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

How a Crucial Tropical Forest is Responding to Climate Change

by Pushan Hinduja

How are Mangrove forests throughout tropical areas of the world responding to the rising sea levels attributed to climate change? Daniel M. Alongi, of the Australian Institute of Marine Sciences, analyzed historic responses to changes in sea levels in Mangrove forests as well as current data to determine how well these forests are reacting to the climate crisis (Alongi 2015). Mangrove forests tend to occupy the border between land and sea in low latitudes, making them especially susceptible to the effects of climate change. Fortunately for mangroves, they have an outstanding ecological stability, in part due to their large subterranean storage capabilities. However, despite responses to develop resilience to environmental disturbances, mangrove forests are still suffering. In terms of human impact, mangrove forests are being deforested at a rate of 1-2% per year, leaving only about a century before these forests disappear entirely. Mangroves are crucial to the environment; they serve as breeding and nursery grounds for fish, birds and other animals, prevent erosion and damage from natural disasters like tsunamis, serve as a renewable source of wood for fuel, and are key components in filtering ocean contaminants. Continue reading

Can Corals Acclimate to Large Temperature Changes?

by Dawn Barlow

Over just the past few decades ocean temperature has contributed to significant losses in global coral cover, and the extent to which corals can undergo physiological acclimatization or genetic adaptation to thermal changes remains uncertain. However, this information will be crucial for the effectiveness of conservation strategies and accuracy of projections of reef futures. This study conducted by Howells et al. (2013) investigates the potential for corals to acclimatize to temperatures that exceed historical thermal regimes. This is done by investigating several parameters—bleaching, mortality, Symbiodinium type fidelity, and reproductive timing—in coral colonies that have been transplanted between warm central regions and cool southern regions of the Great Barrier Reef for a period of 14 months. Continue reading