Seabed mapping on Australia's southern margin: Baseline information for science and marine management

In ratifying the United Nations Convention on the Law of the Sea in 1994, Australia took responsibility for a marine jurisdiction that is more than 1.5 times the area of the landmass. While ownership of offshore resources provided under UNCLOS bestows certain rights (including exploitation), it also carries a range of obligations, including the protection and preservation of the marine environment. In order to fulfil these obligations, there is a key need for the acquisition and interpretation of baseline scientific information that will support the sustainable use and management of marine resources. The most critical baseline information required is the detailed depth and shape of the seafloor and the nature of the shallow substrate, particularly in high-use areas. Such information underpins the activities of virtually all government, industry and academic sectors working offshore, including petroleum and minerals, fisheries and mariculture, engineering, defence, transport, tourism and environmental management. Knowledge of the seabed is also critical for the issues of multiple sequential land use to be addressed offshore. The current state of such knowledge is extremely variable, with the highest quality 3-D seabed mapping data being available over only about 5% of the Australian marine jurisdiction. Certain basic data sets should be available to all organisations and individuals working in the marine environment. Description and discussion of the seabed mapping component of acquiring those data sets on the southern margin of Australia form the basis of this paper. Priorities for seabed mapping are suggested, e.g. the southeastern and somhwestern margins of the continent

Photosynthetic impact of hypoxia on in hospite zooxanthellae in the scleractinian coral Pocillopora damicornis

Shallow water coral reefs may experience hypoxia under conditions of calm weather doldrums. Anaerobic responses of endosymbionts (i.e. zooxanthellae) within Pocillopora damicornis coral colonies were tested using both slow and fast chlorophyll a fluorescence induction kinetics. Zooxanthellae were examined in hospite when exposed to control conditions (26°C, 200 μmol photons m-2 s-1, 100% air-saturation, 4 cm s-1 flow) and to 2 treatments of reduced air content (40 and 0%), achieved by controlling the N2:O2 ratio in water circulating at 2 cm s -1. Furthermore, the impact of water flow on photosynthesis was examined at 0% air saturation by turning off the flow entirely (0 cm s -1), thereby mimicking the environmental conditions of calm weather doldrums. Corals exposed to depleted air content (0 % with and without flow) showed a significant decrease (p < 0.001) in effective quantum yield (φPSII) in comparison with controls. Maximum quantum yield was significantly reduced when gas exchange was inhibited (0% without flow), whereas non-photochemical quenching (NPQ) was not affected. Fast polyphasic fluorescence transients of chlorophyll a fluorescence showed a significant increase in minimum dark-adapted fluorescence, F0, when corals were exposed to anaerobic conditions. Furthermore, an increase in the J peak (2 ms) corresponding to the reduction of the primary electron acceptor, QA, was observed in 0% air-saturation with flow. We found that the most sensitive parameters for detecting physiological change associated with hypoxia were φPSII using slow (pulse-amplitude modulation) fluorescence kinetics, as well as an increase in the O peak, φPo(electron transport efficiency before QA), and an elevation of the J peak on a double-normalised transient using fast (Plant Efficiency Analyser) induction kinetics. © Inter-Research 2005

Selection on testis size as an indicator of maturity in growing animals. II Correlated responses in reproductive rate

International audienc

Selection on testis size as an indicator of maturity in growing animals. I Direct and correlated responses in growth

International audienc

Robust Estimation for Linear Panel Data Models

In different fields of applications including, but not limited to, behavioral, environmental, medical sciences and econometrics, the use of panel data regression models has become increasingly popular as a general framework for making meaningful statistical inferences. However, when the ordinary least squares (OLS) method is used to estimate the model parameters, presence of outliers may significantly alter the adequacy of such models by producing biased and inefficient estimates. In this work we propose a new, weighted likelihood based robust estimation procedure for linear panel data models with fixed and random effects. The finite sample performances of the proposed estimators have been illustrated through an extensive simulation study as well as with an application to blood pressure data set. Our thorough study demonstrates that the proposed estimators show significantly better performances over the traditional methods in the presence of outliers and produce competitive results to the OLS based estimates when no outliers are present in the data set

Seasonal variation in the photo-physiology of homogeneous and heterogeneous Symbiodinium consortia in two scleractinian corals

Seasonal variation in the composition of the algal endosymbiont community and photophysiology was determined in the corals Pocillopora damicornis, which show high local fidelity to one symbiont type (Symbiodinium C1), and Acropora valida, with a mixed Symbiodinium symbiont community, comprising members of both clades A and C. The relative abundances of Symbiodinium types varied over time. A significant decline in symbiont densities in both coral species during the summer of 2005 coincided with a NOAA 'hotspot' warning for Heron Island. This also coincided with a relative increase in the presence and dominance of clade A in A. valida, particularly in sun-adapted surfaces. The effective quantum yield of Photosystem II (ΦPSII) suggested that sun-adapted surfaces of P. damicornis are more sensitive than shade-adapted surfaces to combined effects of higher temperature and irradiance in summer. Xanthophyll cycling was greater in P. damicornis than A. valida, irrespective of branch position and sampling time; this may be a mechanism by which P. damicornis compensates for its fidelity to Symbiodinium C1. Furthermore, xanthophyll de-epoxidation in P. damicornis symbionts was greater in sun-adapted than shade-adapted surfaces, correlating with non-photochemical quenching (NPQRLC). No variation was found in A. valida, indicating that resident symbiont communities may not have been physiologically compromised, perhaps as a result of changes in the composition of the Symbiodinium community consortia. © Inter-Research 2008

Light respiratory processes and gross photosynthesis in two scleractinian corals

© 2014 Schrameyer et al. The light dependency of respiratory activity of two scleractinian corals was examined using O2 microsensors and CO2 exchange measurements. Light respiration increased strongly but asymptotically with elevated irradiance in both species. Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes. Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range. P. decussata also harboured twice as many algal symbionts and higher total protein biomass compared to P. damicornis, possibly resulting in self-shading of the symbionts and/or changes in host tissue specific light distribution. Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont

Rapid photoprotection in sea-ice diatoms from the East Antarctic pack ice

Photoinhibition and D1 protein re-synthesis were investigated in bottom-dwelling sea-ice microalgal communities from the East Antarctic pack ice during early spring. Bottom-dwelling sea-ice microalgal communities were dominated by diatoms that exhibited rapid photoprotection when exposed to a range of different light levels (10 μmol photons m-2 s -1, 50 μmol photons m-2 s-1, 100 μmol photons m-2 s-1, and 200 μmol photons m-2 s-1). Photosynthetic capacity of photosystem II (PSII) dropped significantly over 3 h under 200 μmol photons m-2 s-1, but largely recovered when placed in a low-light environment (10 μmol photons m-2 s-1) for an additional 3 h. PSII repair rates increased with increasing irradiance, and the D1-protein pool remained steady even under high light (200 μmol photons m-2 s-1). Sea-ice diatoms showed a low intrinsic susceptibility to photoinactivation of PSII across all the light treatments, and a strong and irradiance-dependent induction of nonphotochemical quenching, which did not depend upon chloroplast protein synthesis, was also seen. These highly plastic organisms, once thought to be adapted to shade, are in fact well equipped to withstand rapid and relatively large changes in light at low temperatures with minimal long-term effect on their photosynthetic machinery. © 2010, by the American Society of Limnology and Oceanography, Inc