Cladophora glomerata is the dominant spring and summer epilithic macroalga in the lower Laurentian Great Lakes, and was a notorious nuisance prior to nutrient management of the early 1970s. It is an indicator of excessive nutrient supply and appears to be experiencing a resurgence in the nearshore of the lower Great Lakes. This thesis examines the ecology of C. glomerata in an urbanized location of Lake Ontario and addresses decadal scale environmental changes to the lake and their impact on this macroalga. A Cladophora growth model (CGM) was calibrated and validated to simulate attached and sloughed Cladophora biomass using two years of collected input data and independent measurements of Cladophora biomass. The CGM was used to hindcast Cladophora growth using multiplicative factors of seasonal minimal tissue phosphorus concentrations (QP) and seasonal mean nearshore light attenuation (KdPAR) of the early 1970s and 1980s relative to contemporary data. Cladophora QP in Lake Ontario is currently lower than in the early 1980s, resulting in reduced Cladophora biomass at all depths in the euphotic zone. KdPAR has also declined, most strongly since the mid-1990s, following Dreissena mussel invasion, driving an increase in macroalgal biomass between 3.5 and 10 m depth. Combining these effects, the CGM predicted that biomass is currently lower in Lake Ontario than in the early 1980s. However, increases in QP in this post-dreissenid mussel period are predicted to result in greater Cladophora proliferation than in previous decades due to increased nearshore water clarity. The in situ rates of primary production on Cladophora-dominated rocky substrata at 1m depth were measured through the spring and summer. Net primary production (NPP) was measured as change in dissolved inorganic carbon (using IRGA) in benthic incubation chambers flushed continuously with water. Incubations were of 15- 20 minutes duration, permitting measurements of productivity rates over diurnal and seasonal scales. Maximum biomass-specific net photosynthetic rates (PBmax) were highest in the spring and late-summer/fall (2.39, 1.98 mgC gDM-1 hr-1, respectively) and decreased to negative rates by early summer (−0.76 mgC gDM-1 hr-1). Directly measured rates of net primary production were simulated with the CGM. Simulated depth-integrated rates of Cladophora primary production were compared with published depth-integrated measurements of planktonic primary production from Lake Ontario. From the shoreline to the 12 m depth contour, the benthos was estimated to contribute 70% of the areal primary production. On a seasonal basis, attached macroalgae are an important component of the energy flux in the Lake Ontario nearshore. This phenology of Cladophora glomerata growing in the western end of Lake Ontario is also described. Based on internal stoichiometric ratios (C:P and N:P), and a positive correlation between the decrease in the biomass-specific maximum photosynthetic rate (PBm) and phosphorus quota (QP), Cladophora productivity at shallow depths was shown to be P limited. In addition, light attenuation through the Cladophora canopy was estimated to be 24.1 ± 3.3 (standard deviation) m-1 using paired light loggers deployed in situ. Acclimation to lower light levels through the Cladophora stand was demonstrated by significantly higher Cladophora chlorophyll concentrations at the base of the canopy. Decreases in Cladophora canopy cover in the summer resulted in increased PBm, even when QP remained near the minimal cell quota, indicating potential co-limitation of Cladophora productivity by light during peak standing crop. Cladophora growing at 1m depth was also shown here to be tolerant of high irradiance, with an average decline of less than 10% in Fv/Fm at during peak midday insolation, regardless of nutrient status or ambient water temperature. In conjunction with its role as a seasonally important nearshore primary producer, Cladophora appears to play a role as a seasonal nutrient regulator in the nearshore of Lake Ontario. The nutrient chemistry of nearshore lake water, Cladophora tissue, and a dominant tributary to western Lake Ontario were examined over the growing season of 2 years. As Cladophora grew and assimilated nutrients in the spring, total phosphorus (TP) and soluble reactive P (SRP) concentrations declined in the nearshore. Detachment and sloughing of Cladophora in the late summer was associated with increasing TP in the water column. These changes in nearshore nutrient concentrations were correlated with Cladophora phenology and not catchment loading. Nutrient loading from Oakville Creek was compared with the nutrient uptake of an adjacent Cladophora stand. The TP supply directly from the creek during the growing season was insufficient to meet the concentration of stored P in Cladophora tissue. It appears Cladophora is growing on P regulated by recycling within the lake, supporting the hypothesis that dreissenid mussels are sustaining Cladophora growth through recycling of TP in the lake. Cladophora remains P limited, however, such that increases in catchment loading would further augment its resurgence.

