scholarly journals Temporal variability of larval drift of tropical amphidromous gobies along a watershed in Réunion Island

2017 ◽  
Vol 74 (6) ◽  
pp. 948-957 ◽  
Author(s):  
Raphaël Lagarde ◽  
Nils Teichert ◽  
Henri Grondin ◽  
Hélène Magalon ◽  
Agathe Pirog ◽  
...  
Keyword(s):  
Linear Models ◽  
River Mouth ◽  
Austral Summer ◽  
Early Summer ◽  
Reunion Island ◽  
Tropical Islands ◽  
Monthly Basis ◽  
Larval Drift ◽  
Periodic Linear ◽  
Réunion Island

Freshwater gobies of tropical islands are amphidromous: adults reproduce in rivers and larvae passively drift down to the sea immediately after hatching. Describing the phenology of this larval drift is essential to understanding the population dynamics of amphidromous gobies and to developing ecologically based recommendations for managing the watersheds. The larval drift patterns of two amphidromous gobies of Réunion Island, Sicyopterus lagocephalus and Cotylopus acutipinnis, were studied on a monthly basis for 1 year using plankton nets at two sites on the Mât River, located 20 km and 7 km from the river mouth. Genetic analyses showed that larval assemblages were dominated at 90% by S. lagocephalus, although the proportion of C. acutipinnis increased during early summer. Our findings highlighted a marked larval drift peak in full austral summer. The diel larval drift dynamic was described using periodic linear models. A diel pattern was only observed downstream, peaking a few hours after sunset. Finally, this study presents a new approach that improves standard methods for sampling and analyzing larval drift of amphidromous species.

Characterisation of post-larval to juvenile stages, metamorphosis and recruitment of an amphidromous goby, Sicyopterus lagocephalus (Pallas) (Teleostei : Gobiidae : Sicydiinae)

2008 ◽  
Vol 59 (10) ◽  
pp. 876 ◽  
Author(s):  
P. Keith ◽  
T. B. Hoareau ◽  
C. Lord ◽  
O. Ah-Yane ◽  
G. Gimonneau ◽  
...  
Keyword(s):  
River Mouth ◽  
Reunion Island ◽  
La Réunion ◽  
Stock Management ◽  
Fishing Activity ◽  
Larval Stages ◽  
Réunion Island ◽  
Juvenile Stages ◽  
Important Food Source ◽  
La Réunion Island

Sicyopterus lagocephalus post-larvae migrating in Mascarene Archipelago rivers, La Réunion Island, provide an important food source to local populations and fishing activity has a socioeconomic impact. Improved knowledge of the life traits and the characterisation of post-larval stages should enable a better understanding of physiological changes triggering migratory behaviour. It would also help to explain the recruitment processes to managers and to implement conservation measures for stock management. Sicyopterus lagocephalus is an amphidromous fish: adults live in rivers, but larvae are carried to the sea after hatching. The present study characterised the metamorphosis and post-larval stages of Sicyopterus lagocephalus during river recolonisation on La Réunion Island. The results show that cranium reorganisation and pectoral fins transformation are part of the first and major transformations and are completed less than 2 weeks after freshwater colonisation (post-larval stages PL1 and PL2). These transformations, mobilising all the available calcium, seem to be critical for survival in their new environment. Individuals then progressively acquire pigmentation, complete scalation and the fork at the end of the caudal fin disappears (juvenile stages J1 and J2). The end of the recruitment phase takes place 21 to 28 days after entering the river mouth, when territorial behaviour appears.

scholarly journals Rescue of the Mascarene Petrel, a Critically Endangered Seabird of Réunion Island, Indian Ocean

The Condor ◽  
2003 ◽  
Vol 105 (2) ◽  
pp. 387-391 ◽  
Author(s):  
Matthieu Le Corre ◽  
Thomas Ghestemme ◽  
Marc Salamolard ◽  
François-Xavier Couzi
Keyword(s):  
Indian Ocean ◽  
Austral Summer ◽  
Small Population ◽  
Reunion Island ◽  
The Public ◽  
The World ◽  
Réunion Island ◽  
Conservation Plan ◽  
The Indian Ocean ◽  
First Time

