The article discusses different ways to measure diversity in samples of benthos, which are organisms living at the bottom of bodies of water. Diversity is not just about the number of species present, but also about how many individuals of each species there are. The researchers explain that measuring diversity involves looking at both species richness (the number of species) and evenness (how evenly individuals are distributed among species). They mention that there are many ways to calculate diversity, including using indices that take into account both species richness and evenness. The article also references other sources for more detailed information on diversity measurement.