This study is to investigate macroalgal community in the intertidal regions of Nanwan and Homei in 2001. Similarity between Nanwan and Homei is 0.12-0.27, indicating two different communities. Biomass in Nanwan (1016.8 gWWt¡Dm-2) is higher than in Homei (709.50 gWWt¡Dm-2). DIN is >1.0 £gM and DIP is >0.1£gM both in Nanwan and Homei. Thus, nutrition is not a limiting factor for the macroalgae growth.

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This study involved the development and evaluation of a number of biomonitoring techniques for use with members of the Ulvaceae, Enteromorpha intestinalis (L.) Link, and Viva iactuca (L.). The techniques included both previously established ones and those which required development. The two main procedures developed for these algae were the neutral red retention technique (making use of a vital stain) and the ion leakage Health Index (based upon electrolyte leakage). Following optimisation both were used to produce quantitative structure-activity relationships (QSARs) for a series of n-alcohols using log Kow as the physicochemical parameter. The resultant QSARs were statistically indistinguishable with line equations of -0.88 log Kow + 2.87 and -0.95 log Kow + 2.83 respectively, with r values of 0.98, suggesting that both reflect the same non-specific narcotic effect on membrane integrity. However the neutral red retention technique was less useful than the Health Index with low reproducibility and is therefore unsuitable for use as an environmental biomonitor. The effects of other compounds with specific modes of action were established using the ion leakage technique, the high toxicity of the antifouling compound tributyltin being reflected in the Health Index. Further development of the ion leakage technique involved inductively coupled - plasma mass spectrometry (ICP/MS) in the identification of ions lost during leakage. Synergistic toxicity was investigated exposing the algae to UV light and anthracene, simulating photo-induced toxicity. No photo-induced toxicity was observed although UV exposure did reduce the Health Index. An environmental assessment was carried out for algae from clean sites and organically and inorganically polluted sites, comparing the Health Index with other measures of health and bioaccumulation data. A long term study of a clean site showed the algal Health Index to be influenced by seasonally dependent physical parameters, but reflected reduced health in algae exposed environmentally to organic pollutants. Algae exposed to long term heavy metal pollution in the Fal Estuary had 'normal',. Health Indices, however chlorophyll fluorescence induction techniques did highlight a reduced photosynthetic efficiency in these algae. The ion leakage technique has potentially a wide application in field and laboratory based biomonitoring and direct toxicity studies. Chlorophyll fluorescence analysis was also shown to be useful although it requires further investigation and evaluation.

