Cambios estacionales del fitoplancton en el área marina de pesca responsable de Paquera-Tambor, Golfo de Nicoya, Costa Rica

Abstract

La implementación de Áreas Marinas de Pesca Responsable (AMPR) es una herramienta para el ordenamiento pesquero, por ello, los estudios de línea base juegan un rol importante para comprender la dinámica ecológica desde las bases de la red trófica en las AMPR. El objetivo de este trabajo fue caracterizar la abundancia de los grupos taxonómicos del fitoplancton en el AMPR-Paquera-Tambor, para la determinación de cambios estacionales entre variables abióticas y el fitoplancton. Se realizó un muestreo mensual (de septiembre-2013 a agosto-2014) para la toma de muestras de factores fisicoquímicos, así como de microalgas planctónicas. Los datos evidenciaron una variación temporal tanto de los factores ambientales como del fitoplancton. Las microalgas más representativas fueron las diatomeas y los dinoflagelados con una riqueza de 51 y 32 especies, respectivamente, donde se resalta la presencia de algunas especies productoras de florecimientos algales como Cochlodinium catenatum con una concentración de 5.85x104cél L-1. Con respecto a las diatomeas y los parámetros, como la profundidad del disco Secchi (r = -0.558) y el porcentaje de saturación de oxígeno (r = -0.490), se reflejó una correlación negativa debido a la variabilidad climática de la zona. Se identificaron organismos del grupo zooplanctónico de los tintínidos, los cuales presentaron una correlación positiva con las diatomeas (r = 0.433). Se evidenció una dinámica ecosistémica fundamental para el desarrollo trófico del AMPR-Paquera-Tambor, que fundamenta la importancia pesquera de la zona y refleja la relevancia de continuar con un monitoreo biótico y abiótico para la zona.

The River Influence Controls Water Quality and Spatio-Temporal Microalgal Distribution in Pacific Estuaries (Padre Ramos and Salinas Grandes) of Nicaragua

“…The dinoflagellates appear mainly at the time of transition from rain to drought and appeared throughout the estuary, therefore they do not seem to be linked to the most coastal zone as in the Gulf of Nicoya [13]. The densities reached by diatoms in the EPR and ESG are comparable to those mentioned for the interior of the Gulf of Nicoya (average 186 ± 159 ind/mL and 130 ± 23 ind/mL, respectively; [13]), but much lower than those that occur in its external area [39]. The density of toxic dinoflagellates is directly related to greater eutrophication of the coast [22,58] and a contribution of this coastal water to the estuary [13].…”

“…For now, we can suggest a pattern that takes into account the MIC variations in both studied estuaries. Diatoms do not show any trend over time, as observed in the Gulf of Nicoya [39]; and they were somewhat more abundant at two moments of the hydrological year: at the end of the rainy season (October to November), which is the period considered to be the transition to the dry season, and in the middle of the dry season (February). Chlorophytes, more typical of fresh water, were more abundant at the end of the dry season (April and September) and they decreased as the rainy season progressed.…”

“…There is very little information on the dynamics of the taxonomic and functional groups of the MIC on the estuaries of the Pacific coast of Nicaragua (except for the specific works carried out by students of the University of Nicaragua). Reviewing the information on the most-studied tropical and subtropical Pacific coast estuaries, such as the externaloceanic or internal-fluvial zones of the Gulf of Nicoya (e.g., [13,39,54] or in the Gulf of Papagayo in Costa Rica [55], we can see that hydrology (river flow, flushing and tidal extension) and nutrients conditioned by hydrology are the main control factors of MIC groups. In the aforementioned estuaries, Chlorophytes are not relevant nor are they included in broad functional groups such as small flagellates (mainly Prasinophytes).…”

“…The density of toxic dinoflagellates is directly related to greater eutrophication of the coast [22,58] and a contribution of this coastal water to the estuary [13]. Thus, in the marine area of the Gulf of Nicoya, an annual average density of 59 ± 9 ind/mL has been described [39], and in the interior of the estuary, the density of dinoflagellates does not exceed 25 ind/mL [13]. Therefore, we can consider that the lack of eutrophication, and the fluvial nature of the ERP and ESG, protect them from the growth of these toxic dinoflagellates along their course, since they did not exceed 3 ind/mL.…”

“…The taxonomic classification of the MIC was carried out, differentiating between the large groups of algae: Chlorophytes, Diatoms, Dinophytes, Euglenophytes and Cyanobacteria [37]. The organisms were identified at the finest possible taxonomic resolution following standard references (cited in [38]) as well as some local recommendations for organisms of possible marine origin and from tropical areas [39][40][41]. For the counting and subsequent calculation of the population densities, Neubauer and Sedgwick-Rafter chambers [42] were used to analyze the 20 mL concentrate at 100× magnification; both chambers were filled and counted six times to get average values.…”