SPEAKER ABSTRACTS Effect of Sediment Impacts of Opportunistic Multi-disciplinary Accumulation on the Algae on the Early Life Approach to Study Larval Productivity of Habitat- History of a Habitat- Development forming Seaweeds forming Fucoid Edwin AINLEY // The University of Tommaso ALESTRA // University of Andrea Alfaro // Auckland Auckland Canterbury University of Technology Dr Nick Shears, Dr Alwyn Rees // The David Schiel // University of Canterbury Tim Young, Annapoorna Ganesan, University of Auckland Adam Rusk, Le Viet Dung, Neil de Jong, A decline of extensive populations of Colleen Higgins, John Brooks, Chris Pook Increasing human population, coastal fucoid macroalgae has been reported // Auckland University of Technology development, infrastructure and land use worldwide as a result of human-driven changes are causing large amounts of coastal habitat degradation. Contributing One of the most enigmatic processes in sediment to be transported into adjacent to such declines may be the influence the lives of marine invertebrates is the marine ecosystems. Macroalgae are of opportunistic algae which respond development of larvae into juveniles. A often at the heart of these ecosystems, quickly to stresses such as nutrient wide range of strategies exists among and yet there is little information on the loading and warmer sea temperatures, species, which involve morphological, effect that sediment has on subtidal thereby outcompeting the early life physiological and behavioural changes macroalgal stands in New Zealand. This stages of fucoids. Here we examine the geared to enhance survival and study monitored the temporal and spatial interactions between early life stages of recruitment into adult populations. variability in sediment accumulation the intertidal fucoid Hormosira banksii and These rapid and complex changes are on Ecklonia radiata and Carpophyllum fast-growing, opportunistic green algae, associated with high energy requirements flexuosum at a range of sites throughout Ulva spp. Through a series of laboratory and elaborate sensory mechanisms that 2011, and determined the primary experiments, we test: 1) the impact of allow larvae to respond to their immediate environmental drivers responsible Ulva on the settlement of H. banksii environment. Even with these adapted for this. In addition we examined the zygotes; 2) the impact of Ulva on the rates evolutionary strategies, exceedingly effects of experimentally simulated of post-settlement survival and growth of high larval mortalities are a common sediment accumulation on the growth H. banksii germlings, under both normal occurrence in the marine environment and photosynthetic rates of E. radiata and increased levels of temperature and and within aquaculture settings. The and C. flexuosum for up to 11 days. nutrient concentration; 3) the interactions consequences of these high early larval The results showed that the amount of between the two species under grazing mortalities are vast, since they may sediment accumulating on seaweeds pressure of the abundant intertidal snail directly impact on the persistence and was temporally and spatially variable, and Lunella smaragdus. Ulva was facilitated by structure of wild populations and/or may primarily related to two environmental increased temperature and nutrients and result in significant financial constraints drivers: wave action and rainfall. The it negatively affected H. banksii by both for hatchery production. Thus, great maximum amount of sediment recorded impairing the settlement of the zygotes scientific interest has been placed on on E. radiata was 4.5mg cm-2 which was and by limiting the growth of germlings. the understanding of developmental estimated to reduce light levels by more Post-settlement survival of germlings was processes and the mechanisms that than 75%. Not surprisingly sediment not affected by competition with Ulva, underpin these dramatic changes. Within addition to E. radiata in the laboratory but there was an indication that this may the Aquaculture Biotechnology Group caused plants to lose weight, and caused decline with warmer waters. Both species at AUT, we have used traditional and bleaching, rotting and perforations on the were consumed by L. smaragdus, but a new techniques to investigate larval thalli. Subsequently this had detrimental preference for Ulva indirectly facilitated H. developmental processes for a range effects on photosynthesis, considerably banksii. These findings augment extensive of marine invertebrate species. Herein, reducing oxygen production of the plant. field-based research showing the effects we present some of the advances we Conversely, C. flexuosum was slightly of small, ephemeral understory species have achieved with this multi-disciplinary more tolerant of sediment accumulation. on biogenic habitat-formers and highlight approach. Furthermore, the results from By better understanding the the threat posed by their synergisms with these studies have been used to derive consequences that increased terrestrial degraded physical conditions, which are comparative analyses of strategies among sedimentation is having on natural now occurring in coastal ecosystems taxa. marine systems we can emphasise the throughout the world. importance of improved policies and land management practices to ensure the maintenance of this important life- supporting habitat. 