Temporary changes in macroalgal abundance, percentage cover and areal biomass were surveyed on Nanwan (GPS: 21o56'00'N; 120o50'10'E) and Tiaoshi (GPS: 21o55'30'N; 120o 50'40'E) reefs (Kenting, Taiwan, Republic of China), during 1999-2000. Community structure and areal biomass showed significant changes in time and the maximal biomass was observed during March-April due to Sargassum spp. at Nanwan and Codium spp. at Tiaoshi. The maximal total areal biomass is not different between two years for Nanwan but significantly different for Tiaoshi mainly due to a marked biomass of Codium edule during 2000. Eutrophication on Nanwan and Tiaoshi reefs is the main cause for macroalgal blooming. Tissue composition analysis, nutrient enrichment and starvation treatments, bioassay and in situ extracellular alkaline phosphatase activity determination showed that growth of Sargassum duplicatum, Codium edule and Ulva latuca were limited by phosphorus during the early growth period while nitrogen during the fast growth period. Growth of Enteromorpha linza, Gracilaria coronopifolia and Laurencia papillosa were limited by phosphorus. Water temperature is the factor affecting the time for the start of development of young shoots and also for the peak of areal biomass and subsequent die-off of thallus. This investigation suggests that the reduction of water nutrient levels is an effective way in the retardation of over-growth of macroalgae on Nanwan and Tiaoshi reefs.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Dentre os recursos oriundos do mar, as macroalgas destacam-se como as de maior aproveitamento industrial. A sua abundÃncia e diversidade as tornam fontes de matÃria-prima para uma infinidade de produtos de uso humano e animal, alÃm dos benefÃcios ambientais resultantes da atividade algal na forma de O2 atmosfÃrico, remoÃÃo de nutrientes da Ãgua, modulaÃÃo climÃtica, combustÃveis fosseis e tambÃm na colheita de organismos que se alimentam das algas. A carcinicultura depende diretamente da boa qualidade da Ãgua para obter resultados satisfatÃrios de produÃÃo, portanto manter a qualidade do efluente da carcinicultura significa perpetuar a atividade. As macroalgas utilizam os nutrientes absorvidos para seu crescimento, enquanto contribuem com o melhoramento da qualidade ambiental dos ecossitemas aquÃticos. EspÃcies do gÃnero Gracilaria destacam-se pela capacidade de absorver rapidamente grandes quantidades de nutrientes dissolvidos orgÃnicos e inorgÃnicos. Neste trabalho objetivou-se avaliar a remoÃÃo de nutrientes da Ãgua de efluente de carcinicultura por macroalgas marinhas G. birdiae, a fim de fornecer informaÃÃes para um possÃvel cultivo integrado entre as espÃcies Litopenaeus vannamei e Gracilaria birdiae. Para isso, foram utilizados 25 recipientes onde foram distribuÃdos, aleatoriamente, 5 tratamentos com 5 repetiÃÃes, contendo 5, 10, 15 e 20 g de algas em 3 L de Ãgua de efluente de carcinicultura e ainda um controle sem algas. Este procedimento foi realizado com iluminaÃÃo constante e ainda com fotoperÃodo de 12h de claro e escuro, sendo tambÃm verificado a resistÃncia dos animais a situaÃÃo de dÃficit de oxigÃnio e o aporte de nutrientes para a Ãgua de cultivo dos animais. Cada experimento durou duas semanas e os resultados mostraram que a alga G. birdiae tem capacidade de retirar da Ãgua do efluente da carcinicultura em um curto perÃodo de tempo e em quantidades satisfatÃrias amÃnia e fÃsforo e ainda manter, sob iluminaÃÃo, concentraÃÃes suficientes de oxigÃnio na Ãgua. / Among marine resources, seaweeds have emerged as the one which have the largest industrial use. Their abundance and diversity make them a great source of raw material for countless products for human and animal use. More over seaweeds have a widely environmental importance, regarding to the atmospheric O2, water nutrients removing, fossil fuels, and also on the harvest of animals that eat marine algae. Shrimp culture is directly dependent on a good water quality for satisfactory production, therefore maintain the quality of shrimp farms effluent means to perpetuate the activity. Seaweeds absorb nutrients from the water and use them for their growth, while contribute to the environmental improvement of aquatic ecosystems. Gracilaria species stand out for the ability to quickly absorb large amounts of dissolved nutrients, not only organic, but also inorganic nutrients. This study aimed to evaluate the nutrients removal from the effluent water from a shrimp farm by the seaweed G. birdiae, in order to provide information for a possible integrated shrimp (Litopenaeus vannamei) and seaweed (G. birdiae) culture. For this, we used 25 containers, randomly distributed, with five treatments and five replications of 5, 10, 15 and 20 g of seaweed in 3 L of the effluent water from shrimp farm plus a control without seaweed. These procedures were performed with constant illumination and with a 12h light and dark photoperiod. The animals resistance of to periods of low oxygen, and the nutrients input generated by cultured animals have been checked. Each experiment lasted two weeks and the results showed that the alga G. birdiae has the capacity to withdraw from the shrimp farm effluent a satisfactory amount of ammonia and phosphorus in a short period of time, and still maintain, under illumination, sufficient concentrations of oxygen in the water. LISTA DE

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.