Eutrophication due to enhanced nutrient concentrations can affect marine communities by altering the species composition of macroalgae and marine invertebrates, where certain species have shown tendencies to increase. The aim with this study was to assess how the species composition changed in relation to the distance from a nutrient enriched stream discharge. The study was conducted in an area with rocky shores and Fucus vesiculosus as the dominant alga, and also included the mouth of the eutrophic stream Kvarnabäcken. Macroalgae and invertebrate abundance was examined in eight locations (including an unaffected reference location) at different distances from the mouth of Kvarnabäcken. The concentrations of total nitrogen and total phosphorus were measured in the marine locations as well as in the stream. Although Kvarnabäcken displayed elevated nutrient concentrations, no distinct nutrient gradient was detected in the marine locations due to distance from the stream. The abundance of invertebrates and macroalgae varied to some extent in the locations, where the location in the immediate mouth area showed most differences, which contributed to the conclusion that the direct impact of nutrient discharge is limited. Although there are aspects indicating that the alterations in animal and algae abundance are consequences of nutrient discharge, other factors that regulate community composition must be considered when evaluating eutrophication in marine communities. / Övergödning kan påverka marina samhällen genom att artsammansättningen av makroalger och marina evertebrater ändras till följd av förhöjda närsalter, bland annat genom att vissa arter tenderar att öka i förekomst. Syftet med denna studie var att undersöka om artsammansättningen av marina evertebrater förändrades i relation till avståndet från ett utsläpp från en bäck med förhöjda närsaltkoncentrationer. Studien utfördes i ett område med klippiga stränder och Fucus vesiculosus som den dominerande algen och inkluderade även mynningen av den övergödda bäcken Kvarnabäcken. Förekomst av makroalger och evertebrater undersöktes i åtta lokaler (en opåverkad referenslokal inkluderad) längs kusten på varierande avstånd från bäcken. Koncentrationerna av totalkväve och totalfosfor mättes i de marina lokalerna och i bäcken. Trots att Kvarnabäcken visade höga halter av närsalter, visade inte resultatet någon tydlig näringsgradient från bäcken, medan det fanns en antydan till förändrad förekomst av evertebrater och alger i lokalerna. Lokalen närmast utsläppet skiljde sig något från övriga, vilket kan indikera att den direkta påverkan av näringstillförsel kan vara begränsat. Därtill är det viktigt att understryka att även om skillnader i förekomst av evertebrater och alger i lokalerna kan bero på närsalter från bäcken måste övriga faktorer tas hänsyn till vid undersökningar av marina samhällen.

Fatty acid (FA) analysis is a powerful ecological tool for examining trophic relationships among marine organisms. Its application in benthic food webs may be limited because many benthic organisms consume a highly mixed diet, and FA metabolism of benthic invertebrates may obscure dietary markers. This thesis examines the use of FA as dietary tracers for studying the diets of benthic invertebrates and the fate of primary production in rocky subtidal food webs. In Chapter 2, I review the use of FA for studying benthic marine food webs, and suggest that field studies using FA analysis should also include data from controlled feeding experiments, gut contents, or stable isotope analysis to provide more reliable results. In Chapter 3, I compare FA composition among sea urchins fed four natural algal diets in a controlled feeding study. These sea urchins substantially modified their dietary FA but differed in their overall FA composition according to diet. In Chapter 4, I use FA to trace the invasive alga Codium fragile ssp. fragile and the native kelp Saccharina longicruris through two trophic transfers in an experimental food web. Substantial signal attenuation occurred with each trophic transfer, suggesting that FA analysis may be of limited use for tracing benthic primary producers in field studies. In Chapter 5, I use FA in conjunction with stable isotope analysis and gut contents analysis to investigate the contribution of detrital kelp to the diet of sea urchins in habitats adjacent to kelp beds. FA analysis was unable to distinguish among sea urchins at different distances from the kelp bed, but the results of all analyses indicated that the availability of kelp detritus declines with distance from the kelp bed, and that sea urchins in low-productivity habitats rely on both kelp detritus and benthic diatoms. In Chapter 6, I summarize the overall findings and suggest experimental and statistical methods to address some of the problems associated with using FA analysis to study trophic relationships in benthic food webs.

