,094 short-finned pilot whale sightings. The species was recorded year-round and distributed non-uniformly around the archipelago, with greater densities concentrated in patchy areas mainly on the leeward side of the main islands. A total of 1,320 well-marked individuals were identified, which exhibited a large degree of variability in site fidelity (from core residents to transients). Evidence of an island-associated sub-population and a transient one was found. Longitudinal data were used to infer population structure and estimate abundance, while a spatial modelling approach was used to study spatio-temporal patterns in habitat use, distribution and abundance. Spatial modelling revealed habitat preferences in areas between depths of 1000m and 1500m, and higher densities in the south-west of Tenerife and La Gomera (117 short-finned pilot whales recaptured within the two islands). Abundance of 1,980 individuals (CV = 0.33, 95% CI=1,442 – 2,324) was estimated for the entire archipelago, with higher density predicted during the summer months. Mark-recapture analysis estimated 636 resident individuals (CV = 0.028, 95% CI=602 - 671) in the southwest waters of Tenerife between 2007 and 2009. The social and temporal analyses of the behavioural relationships between pairs of individuals revealed a well-differentiated society with long-lasting and non-random social structure built of constant companions. A hierarchical social system is proposed composed of a population encompassing several clans of pilot whales, each one containing several pods. Nine long-term units were identified with a high degree of association (0.62 - 0.83). This study, the first to provide combined results on distribution, habitat use, and social structure of the species, provides essential information towards the development of recommendations for much needed conservation measures

Ecology and behaviour of postlarvae and juveniles of the velvet swimming crab Necora puber (L.)

Merged with duplicate record 10026.1/2428 on 27.02.2017 by CS (TIS)Ecological studies of early benthic stages of brachyurans are rare for most of the species, leaving a gap in the understanding of processes regulating the recruitment to adult populations. The velvet swimming crab Necora puber (L. ) is a valuable commercial species where most of studies have been focused on the adult population. Little is known about the supply-side ecology and the post-settlement processes that affect the dynamics of the adult populations. The aims of the present study were to investigate the physical processes affecting the supply of recruits to the nearshore, to examine the processes associated with habitat selection during settlement, and to describe the biology and ecology of the juveniles of N. puber. The study was carried out in the shallow waters and on the rocky shores of Plymouth Sound, on the southwest coast of the UK. Distribution of the pelagic postlarvae was patchy, and the abundance varied spatially in tens and thousands of metres. In temporal scales, the annual pattern was dominated by low occurrence of megalopae, punctuated by episodic peaks of high abundance. In the water column, most of the megalopae were collected at the surface and their abundance appears to be regulated by the tidal cycle, as megalopae were more abundant during flood than ebb tides. This behaviour could produce a net shoreward transport of megalopae. Laboratory experiments indicated that flow conditions set initial patterns of distribution of settlers on substrata of different tri-dimensional structure. However, active habitat selection occurred and the settlers were actively modifying the distribution patterns set by the hydrodynamics. Ontogenetic shift in habitat use occurred early in the juvenile phase and first juvenile instars were less habitat specific than megalopae. During the benthic phase, juvenile growth was markedly seasonal, and virtually no growth occurred in winter. Results from the present study indicated that juvenile growth rate is slower than previously described for N. puber. Magnitudes of juvenile recruitment were variable between years, but level off at the end of the 1+ year class on most of the shores studied. This suggests that mortality is high for early juveniles and appears to be density dependent on some shores. High density-dependent mortality can obscure the connectivity between larval and adult populations, so for the population of N. puber studied, better correlations may be obtained from juvenile-to-adult relationships

From A to B, statistical modelling of the ecology of ants and badgers

Biological systems involve features/behaviours of individuals and populations that are influenced by a multitude of factors. To explore the dynamics of such systems, a statistical description offers the possibility of testing hypotheses, drawing predictions and more generally, assessing our understanding. In the work presented, I analyse the properties of various biological systems of two very different organisms: Pharaoh‟s ants (Monomorium pharaonis) and badgers (Meles meles). The basis of the work, in the two projects on these biological systems, relies heavily on data collection and explaining observations using quantitative methods such as statistical analysis and simulations. In the first part of this thesis, I describe animal movement in space and time using data collected on the foraging behaviour of ants. A new model is presented which appears to reflect, with a high degree of accuracy, the behaviour of real organisms. This model constitutes the basis of the second chapter in which the qualities of searching strategies are explored in the context of optimal foraging. The final chapter of first part of this thesis concludes with a detailed analysis of the rate of exploration of individuals. As an essential part of foraging, the rate of individuals leaving their nest is analysed using collected data, and contrasted with results derived from a mathematical model. The second part of this thesis focuses on badgers. A first chapter explores the significance of palate maculation that is observed in badgers and relates their symmetry to parasitic infection. I then explore the population dynamics of a population of badgers subject to natural variation in climatic conditions. A first analysis is based on local climatic conditions, while a second analysis focuses on a more general property of climate (i.e. its unpredictability) to infer population dynamics

