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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Spatial And Temporal Variability Of Benthic Respiration In A Developing Deltaic Estuary (wax Lake Delta, Louisiana)

January 2014 (has links)
The Wax Lake Delta (WLD) is one of the few areas of land gain in coastal Louisiana and provides an analog for a naturally developing subdelta created by a river diversion. This study examined the spatial and temporal variability of benthic respiration to broaden our current understanding of the biogeochemical functioning of diversion-created estuarine systems. Spatial and seasonal benthic respiration rates were quantified during distinct periods of discharge and water temperature conditions, which included a spring period of peak river discharge (May 2012, 2013), a summer period of low discharge and maximum seasonal water temperatures (August/Sept, 2012), and an autumn period of low discharge and intermediate water temperatures (October 2013). Benthic respiration rates for the Wax Lake Delta ranged from 4.4 – 46.8 and averaged 16.7 (± 1.5) mmol O2 m-2 d-1 . Atchafalaya Bay sites ranged from 10.3 - 26.5 and averaged 17.1 (± 1.5) mmol O2 m-2 d-1 across all sites and seasons. Benthic respiration generally increased along two spatial gradients: 1) with distance offshore from the delta into Atchafalaya Bay, and 2) toward the interior of a mouth bar island. These patterns were related to similar increases in sediment OC and N content, which were derived from a mix of terrigenous and marine sources and varied with season. Sediment organic (OC and N) content and water temperature were identified as main drivers influencing benthic respiration in the Wax Lake Delta estuary. Seasonal changes in riverine discharge and wind-driven sediment resuspension events were likely to influence the seasonal variability of benthic respiration by governing water temperature and organic matter supply to the sediments. Benthic oxygen consumption rates in the Wax Lake Delta were most sensitive to increases in water temperature during low discharge conditions (< 2,000 m3 /s) of the MI-AR system. In context of coastal restoration, results from this study suggest that opening a sediment diversion during spring peak discharge conditions will have less of an effect on benthic oxygen consumption rates than during warmer low flow conditions. / acase@tulane.edu
222

Relationship of Certain Environmental Factors to Benthic Fish Densities in Bear Lake, Idaho-Utah

Hassler, Thomas J. 01 May 1960 (has links)
The project was initiated in June of 1958 and financed by the National Science Foundation and the Wildlife Management Department of Utah State University. The broad aspects of the study were to determine if a relationship exists between certain physical and biological factors and benthic fish densities. The project vas divided into two parts: (l) to determine the time and extent of thermal stratification, zooplankton densities, conductivity changes within the lake and conductivity differences between the lake and its tributaries; (2) to determine it a relationship exist between benthic fish densities, temperatures, depths, conductivities and benthic zooplankton densities. The data were analyzed statistically and a separate regression analysis was run on each factor to determine the degree of relationship between that factor and benthic fish densities.
223

Interrelationships Between Benthic Macroinvertebrates and Habitat in a Mountain Stream

Payne, John M. 01 May 1979 (has links)
A study to determine habitat differences of benthic macroinvertebrates was conducted on the upper Strawberry River, Utah. The investigation was part of a large scale project to determine minimum stream flow requirements for trout. The effects of time, habitat, depth and velocity on the distribution of benthic fauna were evaluated. Samples of benthic invertebrates (146 total) were collected every 2 months at 8 stations on the river from November, 1975 through August, 1976. Representatives of 59 taxa were collected. Eight taxa comprised 90 percent of the mean annual community standing crop in numbers. Biomass was not dominated by any group of taxa. Community standing crop decreased from late Fall 1975 until early Summer 1976. The largest increase in standing crop occurred during August. Prediction of benthic distribution through the use of depth and velocity categories was unsuccessful. Three-dimensional plots of the relative density of a taxon versus depth and velocity indicated the contagious nature of the animals' distributions but their preference for specific categories could not be demonstrated. The results suggested that macroinvertebrates could tolerate large variations in current and depth and that these physical factors are only indirectly related to faunal distribution. Results of analysis of variance and covariance showed time to be the factor which influenced the distribution of most taxa (85%), followed by the time x habitat interaction (20%), velocity (18%), habitat (11%), and depth (9%). Comparisons in animal abundance were made between 4 riffles and 4 ''pools". These two habitats did not differ significantly in substrate type or velocity, however depth did show significant differences. Results of nonparametric tests suggested that the majority of taxa migrated into "pools" during periods of snow, ice, and low flows, an indication that "pools" may provide refuge to macroinvertebrates during periods of stream dewatering and diversion.
224

