Francisco Omar López-Fuerte

Cocconeis thalassiana sp. nov., a new alveolate diatom (Bacillariophyta) from the Mexican Caribbean

Based on light and scanning electron microscopy observations, a detailed description of a new marine alveolate Cocconeis Ehrenberg, C. thalassiana sp. nov., is presented. This large Cocconeis was found in samples collected from a shallow marine coastal lagoon of the Mexican Caribbean, as an epiphyte on the marine seagrass Thalassia testudinum Banks ex König. Among alveolate Cocconeis, the presence of long alveoli for every stria opening into the frustule interior by two long internal apertures of the sternum valve (SV) is a unique character. Other typical frustule features are: bilayered, convex SV thicker than the concave raphe–sternum valve (RSV), the inner face of the SV with hyaline areas between the two apical rows of apertures, the monolayered RSV with a narrow submarginal hyaline area following the valve outline, and the girdle consisting of only two valvocopulae (one for each valve).

Species composition and assemblage structure of microfouling diatoms growing on fiberglass plates off the coast of Yucatán, Mexico

Background. It is generally accepted that exopolymer films secreted by diatoms promote the onset of macrofouling on surfaces of materials used in marine environments. However, few studies provide precise information at species level regarding the microfouling process. The use of anti-fouling paints on different surfaces to create a toxic environment may aid in precluding development of the initial diatom microfilm leading to macrofouling. Goals. To describe the species composition and the structure of fouling diatoms. Methods. We analyzed assemblages growing on fiberglass plates, coated and uncoated with antifouling paint, fixed on PVC stands submerged at a 10-m depth. Because diatoms are opportunistic, fast growing microalgae that proliferate on many substrates, our hypothesis was that diatom assemblages growing on fiberglass surfaces, coated or uncoated with antifouling paint, would not differ in their structure. Results. Floristic analysis yielded 170 diatom taxa and similar assemblages with high values of diversity occurring on both surfaces. Conclusions. In keeping with our hypothesis, both colonized fiberglass surfaces compare to living substrata that favor the growth of diatom associations that exhibit high species diversity. This information will be useful in environmental studies, such as pollution abatement, and for the design and maintenance of fishing boats and industrial equipment prone to biofouling.