6,356 research outputs found
Using marine ecoengineering to mitigate biodiversity loss on modified structures in the Waitematā Harbour : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Albany, New Zealand
The construction of infrastructure on the foreshore is an unavoidable consequence of an
ever-expanding human population. Traditionally, this infrastructure has replaced softsubstrates
with hard substrates. Furthermore, even for native biota which occupy hard
substrates, the flat, featureless construction of most marine infrastructure provides little
habitat heterogeneity and results in depauperate communities with little biotic resistance
against non-indigenous species. Marine ecoengineering provides a possible solution to this
global phenomenon by using intelligent construction techniques that promote the
accumulation of native biodiversity. Here, I used eco-engineered settlement plates to
examine the effect of habitat complexity on the biodiversity of communities inhabiting
existing. Additionally, we examined the effects of climate change driven increases in rainfall
on the performance of ecoengineered substrates in the mid-intertidal zone. Last, we
reviewed and synthesised the available literature on the species present in The Waitematā
Harbour and, to the best of my knowledge, provide the most complete species lists to date.
In chapter two, we transplanted eco-engineered settlement plates seeded with local
bivalve, Perna canaliculus, onto an existing seawall and monitored the accumulation of
biodiversity. Overall, we show that both structural and biological habitat heterogeneity
enhanced the biodiversity of the seawall community. Additionally, we found that the
cemented pavement of volcanic rock that constituted the existing seawall, accumulated
biodiversity faster than flat concrete settlement plates, supporting the use of this type of
seawall construction over flat concrete seawalls. However, benefits to biodiversity could be
further enhanced by explicitly adopting ecoengineering designs that provide crevices for
intertidal organisms.
In chapter three, we examined the performance of ecoengineered substrates under the
prediction that climate change will enhance rainfall by 20% in the Auckland region. While no
effect of increased rainfall was observed for the mobile invertebrate community or the flat
plates, increased rainfall did influence the biodiversity of the fouling community on the
ridged plates, likely as a consequence of reduced desiccation stress. Although this was only
a short-term experiment we predict that given time to develop, a distinct fouling community
could influence the diversity mobile invertebrate community, shifting the whole community
vertically up the seawall.
The review of the Waitematā taxonomy presented in chapter four, provides a reference for
future studies of the biodiversity of the Waitematā harbour as well as identifying several
gaps in our understanding, a cause for concern. Specifically, we show that non-indigenous
species make up a considerable proportion of the fouling species listed for the Harbour and
suggest that some of this could have been avoided by the adoption of ecoengineering
techniques.
Overall, this thesis recognises that habitat heterogeneity, be it natural or man-made, is a
vital driver of biodiversity. Each chapter provides additional insight, supporting the benefits
of marine ecoengineering. These positive results within the Waitematā Harbour show
potential for larger scale experimental trials and for the broader application of these
techniques in other locations. By implementing intelligent design and eco-friendly materials
in marine infrastructure, we can reduce the impact on local intertidal communities and
indirectly reduce the spread of non-indigenous species
Automated analysis of non destructive evaluation data
Interpretation of NDE data can be unreliable and difficult due to the complex interaction
between the instrument, object under inspection and noise and uncertainties about the system or
data. A common method of reducing the complexity and volume of data is to use thresholds.
However, many of these methods are based on making subjective assessments from the data or
assumptions about the system which can be source of error. Reducing data whilst retaining
important information is difficult and normally compromises have to be made. This thesis has
developed methods that are based on sound mathematical and scientific principles and require
the minimum use of assumptions and subjective choices.
Optimisation has been shown to reduce data acquired from a multilayer composite panel and
hence show the ply layers. The problem can be ill-posed. It is possible to obtain a solution close
to optimum and obtain confidence on the result. Important factors are: the size of the search
space, representation of the data and any assumptions and choices made. Further work is
required in the use of model based optimisation to measure layer thicknesses from a metal
laminate panel. A number of important factors that must be addressed have been identified.
Two novel approaches to removing features from Transient Eddy-Current (TEC) data have been
shown to improve the visibility of defects. The best approach to take depends on the available
knowledge of the system.
Principal Value Decomposition (PVD) has been shown to remove layer interface reflections
from ultrasonic data. However, PVD is not suited to all problems such as the TEC data
described. PVD is best suited in the later stages of data reduction.
This thesis has demonstrated new methods and a roadmap for solving multivariate problems,
these methods may be applied to a wide range of data and problems
MARKET COMPETITION AND METROPOLITAN-AREA GROCERY PRICES
This paper examines the relationship of 1987 retail grocery prices to supermarket sales concentration across 95 U.S. metropolitan areas. The regression model incorporates a large number of population, retail-cost, and retail competition factors and separate prices by type of grocery item. We find that the concentration-price relationship is sensitive to item type: positive for packaged, branded, dry groceries and unrelated for produce, meat, and dairy product prices. As for market rivalry, we find that small grocery stores provide no grocery price competition for supermarkets. However, branded grocery prices are driven down by fast-food places and by rapid price churning, whereas for unbranded foods the presence of warehouse stores places downward pressure on supermarket prices while fast-food presence does not. For the branded-groceries component, we also find prices higher in large, fast-growing, low- income, Eastern cities. We also find that cities where rents, wages, and electricity costs are high tend to have high dry grocery prices. However, for the unbranded-products component retail costs are unrelated to prices, and cities in the South have the highest prices.retail grocery trade, pricing policy, variable price merchandising, market competition, category management, market structure, sales concentration, price discrimination, price rivalry, oligopoly, food demand, food prices, Consumer/Household Economics,
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