Modeling USA stream temperatures for stream biodiversity and climate change assessments

Hill, Ryan A. 01 May 2013 (has links)
Stream temperature (ST) is a primary determinant of individual stream species distributions and community composition. Moreover, thermal modifications associated with urbanization, agriculture, reservoirs, and climate change can significantly alter stream ecosystem structure and function. Despite its importance, we lack ST measurements for the vast majority of USA streams. To effectively manage these important systems, we need to understand how STs vary geographically, what the natural (reference) thermal condition of altered streams was, and how STs will respond to climate change. Empirical ST models, if calibrated with physically meaningful predictors, could provide this information. My dissertation objectives were to: (1) develop empirical models that predict reference- and nonreference-condition STs for the conterminous USA, (2) assess how well modeled STs represent measured STs for predicting stream biotic communities, and (3) predict potential climate-related alterations to STs. For objective 1, I used random forest modeling with environmental data from several thousand US Geological Survey sites to model geographic variation in nonreference mean summer, mean winter, and mean annual STs. I used these models to identify thresholds of watershed alteration below which there were negligible effects on ST. With these reference-condition sites, I then built ST models to predict summer, winter, and annual STs that should occur in the absence of human-related alteration (r2 = 0.87, 0.89, 0.95, respectively). To meet objective 2, I compared how well modeled and measured ST predicted stream benthic invertebrate composition across 92 streams. I also compared predicted and measured STs for estimating taxon-specific thermal optima. Modeled and measured STs performed equally well in both predicting invertebrate composition and estimating taxon-specific thermal optima (r2 between observation and model-derived optima = 0.97). For objective 3, I first showed that predicted and measured ST responded similarly to historical variation in air temperatures. I then used downscaled climate projections to predict that summer, winter, and annual STs will warm by 1.6 °C - 1.7 °C on average by 2099. Finally, I used additional modeling to identify initial stream and watershed conditions (i.e., low heat loss rates and small base-flow index) most strongly associated with ST vulnerability to climate change.
225

A Molecular Approach to Assessing Meiofauna Diversity in Marine Sediments

Hamilton, Heather C 18 July 2003 (has links)
A Molecular Approach to Assessing Meiofauna Diversity in Marine Sediments Heather C. Hamilton Abstract The purpose of this study was to determine if a molecular approach could be applied to calculating the diversity of meiofauna in marine sediments from two sites in Tampa Bay, FL, similar to the approach of McCaig et al, 1999 in calculating the diversity of microbes in pastureland soils. The approach includes extracting total DNA directly from the sediment and amplifying the 18S rRNA gene by PCR. Clone libraries from the 18S gene would be created for each site and 300 sequences from each clone library would be obtained. These sequences would then be phylogenetically analyzed and assigned to an OTU, from which diversity indices can be calculated. The phylogenetic analysis of the sequences from the two sites revealed that of the 102 OTUs assigned from the sequences, only 7 OTUs included sequences from both sites, while 93 OTUs contained sequences from one site or from the other. Thus the sites were phylogenetically different from each other. Shannon diversity indices calculated for each site showed a difference between the two sites and paralleled diversity indices for macrofauna data for each site collected by the Hillsborough County Environmental Protection Commission. Sequences from 30 OTUs were completely sequenced and identified by phylogenetic comparison with a metazoan reference alignment. A discrepancy between the sequence data and data collected from preserved samples taken at each site was evident upon analysis: roughly 60% of each preserved sample consisted of nematodes and 10% consisted of copepods, while roughly 30% of the identified OTUs consisted of copepods and 10% consisted of nematodes. This discrepancy could be explained if the OTUs that were not identified consisted of nematode sequences or if a primer bias were present in the PCR amplification such that the regions flanking the primer site in the nematode sequences inhibited primer annealing.
226