Oxygenic photosynthesis is responsible for virtually all of the biochemical production of organic matter in both marine and terrestrial ecosystems. Despite the large amount of research on phytoplankton, macroalgae have received less attention despite them being, on a per-area basis, one of the most productive ecosystems on earth. Furthermore, there has been a tendency of studies to measure primary production in single thalli, or monospecific stands. The lack of studies examining in situ production of whole assemblages using photorespirometry, as is common practice in soft-sediment systems, may be related to a lack of suitable apparatus. This research aimed to develop unique techniques and an apparatus for measuring primary production of intact macroalgal assemblages in laboratory and field conditions. Photorespirometry chambers were developed and tested on in situ macroalgal assemblages, giving information on the role of species identity, biodiversity, irradiance and community structure on overall primary production. Furthermore, the successful application of these methods was used to model annual primary production over local and regional scales, as well as the potential effects of human disturbance on production. In this study, photosynthesis-irradiance relationships (P-E curves) of intact intertidal algal assemblages showed no signs of saturation at high irradiance levels, as is typically seen in single species curves. Furthermore, diverse macroalgal assemblages showed a two-stage rise in production, with a significant enhancement of production at high irradiance. Evidence from this study suggests that the three-dimensional structure of natural assemblages, functional diversity and their interaction with a complex light environment is responsible for the unique P-E curves. The increased efficiency of light use in complex assemblages suggests an important role of species complmentarity in enhancing production with species diversity. This research also shows the potential consequences of disturbance on macroalgal assemblages, with the loss of several species causing a major decline in net production. The methods developed in this thesis have allowed simple modelling of annual rates of primary production and the parameters driving production of macroalgae over long time-scales. Respiration rates have a particularly large influence on production models and indicate that increasing temperature due to climate change could have significant consequences for net carbon fixation of macroalgae. This research gives valuable insight into the production of marine macroalgae and reinforces the notion that they are amongst the most productive systems on earth. These results revealed the importance of examining natural communities, as opposed to randomised assemblages and suggest a vital role of species diversity and community composition. Although there was no functional redundancy of the canopy forming species there did appear to be significant redundancy within the subcanopy assemblage. The identity of subcanopy species had little effect on production, but over longer temporal scales, as species come and go, they may help buffer the communities in terms of primary production. Furthermore, the relationship between biodiversity and ecosystem function (primary production), although driven by diversity, is moderated by resource levels. The complex relationship between irradiance, diversity and production shows the importance of resource levels in the enhancement of function with increasing biodiversity. Due to fundamental differences in terrestrial and marine systems, I was able to examine the effects of discrete levels of irradiance on production, which indicated an important role of complementary light use. This study represents advancements not only in the understanding of primary production in macroalgal assemblages, but also has implications for how diversity may enhance function in other autotrophic systems. The important role of enhanced efficiency of photon capture in multi-canopy layer communities may prove an essential process in ecosystems as diverse as macroalgal beds and tropical rain-forests.

