After the Fall: Legacy Effects of Biogenic Structure on Wind-Generated Ecosystem Processes Following Mussel Bed Collapse

Blue mussels (Mytilus edulis) are ecosystem engineers with strong effects on species diversity and abundances. Mussel beds appear to be declining in the Gulf of Maine, apparently due to climate change and predation by the invasive green crab, Carcinus maenas. As mussels die, they create a legacy of large expanses of shell biogenic structure. In Maine, USA, we used bottom traps to examine effects of four bottom cover types (i.e., live mussels, whole shells, fragmented shells, bare sediment) and wind condition (i.e., days with high, intermediate, and low values) on flow-related ecosystem processes. Significant differences in transport of sediment, meiofauna, and macrofauna were found among cover types and days, with no significant interaction between the two factors. Wind condition had positive effects on transport. Shell hash, especially fragmented shells, had negative effects, possibly because it acted as bed armor to reduce wind-generated erosion and resuspension. Copepods had the greatest mobility and shortest turnover times (0.15 d), followed by nematodes (1.96 d) and the macrofauna dominant, Tubificoides benedeni (2.35 d). Shell legacy effects may play an important role in soft-bottom system responses to wind-generated ecosystem processes, particularly in collapsed mussel beds, with implications for recolonization, connectivity, and the creation and maintenance of spatial pattern

A Comparison of Qualitative and Quantitative Ecological Assessment Methods of Mangroves in Southwestern Madagascar

Mangroves are unique, tropical, intertidal forests that, among many other important functions, serve as large carbon sinks for the sequestration of atmospheric CO2. This project qualitatively assessed the mangrove forest of Honko Mangrove Conservation and Education (Tulear, Madagascar) in conjunction with Blue Ventures for a proposed Plan Vivo carbon stock project. The qualitative results were then compared with quantitative measurements in order to determine the most effective method of ecological assessment. Sixty-three stands of mangrove forest covering 9.72km2 were identified and mapped. Level of harvest, species composition, density, canopy cover, dominant height, dominant DBH, forest condition and composition were compared between the studies. Qualitative results agreed with quantitative measurements in species composition, dominant height, dominant DBH and forest condition. While there were some differences between level of harvest classifications, density, canopy cover and composition, neither method was determined to be superior to the other. Qualitative and quantitative data both support and correct each other and it is recommended that quantitative data be combined with qualitative observation to avoid oversight in future carbon stock assessments. This paper was written for the Madagascar: Biodiversity and Natural Resource Management program

After the Fall: Legacy Effects of Biogenic Structure on Wind-Generated Ecosystem Processes Following Mussel Bed Collapse

Blue mussels (Mytilus edulis) are ecosystem engineers with strong effects on species diversity and abundances. Mussel beds appear to be declining in the Gulf of Maine, apparently due to climate change and predation by the invasive green crab, Carcinus maenas. As mussels die, they create a legacy of large expanses of shell biogenic structure. In Maine, USA, we used bottom traps to examine effects of four bottom cover types (i.e., live mussels, whole shells, fragmented shells, bare sediment) and wind condition (i.e., days with high, intermediate, and low values) on flow-related ecosystem processes. Significant differences in transport of sediment, meiofauna, and macrofauna were found among cover types and days, with no significant interaction between the two factors. Wind condition had positive effects on transport. Shell hash, especially fragmented shells, had negative effects, possibly because it acted as bed armor to reduce wind-generated erosion and resuspension. Copepods had the greatest mobility and shortest turnover times (0.15 d), followed by nematodes (1.96 d) and the macrofauna dominant, Tubificoides benedeni (2.35 d). Shell legacy effects may play an important role in soft-bottom system responses to wind-generated ecosystem processes, particularly in collapsed mussel beds, with implications for recolonization, connectivity, and the creation and maintenance of spatial pattern

What Happens After Mussels Die? Biogenic Legacy Effects on Community Structure and Ecosystem Processes

Once-thriving mussel beds are disappearing from the Gulf of Maine, leaving behind massive amounts of long-lasting empty and broken shells. We found significantly different sediment, species assemblages, and water flow dynamics in patches of this shell material compared to live mussels and bare sediment. Mussel bed collapse alters the ecology of the seafloor