Abstract The Mascarene Petrel (Pseudobulweria aterrima), an endemic seabird of Réunion Island, is one of the rarest and least known birds in the world. In this note we report on light-induced mortality in this species at Réunion Island, in the Indian Ocean. Throughout most of the twentieth century, when Réunion Island's population was relatively small, only three birds were found dead or dying. After instituting in 1996 a program encouraging the public to rescue downed seabirds, we received eight Mascarene Petrels, among which seven were banded and released. Four birds were fledglings attracted by lights while on their first flight to sea. These findings show for the first time since the end of the nineteenth century that Mascarene Petrels still breed at Réunion. All fledglings were found in March (late austral summer), suggesting a synchronous summer breeding season. We discuss past and present effects of urban lights on this small population and propose a conservation plan. Rescate de Pseudobulweria aterrima, un Ave Marina Críticamente Amenazada de la Isla Reunión, Océano Indico Resumen. Pseudobulweria aterrima, un ave marina endémica de la isla Réunion, es una de las aves más raras y menos conocidas del mundo. En esta nota exponemos los resultados de un estudio sobre mortalidad en esta especie provocada por la iluminación artificial en la isla Reunión. A través de la mayor parte del siglo veinte, cuando la población en la isla era relativamente pequeña, sólo tres aves fueron encontradas muertas o muriendo. Luego de instituir en 1996 un programa que incentivó al público a rescatar aves abatidas, recibimos ocho aves de las cuales siete fueron anilladas y liberadas. Cuatro de las aves eran volantones jóvenes que fueron atraídos por las luces durante su primer vuelo hacia el mar. Estos resultados muestran por primera vez desde fines del siglo diecinueve que P. aterrima se sigue reproduciendo con éxito en esta isla. Los cuatro volantones fueron encontrados en el mes de marzo, lo que nos hace suponer que la reproducción se realiza sincrónicamente durante el verano austral. Discutimos las consecuencias pasadas y actuales de las luces artificiales sobre esta pequeña población y proponemos un plan de acción para su conservación.

scholarly journals Tropospheric ozone climatology at two Southern Hemisphere tropical/subtropical sites, (Reunion Island and Irene, South Africa) from ozonesondes, LIDAR, and in situ aircraft measurements

2009 ◽  
Vol 9 (5) ◽  
pp. 1723-1734 ◽  
Author(s):  
G. Clain ◽  
J. L. Baray ◽  
R. Delmas ◽  
R. Diab ◽  
J. Leclair de Bellevue ◽  
...  
Keyword(s):  
South Africa ◽  
Tropospheric Ozone ◽  
Lower Layer ◽  
Austral Summer ◽  
Data Sets ◽  
Positive Trend ◽  
Reunion Island ◽  
Upper Troposphere ◽  
Réunion Island ◽  
Sky Conditions

Abstract. This paper presents a climatology and trends of tropospheric ozone in the Southwestern Indian Ocean (Reunion Island) and South Africa (Irene and Johannesburg). This study is based on a multi-instrumental dataset: PTU-O3 ozonesondes, DIAL LIDAR and MOZAIC airborne instrumentation. The seasonal profiles of tropospheric ozone at Reunion Island have been calculated from two different data sets: ozonesondes and LIDAR. The two climatological profiles are similar, except in austral summer when the LIDAR profiles show greater values in the free troposphere, and in the upper troposphere when the LIDAR profiles show lower values during all seasons. These results show that the climatological value of LIDAR profiles must be discussed with care since LIDAR measurements can be performed only under clear sky conditions, and the upper limit of the profile depends on the signal strength. In addition, linear trends have been calculated from ozonesonde data at Reunion and Irene. Considering the whole tropospheric column, the trend is slightly positive for Reunion, and more clearly positive for Irene. Trend calculations have also been made separating the troposphere into three layers, and separating the dataset into seasons. Results show that the positive trend for Irene is governed by the lower layer that is affected by industrial pollution and biomass burning. On the contrary, for Reunion Island, the strongest trends are observed in the upper troposphere, and in winter when stratosphere-troposphere exchange is more frequently expected.