Bermuda has one of the highest concentrations of cave systems of any country in the world, but as the resident human population and tourism expand, this unique habitat is becoming increasingly threatened by development and water pollution. A water quality assessment was performed in six of Bermuda’s anchialine cave pools during summer 2007. Vertical water profiles were collected at each site to determine temperature, salinity, dissolved oxygen, and pH levels throughout the water column. Each cave pool had its own unique hydrological patterns. Additionally, water samples were collected at the surface and at the maximum depth to determine the concentration of nitrate, nitrite, ammonium, phosphate, and urea in the water. Further samples were collected to establish the fecal bacteria content in the surface waters. High nitrate levels were measured in two of the cave pools, while unsafe bacterial levels were measured in three pools. In situ nutrient addition experiments were used to examine effects of nutrient enrichment on algae naturally occurring in the six cave pool. Initial assessments of the pools determined distribution of foliose species. Six algal species (Ulva sp., Caulerpa mexicana, C. racemosa, C. sertularioides, Halymenia floresii, and Cryptonemia sp.) inhabited multiple sites, but not all species occurred at all sites. Changes in the biomass of individual plants were recorded for 6 to 12 days in response to N (nitrate), P (phosphate), and NP additions. The effect of nutrient addition on increase in biomass was significant over a 6 day period for Ulva sp. and H. floresii. Intermediate to no growth was seen in C. mexicana and Cryptonemia sp. C. mexicana exhibited both increases and in biomass depending on the site. Cryptonemia sp. had low but positive growth. A significant decrease in biomass occurred with C. racemosa and C. sertularioides. Primary productivity was measured using the traditional light dark bottle method. Differences in net productivity and respiration may explain why some plants responded positively and other negatively to nutrient additions. Ulva sp. and H. floresii showed potential as bioindicators for groundwater quality.

Temporal variations of macroalgal cover and biomass (wet weight and dry weight) abundance and assemblage structure, and also the relationships between abiotic factors and assemblage structure, were studied in northeastern Taiwan (GPS: 25o06¡¦80¡¨N; 121o54¡¦60¡¨E¡^during 2001-2003. This study also investigated the causes affecting Gelidium natural resource and its management. Twenty-seven families with 67 species (5 families with 13 species for Chlorophyta, 3 families with 8 species for Phaeophyta, 19 families with 46 species for Rhodophyta) were recorded. The dominant species such as Pterocladiella capillacea and Polyopes polyideoides belong to temperate species. Macroalgal coverage, areal biomass, diversity, eveness and assemblage structure during 2001-2003 showed significant temporal changes with year and seasonal variations; however, the seasonal rhythm is changing between years. The seasonal pattern is different between 2001 and 2002/2003, biomass peaked in spring of 2002 and 2003. Pterocladiella capillacea, Polyopes polyideoides, Marginisporum crassissimum, Jania ungulate and Chondrus ocellatus contribute to temporal variations in assemblage structure. The results of multi-variate and uni-variate analysis suggest significant temporal variations in macroalgal assemblage structure in northeastern Taiwan, and the data from ANOSIM and SIMPER analysis demonstrated that the seasonal pattern was variable between years, in which it is coincident with seasonal variations in macroalgal abundance. Water temperature, summer high temperature, winter low temperature, nutrient and typhoon are attributable to temporal variations in macroalgal assemblage structure. Low temperature in winter, nutrient availability, and also typhoon restrict the natural resource of Gelidium in northeastern Taiwan; it is hypothesized that low P condition together with enhanced collection deep the decline of Gelidium resource, finally limiting the recovery of Gelidium population in next year. We found that the agar contents of Pterocladiella capillacea showed year and season variations with a negative relationship to biomass. Temporal fluctuations in agar contents was enhanced by low temperatures and high P but decreased by high N. Based on the observations, we conclude that over-collection in winter results in a decline of Gelidium resource in the coming years, thus it could be suggested that winter collection has to be controlled to maintain the sustainable utilization of Gelidium in northeastern Taiwan.

No description available.

