Composition, spatial and temporal variations of chaetognatha in Guanabara Bay, Brazil

Abstract

This paper presents the specific composition and distribution of adult chaetognaths in Guanabara Bay, Brazil. A comparison has been made between chaetognath and copepod distribution patterns. Three areas were distinguished within Guanabara Bay: an external area, influenced by oceanic waters; an internal area, influenced by fluvial waters: and a transitional area between the two. Monthly samples were collected by horizontal surface hauls using a conical net with 200 μm mesh. Three species were identified: Sagitta friderici, S. enflata and S. hispida. Sagitta friderici was the dominant species and occurred throughout the year at the three areas. Sagitta enflata and S. hispida were limited to the more saline waters. Generally, greater densities of chaetognaths were observed following copepod peak densities. Temperature and salinity associated with copepod abundance were the most important factors affecting the distribution pattern and the abundance of chaetognath species in Guanabara Bay.