Reproductive strategies and energy sources fuelling reproductive growth in a protracted spawner

Most marine invertebrates experience variable environments and for broadcast spawners, fertilisation success increases with greater synchronisation of spawning, so a capital breeding strategy is predicted. However, this prediction should be tested for species with protracted breeding seasons, since it is not clear how reproduction is fuelled over several consecutive months of spawning. The simultaneous hermaphrodite scallop <i>Pecten fumatus</i> was used to test the hypothesis that protracted spawning is supported by both capital and income strategies, depending on the state of energy reserves and food availability at the time of oocyte maturation. The study was carried out in Great Bay, Tasmania, Australia (147.335W, 43.220S) in 2010/2011. The use of glycogen, protein and lipid in the muscle, gonad, and digestive gland was examined, along with the role of atretic eggs as an alternative energy source for oogenesis and maturation. The reproductive stage of an individual was determined using only the ovaries. <i>P. fumatus</i> uses a capital breeding strategy early in the reproductive cycle during winter and spring (August–October) with muscle glycogen and protein and digestive gland lipid providing energy for oogenesis. Given there was no evidence of energy stores being used later in the reproductive cycle in late spring and summer (November–March), when less food was available for direct fuelling of reproduction, it appears that metabolites produced from oocyte lysis may have fuelled oogenesis. Recycling of energy from oocyte resorption must be considered as part of the strategy of energy use to fuel reproduction in marine invertebrates

Forest carbon in North America: annual storage and emissions from British Columbia’s harvest, 1965–2065

<p>Abstract</p> <p>Background</p> <p>The default international accounting rules estimate the carbon emissions from forest products by assuming all harvest is immediately emitted to the atmosphere. This makes it difficult to assess the greenhouse gas (GHG) consequences of different forest management or manufacturing activities that maintain the storage of carbon. The Intergovernmental Panel on Climate Change (IPCC) addresses this issue by allowing other accounting methods. The objective of this paper is to provide a new model for estimating annual stock changes of carbon in harvested wood products (HWP).</p> <p>Results</p> <p>The model, British Columbia Harvested Wood Products version 1 (BC-HWPv1), estimates carbon stocks and fluxes for wood harvested in BC from 1965 to 2065, based on new parameters on local manufacturing, updated and new information for North America on consumption and disposal of wood and paper products, and updated parameters on methane management at landfills in the USA. Based on model results, reporting on emissions as they occur would substantially lower BC’s greenhouse gas inventory in 2010 from 48 Mt CO₂ to 26 Mt CO₂ because of the long-term forest carbon storage in-use and in the non-degradable material in landfills. In addition, if offset projects created under BC’s protocol reported 100 year cumulative emissions using the BC-HWPv1 the emissions would be lower by about 11%.</p> <p>Conclusions</p> <p>This research showed that the IPCC default methods overestimate the emissions North America wood products. Future IPCC GHG accounting methods could include a lower emissions factor (e.g. 0.52) multiplied by the annual harvest, rather than the current multiplier of 1.0. The simulations demonstrated that the primary opportunities for climate change mitigation are in shifting from burning mill waste to using the wood for longer-lived products.</p