International Polychaete Day Feature Series IV – St John's Island National Marine Laboratory

Deep sea polychaetes research

From local biodiversity to ecologically important tubeworms and their larval culture, we focused on various aspects of polychaete biology research conducted by scientists at the St John’s Island Marine Laboratory (SJINML). As we wrap up the International Polychaete Day special series, we share one more exciting research ― polychaetes found from deep sea biodiversity expeditions undertaken by scientists at the SJINML.

Abyssal Baseline Project (ABYSSLINE 02), Pacific Ocean

During 12 February to 25 March 2015, researchers from the Tropical Marine Science Institute (TMSI, NUS), Keppel-NUS Corp Lab and Ocean Mineral Singapore (OMS) were onboard the US vessel R/V Thomas G. Thompson to participate in an environmental survey cruise ABYSSLINE 02 (AB02), at the Clarion-Clipperton Fracture Zone (CCFZ), eastern Pacific Ocean. This 43-day joint expedition between OMS and UK Seabed Resources was led by Chief Scientist Prof. Craig R. Smith from the University of Hawaii at Manoa, USA.

Macrofaunal polychaetes (250 μm – 2 cm) from the deep seafloor were collected by a boxcorer deployed at 12 stations within the OMS survey area, at an average depth of 4000 m. The polychaete specimens collected were dominated by the families Cirratulidae, Spionidae, Paraonidae, Sabellidae, and Syllidae, comprised more than half of the total polychaete abundance.

The most conspicuous feature of the abyssal polychaetes is their uniform small sizes and the reduced number of body segments at maturity, as compared with their shallow water relatives. The body tends to be linear and plain; most species have muted colours if any, or the body is translucent to dusky, with no visible pattern. Rose Bengal is often used to stain the samples to facilitate the sorting work. Polychaetes are especially fragile; deep sea specimens often fragment, the loss of their anterior palps and branchiae or loss of posterior end and pygidium are conditions routinely seen in deep-sea specimens.

Here are selected deep-sea polychaetes from the eastern Pacific Ocean (depth range: 4041 – 4183 m). Some were stained pink by Rose Bengal:

South Java Deep-Sea (SJADES) Biodiversity Expedition, Indian Ocean

Researchers from National University of Singapore (NUS) and Indonesian Institute of Sciences (LIPI) participated in the South Java Deep-Sea (SJADES) Biodiversity Expedition 2018 (23 March – 5 April). The team sailed anti-clockwise along the Sunda Strait towards Cilacap in southern Java and back, covering a total distance of 2200 km. During the two-week research cruise, a total of 63 stations with depths ranging from 100 m to 2355 m were surveyed. About 1000 polychaete specimens were collected from this cruise, using the beam trawl and dredge. More polychaetes will be sorted out from the sediment collected using the box corer and multiplecorer.

Here are selected deep-sea polychaetes found during the expedition, using either the dredge or beam trawl sampling gears.