Zgliczynski, B.

The Waitt Institute and Dr. Stuart Sandin’s laboratory at Scripps Institution of Oceanography collaborated to organize an expedition to conduct a rapid scientific assessment of the coral reefs around the windward Caribbean islands, namely Sint Maarten, Sint Eustatius, Saba, Redonda, and a submarine atoll, Saba Bank. To complement these efforts, the expedition was supported by the Government of Antigua and partners in the nearby Dutch-affiliated islands (St Eustatius, Saba, and St Maarten). 

The collaboration is part of a larger effort to establish a regional scale perspective of coral reef health, investigating how reefs are structured, how they change over time, and how we can better manage them in the face of global change. 

The research conducted during thiscruise aimed to investigate the independent and interactive effects of oceanography and human activities in affecting the structure and dynamics of coral reef communities. The survey design controls for within-island variables by conducting the core surveys within the same habitat type – forereef habitat at 7-15m depth. To assess the benthic and reef fish communities, the GCRMN methodology was utilized in conjunction with large-area ‘photomosaics’ to quantify the structure and the workings of each coral reef community at 1-2 km intervals surrounding each island. 

To complement the ecological data colelcted, two sea temperature recorders (HOBO Pro v2 Logger) were deployed around each island. The temperature recorders were programmed to record the seawater temperature at an interval of thirty minutes. We expect to retrieve these recorders and download the temperature record in approximately 2 years. 

Across the 4 islands and submarine atoll, 65 sites were surveyed. This effort resulted in a total of 325 fish and benthic transects, following the GCRMN guidelines. Additionally 38 photomosaics were imaged: 6 on Redonda, 11 on Sint Eustatius, 11 on Sint Maarten, 8 on Saba, and 2 on the Saba Bank.

Microbial viruses can control host abundances via density-dependent lytic predator-prey dynamics. Less clear is how temperate viruses, which coexist and replicate with their host, influence microbial communities. Here we show that virus-like particles are relatively less abundant at high host densities. This suggests suppressed lysis where established models predict lytic dynamics are favoured. Meta-analysis of published viral and microbial densities showed that this trend was widespread in diverse ecosystems ranging from soil to freshwater to human lungs. Experimental manipulations showed viral densities more consistent with temperate than lytic life cycles at increasing microbial abundance. An analysis of 24 coral reef viromes showed a relative increase in the abundance of hallmark genes encoded by temperate viruses with increased microbial abundance. Based on these four lines of evidence, we propose the Piggyback-the-Winner model wherein temperate dynamics become increasingly important in ecosystems with high microbial densities; thus 'more microbes, fewer viruses'.

Abstract:

On coral reefs, herbivorous fishes consume benthic primary producers and regulate competition between fleshy algae and reef-building corals. Many of these species are also important fishery targets, yet little is known about their global status. Using a large-scale synthesis of peer-reviewed and unpub- lished data, we examine variability in abundance and biomass of herbivorous reef fishes and explore evidence for fishing impacts globally and within regions. We show that biomass is more than twice as high in locations not accessible to fisheries relative to fisheries-accessible locations. Although there are large biogeographic differences in total biomass, the effects of fishing are consistent in nearly all regions. We also show that exposure to fishing alters the structure of the herbivore community by disproportionately reducing bio- mass of large-bodied functional groups (scraper/excavators, browsers, grazer/ detritivores), while increasing biomass and abundance of territorial algal- farming damselfishes (Pomacentridae). The browser functional group that consumes macroalgae and can help to prevent coral–macroalgal phase shifts appears to be most susceptible to fishing. This fishing down the herbivore guild probably alters the effectiveness of these fishes in regulating algal abun- dance on reefs. Finally, data from remote and unfished locations provide important baselines for setting management and conservation targets for this important group of fishes.