No description available.

No description available.

Dendritic stream networks are inherently spatially and hierarchically structured, but the effects of this structure on stream communities are largely unknown. My aim was to investigate spatial patterns in stream networks using extensive spatial sampling of both adult and benthic macroinvertebrates in four stream networks on the West Coast of the South Island, New Zealand. Using spatial modelling and analyses, I answered questions about appropriate spatial measurements to capture ecological processes in stream networks, metacommunity processes at different scales in space and time, and how local and regional processes interact to structure metacommunities in stream networks. Spatial eigenfunction analyses showed that distance measures that explained most variance in stream macroinvertebrate communities were stream distance and weighted stream distance measures. They performed better than Euclidean distance to measure spatial structure that is ecologically relevant to stream network communities. The spatial pattern of benthic stream macroinvertebrates was stable over time, whereas community composition changed significantly, as shown by space-time interactions modelled by MANOVA-like redundancy analysis. Thus, spatial processes structuring stream metacommunities remained constant, in agreement with neutral model predictions. Network-scale properties, particularly flood disturbances, influenced the relative importance of spatial and environmental variation in stream network metacommunities. Additionally, quantile regression indicated that three key variables, habitat size, isolation and local habitat conditions, jointly limited community structure in stream networks, providing empirical support for both island biogeography and metacommunity theories. My study indicated that spatial structuring has an important influence on stream macroinvertebrate communities. The results contribute to broader ecological theory and understanding of community assembly by relating empirical results to theoretical predictions. In particular, they advance understanding of spatial processes in stream networks. The research also highlights a number of new methods, which were successfully applied to stream systems to elucidate complex spatial patterns.

Studies were undertaken to evaluate the potential of random amplified polymorphic DNA (RAPD) to detect DNA effects (including DNA damage and mutations) in aquatic invertebrates, following their exposure to a variety of environmental contaminants under laboratory conditions. After rigorous optimisation of the RAPD method, the protocol, which used a high annealing temperature (50"C for 10-mer primers), was found to generate good-quality DNA profiles from groups of organisms belonging to the bacterial, plant and animal kingdoms. The RAPD method was initially used to detect benzo(a)pyrene [B(a)P] and copper-induced DNA effects in the water flea Daphnia magna and ultraviolet-mediated DNA effects in the marine alga Palmaria palmata. The results clearly showed that changes occurred in RAPD profiles obtained from the exposed populations when compared to controls. In these studies, the effect of the genotoxins at higher levels of biological organisation (e.g. Darwinian parameters and/or fitness parameters) were also investigated and were compared with genomic DNA template stability (GTS), a qualitative index representing clear changes in panems compared to control RAPD profiles. The results from these experiments revealed that GTS could be more sensitive than growth parameters and showed at least equal or even greater sensitivity than other measures of fitness. Changes in RAPD profiles were believed to be the result of DNA effects, namely adduct formation, DNA breakage, oxidative damage and mutations and possibly other effects (e.g. variation in gene expression). Nevertheless, the nature and amount of DNA effects could only be speculated because diverse events may induce the same category of changes (i.e. variation in band intensity, appearance of bands, and disappearance of amplicons) in RAPD patterns. Further studies confirmed that RAPD had the potential to qualitatively detect oestrogen and xeno-oestrogen -induced DNA effects in barnacles. Additional experiments emphasised that oxygen radicals and variation in gene expression may induce significant changes in RAPD profiles. To further understand the effects of DNA lesions and mutations on RAPD patterns, individual types of DNA damage were created in vitro. The results clearly indicated that BaP DNA adducts, DNA photoproducts. and DNA breakages had significant effects on RAPD profiles but that diverse types of DNA damage may induce the same category of changes in RAPD patterns which render the interpretation of the results difficult. It was also concluded that mutations could be detected provided they do not arise in a random fashion. Finally, an attempt was made to determine the kinetics of DNA damage and DNA repair and whether changes in patterns obtained from B(a)P exposed Daphnia magna could be transmitted to successive generations. This strategy was developed to distinguish between mutations and DNA damage. The results showed that some bands obtained from the exposed populations were transmitted to the first and/or second generation but not to the third. It was concluded that the transmission of modified genetic material to the offspring was more likely to be the result of large genomic rearrangements and/or base methylation (epigenetic processes) rather than point mutations. In conclusion, the results presented in this research project show the potential of the RAPD assay as a useful method for the qualitative assessment of DNA effects including genotoxicity and changes in gene expression. The main advantage of this technique is that it can be applied to any species without requiring any information about the nucleotide sequence. In the field of ecogenotoxicology, its main advantage lies in its sensitivity and speed to detect a wide range of DNA damage including DNA breakage, DNA adducts, oxidative damage as well as mutations (including point mutations and large rearrangements). On the other hand, RAPD only allows a qualitative assessment of the DNA effects and the nature of the changes occurring in profiles can only be speculated. Finally, a great deal of further experimentation and validation are required in order to assess the applicability of the technique to a variety of other species and pollutants, particularly under field conditions.