Écologie des foraminifères benthiques en domaine arctique dans un contexte de changements climatiques : cas des mers de Chukchi, Barents et Baffin / Ecology of modern arctic benthic foraminifera within a context of climate change : case studies in the Chukchi Sea, Barents Sea and Baffin Bay

Racine, Calypso 28 January 2019 (has links)
Les foraminifères benthiques sont largement utilisés en océanographie comme bio-indicateurs paléoclimatiques et paléoenvironnementaux du fait de leur présence dans tous les milieux marins, leur sensibilité aux changements environnementaux et leur grande capacité de fossilisation. Néanmoins, leur utilisation nécessite une connaissance approfondie de leur écologie et des paramètres contrôlant leur distribution. Si les connaissances sur l’écologie des foraminifères benthiques sont de plus en plus complètes, elles demeurent très sporadiques dans la zone arctique, système complexe caractérisé par des interactions multiples entre l'atmosphère, l'océan et la cryosphère, pourtant au coeur du changement climatique global. L'amplification polaire du changement climatique conduit les régions des hautes latitudes à se réchauffer près de deux fois plus vite que les régions tempérées. Dans ce contexte, cette thèse s'attache à mieux comprendre l'écologie des foraminifères benthiques vivants dans plusieurs régions arctiques et définir l'importance du contrôle des paramètres environnementaux sur les faunes tels que les propriétés des masses d'eau, la productivité primaire et le flux de matière organique ainsi que la dynamique de la glace de mer. Les foraminifères benthiques vivants ont été analysés dans les premiers centimètres de sédiment de 21 carottes d’interfaces prélevées dans trois régions arctiques durant les étés 2014 et 2015 : la mer de Barents, la baie de Baffin et la mer de Chukchi. Ces trois régions présentent des particularités en termes de couvert de banquise, de circulation des masses d’eau ou de dynamique de la production primaire. Nos résultats montrent que ces facteurs influencent la distribution des foraminifères benthiques. Le flux de matière organique qui résulte de la forte productivité primaire printanière aux abords des fronts polaires hydrographiques, des bordures de glace de mer (zones marginales de glace) et dans la polynie des eaux du nord (baie de Baffin) impacte la densité et la diversité des faunes et favorise le développement de certaines espèces. Nonionellina labradorica dans les eaux arctiques froides et Cassidulina neoteretis associée aux eaux atlantiques répondent aux apports de matière organique fraîche tandis que Melonis barleeanus s’accommode des milieux riches en matière organique plus dégradée. Dans les environnements oligotrophes plus profonds, Oridorsalis tenerus est une espèce ubiquiste. Cette espèce est associée à Cibicidoides wuellerstorfi sur la marge ouest de la mer de Barents et Ioanella tumidula dans le bassin plus profond au nord de la mer de Chukchi. Les propriétés physiques et chimiques des masses d’eau contraignent également la distribution faunistique. En baie de Baffin et sur le plateau de la mer de Chukchi, les eaux corrosives engendrent la dissolution des carbonates, favorisant la dominance des espèces agglutinées. Les études menées dans le cadre de cette thèse permettent de calibrer l'outil foraminifère benthique dans l'actuel et d'affiner leur utilisation en tant que proxy paléoclimatique et paléoenvironnemental en Arctique. Enfin, une étude préliminaire sur les foraminifères benthiques fossiles de trois carottes de la mer de Barents a permis de montrer les variations des conditions paléoenvironnementales au cours des deux derniers siècles. / Benthic foraminifera are widely used in oceanography as paleoclimate and paleoenvironmental bio-indicators due to their presence in all marine environments, their sensitivity to environmental changes and their great capacity to fossilize. However, the use of benthic foraminifera as paleoenvironmental proxies requires a good knowledge of the ecological conditions and the parameters controlling species distribution. Although knowledges about the ecology of benthic foraminifera are improving, they remain sporadic in Arctic area, a complex ecosystem characterized by multiple interactions between the atmosphere, the ocean and the cryosphere and particularly sensitive to change and vulnerable to global warming. Temperatures in the Arctic have risen twice as fast as the global average over the past decades, a phenomenon that has been dubbed the “polar amplification of global warming”. In this context, this thesis aims at better understanding the ecology of living benthic foraminifera in Arctic regions and at defining the importance of environmental controls on fauna such as water mass properties, primary productivity, organic matter flux as well as sea-ice dynamics. Living benthic foraminifera were identified in the first centimetres of 21 surface sediment cores collected in three Arctic areas during summer in 2014 and 2015: Baffin Bay and the Barents and Chukchi Seas. These three regions present specific characteristics in terms of sea-ice cover, water mass circulation or primary productivity. Our results suggest that these factors influence the distribution of benthic foraminifera. The flux of organic matter resulting from primary productivity intensified during spring and summer periods near hydrographic polar fronts, sea-ice edges (marginal ice zones) and in the north water polynya (Baffin Bay) increases the fauna’s densities and diversity and favours the development of specific species. Nonionellina labradorica in cold Arctic waters and Cassidulina neoteretis associated with Atlantic waters respond to fresh supply of organic matter while Melonis barleeanus is found in environment rich in degraded organic matter. In deeper oligotrophic environments, Oridorsalis tenerus is a ubiquitous species associated with Cibicidoides wuellerstorfi on the west continental margin of Barents Sea and Ioanella tumidula in the deeper basin in the north of the Chukchi Sea. Physical and chemical water mass properties also affect the distribution of living benthic foraminifera. In the Baffin Bay and the continental shelf of the Chukchi Sea, corrosive waters lead to carbonate dissolution, favouring the dominance of agglutinated species. This thesis hence contributes to calibrate the benthic foraminifera to their environment and to improve their application as paleoclimate and paleoenvironmental proxies in the Arctic. Finally, a preliminary study about fossil benthic foraminifera in three cores of Barents Sea allowed to show variations of environmental conditions during the last two centuries.
227

