TY - JOUR

T1 - A desert in the ocean – Depauperate fouling communities on marine litter in the hyper-oligotrophic South Pacific Subtropical Gyre

AU - Rech, Sabine

AU - Gusmao, Joao Bosco

AU - Kiessling, Tim

AU - Hidalgo-Ruz, Valeria

AU - Meerhoff, Erika

AU - Gatta-Rosemary, Magdalena

AU - Moore, Charles

AU - de Vine, Raquelle

AU - Thiel, Martin

PY - 2021/3

Y1 - 2021/3

N2 - The hyper-oligotrophic waters of the South Pacific Subtropical Gyre (SPSG) and the productive coastal Humboldt Current System (HCS) constitute an extreme nutrient gradient in the eastern South Pacific Ocean. Rich and dense fouling communities are known from floating objects in the HCS, but they have not been studied in the SPSG and it is not known which factors are influencing their richness and abundance. Here we present the first extensive study of rafting by marine invertebrates on floating anthropogenic debris in the eastern SPSG. We compared the effect of 9 raft-related categorical predictors on epibiont richness and fouling cover. Raft complexity was the most important predictor of richness. Fouling was dominated by thin crusts and biofilms, with more advanced communities only observed on few items. Fouling cover could not be predicted by any of the categorical factors tested. However, when tested as continuous predictors, raft volume and surface area were significantly correlated with both cover and richness. The most frequently encountered epibionts were common pelagic rafters, particularly Lepas spp., Planes spp., and Jellyella spp. Low fouling cover suggests that the SPSG's hyper-oligotrophic conditions strongly limit fouling growth, while the low frequency of coastal taxa points to the HCS/SPSG nutrient gradient acting as a filter for such organisms.

AB - The hyper-oligotrophic waters of the South Pacific Subtropical Gyre (SPSG) and the productive coastal Humboldt Current System (HCS) constitute an extreme nutrient gradient in the eastern South Pacific Ocean. Rich and dense fouling communities are known from floating objects in the HCS, but they have not been studied in the SPSG and it is not known which factors are influencing their richness and abundance. Here we present the first extensive study of rafting by marine invertebrates on floating anthropogenic debris in the eastern SPSG. We compared the effect of 9 raft-related categorical predictors on epibiont richness and fouling cover. Raft complexity was the most important predictor of richness. Fouling was dominated by thin crusts and biofilms, with more advanced communities only observed on few items. Fouling cover could not be predicted by any of the categorical factors tested. However, when tested as continuous predictors, raft volume and surface area were significantly correlated with both cover and richness. The most frequently encountered epibionts were common pelagic rafters, particularly Lepas spp., Planes spp., and Jellyella spp. Low fouling cover suggests that the SPSG's hyper-oligotrophic conditions strongly limit fouling growth, while the low frequency of coastal taxa points to the HCS/SPSG nutrient gradient acting as a filter for such organisms.

KW - Science communication and enrichment

KW - Oceanic rafting

KW - Plastic pollution

KW - Coastal species

KW - Fouling cover

KW - Community richness

KW - Epibionts

U2 - 10.1016/j.scitotenv.2020.143545

DO - 10.1016/j.scitotenv.2020.143545

M3 - Journal article

VL - 759

JO - Science of The Total Environment

JF - Science of The Total Environment

SN - 0048-9697

M1 - 143545

ER -