Resource availability and meiofauna in sediment of tropical seagrass beds: Local versus global trends

Abstract

Characterisation of productivity-diversity relationships forms an essential step towards a better understanding of biodiversity. In terrestrial systems this is a topical subject and most studies reported a hump-shaped relationship. For marine systems, however, the number of studies dedicated to this is low despite the high interest in this productivity-diversity relationship.The present study reports on meiofauna density/diversity patterns in relation to resource availability as an indicator for the productivity of the ecosystem. Standardised meiofauna samples were collected in tropical seagrass beds from three localities (Kenya, Mexico, the Philippines) in order to contrast local patterns with a more global scale. Although these sites were physically comparable, a range of resource availabilities was found. These differences between localities were mainly due to different tidal regimes and related input of organic matter. At all sites a significant positive effect of resource increase on meiofauna densities was found. This positive effect was less clear for meiofauna diversity. Highest density and diversity levels were reported for the Kenyan site and this is probably linked to a high tidal range. Pooling all localities together resulted in a significant positive linear relationship between resource availability and meiofauna density/diversity. Caution should be taken when choosing resource indicators. Chlorophyll a concentrations, for example, resulted in a positive density-productivity relationship while organic carbon content, an indicator for more refractory material, showed a negative relationship. In all cases, no hump-shaped relationship could be found suggesting that each ecosystem and each group of organisms may show a particular productivity-diversity/density relationship.

Broad-scale patterns in local diversity of marine benthic harpacticoid copepods (Crustacea)

“…A positive relationship between total meiofaunal abundance and the input of organic matter has been reported repeatedly (De Troch et al 2006, Mokievsky et al 2007, Lampadariou et al 2009). Thus, the total abundance could be treated (under some reservations) as a proxy for the available food supply.…”

Assessment of regional and local biodiversity in tropical and subtropical coastal habitats in the East African Marine Ecoregion

“…Lower meiofaunal diversity in the seagrass beds within the Northern Location may also suggest a lower productivity here than the seagrass beds in the subtropical Southern Location (De Troch et al 2006), the latter being more dense. However, with only one Location representing each Region, it is not possible to state at which spatial scale these differences occur.…”

“…Others have recorded reduced or equal meiofaunal abundance in seagrass beds relative to bare sediments relating this to hydrological or predation regimes (Decho et al 1985;Siebert and Branch 2007). In the former case, seagrass beds are suggested to proved increased resource availability for meiofauna (Danovaro 1996;De Troch et al 2006). In the latter it is thought they provide 'better' shelter for macrofauna and small megafauna, resulting in increased predation of the meiofauna (Decho et al 1985).…”

Seasonal dependence on seagrass detritus and trophic niche partitioning in four copepod eco-morphotypes

“…Given those differences, it is likely that feeding habits, and therefore the role of these copepods in EMAs' food web functioning differs. In other environments, trophic niches of copepod species belonging to the same eco-morphotype can be different (Arroyo et al, 2006;Azovsky et al, 2005;Carman and Fry, 2002;Carman and Thistle, 1985;De Troch et al, 2006b;Pace and Carman, 1996;Steinarsdóttir et al, 2010). How resource partitioning determines co-existence of dominant eco-morphotypes in EMAs remains unknown.…”