Can Waters Around Durney Key, Pasco County, Florida, Support Coral Recruitment to Artificial Substrates?

Anderson, Kelley L 10 November 2008 (has links)
To determine whether an artificial reef installation is feasible, there must be a thorough characterization of the habitat. An understanding of both small-scale and large-scale environmental processes is needed to determine factors that potentially will influence the reef. Large-scale processes include coastal circulation, wave climate, and sediment dynamics that take place over spatial scales of tens to hundreds of kilometers in the region of the reef. Small-scale processes include the physical characteristics in the immediate vicinity of the reef - the local current, wave and tide characteristics, temperature, salinity, and suspended and bottom sediments at a proposed reef site. The city of Port Richey, Florida, was considering installing an artificial reef of porcelain modules near Durney Key, a dredge spoil island just offshore. To assist in determining the feasibility of this proposal, I pursued three objectives: a) to characterize the oceanographic setting of Durney Key, including hydrodynamics, water quality and invertebrate biota; b) to investigate the potential for successful coral recruitment and growth in Durney Key waters; and c) to determine if porcelain is a suitable substrate for settlement of the larvae of coral species present in west central Florida. An array of Acoustic Doppler Current Profilers (ADCPs) were used to measure water velocity, water stage and temperature around Durney Key. ADCP data showed currents around Durney Key are tidally dominated with velocities increasing in winter due to frontal passages. Seasonal stage variation ranges from 0.29 m (11.4 in) to 0.64 m (2.1 ft) and seasonal temperature ranged from 10°C and 35°C for winter and summer, respectively. Atmospheric data from the Port Richey COMPS site showed average wind speeds were higher in winter (3.7 m/s or 12.4 ft/s) than summer (3.1 m/s or 10.2 ft/s), corresponding to increased average water velocities. Inorganic nutrients, salinity and pH were measured and compared to data from patch reefs in the Florida Keys to characterize the water quality and determine its suitability for coral recruitment and growth. Compared to Florida Keys patch reef waters, Durney Key water salinity averaged 12 parts per thousand (ppt) lower, pH was more variable with a lower minimum, and total phosphorus was much higher. Ceramic and porcelain recruitment tiles deployed to investigate larval recruitment were colonized by turf, coralline and macroalgae, with barnacles recruiting secondarily. Sediment cores revealed foraminiferal and molluscan assemblages characteristic of productive estuarine conditions. The Durney Key area was deemed not suitable for coral recruitment and growth on an inshore artificial substratum because of temperature extremes, potential for minimal water movement during summer, frequent occurrences of low salinity and pH, and high total organic phosphorus. Faunal studies demonstrated that the dominant recruitment reflects the common coastal/estuarine biota, which does not include reef-building corals.
228

