Investigating the relative roles of physical and biological factors in determining community structure across gradients of emersion and wave exposure in the rocky shore intertidal has been one of the principal areas of interest in marine ecology. However, the way in which the role of these factors changes over large latitudinal scales across European shores has not been quantitatively assessed. Using a large scale survey across the European coastline changes in community structure from a local to a European scale were assessed in a quantitative manner, with particular focus on the dominant primary producers, fucoid macroalgae, and key grazers, patellid limpets. Following this quantitative descriptive approach, key controlling processes that ultimately could lead to alterations in the community structure and energy flow between ecosystems were also explored. The large scale survey gave a broad scale quantitative description of major functional intertidal groups over a latitudinal gradient from northern Scotland to southern Portugal (Chapter 2). This descriptive work explicitly operated at a very coarse scale of resolution to essentially differentiate between algal dominated and sessile invertebrate dominated assemblages. In describing latitudinal patterns, a key confounding variable, wave exposure, was addressed by independently categorising shores into three categories according to the I / degree of wave action. This was achieved using a GIS model based on wave fetch. The quantification of patterns of biomass and percentage cover over latitudinal scales resulted in the development of a database for different intertidal functional groups covering a large area of the European rocky intertidal, which can be used by future studies for temporal comparisons and evaluation of the effects of possible climatic alterations. The survey showed a decline in total fucoid biomass and percentage cover in the Portuguese region, but little variation over the extent of the British Isles. The expected corresponding increase in filter feeder cover was not obvious and an increase in Patella grazer density and biomass in Portugal was not found. A number of targeted field experiments and collections were undertaken in Wales and Portugal to ascertain the causal factors leading to the observed gradient in algal-animal balance in the intertidal over a European scale. A factorial experiment (Chapter 3) was undertaken in the field to determine the interactive effect of grazing pressure and physical environment (shade and moisture) on patterns offucoid recruitment. Amelioration of the physical environment did not improve recruitment at either geographical region, while grazing pressure was found to be an important process regulating fucoid recruitment only on northern European shores. Adult algal characteristics, specifically stress levels (Chapter 4) and reproductive capacity (Chapter 5), were assessed, through experimental work, to determine their contribution to latitudinal scale patterns. The results showed that stress levels (measured as photosynthetic resilience) increase in fucoid populations when they were subjected to physical conditions characteristic of a summer day in Portugal, with specimens not being able to fully recover even after a 16 hour recovery period. Environmental conditions in southern regions were also found to promote fucoid populations with lower numbers of receptacles and lower reproductive tissue biomass, which indicates reduced reproductive capacity. Using the data collected and conclusions about patterns and processes from the experiments undertaken during the PhD, changes in algal productivity and filter feeder abundance were discussed, while predicting energy flow from and to the coastal environment at local and large geographical scales. The work demonstrates the importance of undertaking quantitative surveys over large scales whilst controlling for key confounding variables. Whilst many of the patterns expected from previous qualitative descriptions and quantitative work undertaken at local scales were verified, there were important unexpected outcomes. In addition, experimental work undertaken in different geographical regions has provided some insight into key processes determining large scale patterns.

Many important marine ecosystem functions, goods and services rely on healthy, productive benthic communities, yet these communities are at risk from anthropogenic activity such as bottom fishing and aggregate dredging. Marine spatial management measures such as marine protected areas could help protect benthic communities from these activities and ensure the continued provision of the ecosystem goods and services that they support. The establishment of MPAs to protect benthic communities could be prioritised based on benthic invertebrate production, an indicator of benthic ecosystem quality that is comparable across different habitats. This thesis has considered the development and utility of modelled benthic infaunal production as a practical selection criterion for MPA design in the Irish Sea. The ability to model production over large scales and the spatial association between production and biodiversity have been investigated to determine whether or not benthic production can be and needs to be explicitly included as a selection criterion in MPA design to ensure protection from anthropogenic activities such as fishing. Results indicate that an empirical, size-based model that incorporates strong environment-production relationships can successfully predict relative benthic infaunal production over large scales in the Irish Sea. The model can also investigate bottom fishing impacts and the subsequent recovery of benthic production and biomass, all of which have utility for informing MPA design. A lack of spatial association between benthic production and biodiversity suggests that sites where the protection of biodiversity and production could be achieved simultaneously are limited in number, and therefore marine ecosystem function needs to be explicitly included as a selection criterion in MPA network design to ensure protection from anthropogenic activities. The implications of results for the spatial management of benthic communities are discussed, and general recommendations for MPA network design are made.

