Baleares Station (Site 57)

Publicado

Orden Calanoida

Versión del edito

Zooplankton vertical distribution in waters of the Mallorca shelf: autumn and summer

The zooplankton vertical distribution (VD) has been studied in two areas of the Mallorca shelf during December 2009 and July 2010. Five and eight, depth levels were sampled at day/night by using BIONESS an MOCNESS multinet. 17 zooplankton groups were found, where copepods were the most abundant (70%), being responsible of the whole zooplankton VD pattern. Copepod high diversity was found in both months (4.3 bits and 3.3bits) and more than 88 species identified. The highest diversity was found in deeper waters (90-120 m) in the afternoon than during day time (0-90m) in December but in July, always found at deeper layer (100-150 m), suggesting that epipelagic and mesopelagic copepods co-occurred, and diel changes induced the increased diversity. Clausocalanus arcuicornis (13%), Nannocalanus minor (10%) and Pleuromamma (P. gracilis and P. abdominalis, 8% and 6%) were the most abundant. However others such as Acartia clausi and Clausocalanus furcatus appeared in December and Centropages typicus, Euchaeta acuta and Lucicutia flavicornis in July. In relation to water conditions the VD exhibited different patterns with a higher difference in autumn between the two sites than in summer when the zooplankton was concentrated around the FMD. Species like N. minor, A. clausi, as well as all Clausocalanus and Oithona did not show clear vertical movements; but others showed weak, intermediate or strong migration, such as Lucicutia, Euchaeta and Pleuromamma which exhibited clear nocturnal VD. The importance of these species in the active carbon transfer is discussed in this oligotrophic area of the central western Mediterranean

North Atlantic climate control on plankton variability in the Balearic Sea, western Mediterranean

Publicado

11 Year zooplankton time-series related to North Atlantic climate changes in waters of the Balearic Sea (western Mediterranean)

Workshop I: Climate impact on ecosystem dynamics of marginal and semi-enclosed sea

Annual cycle of zooplankton biomass, abundance and species composition in the neritic area of the Balearic Sea, western Mediterranean

Publicado

Phytoplankton composition in a neritic area of the Balearic Sea (Western Mediterranean)

From September 2000 to September 2001 the concentration of chlorophyll a, and the abundance and composition of the phytoplanktonic community was studied in a neritic station of the Mallorca Channel (Western Mediterranean). Sampling was performed approximately every 12 days. Chlorophyll a concentration and phytoplankton abundance reached maxima of 1.79 mg L2l and 352 cells mL21, respectively. It was a relatively productive period, as a result of the high convective mixing in winter and the prevalence of northern waters during most of the cycle. Phytoplankton proliferations (chlorophyll-a concentration .1 mg L21) were detected in January, February, March and June. Those blooms mainly happened under the influence of northern waters, with the exception of the February proliferation, when mixing conditions were found. During bloom conditions it highlights the presence of coccolithophores as proliferation precursors. During no-bloom situations the phytoplankton community was mainly constituted by nanoplanktonic flagellated forms. The Winter Mixing period was dominated by different groups of nanoflagellates, including coccolithophores, undetermined flagellates and dinoflagellates. However, in the most oligotrophic conditions (from April until November) dinoflagellates were clearly dominant, except in the DCM in summer where diatoms prevailed.Versión del edito

Annual variations of major oceanographic and planktonic variables at a neritic station in the Balearic Sea (1993-1994)

Seasonal variations between April 1993 and April 1994 of the major oceanographic parameters, as well as planktonic communities, of a neritic station (at 76 m) in the Balearic Sea are described. Hydrographic sampling shows a typical Western Mediterranean thermic regime, with temperatures ranging from 13.5 to 26.7 °C, and salinity values from 36.7 to 38.1 psu. During six months, a seasonal thermocline at a depth of 20-50 m conditioned all biological distribution. The winter homothermia, with typical Mediterranean waters, triggered a short but in tense fitoplanktonic bloom in the water column (1.11 µg Chl a/l) where the diatoms were most abundant, providing a zooplanktonic peak in March (5 940 indiv/m³). However, a fertilisation process appeared below the thermocline in late spring, when the phytoplankton maximum was found (1.75 µg Chl a/l), producing the highest zooplankton peak in summer (6 192 indiv/m³). Copepods were the most abundant zooplankton (62 %), although during summer other seasonal groups were also very abundant, such as cladocerans and Mollusca larvae. The estimated annual zooplankton average was 1 842 indiv/m³ and 7.34 ± 3.79 mg dry weight/m³. These oceanographic variables' variations over time highlight the short-lived, rapidly developing processes ocurring in the area, whose hydrography has a strong impact on the distribution of planktonic communities. A complex planktonic structure can be seen in this hydrological transition area between the northern and southern waters of the Western Mediterranean.Se describe el patrón de variación temporal de las principales variables oceanográficas entre abril de 1993 y abril de 1994, así como el de las comunidades de fito y zooplancton, en una estación nerítica (a 76 m) al suroeste de la isla de Mallorca. El muestreo hidrográfico permitió observar una distribución del régimen térmico típica del Mediterráneo occidental, siendo un año relativamente cálido con temperaturas que oscilaron entre 13,5 y 26,7 °C, y una salinidad entre 36,7 y 38,2 ups. Una termoclina estacional, entre 20 y 50 m de profundidad, condicionó la producción biológica durante seis meses del año, restringiendo los máximos a las capas más profundas. Durante el invierno, las aguas salinas del norte del Mediterráneo que se registraron en la zona originaron un corto pero importante florecimiento fitoplanctónico (1,11 µg de Cl a/l), lo que condicionó un pico de zooplancton (5 450 indiv/m³) a comienzos de marzo. El máximo valor de fitoplancton, sin embargo, se detectó a finales de la primavera debajo de la termoclina (1,75 µg de Cl a/l), dando lugar al máximo zooplanctónico anual en el periodo estival (6 192 indiv/m³). El grupo de los copépodos fue predominante (62 %) siendo máximo en invierno (98 %) y mínimo en verano (40 %) cuando otros grupos, como cladóceros y larvas de moluscos, aumentaron en número considerablemente. El valor medio se estimó en 1 842 indiv/m³, con una biomasa de 7,34 ± 3,79 mg peso seco/m³. Se pone de manifiesto la importancia de procesos cortos y rápidos en el desarrollo de los picos de abundancia planctónica, resaltando la enorme complejidad estructural de sus comunidades fuertemente influidas por la zona de transición hidrológica en que nos encontramos, entre aguas del norte y sur del Mediterráneo occidental.Instituto Español de Oceanografí