Sponge loop

This month’s issue focuses attention on a very important species group – butterflies. Due to their sensitivity to environmental conditions, butterflies may serve as bioindicators for local and global environmental change. In addition to butterfly inventories and research across our islands, five years of butterfly monitoring on St. Eustatius is beginning to produce clear trends that indicate broader ecosystem change.

Also in this issue, on Saba the seafloor of the well-known site ‘The Pinnacles’ has been surveyed for the third time since 1991, resulting in the most detailed map of the seabed to date, demonstrating the benefit of improving technology for nature conservation(ists).

• ‘Research of the Month‘: Butterflies of the Windward Islands
• Butterflies as Beautiful Bio-indicators
• Butterfly Monitoring Programme on Statia
• Underwater Mapping on Saba
• Overview of Research and Monitoring Efforts
• Calendar of Upcoming Events, Meetings and Workshops

Ever since Darwin’s early descriptions of coral reefs, scientists have debated how one of the world’s most productive and diverse ecosystems can thrive in the marine equivalent of a desert. It is an enigma how the flux of dissolved organic matter (DOM), the largest resource produced on reefs, is transferred to higher trophic levels. Here we show that sponges make DOM available to fauna by rapidly expelling filter cells as detritus that is subsequently consumed by reef fauna. This “sponge loop” was confirmed in aquarium and in situ food web experiments, using 13C- and 15N-enriched DOM. The DOM-sponge-fauna pathway explains why biological hot spots such as coral reefs persist in oligotrophic seas—the reef’s paradox—and has implications for reef ecosystem functioning and conservation strategies.