Ecological patterns of macrofauna in sandy beaches of Costa Rica: A Pacific-Caribbean comparison

• Published in: Estuarine, coastal and shelf science Vol. 223; pp. 94 - 104
• Main Authors: Sibaja-Cordero, Jeffrey A., Camacho-García, Yolanda E., Azofeifa-Solano, Juan Carlos, Alvado-Arranz, Bárbara
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 31.07.2019
• Subjects: Coastal zone; Community ecology; Environmental factors; Intertidal invertebrates; Tropical beaches; Community ecology; Tropical beaches; Environmental factors; Intertidal invertebrates; Coastal zone
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2019.04.032

The present study compares the ecological patterns of macrofauna in sandy beaches between the Caribbean and Pacific coasts of Costa Rica. At each beach, the intertidal zone was divided into five strata from low to high tide level. In each stratum, sediment samples (corer area: 20.2 cm2, diameter: 5.07 cm) were collected to analyze the macrofauna. Additionally, grain size composition, total organic matter and carbonates of the sediments were determined. The macrofauna diversity was higher in the Pacific coast (15 taxa, per beach) than in the Caribbean (4 taxa, per beach). The most diverse taxon group was the annelids, followed by arthropods and mollusks. Within the mollusks, the bivalves and the gastropod family Olivellidae were only present in the Pacific coast. Both Caribbean and Pacific coasts had a vertical zonation of taxa distribution from high to low tide level. Typically, the low tide level was populated by several polychaetes, mid littoral by crustacean and mollusks, and the high tidal level was populated by isopods (Cirolanidae). Faunal differences in richness, abundance and composition of assemblages between both coasts can be explained by environmental differences. The tidal range is narrower on the Caribbean (0.5–1.5 m) than the Pacific coast (2–3 m). The slope of the beach is steep in several beaches of the Caribbean, whereas the Pacific has several dissipative beaches with gentle (or flat) slopes. The organic matter was lower (1.00%) in the Caribbean than in the Pacific (2.25%). In the Caribbean coast, the sediment is ∼90% fine sand (500–63 μm), while in the Pacific this fraction was ∼65%, resulting in more heterogeneous sediments in the Pacific. Finally, evidence of change in the abundance and species composition with the latitude in each coast was detected; indicating that these communities are highly variable within a local scale, which could be due to the diversity of sandy beaches and environmental variation that Costa Rica has in both coasts. Our results indicate that beaches with higher number of species or abundance were not necessarily designated as Marine Protected Areas. This information should be considered in the future for the establishment of new Marine Protected Areas. •Tropical sandy beaches presented differences in macrofaunal diversity associated to tidal range and beach profile.•Local beach environmental conditions influence the tropical macrofauna within the same coast.•Marine protected areas have not been established considering high diversity sandy beach macrofauna.•Interaction of sediment type, beach profile, and spatial scales explain only part of the biological assemblages.