Environmental influences on tuna movement patterns in the Indian Ocean

The Indian Ocean Tuna Commission conducted a small-scale tagging programme (2002-2009) and also a large-scale tagging programme: the Regional Tuna Tagging Programme of the Indian Ocean (RTTP-IO, 2005-2009). Both tagging programmes known as the Indian Ocean Tuna Tagging Project (IOTTP), targeted three main species of tuna commercially exploited in the Indian Ocean: bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacares). The two programmes tagged 219,149 tuna and 34,294 recaptures were reported to the commission. This study focused on tuna behaviour in the Indian Ocean looking at seasonal impacts, inter-annual variability in relation to ocean environment, survival estimates, movement patterns, size-groups and school-type: Free Schools (FS) and Fish Aggregating Devices (FADs). Using a multivariate approach, it was found that the years 2005 to 2007 were most abundant in recoveries of skipjack adults (77.45%) while yellowfin adults were mainly abundant during 2008 to 2011. It also showed that year and zone were significant factors influencing local abundance in tuna. The Kaplan-Meier survival curves enabled estimates on the longevity of the three species to be made. It was estimated that the cohorts (99%) vanished at 12, 5.8 and 10 years for bigeye, skipjack and yellowfin, respectively. The years 2006 (cold-productive phase) and 2007 (warmchlorophyll depleted phase) showed tuna movement patterns changing with an El Ni˜no event and primary productivity. Tuna tagged in the Tanzanian region, showed that those under FADs moved pre-dominantly towards the Somalian and Seychelles waters, while those in FS moved to the Seychelles and Mozambique waters. General Additive Model (GAM) analyses showed that the area bounded by 5⁰N-5⁰S and 45⁰-55⁰E was the main tag recovery regions for tuna under FADs. While in FS, the core recovery region was observed to be from 0⁰N-10⁰S and 50⁰-60⁰E. Recoveries were distributed in the temperature range 25-29 ⁰C. Modelling tuna movement and drift related to ocean surface currents and swimming speed, a closer match between simulated and actual recovery positions were obtained for large tuna (particularly free schools) in comparison to small tuna associated with FADs

Movement of Selected Nearshore Temperate Reef Fishes Along California\u27s Central Coast

Worldwide fisheries decline has spurred the utilization of new conservation and management approaches, including the implementation of marine reserves. The diversity of goals and expected outcomes should guide the marine reserve design process, coupled with a thorough understanding of the ecology of all species targeted for protection. Central California’s network of coastal marine protected areas (MPAs) was established in an environment of some uncertainty regarding the expected outcomes for temperate nearshore fish species, especially the Sebastes genus (rockfishes). Movement behavior of temperate reef-fishes plays an important role in the level of protection that a reserve will afford a species. Consistent small-scale movements (\u3c10 km) and limited home range sizes decrease the likelihood that individuals will encounter fishing mortality. Conversely, large-scale movements outside of reserve boundaries may contribute to fisheries in surrounding waters (‘spillover’). The current study sought to further elucidate the movement behavior of some shallow-water temperate reef fish species throughout California’s central coast, with goals of providing useful data for future MPA design processes. Tag-and-recapture methodology was utilized in order to observe fish movements, centered on a public participation program for acquiring information on recaptured tagged fishes. A total of 476 fishes representing 14 species were recaptured from a sample of 37,111 tagged (1.3%) over a five-year period spanning 2005-2009. The majority (75%) of distances traveled were less than one kilometer, however some species made consistent far-ranging travels on the order of hundreds of kilometers as well. Analyses of factors with potential for shaping movement behavior included geographic variation, source of recapture data, gear type, days at liberty, length, initial capture depth, handling condition, and fish density. Additionally, the applicability of tag-and-recapture methodology is examined as an effective source of fish movement information. The results of this research corroborate findings of previous studies as well as provide new insight into the movement patterns of some nearshore temperate reef species

In Support of a Rationally Managed Fishery: Age and Growth in Patagonian Toothfish (\u3ci\u3eDissostichus eleginoides\u3c/i\u3e)

Patagonian toothfish (Dissostichus eleginoides) occur on the continental shelves and shelf breaks of southern South America and the Southern Ocean. Stock structure, critical to good fisheries management, can be inferred from growth differences between areas, but available growth data are compromised by inconsistencies in age estimation methods, sampling and sample sizes, and techniques used to derive estimates. I asked the scientific question: how is growth in Patagonian toothfish structured spatially within the Southern Ocean? I developed a multi-stage randomized design to sample fish caught by commercial longline, and an age estimation methodology. Because toothfish are difficult to age, I developed an ANOVA model for estimating precision and accuracy of age data relative to a standard, as the basis for a protocol for quality control of age data. The methodology was used to obtain age data from toothfish taken from the Falkland Islands and South Georgia in the South Atlantic, and the Kerguelen Islands and Heard Island in the southern Indian Ocean. I estimated von Bertalanffy growth parameters for each area, constructed models to describe rival hypotheses of stock mixing and separation between areas, and selected between the models using normal likelihood methods. The abundance of the captured population varied at a scale of c500 m (76% of variance), and between fishing days (24%). Most variation in length composition was captured at scales less than 500 m (79%). I calculated that sampling 16 10-coil lengths of line/day on 36 days of a voyage of 60 days hauling would be the optimal sampling strategy. Significant bias in age estimation was found between readers and between readings by one reader but, once accounted for, precision of age estimation remained similar between sexes; however, a validation test of the accuracy of the age estimation methodology was inconclusive. Growth data supported the hypothesis of stock separation between the Falkland Islands and South Georgia, but not between South Georgia and Kerguelen