Sediment tolerance and mortality thresholds of benthic habitats

Sediment tolerance chambers in the Marine Environmental Manipulation Facility at NIWA Wellington. © Jennifer Beaumont, NIWA

We investigated the effects that suspended sediment from human activities has on the health and survival of deep-sea species in the South Taranaki Bight.

Project leader: Malcolm Clark, NIWA

Duration: October 2016 – January 2019 
Budget: $300,000 
Status: Completed 

Human activities, such as mining and fishing, can generate suspended sediment that affect the health and survival of deep-sea species. We used innovative laboratory experiments to understand how resilient species are, and how quickly they can recover. 

We have completed trials on two deep-sea animals: dog cockles (Tucetona laticostata) and a sponge (Crella incrustans) found in the Taranaki Bight area. 

We put collected specimens in seawater to see how they responded to different conditions. The seawater ranged from clean to very murky with a high concentration of suspended sediment. We measured their survival, feeding, respiration, buoyant weight, tissue condition, internal sediment accumulation, and various stress responses such as budding and mucous production over time. After four weeks, we returned the specimens to normal seawater and monitored how well they recovered from our experiment.   

Our research will determine the level of suspended sediment that has an impact on these deep-sea species. From these results, we can predict when management or mitigation strategies will be needed to protect them.

Journal articles

Ellis JI, Clark MR, Rouse HL and Lamarche G (2017) Environmental management frameworks for offshore mining: the New Zealand approachMarine Policy 84:178-192 DOI: 10.1016/j.marpol.2017.07.004

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