Effects of annual changes in primary productivity and ocean indices on breeding performance of tropical roseate terns in the western Indian Ocean

Abstract

We assessed the influence of inter-annual changes in primary productivity and local, regional and large scale ocean indices on the breeding parameters of roseate terns Sterna dougallii on Aride Island, Seychelles, western Indian Ocean. Productivity (chicks per breeding pair), timing of breeding and clutch and egg sizes were monitored annually for 8 yr and correlated with local ocean productivity (denoted by Sea-viewing Wide Field-of-view Sensor, SeaWiFS, estimates of chlorophyll concentration, CC), sea surface temperature and indices recording the status of the Indian Ocean Dipole and of El Niño. The rate of increase in CC between mean laying date and CC peak value was positively related to roseate tern productivity and mean clutch size over the 1998 to 2005 study period. Colony productivity seemed also to be influenced by the Multivariate El Niño Index. In most years, the breeding phenology of roseate terns corresponded to the local increase in CC around Aride, and failure to adjust timing of reproduction to the timing of the phytopankton bloom decreased the probability of breeding success. This is the first study showing that a tropical seabird species is sensitive to inter-annual variations in the intensity and timing of the phytoplankton bloom, which should be connected to annual variations in the availability of its main fish prey (juvenile goatfishes). Overall, these patterns indicate that the reproduction of this top marine predator is dictated by the temporal variability in oceanographic conditions. We suggest that CC data available over the world's oceans may be a useful tool to develop models predicting the fate of colonies of inshore feeding seabirds when other, more conventional, monitoring methods cannot be used.

Movements, at-sea distribution and behaviour of a tropical pelagic seabird: the wedge-tailed shearwater in the western Indian Ocean

“…Food availability in tropical marine environments is usually described as low and unpredictable, and considered to show limited seasonal variation (Harrison & Seki 1987, Weimerskirch 2007. Nevertheless, in the Seychelles archipelago there is a clear seasonality in food availability, which seems to be directly related to phytoplankton blooms (Monticelli et al 2007). Two blooms occur with some predictability each year: a small one from December to February, and the main one from May to August (Monticelli et al 2007).…”

“…Nevertheless, in the Seychelles archipelago there is a clear seasonality in food availability, which seems to be directly related to phytoplankton blooms (Monticelli et al 2007). Two blooms occur with some predictability each year: a small one from December to February, and the main one from May to August (Monticelli et al 2007). These 2 periods of enhanced ocean productivity around the archipelago seem to play an important role in determining the breeding phenology and movements of wedge-tailed shearwaters.…”

Recoveries of juvenile Giant Petrels in regions of ocean productivity: potential implications for population change

“…Ecosystem regime shifts have been correlated with variability in atmospheric and oceanographic properties (Shannon et al 1986, Chavez et al 2003, Alheit and Niquen 2004, Surman and Nicholson 2009, the results of which have catastrophic local and regional consequences (Rodhouse 2001, Sydeman et al 2001, Thompson and Grosbois 2002, Alheit and Niquen 2004, Monticelli et al 2007, Rolland et al 2008. The effects of the El Nino Southern Oscillation (ENSO), for example, can be seen locally along the western coastline of South America or can propagate through global atmospheric teleconnections (Alexander et al 2002, Garcia et al 2003, Pshennikov et al 2005 to influence distant ecosystems (Behrenfeld et al 2006, Trathan et al 2007).…”

Impacts of climate variation and potential effects of climate change on South American seabirds – a review

“…Impacts of ENSO on reproduction of seabird populations have been detected in places far from the equatorial Pacific, where they often occur after a lag of few months or years (e.g., Ainley et al 1995;Guinet et al 1998;Chambers 2004;Quillfeldt et al 2007), depending on the distance of the site from the equatorial Pacific and on the time required for bottom-up processes to cascade to upper trophic levels (Monticelli et al 2007). The Southern Oscillation Index (SOI) summarizes the state of the ENSO on a global scale, and appears to be strongly related to the breeding success and survival of seabirds ranging widely, such as albatrosses and many petrels (e.g.…”

“…Long-term observations of seabirds show that increases in sea surface temperature (SST) typically cause low availability of seabird prey, and consequently deferred reproduction, lowered growth rates and high mortality of chicks in different oceans such as the Antarctic (Jenouvrier et al 2005b;Le Bohec et al 2008), the Indian Ocean (Monticelli et al 2007), the North Atlantic (Durant et al 2004;Riou et al 2011) and the Southern Ocean . Thus, global ocean warming places an added burden on many seabird species (e.g.…”