Aquatic invertebrate fauna of Matapouri, Northland.

Pohe, Stephen Robert January 2008 (has links)
A study of the aquatic invertebrate communities from two locations (Location 1 and Location 2) within the Matapouri catchment in Northland, New Zealand, was conducted to assess community structure in differing local-scale habitats. Four data collection methods were utilised generating 33,058 adult or larval invertebrates. The sampling methods comprised benthic kick-sampling, sticky trapping, light trapping, and emergence trapping. For the sticky trapping and light trapping, sampling was carried out at three different sites (Sites 1–3) within each location. The sites were situated within three habitat types; native forest, native forest-fringe, and raupo wetland. Emergence trapping also commenced within the three sites, at both locations, but was discontinued after two months, due to the equipment being destroyed by consecutive flooding events (method described in Appendix 1). Benthic sampling was carried out within the Forest and Forest-fringe habitats. Benthic sampling, sticky trapping, and light trapping were carried out following a monthly schedule between June and November 2005. Conductivity, pH, and water temperature measurements were taken concurrently with benthic sampling on a monthly basis, while water velocity and substrate measurements were taken once to assist in habitat characterisation. Overall, 71 taxa were recorded by benthic sampling over the six month period, with a mean of approximately 30 taxa per site per month. In comparison with similar studies elsewhere in New Zealand, a figure of around 30 taxa per sample was high. The benthic macroinvertebrate fauna at all sites was dominated by Trichoptera (19 taxa), Diptera (16 taxa) and Ephemeroptera (10 taxa). This pattern of diversity is similar to that reported in other New Zealand studies. However, in contrast to previous studies, the leptophlebiid mayfly genus Deleatidium was not numerically dominant over the rest of the community, and other leptophlebiid genera (Acanthophlebia, Atalophlebioides, Mauiulus and Zephlebia) were equally represented, possibly reflecting niche partitioning between the groups. The genus Nesameletus was not recorded at any site, despite being one of the core mayfly species in New Zealand streams. The rare mayfly Isothraulus abditus was recorded at one of the forest locations. There are no published records of this species from Northland. Although acknowledged as another of the core New Zealand benthic taxa, the hydropsychid caddisfly Aoteapsyche was not recorded during the study. However, another hydropsychid, Orthopsyche, was commonly recorded, and these may be filling a similar niche to the Aoteapsyche genus. In contrast to the Trichoptera, Diptera, and Ephemeroptera, the Plecoptera fauna was relatively depauperate, probably reflecting the warmer climate of the region and lack of temperature-buffered spring-fed streams. Surprisingly, Zelandobius, a core New Zealand genus, was absent but is regularly recorded in Northland. A species of conservation interest, Spaniocercoides watti, currently recognised as a Northland endemic, was recorded in low numbers. There were no apparent trends in diversity or abundance of benthic invertebrates over time. Also, there were no significant differences in species diversity between the two locations. However, in many cases, taxa were more abundant at Location 2. This may have been due to steeper gradients at Location 2, and the consequent effects on substrate size and streambed stability, as all other physical factors appeared similar between locations. Although several significant differences of individual benthic taxa were recorded, no broad effect of habitat (sites) on species diversity was observable. However, at Location 2, abundances were significantly higher at Site 3 (Forest) compared to Site 2 (Forest-fringe). The reasons were uncertain, but may be attributed to higher retention of allochthonous organic materials, trapped by in-stream cover and larger substrates. Investigations of adult stages by sticky traps supported benthic results recording community compositions and abundances dominated by Trichoptera and Diptera. Plecoptera were poorly represented. Location 2 recorded higher abundances of taxa, particularly Ephemeroptera and Plecoptera. Investigations of adult stages by light traps however did not produce any statistically significant differences in abundances between sites, between locations, or between sites across locations, and it is believed to be due to limited sampling replication combined with some biases of light trapping. This study indicates that the aquatic invertebrate community at Matapouri is diverse but also reasonably representative. Several rare or uncommon insects inhabit the catchment. It is therefore important that Iwi and the local Landcare Group, who invited and supported this research, together with the Department of Conservation, continue their efforts in protecting these areas. The resident fauna have the capacity to restock areas downstream, which are intended to be improved and restored through sediment control and riparian management.
229