Pyrolysis mass spectrometry (PyMS) is a rapid, automated analytical technique that is used for chemical and biological characterisation of organisms. It has been limited in its use outside the discipline of microbiology and has rarely been applied to the analysis of multi-cellular organisms. This study aimed to investigate the potential of using PyMS as a routine analytical tool to resolve problems in marine algal systematics. The technical constraints of PyMS were also examined. The effect of sample concentration proved to be an important consideration for the production of meaningful results. PyMS analysis of macroalgae from the order Fucales demonstrated that this technique was robust to the influence of environmental variability and challenged the assertion that it is limited to use as a phenotypic technique only. Characterisation of samples was also possible at the sub-species level. Experimentally induced variation among cultures of the diatom Skeletonema costatum, including silicate limitation, low salinity and reduced irradiance, was detectable by PyMS. PyMS is subject to technical limitations including day to day variability among spectral data and does not produce a permanent classification. This study showed that PyMS is a highly discriminatory, sensitive technique that is capable of resolving chemical and biological variability among marine algae.

As anthropogenically-forced ocean temperatures continue to rise, the physiological response of marine macrophytes becomes exceedingly relevant. The Red Sea is a semi-isolated sea- the warmest in the world (SST up to 34°C) - already exhibiting signs of rapid warming rates exceeding those of other tropical oceans. This will have profound effects on the physiology of marine organisms, specifically marine macrophytes, which have direct influence on the dynamic carbonate system of the Red Sea. The aim of this paper is to define the physiological capability and thermal optima and limits of six ecologically important Red Sea macrophytes- ranging from seagrasses to calcifying and non-calcifying algae- and to describe the effects of increasing thermal stress on the performance and limits of each macrophyte in terms of activation energy. Of the species considered, Halophila stipulacae, Halimeda optunia, Halimeda monile and Padina pavonica thrive in thermal extremes and may be more successful in future Red Sea warming scenarios. Specifically, Halimeda opuntia increased productivity and calcification rates up to 38°C, making it the most thermally resilient macrophyte. Halophila stipulacae is the most productive seagrass, and hence has the greatest positive effect on Omega saturation state and offers chemical buffer capacity to future ocean acidification.

A consequence of eutrophication in the Baltic Sea is growth of algae that accumulates in the coastal areas and beaches. Dense algal mats may cause anoxia or hypoxia and greatly reduce the recreational value of the area. Algae also functions as hyper accumulators of heavy metals and their metal levels may become toxic to higher trophic levels. The project Wetlands, Algae and Biogas (WAB) aims at removing algal beach cast for commercial use in biogas production and further use of the fermentation residues as fertilizer. Collection of algae would remove both nutrients and heavy metals from the Baltic Sea but leave us with large amounts of algae containing heavy metals. A concern for the biogas production based on these Baltic algae is the effects from the heavy metals, during fermentation, in the residues and the use of them as fertilizer. A literature review shows that the levels of heavy metals should not inhibit the biogas production but during the fermentation there is a loss of (48%) biological material and the metals are concentrated in the residues. Samples of algae from Trelleborg (SE) show higher concentrations of cadmium (Cd) than algae from Poland (PL). The Swedish residues border or surpass the legislative amount of heavy metals that are allowed to be applied to arable land in Sweden. This is both due to the higher concentrations of heavy metals and the differences between European and Swedish legislation. To use the residues as fertilizer detoxification is required, mainly for Cd in Sweden. There are effective methods, chemicals and ion exchangers (70-80%), for removing heavy metals from organic leachate. But these methods lack testing on a large scale, the costs and the environmental aspect of these methods on tons of algae per year are unknown. Co-fermentation with a suitable substrate would dilute the heavy metal concentration and could reduce possible problems such as hydrogen sulfide accumulation in the biogas. Another possible pathway for dealing with the heavy metal rich residues is as fertilizer for non-food crops such as the biofuel species willow (Salix). Willow is a fast growing tree that is a known accumulator of heavy metals and can be used as a remediation for contaminated soil. Based on the metal concentrations and respective legislation, estimations of 20 000 ha of willow for Trelleborg and 400 ha for Sopot beach (PL) is needed to process harvested algae. / Wetlands, Algae and Biogas (WAB)

