Ocean Acidification can Mediate Biodiversity Shifts by changing Biogenic Habitat

by Elizabeth Rodarte

Ocean acidification is the process in which the pH of the world’s oceans decreases due to the production of atmospheric CO2. The increase of CO2 and decrease in pH leads to changes in calcification, growth, and abundance of species such as coral reefs, mussels, seagrass, and macroalgae. Habitats experience the indirect effects of such CO2 increases. They must remain resistant to sudden changes in pH and CO2 in order to benefit the organisms they support. By modeling the effects of lowering pH in habitats with corals, mussels, seagrass, and microalgae, we can determine the costs to these species. Coral reefs and mussels are calcifying organisms that are negatively affected by the pH which limits survival and stunts, or even stops, growth and development. Lower pH decreases the species complexity of corals and mussels and ultimately the species richness in habitats. Mytilus mussels, for example, require specific pH to function. The species of mussels, other than Mytilus, that survive decreases in pH lack “structural complexity” to support dense surrounding vegetation. Therefore, the loss of Mytilus mussels due to ocean acidification allows for a more stable yet less diverse habitat. Continue reading

The Best Way to Regulate the Indigenous Dugong Harvest is to Let Tradition Run Its Course

by Wendy Noreña

Indigenous communities around increasingly finding that their traditional fishing practices clash with new, externally-imposed conservation policies and societal expectations. Finding an appropriate answer to these disagreements is difficult, especially since there are not enough data about most traditional, or even modern, marine fisheries to be able to create accurate scientific models that could help guide potential management strategies. Marsh et al. (2015) investigate the indigenous Dugong harvest in the Torres Straits, an area that spans the ocean space between Papua New Guinea (PNG) and the Northern Australian coast. Based on Marsh et al.’s preliminary research, the harvests here have been taking place for 4,000 to 7,000 years and have been “substantial,” for 400 to 500 years. With concerns about the conservation of ecosystems becoming more prevalent and politically involved, more and more people in Australia and PNG are calling for a ban or for restrictions to Dugong harvests. So far, regulations have already been set in place to limit hunting in certain areas and with certain equipment, but, because of the Australian Native Title Act, the Torres Strait islanders are lawfully allowed to hunt in what is known as their, “sea country,” as long as they follow a few restrictions. Marsh et al. argue that previous studies which stated that dugong harvests are largely unsustainable are actually incomplete due to the absence of good population and hunting data. Marsh et al. estimate that the Dugong harvest is sustainable and suggest that typical conservation methods should not be used to manage the Dugong harvests. Instead, they suggest that until sufficient data is available to use more popular management methods, a cultural reinforcement strategy currently in use, which involves ancient, traditional limitations on when, where, and how many Dugong can be harvested, should be implemented to manage this harvesting activity. These cultural reinforcements, driven by the indigenous communities themselves, must be coupled with detailed hunting reports as well as collaborations between government officials and indigenous leaders to create a more efficiently tailored management system for the dugong harvest. Continue reading

Large Forest Blocks are Essential for Biodiversity Protection and Carbon Storage

by Stephen Johnson

Habitat loss is the primary threat to the survival of most tropical biodiversity. Typically, this habitat loss is driven by deforestation for agricultural use. However, deforested landscapes are rarely homogenous fields with low diversity; most often, forest fragments are left embedded in a matrix of varying types of agriculture, from open field monocultures, to pastures and forest-mimicking shaded plantations. The process of fragmentation has a significant negative effect on the biodiversity present in the area; however, fragments are often able to support a variety of species, as are some types of agriculture, such as agroforestry. Less is known about the capacity of such landscapes to sequester and store carbon. What little has been done has focused on carbon in agroforestry systems, with promising, though mixed, results. Continue reading

Are No-Take Marine Reserves Really Effective?

 

by Weronika Konwent

No–take marine reserves (NTMRs) are established to promote marine biodiversity and to reign in exorbitant fishery behavior through the prohibition of all fishing and resource extraction. In the past several decades, the quantity of NTMRs has risen greatly across the world. While this seems like an obviously positive trend, many regard the existence of NTMRs as controversial. While most NTMR results appear positive, the opposition claims that faulty study design and a lack of objective empirical data may cause inaccurate portrayals of NTMR effects. Continue reading

Resilience of Marine Turtle Regional Management Units to Climate Change

by Samantha Thompson

Scientists are searching for ways to avoid losing biodiversity to global warming. One way is by enhancing species resilience to environmental change. Resilience is the ability of an ecosystem or species to maintain key functions and processes in the face of stresses or pressures, either by resisting and/or adapting to change. Fuentes explored the resilience of 58 marine regional turtle management units (RMUs) to climate change, including all species of marine turtles worldwide. Using expert opinions from 33 different IUCN-SSC Marine Turtle Specialist Group respondents, the researchers were able to develop a Resilience Index. This was used in order to consider qualitative characteristics of RMUs such as population size, rookery vulnerability, and genetic diversity, and non climate related threats, such as fisheries, take, and coastal development. Through this information researchers were able to identify the world’s 13 least resilient marine turtle RMUs to climate change. Continue reading