No description available.

The responses and morphology of nine sound-sensitive interneurons are described in the cricket Teleogryllus oceanicus. Each of the neurons receives direction-specific input in the prothoracic ganglion, and each projects at least one interganglionic axon. Five of the neurons respond best to high frequencies ($>$10 kHz); four are most sensitive to low frequencies (3-10 kHz). Responsiveness to model calling songs was examined in addition to testing sensitivity to wind and light. Anatomical observations reveal that seven of the neurons receive auditory input via polysynaptic pathways, and that at least five of the neurons have morphology consistent with them providing input to mesothoracic motor neurons which are involved in behavioral responses to sound. Correlations between structure, topographic organization, and spectral sensitivity were found. The structure of one previously identified, auditory neuron was examined and found to change during late post-embryonic life. This represents a novel developmental pattern.

Assessing time of death is a notoriously difficult, yet critical component of coronial death investigations. Forensic entomoloy can provide reliable death time estimates using knowledge of local carrion insect species ecology and larval development times. However, inadequate data are available for Victoria, and thus forensic entomology techniques cannot be fully exploited in this jurisdiction. This study aimed to provide data that will enable a basic forensic entomology service to be provided in Victoria, as well as initiate further development of forensic entomology in this state. There are few quantitative data available on the carcass colonisation patterns of blowflies and flesh flies, however these data are forensically valuable. Colonising maggots form feeding masses that generate heat, and therefore speed the growth of their members. This should be integrated into larval age estimates, however there is little knowledge of the factors controlling mass size and persistence. Additionally, it is important to understand more clearly the behaviour of larvi- and ovipositing female flies since qualitative assessments of abnormal colonisation patterns may be used to indicate pre-mortem trauma to a body.

Riparian buffers along stream margins have been widely adopted as a management strategy to mitigate the adverse effects of plantation forestry on stream ecosystems. However, the efficacy of these riparian buffers can be jeopardised by variations in width, length, and vegetation which can range from native and exotic scrub (including bracken, gorse, broom and blackberry) to remnant beech forest. This thesis investigates the influence of riparian vegetation age and composition, on stream ecosystems within exotic pine plantations. Initially, a survey of 50 streams within pine forests of various ages and riparian composition was conducted at sites from mid-Canterbury to Hanmer Springs over the summer of 2004-2005. Additionally, terrestrial subsidies were compared between young pine, mature pine and indigenous forest streams to ascertain differences or similarities between vegetation types. A range of physico-chemical and biological characteristics were recorded, while vegetative age and composition with catchment, riparian buffer and reach scales were determined using GIS. Forestry activities were found to vary temporarily and tended to adversely impact upon streams where riparian buffers were narrow and lacked indigenous vegetation. Stream instability and sedimentation were consistently higher in catchments lacking indigenous riparian vegetation, and more markedly so in recently harvested catchments compared with more mature forests. Streams dominated by pine forests had finer substrates with higher water temperatures and levels of turbidity, while those dominated by indigenous forest had coarser substrates, higher flows and dissolved oxygen levels, and less in-stream debris. Benthic community composition was similar among sites, although taxonomic richness, EPT diversity, and invertebrate abundances were enhanced by indigenous riparian vegetation.