Distribution and abundance ofAbarenicola affinis(Arenicolidae, Polychaeta) in tidal inlets of Otago, New Zealand

Abstract

Lugworms are important members of the macrobenthos of sheltered intertidal sediments, and this study assessed the abundance and distribution of Abarenicola affinis in Otago, southern New Zealand. Using a faecal cast:lugworm ratio (1.00:1.09) revealed a patchy distribution across inlets, with an overall mean abundance of 11.1 individuals/m 2 (range: 3.8 to 21.3 individuals/m 2 ). Distribution patterns varied among inlets, with lugworms mostly confined to the high intertidal zone, but spread across all intertidal zones in one inlet. The lugworm habitat was characterised by muddy to medium sand (55Á233 mm mean grain size) with low organic matter (B 2%) and chlorophyll a (1Á12 mg/g dry sediment) contents. Depending on the inlet, lugworm abundance was related to sediment parameters, indicating that their distribution across Otago inlets is habitat dependent. The present findings also indicate that factors other than those measured contribute to A. affinis distribution and abundance patterns in this region.

Lugworm (Abarenicola affinis) in seagrass and unvegetated habitats

“…Furthermore, the generally low population density of A. affinis in southern New Zealand (e.g. compared with A. marina in north European tidal bays, Reise et al 2001;Goerlitz et al 2013) meant that individual numbers were low. Whereas previous studies have shown that lugworm populations are characterised by temporal stability (Flach and Beukema 1994), seasonal variation may occur, e.g.…”

“…There, the species covers about 70 % of c. 4,700 km 2 tidal flat area with an average density of 20-40 individuals per m 2 and is considered a structuring agent of regional landscape-forming processes (Beukema 1976;Riisgard and Banta 1998;Reise et al 2010). In contrast, less is known about lugworm species in other regions of the world, including populations in small semi-enclosed tidal bays, where lugworms are less dominant and exhibit a more patchy distribution (Hobson 1967;Wilson 1981;Krager and Woodin 1993;Goerlitz et al 2013). Previous studies have shown that lugworm distribution in tidal bays can be limited to certain locations on the shore, which has been associated with changes in habitat type, e.g.…”

“…In southeastern New Zealand, the lugworm Abarenicola affinis (Ashworth 1903) is common in tidal inlets and estuaries, where it co-occurs with the seagrass Zostera muelleri (Irmisch ex Ascherson 1867) in a number of habitats (Wells 1963;Leduc et al 2006;Goerlitz et al 2013). Zostera muelleri is a short-bladed seagrass (5-15 cm blade length), which is common on intertidal flats throughout New Zealand, where it often exhibits a patchy distribution (Turner 2007).…”

Abarenicola pusilla (Quatrefages, 1866): A novel species for fish waste bioremediation from marine recirculating aquaculture systems

“…A substrate layer with a depth of 5 cm (grain size <0.5 mm) was implemented in each bed (Crane & Merz, ) and was transformed into inert material after incineration (723.15 ± 50 K for 24 hr) (Bischoff, ). Above the substrate, a layer of 4 cm of filtered seawater (pH = 7.74 ± 0.19; T ª = 291.7 ± 1.24 K; 36 psu) permanently covered the experimental units (Görlitz, ). Marine RAS sludge was added as 0.5%, 2%, 4% and 10% for each of the series of experimental beds, relative to the total inert substrate content.…”