Navicula amoyensis sp. nov. (Bacillariophyceae), a new benthic brackish diatom species from the Jiulong River estuary, Southern China

Based on the light and scanning electron microscopy observations, we present a detailed description of a new brackish diatom Navicula amoyensis sp. nov. Samples were collected from an intertidal sand flat in the Jiulong River estuary, Southern China. The key diagnostic features of this species include the simple terminal raphe endings, broad terminal area, two rows of perpendicular apical pores, a wide contracted girdle region with pectinate margin and internal proximal raphe endings with a raised siliceous rib and accessory rib. Furthermore, the main taxonomic features of N. amoyensis sp. nov. and the genera Hippodonta and Navicula are also discussed in detail.

Microphytobenthic biomass on a subtropical intertidal flat of Paranaguá bay (Southern Brazil): spatio-temporal distribution and the influence of environmental conditions

Seasonal and spatial dynamics of the microphytobenthic biomass on a subtropical intertidal sand flat (25°32'S; 48°24'W) was investigated monthly from September 1995 to July 1996. Chlorophyll-a and Phaeophytin-a contents, temperature, salinity, inorganic nitrogen and phosphate pore water concentrations and sediment characteristics were assessed in the upper (HW), middle (MW) and lower (LW) sections of the flat. Microphytobenthic biomass content showed a conspicuous seasonal and spatial gradient. Higher chlorophyll-a contents were registered in the HW section of the tidal flat (from 11.78 µg.gsed-1 to 38.18 µg.gsed-1) decreasing towards the LW section (from 6.23 µg.gsed-1 to 18.23 µg.gsed-1). Microphytobenthic seasonality was determined mainly by turbulence of the water column, which was influenced by atmospheric events. The sediment properties and nutrient concentrations had a significant effect on the spatial and seasonal distribution of pigments on the intertidal flat.