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Geng X.,New Jersey Institute of Technology | Boufadel M.C.,New Jersey Institute of Technology | Lee K.,Oceans and Atmosphere Flagship | Abrams S.,Langan Inc. | Suidan M.,University of Applied and Environmental Sciences
Water Resources Research | Year: 2015

The aerobic biodegradation of oil in tidally influenced beaches was investigated numerically in this work using realistic beach and tide conditions. A numerical model BIOMARUN, coupling a multiple-Monod kinetic model BIOB to a density-dependent variably saturated groundwater flow model 2-D MARUN, was used to simulate the biodegradation of low-solubility hydrocarbon and transport processes of associated solute species (i.e., oxygen and nitrogen) in a tidally influenced beach environment. It was found that different limiting factors affect different portions of the beach. In the upper intertidal zone, where the inland incoming nutrient concentration was large (1.2 mg N/L), oil biodegradation occurred deeper in the beach (i.e., 0.3 m below the surface). In the midintertidal zone, a reversal was noted where the biodegradation was fast at shallow locations (i.e., 0.1 m below the surface), and it was due to the decrease of oxygen with depth due to consumption, which made oxygen the limiting factor for biodegradation. Oxygen concentration in the midintertidal zone exhibited two peaks as a function of time. One peak was associated with the high tide, when dissolved oxygen laden seawater filled the beach and a second oxygen peak was observed during low tides, and it was due to pore oxygen replenishment from the atmosphere. The effect of the capillary fringe (CF) height was investigated, and it was found that there is an optimal CF for the maximum biodegradation of oil in the beach. Too large a CF (i.e., very fine material) would attenuate oxygen replenishment (either from seawater or the atmosphere), while too small a CF (i.e., very coarse material) would reduce the interaction between microorganisms and oil in the upper intertidal zone due to rapid reduction in the soil moisture at low tide. © 2015. American Geophysical Union. All Rights Reserved. Source


Farley J.H.,Oceans and Atmosphere Flagship | Davis T.L.O.,Oceans and Atmosphere Flagship | Bravington M.V.,Digital Productivity Flagship | Andamari R.,Institute for Mariculture Research and Development | Davies C.R.,Oceans and Atmosphere Flagship
PLoS ONE | Year: 2015

Knowledge of spawning behaviour and fecundity of fish is important for estimating the reproductive potential of a stock and for constructing appropriate statistical models for assessing sustainable catch levels. Estimates of length-based reproductive parameters are particularly important for determining potential annual fecundity as a function of fish size, but they are often difficult to estimate reliably. Here we provide new information on the reproductive dynamics of southern bluefin tuna (SBT) Thunnus maccoyii through the analysis of fish size and ovary histology collected on the spawning ground in 1993-1995 and 1999-2002. These are used to refine previous parameter estimates of spawning dynamics and investigate size related trends in these parameters. Our results suggest that the small SBT tend to arrive on the spawning ground slightly later and depart earlier in the spawning season relative to large fish. All females were mature and the majority were classed as spawning capable (actively spawning or non-spawning) with a very small proportion classed as regressing. The fraction of females spawning per day decreased with fish size, but once females start a spawning episode, they spawned daily irrespective of size. Mean batch fecundity was estimated directly at 6.5 million oocytes. Analysis of ovary histology and ovary weight data indicated that relative batch fecundity, and the duration of spawning and non-spawning episodes, increased with fish size. These reproductive parameter estimates could be used with estimates of residency time on the spawning ground as a function of fish size (if known) and demographic data for the spawning population to provide a time series of relative annual fecundity for SBT. © 2015 Farley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source


News Article
Site: http://phys.org/biology-news/

Together CSIRO, the Western Australian Marine Science Institution (WAMSI), and four Kimberley Aboriginal organisations recently took to the skies to conduct aerial surveys of dugongs—a shy marine mammal that is said to have sparked the legend of mermaids. The information gleaned from the surveys will provide will provide a baseline from which they can create management strategies to help conserve dugongs in the future, according to CSIRO oceans and atmosphere researcher Peter Bayliss. The Kimberley dugong population is both environmentally and culturally important, Mr Bayliss says. "They are considered a keystone species ecologically and are also culturally significant to Aboriginal coastal communities, providing a valuable food source," Mr Bayliss says. "There is a deep cultural knowledge of dugongs in the Kimberley and this will be combined with scientific knowledge for their future management. Dugongs are listed globally as 'vulnerable to extinction' and northern Australia and Torres Strait are thought to be home to the largest remaining healthy populations in the world. However, until now the Kimberley was one of the few areas that had not been subject to scientific survey. Aboriginal rangers from the Balanggarra, Wunambal Gaambera, Dambimangari and Bardi Jawi Native Title groups learnt the techniques of aerial surveying as part of a three-day accredited training course. They then put these skills into practice by boarding a Gippsland G8 Airvan to survey dugongs by flying east-west transect lines over about 30,000 square kilometres of coastal waters—an area nearly half the size of Tasmania. The survey plane flew at a constant height and speed to obtain consistent counts—152m above the water and 185 kilometres per hour—with participants counting dugongs sighted within a 200m strip on each side of the aircraft. They flew 14,000 kilometres during the 18-day survey. The aerial surveying course and surveys are part of the WAMSI Kimberley Marine Science Program's Dugong Management project being run through the Coastal Program of the CSIRO Oceans and Atmosphere Flagship. Explore further: New book inspires children to protect dugongs


Lawson T.J.,Oceans and Atmosphere Flagship | Wilcox C.,Oceans and Atmosphere Flagship | Johns K.,34 Humber Road | Dann P.,Phillip Island Nature Parks | Hardesty B.D.,Oceans and Atmosphere Flagship
Marine Pollution Bulletin | Year: 2015

Marine debris is a global issue that can have devastating impacts on marine mammals. To understand the types of materials that result in entanglement and thus the potential impact of entangling items on marine wildlife, we analysed data collected from items in which Australian fur seals had been entangled in southern Victoria, Australia over a 15. year period. From 1997 to 2012, 138 entangling items were removed from seals. The majority of these entanglements were plastic twine or rope, and seals were entangled in green items more than in any other colour. In general, younger seals were more likely to be entangled than adults. Understanding the effects of marine debris entanglement on the Australian fur seal population can lead to more effective management of the sources of debris and the wildlife that interact with it. © 2015. Source

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