Estuaries and coasts are dynamic and complex ecosystems and are important regions in terms of ecology and productivity. They consist of a wide range of different habitats and are important locations for wildlife. They also tend to be the world’s most intensely used regions, accommodating a range of activities including shipping, ports and harbours, fishing and coastal development. As a result of global population growth and increasing demands for food and energy, estuaries and coasts are coming under intense pressure leading to their degradation. Current management approaches which consider activities in isolation are no longer sustainable. In Ireland, the management of coastal ecosystems is largely carried out in a fragmented, sectoral and uncoordinated manner. There is no overarching national coastal or marine policy and there is no single body with overall responsibility for Irish estuaries and coasts. A more holistic approach is required to deal with the multi-uses, multi-users, multi-scales and multi-effects of estuarine and coastal ecosystems. This research develops an approach for the integrated and sustainable managemeht.of estuaries and coasts in Ireland. Based on a review and critical analysis of integrated environmental management theory and practice, an integrated environmental management and monitoring system (EMMS) was devised for Irish estuaries and coasts. The proposed EMMS was used as a heuristic device to evaluate existing management initiatives and future management approaches in two Irish case studies. This suggested that the EMMS was unable to address all the issues preventing a more sustainable management of estuaries and coasts and exposed more ‘persistent problems’ associated with a system-wide failure in environmental governance and regime impediments. As a response, to this, the thesis makes an original contribution by applying the multi-level perspective from transitions theory as a way of conceptualising the large scale changes to governance that can deliver sustainable integrated management of Irish estuaries.

No description available.

The last two decades have seen a shift of emphasis in ecology; from a focus on the drivers of biodiversity change toward a consideration for its effects on ecosystem functioning. Ecosystem functioning is affected by individual species (i.e. species with functionally dominant biological traits), but can also be influenced by other factors, such as interspecific interactions. Current evidence suggests that biotic influence over marine ecosystem functioning is largely underpinned by the effects of individual species. However, there are indications that this might not constitute a complete understanding of the link between marine biodiversity and ecosystem function (BEF). For this thesis, I applied our current understanding of marine BEF relationships (i.e. the causal link between particular biological traits and particular ecological functions) to long-term benthic community time series and investigated the causes of ecological change and its consequences for ecosystem functioning. A shift in the taxonomic composition of the species assemblage was explained by underlying variation in extrinsic drivers. However, the long-term conservation of trait composition suggests that functioning can be sustained in the face of environmental and ecological change. Experiments conducted to test BEF relationships in intertidal marine benthos reaffirmed the functional importance of the biological traits of species, but also showed that interactions among species can influence the delivery of ecological functions in various ways, including facilitation (i.e. function delivery is enhanced) and antagonism (i.e. function delivery is reduced). The results suggest that biotic influence over marine ecosystem functioning is more complex than previously suggested, and that the impacts of biodiversity change (e.g. species extinctions or shifts in species densities) could be either exacerbated or mitigated depending on the composition of the affected assemblage and the ecological function considered. To produce more realistic results, future indirect assessments of ecosystem functioning would benefit from incorporating interactions among species as well as their biological traits.

The effects of contrasting water residence time on the planktonic community of three water bodies was studied. The sites were Rutland Water, Covenham reservoir and the River Nene, in order of decreasing retention time. The river was the only site where the residence time was sufficiently short to directly impact upon planktonic populations. The importance of physical mechanisms of control in the river was indicated by the dominance of r-selected phytoplankton, namely diatoms and green algae, and zooplankton, namely rotifers. This pattern was in contrast to that of the reservoirs in which slower-growing cyanobacteria and cladocerans dominated. Riverine rotifers were found to have rapid population turnover, due to a combination of short pre-adult duration and high maximum growth rates. Some species also showed a shift in reproductive behaviour to the constant production of resting eggs. This was assumed to convey benefits in a system where resting stages may be less susceptible than adults to downstream displacements. The total chlorophyll 'a' concentration achieved per unit phosphorus was significantly lower in the river than either of the reservoirs. Algal density was negatively associated with discharge in the Nene, suggesting the importance of physical control. The relationship was not a simple one, however, as periods of increased retention time during the summer were associated with low algal density. The absolute density of rotifers was found to be constrained by discharge. Animals were rare above a threshold flow velocity of 0.08ms-1. Simple models of water flow in open channels were insufficient to account for the continued persistence of a plankton in the Nene given the level of advection. It was assumed that the overall retention time of the system was increased by the presence of dead zones within the channel which 'held' planktonic organisms for sufficient time for populations to develop. This behaviour was important during the spring when population density increased in the main channel.

