2020 - Deep Sea Benthos

Sedimentation effects from human activities are poorly known, but an important concern for environmental sustainability of activities in the deep sea.

Voyage number:  TAN2005

Title: Sedimentation effects-the Resilience Of deep-sea Benthos to the Effects of Sedimentation (ROBES)

Area: Chatham Rise

Period:  8 - 22 June 2020

Lead organization: NIWA

Voyage leader: Malcolm Clark


Sedimentation effects from human activities such as seabed mining or bottom trawl fisheries are poorly known yet are an important concern for environmental sustainability of such activities in the deep sea. In 2016 MBIE funded a NIWA-led programme to investigate the effects of sedimentation from such seabed disturbance using a combination of field survey experimentation with in situ observations, and laboratory-based experiments. The work is designed to determine the extent and persistence of sediment plumes, the immediate disturbance impact and subsequent recovery of seafloor characteristics and communities, and the sedimentation effect on the functioning of ecologically significant species.

This survey was the third of a series of three surveys in a seabed disturbance experiment. Disturbance operations occurred in 2018 and 2019 at two different scales. The priority for the survey in June 2020 was to repeat sampling sites filled in 2018 and 2019 to monitor changes over time and evaluate recovery and resilience of the seabed communities. The time series is important to understand both temporal and spatial variability in natural conditions, as well as changes in the environment and faunal communities that may not be immediately obvious from a single survey.

Survey objectives

The main aim of the voyage was to undertake monitoring of a sediment disturbance experiment to investigate the impacts of sedimentation on deep-sea benthic communities.

This objective had the following sub-components:

  • To repeat sample monitoring sites from a wide area in 2018;
  • To repeat sample monitoring sites from the “Butterknife” feature in 2019;
  • To carry out CTD sampling to monitor oceanographic conditions;;
  • To undertake experimental work on selected sediment cores;
  • To monitor trawl disturbance sites from 2019;
  • To undertake further sampling on disturbed/undisturbed sites as time permits;
  • To collect animals for experimental sedimentation studies onshore.

Voyage report

The voyage report is available in PDF format below.