The Diversity of Macroinvertebrate Grazers in Streams: Relationships With the Productivity and Composition of Benthic Algae

McKenny, Claire, n/a January 2005 (has links)
There has been much interest in the last decade concerning the factors that influence diversity, especially how diversity and ecosystem processes may be linked. This study was based in small, cobble streams in South East Queensland. Its aim was to determine how the diversity and composition of consumers (the grazer guild) is influenced by both the production and composition of benthic algae, at different spatial scales. It also aimed to ascertain whether this response differs among grazer sub guilds with different dispersal capabilities. Ten sites in the Upper Brisbane and Mary catchments were sampled. The sites were selected to provide a range of productivity and composition. Grazers from these sites included snails and elmids, and larval mayflies, moths, and caddisflies. Grazer diversity and composition appeared to be structured by catchment scale influences, but environmental variables also affected which animals colonised patches and microhabitats (cobbles) within catchments. Primary productivity and algal composition could not be separated, with highly productive reaches also having a high cover of filamentous algal taxa. Grazer diversity displayed strongly positive, linear relationships with algal variables at the reach scale. It had a negative relationship with filamentous algae at the cobble scale, and a non-significant hump-shaped relationship with primary productivity. Survey data alone could not separate whether grazers were responding to habitat or food-related drivers, or to variations in productivity. Experimental manipulation of algal variables at the patch scale, using light and nutrients, also could not clearly uncouple the relationship between primary productivity and filamentous algal cover. Once reach scale variation was removed, grazer diversity displayed hump-shaped relationships with algal variables, including algal diversity. Much of this variation was due to patterns in mobile grazers, as sedentary grazers did not respond to algal variation at this scale. The density of the more mobile taxa showed similar patterns to those at the cobble scale (hump-shaped). A second field experiment was carried out in order to further investigate the responses of invertebrates to algal community composition at the cobble scale. Data from all three chapters suggested that as sites shifted to a dominance of filamentous algae, often with an associated increase in GPP, there was also a shift in the grazer community towards more sedentary grazers and away from the more mobile taxa. This also occurred at the cobble scale in the second experiment. The gut analysis and diet studies in the third chapter indicated that while many grazers consumed filamentous algae, it was not assimilated. This suggests that the preferences for sedentary taxa for cobbles and reaches dominated by filamentous algae are likely to be due to some other, possibly habitat-related, factor such as flow or predation refuge. The study provides a rare examination of relationships between primary productivity and consumer diversity in freshwater streams, and finds support for the pattern found in other systems of monotonic relationships of these two variables at large scales and hump-shaped relationships at smaller scales. It emphasises the importance of understanding other, potentially confounding, aspects of communities of producers, and investigates the possible roles of the most important of these (community composition) in structuring consumer communities in the small cobble streams of South-East Queensland.
230