In many parts of the tropics, coastal communities are increasingly assuming responsibility for nearshore resources under arrangements known as “locally managed marine areas” or LMMAs. Broadly similar to marine protected areas, LMMAs are managed for sustainable, long-term use rather than biodiversity conservation itself, and typically employ a range of management techniques, including periodic closures, gear restrictions, secure access rights, species-specific reserves and permanently closed, fully protected areas (no-take zones) to achieve this aim. Evidence suggests that, when effective, LMMAs can encourage responsible fishing, strengthen compliance and may help to safeguard food security and increase resource abundance. However, the recently established and informal nature of many initiatives means that several questions remain unanswered. In particular, little is known about the effectiveness of LMMAs in achieving long-term ecological goals, with initiatives often lacking the necessary financial resources to sustain both effective management and the collection and evaluation of robust socio-ecological evidence on which such management often depends. A second unresolved question concerns the status and scale of LMMAs outside the Western and Central Pacific, the region where research interest has concentrated to date. This PhD combines social and ecological research to investigate how to address these key research gaps and improve the effectiveness of locally managed marine areas. The work falls into four interdisciplinary data chapters, with a core focus of examining the role of research design in improving assessments of LMMAs and other spatially explicit tools like marine protected areas, as well as the potential role of tourism as a source of funding and support for LMMAs. The opening two data chapters take an interdisciplinary approach to the assessment of a long-established network of LMMAs in Rarotonga, Cook Islands, beginning with an examination of tourist satisfaction with the network, using respondent completion questionnaires. The results found widespread disappointment, with around half of respondents not satisfied with coral cover or diversity and around 40% dissatisfied with fish abundance, size or diversity. The second data chapter swaps socio-economics for ecology, evaluating the effectiveness of Rarotonga’s LMMAs using three contrasting research approaches. A network-level analysis, which assessed overall responses to protection, suggested no LMMA effects, with abundance and biomass of species targeted by fishers not significantly higher within LMMAs compared to control sites. In contrast, a site-level analysis, which explored the differences between each of the individual LMMAs and their paired controls, revealed significant differences in targeted abundance (2.5-3 times higher), biomass (4.3-5.4 times higher) and community structure between LMMAs and controls at the two sites where hotels were acting as co-management partners. A third analysis, which used an asymmetric approach to examine the performance of each LMMA against multiple control sites, accorded with the second, finding that both targeted biomass and abundance were significantly higher at the hotel-supported sites than at multiple controls. The third data chapter continues to examine the role of research design in improving assessments of area-based management initiatives. A novel double-blind randomised controlled trial using underwater video fish surveys demonstrated that observers who were told that the transects they were assessing came from a no-take marine reserve significantly and erroneously overestimated the effectiveness of the reserve vs. those who were not told, inflating their fish counts by approximately 28% (95% CI 18.5% to 40.5%, p > 0.0001). The final chapter explores new horizons for LMMAs, presenting the first assessment of the status and extent of LMMAs in the Western Indian Ocean (WIO) and supporting legal frameworks. Using the most comprehensive dataset of the region’s LMMAs and marine protected areas yet developed, this analysis revealed that more than 11,000km2 of marine resource in the WIO was managed in LMMAs. The analysis also found that many initiatives were hampered by underdeveloped legal and enforcement mechanisms and argued for a regional network of LMMA practitioners to share best practice on financing and evaluation and to encourage the development of further LMMAs. Taken together, the different chapters expand our knowledge of LMMAs in the Western and Central Pacific and WIO and provide important baselines against which to evaluate future management strategies in the Cook Islands and WIO. They highlight the importance of capturing visitor perceptions of marine resource management and protection efforts in tourism-dependent island states, and provide some evidence for the role coastal hotels can play in supporting and sustaining LMMAs in tropical developing countries. Finally, they demonstrate that both a common analytical flaw and a previously unresearched bias may confound results in evaluations of the ecological effectiveness of protected areas, underscoring the need to incorporate blind assessment and to more carefully consider potentially confounding variables in future research designs.

No description available.

No description available.

No description available.