Un estudio de la comunidad de copépodos de la Ría de Muros en noviembre de 1975: N.º 233

• María Teresa Álvarez Ossorio ^[1]
  1. [1] Laboratorio Oceanográfico de La Coruña
• Localización: Boletín. Instituto Español de Oceanografía, ISSN 0074-0195, Tomo 2, Nº 1, 1977, págs. 75-108
• Idioma: español
• Texto completo no disponible (Saber más ...)
• Resumen

  • In this paper the results about study on copepods from zooplankton samples taken by a 250 microns net in the Ria de Muros on November 1975 are exposed.

    The main results are:

    1. Community composition.

    It is a typical neritic north Atlantic community with small size specimens. The species number is high for the season numbering 27. However only 4 of which Paracalanus parvus, Acartia clausi, Temora longicornis and Psedocalanus elongatus account for 70-80 % of the community.

    2. Quantitative study.

    Cepepods number expresed by cubic meter range from 1100 to 5600, a very high value considering the season (in Plymouth, Harvey et al. (1935) in November 1934, stated a maximum of 500).

    According to density, the community has been divided into 4 categories:

    1. Dominant species: 4, with mean values from 100 to 650 individual/cubic meter.

    2. Subdominant species: 4, with mean values from 20 to 40 ind./c.m.

    3. Secondary species: 9, with mean values from 1 to 20 ind./c.m.

    4. Rare species: 10, less than 1 individual per cubic meter.

    At Station 6 were found the maximum density of copepods, related with maximum of chlorophyll a.

    3. Diversity.

    The diversity is very stable on both sampling days and sampling stations. Diversity values ranged from 1.94 to 2.35, and equitability range from 48 % to 57 %.

    4. Time-espace evolution in the community.

    Density change between sampling stations are only significant (95 % level) in 2 species: Oncaea media and Corycaeus clausi, which demonstrates high homogeneity in the Ria with almost insignificant gradations in this period of sampling.

    The time between sampling days was short, 3 days, but produced significant variations in 4 species, 2 of which (T. longicornis and P. parvus) are dominant and responsible of the total significant community (number of copepods/cubic meter) change from 18th to 21st November.

    5. Similarity among samples.

    There existed a great similarity among the samples taken by 250 microns net reaffirming the homogeneity of the Ria. There also existed a great similarity among the samples taken by same net in different days.

    Between different nets (500 and 250 microns) the similarity drops.

    6. Zooplankton standing stock.

    Biomass expressed as cubic centimeters of plankton sedimented by cubic meter filtered varied significantly (95 % level) in the 3 day period of sampling.

    On the other hand, dry weight and ash-free dry weight values registered no significant change. Values of dry weight ranged from 20 to 54 mg./cubic meter, and ash-free dry weight ranged form 15 to 44 mg./cubic meter. The plankton biomass values found are high, however definite conclusions cannot be ascertained without studying annual cycles.

    7. Regression Zooplankton - Copepods.

    The regression straight line calculated from data of C.C. sedimented zooplankton/cubic meter and copepod’s number/cubic meter was y = 51.94 + 2969.31 x and the correlation coefficient r = 0.802.

    The regression between miligrams dry weight of zooplankton and copepods number/m3 was y = -206.97 + 92.94 x and r = 0.755.

    From this data one can see the great significance of copepods in zooplankton biomass.

    Taking in account existent data on homogeneity of the Ria sampling stations can be reduced and incresed time between sampling periods.