scholarly journals From the threat to the large outbreak: dengue on Reunion Island, 2015 to 2018

2019 ◽  
Vol 24 (47) ◽  
Author(s):  
Muriel Vincent ◽  
Sophie Larrieu ◽  
Pascal Vilain ◽  
Aurélie Etienne ◽  
Jean-Louis Solet ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Family Doctor ◽  
Austral Summer ◽  
Emergency Department Visits ◽  
Reunion Island ◽  
Large Outbreak ◽  
Mandatory Notification ◽  
Réunion Island ◽  
Sporadic Cases ◽  
Set Up

Background With more than 300 million infections estimated annually worldwide, dengue is the most prevalent arboviral infection. On Reunion Island, after a large outbreak in 1977–78, only limited episodes of viral circulation or sporadic cases were reported till 2015. Aim Our objective was to document and report on the circulation of dengue virus after the occurrence of a small outbreak during austral summer 2015/16 and until the large outbreak of 2018. Methods Beside the mandatory notification of biologically confirmed dengue cases, additional systems of surveillance were set up: estimation of dengue-like syndrome in people seeking care by their family doctor, surveillance of emergency department visits related to dengue, surveillance of hospitalised dengue patients and deaths classifications. Results After a moderate outbreak during summer 2015/16 with 231 cases, 2017 was characterised by limited viral circulation (97 cases) which, however, persisted during the austral winter. By February 2018, the number of cases had increased and led to a peak at the beginning of May 2018. More than 6,000 cases were reported this year (dengue virus type 2 only). In addition, six deaths of dengue patients were notified. Conclusion In 2017, the persistence of transmission during winter created favourable conditions for the emergence of an epidemic during summer 2018. After this moderate epidemic wave, the viral circulation persisted during winter 2018 for the second year, opening the door for the second wave in 2019 and for potential endemisation of the disease on Reunion Island in the near future.

scholarly journals Cloud Radar Observations of Diurnal and Seasonal Cloudiness over Reunion Island

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 868
Author(s):  
Jonathan Durand ◽  
Edouard Lees ◽  
Olivier Bousquet ◽  
Julien Delanoë ◽  
François Bonnardot
Keyword(s):  
Sea Breeze ◽  
Satellite System ◽  
Research Infrastructure ◽  
Weather Data ◽  
Reunion Island ◽  
Wet Season ◽  
Trade Winds ◽  
Cloud Radar ◽  
Réunion Island ◽  
Global Navigation Satellite

In November 2016, a 95 GHz cloud radar was permanently deployed in Reunion Island to investigate the vertical distribution of tropical clouds and monitor the temporal variability of cloudiness in the frame of the pan-European research infrastructure Aerosol, Clouds and Trace gases Research InfraStructure (ACTRIS). In the present study, reflectivity observations collected during the two first years of operation (2016–2018) of this vertically pointing cloud radar are relied upon to investigate the diurnal and seasonal cycle of cloudiness in the northern part of this island. During the wet season (December–March), cloudiness is particularly pronounced between 1–3 km above sea level (with a frequency of cloud occurrence of 45% between 12:00–19:00 LST) and 8–12 km (with a frequency of cloud occurrence of 15% between 14:00–19:00 LST). During the dry season (June–September), this bimodal vertical mode is no longer observed and the vertical cloud extension is essentially limited to a height of 3 km due to both the drop-in humidity resulting from the northward migration of the ITCZ and the capping effect of the trade winds inversion. The frequency of cloud occurrence is at its maximum between 13:00–18:00 LST, with a probability of 35% at 15 LST near an altitude of 2 km. The analysis of global navigation satellite system (GNSS)-derived weather data also shows that the diurnal cycle of low- (1–3 km) and mid-to-high level (5–10 km) clouds is strongly correlated with the diurnal evolution of tropospheric humidity, suggesting that additional moisture is advected towards the island by the sea breeze regime. The detailed analysis of cloudiness observations collected during the four seasons sampled in 2017 and 2018 also shows substantial differences between the two years, possibly associated with a strong positive Indian Ocean Southern Dipole (IOSD) event extending throughout the year 2017.

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