engleski

Low faunal abundance and diversity in Mediterranean seagrass is linked to the segregation of seagrass resident predators and their potential prey

Seagrasses are considered superior habitats for fish, especially juveniles, seeking refuge from predation provided by structural complexity, while leading to avoidance of less complex and riskier habitats. However, predation risk is mediated by predation mode and the numerical response of predators and prey. Censusing fauna in geo-/video-referenced scuba transects in a Mediterranean lagoon revealed that mosaic-like distributed habitats (rocky-algal, seagrass, bare sediments) had unique faunal assemblages, equally delineated by the kind of 3D structure and its presence/absence. Seagrass harbored lowest faunal abundance and diversity and was avoided by most taxa ; the opposite was true for bare sediments. Two common ambushing/stalking predators strongly preferred seagrass, while bare sediments were highly preferred by small and juvenile fish. The segregation of predator and prey on a small scale (seagrass vs. neighboring habitats) was highly predictive of faunal abundances on larger scales. These results demonstrate how the relative importance of different predation modes can reduce or increase the value of alternative habitats and how seagrass resident predation can exclude potential prey (especially juvenile fish) ; thereby negatively affecting total faunal abundance and diversity in seagrass.

seagrass superiority; resident predation; Adriatic Sea

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