Coastal fish assemblages and predation pressure in northern-central Chilean Lessonia trabeculata kelp forests and barren grounds

PeerJ

article

Nicolás Riquelme-Pérez¹  Catalina A. Musrri¹  Wolfgang B. Stotz¹  Osvaldo Cerda¹  Oscar Pino-Olivares¹  Martin Thiel¹ 

[1] Facultad de Ciencias del Mar, Universidad Católica del Norte;Millennium Nucleus Ecology and Sustainable Management of Oceanic Island;Centro de Estudios Avanzados en Zonas Áridas

关键词: Tethering assay;    Barren grounds;    Predation;    Coastal fish;    Kelp forests;   

DOI  :  10.7717/peerj.6964

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Kelp forests are declining in many parts of the globe, which can lead to the spreading of barren grounds. Increased abundances of grazers, mainly due to reduction of their predators, are among the causes of this development. Here, we compared the species richness (SR), frequency of occurrence (FO), and maximum abundance (MaxN) of predatory fish and their predation pressure between kelp forest and barren ground habitats of northern-central Chile. Sampling was done using baited underwater cameras with vertical and horizontal orientation. Two prey organisms were used as tethered baits, the black sea urchin Tetrapygus niger and the porcelanid crab Petrolisthes laevigatus. SR did not show major differences between habitats, while FO and MaxN were higher on barren grounds in vertical videos, with no major differences between habitats in horizontal videos. Predation pressure did not differ between habitats, but after 24 h consumption of porcelanid crabs was significantly higher than that of sea urchins. Scartichthys viridis/gigas was the main predator, accounting for 82% of the observed predation events on Petrolisthes laevigatus. Most of these attacks occurred on barren grounds. Scartichthys viridis/gigas was the only fish observed attacking (but not consuming) tethered sea urchins. High abundances of opportunistic predators (Scartichthys viridis/gigas) are probably related to low abundances of large predatory fishes. These results suggest that intense fishing activity on large predators, and their resulting low abundances, could result in low predation pressure on sea urchins, thereby contributing to the increase of T. niger abundances in subtidal rocky habitats.

【 授权许可】

CC BY