Seagrass, mangrove, saltmarshes and macroalgae - the coastal vegetated habitats, offer a promising nature-based solution to climate change mitigation, as they sequester carbon in their living biomass and in marine sediments. Estimation of the macrophyte organic carbon contribution to coastal sediments is key for understanding the sources of blue carbon sequestration, and for establishing adequate conservation strategies. Nevertheless,identification of marine macrophytes has been challenging and current estimations are uncertain. In this dissertation, time- and cost-efficient DNA-based methods were used to fingerprint marine macrophytes and estimate their contribution to the organic pool accumulated in blue carbon habitats. First, a suitable short-length DNA barcode from the universal 18S gene was chosen among six barcoding regions tested, as it successfully recovered degraded DNA from sediment samples and fingerprinted marine macrophyte taxa. Second, an experiment was performed to test whether the abundance of eDNA represents the content of organic carbon within the macrophytes; results supported this notion, indicating a positive correlation (R2 = 0.85) between eDNA and organic carbon. Third, using the chosen barcode, eDNA of marine macrophyte was identified from sediments of seagrass meadows and mangrove forests in the Arabian Red Sea, to further estimate contributions to the organic carbon pools. Estimations based on eDNA were compared against estimations of organic carbon based on stable isotope analyses from the same sediments; results from both methods were similar. In addition, this research provided the first quantitative evidence of the contribution of macroalgae to coastal and oceanic carbon pools. Hitherto, macroalgae have been ignored in blue carbon assessments because their fingerprinting was challenging and there was no evidence of their carbon export. The results of this dissertation demonstrate that eDNA offers an unprecedent taxonomic discrimination, and resolve the contribution of marine macrophytes to the organic pools in blue carbon sediments.

Ocean acidification has the potential to profoundly affect marine ecosystems before the end of this century, but there are large uncertainties on its effects on temperate benthic communities. Volcanic CO2 seeps provide an opportunity to examine and improve our understanding of community responses to ocean acidification. In this thesis, two Mediterranean CO2 seeps (Methana in Greece and Vulcano in Italy) were used to investigate the responses of macroalgae and their epifaunal communities to increased CO2. Changes in plant-herbivore interactions at elevated CO2, as well as adaptation potential of dominant macroalgae and responses of macroalgae and epifauna to concurrent exposure to elevated CO2 and copper pollution, were also examined. Firstly, I determined that volcanic seeps off Methana (Greece) are suitable for ocean acidification studies as they do not have confounding gradients in temperature, salinity, total alkalinity, nutrients, hydrogen sulphide, heavy metals or wave exposure. Calcifying macroalgae abundance decreased as CO2 increased both at Methana and at Vulcano, while fucoid algae seemed to benefit from elevated pCO2 levels. Seasonality greatly affected macroalgal responses to increasing CO2, according to the annual cycles of dominant species. Epifaunal communities of dominant fucoid algae changed at elevated pCO2 as well, with calcifying invertebrates decreasing and polychaetes increasing near the seeps. Herbivore control of macroalgal biomass did not greatly change at elevated pCO2 levels, as limpets had a minor role in controlling macroalgal biomass off Vulcano (Italy) and sea urchins were replaced by herbivorous fish near seeps off Methana. The two macroalgal species examined for signs of long-term acclimatisation (Cystoseira corniculata (Turner) Zanardini and Jania rubens (Linnaeus) J.V.Lamouroux) to ocean acidification using reciprocal transplants did not appear to have permanently acclimatised to elevated pCO2 levels, but changed their physiology in four to nine months depending on the local environment. Furthermore, when exposed to a 36-hour copper pulse at elevated pCO2 levels both seaweed species accumulated more copper in their tissues compared to those exposed to copper in reference pCO2 conditions, and this resulted in altered epifaunal assemblages on C. corniculata. These observations suggest that benthic communities will significantly change as CO2 levels increase, and that long-term acclimatisation is not likely to play a significant role; this would have profound consequences for benthic ecosystems and the services they provide.