In the Absence of Herbivory, Allelochemicals Released by Seaweed cause Coral Bleaching and Death

With an increase in sea-surface temperatures and a flurry of anthropogenic activities, more than 30% of the world's coral species face extinction. Rasher and Hay (2010) propose that the poisonous allelopathic chemicals released by common seaweed contribute to coral death and bleaching. They studied the effects of the secondary metabolites on coral bleaching, coral death and coral photosynthesis. They also transplanted the coral species onto reefs and studied the impact of herbivory on coral-seaweed interactionS. Their results indicate that when the seaweed comes into direct contact with the coral, it releases a lipid-soluble metabolite which damages the coral and leads to bleaching and a decrease in photosynthetic yield. In the reef community, however, herbivores consume the seaweed and mediate the deleterious effect of the seaweed on the coral reefs. Thus, the reef herbivores control the seaweed population and reduce coral mortality and bleaching.— Sachi Singh

Rasher, D. B. and Hay M., E. 2010. Chemically rich seaweed poison corals when not controlled by herbivores. Proceedings of the National Academy of Sciences of the United States of America 107, 9683–9688.

The Potential of Small Caribbean Marine Pro-tected Areas for Ecosystem Preservation

Kopp et al. (2010) examined whether small, established marine reserves could effectively sustain a coral reef ecosystem by enhancing the fish stocks and limiting macroalgae growth. The authors studied two marine protected areas (MPAs) around the island of Guadeloupe, one located around Ilets Pigeon and one in the bay of the Grand Cul-de-Sac Marin, and five non-protected reefs for comparison with the protected reefs. Surveys of the fish and benthic communities revealed that although the mean number of individuals per 100 m² was about the same in MPAs as in non-MPAs, the mean biomass of herbivorous fishes was significantly larger inside MPAs, indicating the presence of larger fish in the MPAs. The study also reported a significantly lower cover of macroalgae in the MPAs than in the non-protected areas, and a significant negative correlation between benthic macroalgal cover and herbivorous fish biomass. Though there was no evidence in the study of the benefits of MPAs extending over their boundaries, they were shown to increase fish biomass and manage macroalgal cover, which contributed significantly to sustaining coral reef ecosystems. — Rachel King

Kopp, D., Bouchon-Navaro, M., Mouillot, D., Bouchon, C., 2010. Herbivorous fishes and the potential of Caribbean marine reserves to preserve coral reef ecosystems. Aquatic Conservation: Marine and Freshwater Ecosystems 20, 516-524.

The Progress and Challenges for the Implementa-tion of REDD+ in Tanzania

New mechanisms for conserving forests to reduce negative impacts caused by climate change are needed. Reducing Emissions from Deforestation and Degradation (REDD) is a proposed policy to reduce carbon emissions into the atmosphere from anthropogenic forces such as logging and agriculture. Tanzania is one of the nine pilot countries for the United Nations REDD+ program and receives significant funding from outside governments and the World Bank. These outside sources have come together in attempt to mitigate greenhouse gas emissions, provide income to rural communities and conserve the ecosystem in Tanzania. In order for REDD+ to succeed in Tanzania, there are many improvements and changes in forest management that must be made. N. D. Burgess et al. (2010) conducted a case study of the progress and challenges Tanzania will face in getting ready for the implementation of REDD+. Even in a country with a lot of donor support, established forest management policies, and developed locally-based forest management approaches, there are many challenges. The potentially successful establishment of REDD+ in Tanzania would serve as a good template for other developing countries, but the difficulties of establishing it also highlight the many challenges other countries must deal with preceding REDD+ implementation. — Abby Cheitlin

Burgess, N. D., Bahane, B., Clairs, T., Danielsen, F., Dalsgaard, S., Funder, M., Hagelberg, N., Harrison, P., Haule, C., Kabalimu, K., Kilahama, F., Kilawe, E., Lewis, S. L., Lovett, J. C., Lyatuu, G., Marshall, A. R., Meshack, C., Miles, L., Milledge, S. A. H., Munishi, P. K. T., Nashanda, E., Shirima, D., Swetnam, R. D., Willcock, S., Williams, A., Zahabu, E., 2010. Getting ready for REDD+ in Tanzania: a case study of progress and challenges, Fauna & Flora International, 44(3), 339–351.

The Effects of Precipitation and Environmental Warming on two Salt Marsh Plant Communities

The response of salt marsh function to climate change depends on its ability to keep pace with sea level rise by expanding both horizontally and vertically through peat accumulation and primary productivity. Climate change is expected to regionally warm the air, soil, and water as well as change tide cycles and the intermittency and volume of precipitation. This will strongly alter the ability of salt marsh ecosystems to export biomass and nutrients, filter runoff, sequester carbon, and protect coastlines from flooding and erosion. Charles and Dukes (2009) studied the effect of precipitation and environmental warming by manipulating the habitats of two salt marsh plant communities, marsh hay/spike grass and cod grass. They analyzed the differences between total above ground biomass, stem height, decomposition rates, and flowering patterns for each treatment plot that differed by the amount of precipitation and increase in temperature. Their research found that salt marsh communities are able to withstand slight increases in temperature and large changes in precipitation. —Acadia Tucker

Charles, H., Dukes, J. 2009. Effects of warming and altered precipitation on plant and nutrient dynamics of a New England salt marsh. Ecological Applications 9, 1758 –1773.

Climatic Water Deficit, Tree Species Ranges, and Climate Change in Yosemite National Park

Lutz et al. (2010) studied annual potential evapotranspiration (PET), actual evapotranspiration (AET) and climatic water deficit with high spatial resolution in Yosemite National Park, California. Understanding the effect of fine-scale heterogeneity of complex terrain on plant water balance is crucial to understanding the potential effects of climate change on species distributions.  Lutz et al. define AET as evaporative water loss from a site covered by a hypothetical standard crop, constrained by the current water availability. Climatic water deficit is the difference between PET and AET.  AET and annual climatic water deficit can be used to predict vegetation presence and growth rates. Vegetation is one of the determinants of water demand along with temperature, solar radiation, relative humidity, wind speed, and surface roughness. Lutz et al. calculated climatic water balance in Yosemite National Park to describe tree distribution in terms of water-balance variables. — Madeleine Busacca

Lutz, J. A., Van Wagtendonk, J. W., Franklin, J. F., 2010. Climatic water deficit, tree species ranges, and climate change in Yosemite National Park. Journal of Biogeography 37, 936–950.