58 19–23 August 2013 // Hamilton // AQUATIC SCIENCE AT THE INTERFACE CONFERENCE 2013 SPEAKER ABSTRACTS Overview of Current Fine-scale Data Present & Future Research on New Zealand Management of the New Applications of Remote Mangrove Ecosystems Zealand Commercial Paua Sensing of Water Quality in Fishery Rotorua Lakes Andrea Alfaro // Auckland Edward ABRAHAM // Dragonfly Mathew ALLAN // The University of University of Technology Science Waikato Kathy Campbell, Melissa Bowen, Christopher Knox David Hamilton, Brendan Hicks // The Lorna Strachan // The University of University of Waikato Auckland Management of the commercial paua Lars Brabyn Sebastian Leuzinger, Mark Duxbury // fishery has been hampered by lack of Auckland University of Technology information at an appropriate scale. The high spatial resolution of Landsat Cyril Marchand, Audrey Leopold // IRD, Since 2009/10, commercial fishers have satellite data and free availability of a New Caledonia begun using GPS loggers that record large image archive spanning more than their position when they are on the 40 years have made Landsat the sensor surface, and depth profiles when thay choice for monitoring inland water Temperate mangroves occupy large are underwater. These loggers provide a areas of northern coastal New Zealand. quality in small lakes. We developed an view of the fishery with unprecedented automated procedure for the retrieval Their ecological role is substantially spatial resolution. In this talk, we show different from their tropical counterparts, of chlorophyll a concentrations from preliminary results from the logger Landsat Enhanced Thematic Mapper which the great majority of mangrove programme and discuss how these data studies have focused on in the past. To imagery of Rotorua lakes. A total of may be used to indicate the status of the 106 Landsat 7 satellite images were alleviate this imbalance, the goal of the paua fishery. Mangrove Research Group supported by captured from 1999 to 2011. Image the Auckland University of Technology, processing routines included radiative Auckland University and the ‘Institut de transfer-based atmospheric correction, Recherche pour le développement’ in using 6sv (Second Simulation of the New Caledonia is to establish a highly Satellite in the Solar Spectrum). A novel interdisciplinary, long-term study site at algorithm was developed using symbolic Mangawhai Harbour Estuary. We will regression to predict chlorophyll a from provide comprehensive data covering visible reflectance of Landsat satellite all aspects of this temperate mangrove imagery. Bio-optical models were applied ecosystem, reaching from detailed to quantify the physical processes habitat mapping, hydrodynamics, responsible for the relationships between sedimentology, geochemistry to food web the reflectance used in regression analysis and mangrove ecophysiology. algorithms, and to examine possible For example, habitat maps will be sources of error. Results from this study established using ultralight aerial vehicles suggest that remote sensing provides with hyperspectral cameras. Further, the a valuable tool to assess temporal and nutrient-, water- and carbon cycles will spatial distributions of chlorophyll a. be characterised, using classic (C, N, P Estimated chlorophyll a concentrations analysis, stable isotope analysis) as well displayed considerable intra- and as state-of-the-art plant physiological inter-lake spatial variability, associated measurements (continuous stem with differences in lake morphology, radius, sap flow and leaf water potential hydrodynamics and chemistry. The future monitoring), and detailed studies of of the NASA Landsat series satellites had carbon pools and fluxes (e.g., eddy flux been assured with the recent launch of an tower, quantification of biomass and litter improved sensor known as Landsat 8. fall/decomposition). Food-web analysis will include detailed studies of diversity and abundance of meiofauna and fish. The results are expected to provide a solid scientific basis for future management decisions as well as detailed insight into all scientific aspects of temperate mangrove ecology. AQUATIC SCIENCE AT