Mapping Benthic Habitats for Representation in Marine Protected Areas

Stevens, Tim, n/a January 2004 (has links)
Virtually all marine conservation planning and management models in place or proposed have in common the need for improved scientific rigour in identifying and characterising the marine habitats encompassed. An emerging central theme in the last few years has been the concept of representativeness, or representative systems of Marine Protected Areas (MPAs). The habitat classification and mapping needed to incorporate considerations of representativeness into MPA planning must logically be carried out at the same scale at which management occurs. Management of highly protected areas occurs almost exclusively at local scales or finer, independent of the reservation model or philosophy employed. Moreton Bay, on Australia’s east coast, was selected for studies at the local scale to map and classify macrobenthic habitats. In a site scale (1 km) trial for the major habitat classification study, remote underwater videography was used to map and characterise an unusual assemblage of epibenthic invertebrates on soft sediments. The assemblage included congregations of the comatulid crinoid Zygometra cf. Z. microdiscus (Bell) at densities up to 0.88 individuals.m-2, comparable to those found in coral reef habitats. There was no correlation between the distribution of this species and commonly used abiotic surrogates depth (6 – 18 m), sediment composition and residual current. This site scale trial is the first quantitative assessment of crinoid density and distribution in shallow water soft-sediment environments. The high densities found are significant in terms of the generally accepted picture of shallow-water crinoids as essentially reefal fauna. The findings highlight the conservation benefits of an inclusive approach to marine habitat survey and mapping. Assemblages such as the one described, although they may be of scientific and ecological significance, would have been overlooked by common approaches to marine conservation planning which emphasise highly productive or aesthetically appealing habitats. Most habitat mapping studies rely solely or in part on abiotic surrogates for patterns of biodiversity. The utility of abiotic variables in predicting biological distributions at the local scale (10 km) was tested. Habitat classifications of the same set of 41 sites based on 6 abiotic variables and abundances of 89 taxa and bioturbation indicators were compared using correlation, regression and ordination analyses. The concepts of false homogeneity and false heterogeneity were defined to describe types of errors associated with using abiotic surrogates to construct habitat maps. The best prediction by abiotic surrogates explained less than 30% of the pattern of biological similarity. Errors of false homogeneity were between 20 and 62%, depending on the methods of estimation. Predictive capability of abiotic surrogates at the taxon level was poor, with only 6% of taxon / surrogate correlations significant. These results have implications for the widespread use of abiotic surrogates in marine habitat mapping to plan for, or assess, representation in Marine Protected Areas. Abiotic factors did not discriminate sufficiently between different soft bottom communities to be a reliable basis for mapping. Habitat mapping for the design of Marine Protected Areas is critically affected by the scale of the source information. The relationship between biological similarity of macrobenthos and the distance between sites was investigated at both site and local scales, and for separate biotic groups. There was a significant negative correlation between similarity and distance, in that sites further apart were less similar than sites close together. The relationship, although significant, was quite weak at the site scale. Rank correlograms showed that similarity was high at scales of 10 km or less, and declined markedly with increasing distance. There was evidence of patchiness in the distributions of some biotic groups, especially seagrass and anthozoans, at scales less than 16 km. In other biotic groups there was an essentially monotonic decline in similarity with distance. The spatial agglomeration approach to habitat mapping was valid in the study area. Site spacing of less than 10 km was necessary to capture important components of biological similarity. Site spacing of less than 2.5 km did not appear to be warranted. Macrobenthic habitat types were classified and mapped at 78 sites spaced 5 km apart. The area mapped was about 2,400 km2 and extended from estuarine shallow subtidal waters to offshore areas to the 50 m isobath. Nine habitat types were recognised, with only one on hard substrate. The habitat mapping characterised several habitat types not previously described in the area and located deepwater algal and soft coral reefs not previously reported. Seagrass beds were encountered in several locations where their occurrence was either unknown or had not previously been quantified. The representation of the derived habitat types within an existing marine protected area was assessed. Only two habitat types were represented in highly protected zones, with less than 3% of each included The study represents the most spatially comprehensive survey of epibenthos undertaken in Moreton Bay, with over 40,000 m2 surveyed. Derived habitat maps provide a robust basis for inclusion of representative examples of all habitat types in marine protected area planning in and adjacent to Moreton Bay. The utility of video data to conduct a low-cost habitat survey over a comparatively large area was also demonstrated. The method used has potentially wide application for the survey and design of marine protected areas.

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