Brachiopods, sipunculans, enteropneusts and metals from two estuarine tidal flats, Pacific, Costa Rica

• Published in: Revista de Biología Tropical
• Main Authors: Vargas Zamora, José Antonio, Acuña-Gonzalez, Jenaro, Vásquez, Fiorella, Sibaja-Cordero, Jeffrey A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidad de Costa Rica 2016
• Subjects: Glottidia; Sipunculus; Apionsoma; acorn worms; tropical benthos; infauna; pollution; depuration; Pacific; The Flats; Polar Biology
• Online Access: https://revistas.ucr.ac.cr/index.php/rbt/article/view/23251; https://doi.org/10.15517/rbt.v64i3.23251

Data on the abundances and metal concentrations in intertidal estuarine macro-invertebrates from the Eastern Tropical Pacific are rare. Thus, the objectives of this report are to make accessible data on the abundances (1984-1987, 49 dates; 2013, 12 dates) of sipunculans (Sipuncula), brachiopods (Brachiopoda) and hemichordates (Enteropneusta) at a sand-mud flat; and on trace metals (1996, 2000) and abundances (2015, 3 dates) of sipunculans and brachiopods at a sand flat in the upper Gulf of Nicoya estuary (10 oN - 85 oW), Pacific coast of Costa Rica. Core (17.7 cm2) samples were collected at the sand-mud flat, and quadrats (0.2 m2) at the sand flat. The flats contrasted (1984 vs 2015) mainly in their sand (65 % vs 90 %) silt+clay (31.5 % vs 5.6 %) and organic matter (2 vs 3 %) contents. The 1984-1987 survey yielded 13 sipunculans (12 Sipunculus nudus, 1 Apionsoma. trichocephalus) 129 brachiopods (Glottidia spp.) and 185 hemichordates (acorn worms). The total area sampled by cores was 1.83 m2. Estimated densities for the dates when the maximum number of each group was found, were: 5.7, 29, and 40 ind./m2, respectively. Abundances were higher during the rainy season of 1984. Strong red tides in the Gulf of Nicoya during 1985 may have influenced the abundances. Trace metal (Fe, Mn, Ni, Cr, Cd, Zn, and Pb) analysis was performed by Atomic Absorption Spectrometry (AAS) in tissues of the infaunal deposit feeder S. nudus (non-depurated vs depurated) and in tissues and shells of the infaunal filter-feeder lingulide brachiopod, G. audebarti. Maximum mean concentrations of metals in S. nudus worms found either during the 1996 or 2000 surveys, were: For non-depurated worms, Fe (16.0 mg/g dw) > Mn (165 µg/g dw) > Zn (81 µg/g dw) > Cu (26 µg/g dw) > Cr (11 µg/g dw) > Ni (10.4 µg/g dw) > Pb (9.3 µg/g dw) > Cd (1.2 µg/g dw). For depurated worms: Fe (5.0 mg/g dw) > Mn (61 µg/g dw) > Zn (39 µg/g dw) > Cu (24 µg/g dw) > Ni (8.4 µg/g dw) > Pb (2.7 µg/g dw) > Cd (0.62 µg/g dw). However, median ...