El Niño 1997-1998 impact on the plankton dynamics in the Gulf of Nicoya, Pacific coast of Costa Rica
Rev. biol. trop
;
49(Supl.2): 103-114, dic. 2001. graf, mapas, tab
Artigo
em Inglês
| LILACS
| ID: lil-502402
ABSTRACT
The impact of the El Niño 1997-1998 phenomenom on plankton dynamics was studied during 1997 at the Punta Morales estuary, Gulf of Nicoya, Pacific coast of Costa Rica. The study covered dry season/transition and the rainy season. Phytoplankton (microphytoplankton > 30 microm and nanophytoplankton) were collected at two depths (50 and 10% light incidence) using a 5 L Niskin bottle, and samples taken to determine chlorophyll a. Temperature, salinity, oxygen, and Secchi depth were measured. Horizontal sub-surface zooplankton hauls were conducted with a conic zooplankton net of 0.49 m diameter and 280 microm mesh width, supplied with a flowmeter. Surface sea water temperature average was 29.9 +/- 0.9 degrees C, with a maximum of 31.5 degrees C in April and a minimun of 28 degrees C in March and October. Chlorophyll a concentration (phytoplankton net) averaged 3.1 +/- 1.7 mg/m3, with higher values during the rainy season and lower values during the transition. Nanophytoplankton chlorophyll a concentration averaged 2.5 +/- 1.2 mg/m3, with a maximum during the transition season. For both fractions there were significant differences between transition and rainy seasons, and for nanophytoplankton between dry and transition seasons (p < 0.05). In the last case, differences were explained by temperature. Herbivorous copepods dominated the abundance and biomass of zooplankton, with a biomass maximun of 167.3 in October and a minimun of 7.1 mg DW/m3 in December. These values are higher than those found some years ago in the same zone and those reported for some places in the Caribbean. The El Niño 1997-1998 phenomenon in the plankton dynamics appears to have produced a change in the phytoplankton structure. This is the first attempt to evaluate the possible impact of El Niño on the plankton dynamics of the Pacific coast of Central America.
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Plâncton
/
Tempo (Meteorologia)
/
Monitoramento Ambiental
/
Biomassa
Limite:
Animais
País/Região como assunto:
América Central
/
Costa Rica
Idioma:
Inglês
Revista:
Rev. biol. trop
Assunto da revista:
Biologia
/
Medicina Tropical
Ano de publicação:
2001
Tipo de documento:
Artigo
País de afiliação:
Costa Rica
Instituição/País de afiliação:
Universidad de Costa Rica/CR
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