Description Ofthe Macrobenthic Community from a Proposed Mussel
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Survey and Monitoring Report No. 5 Description ofthe macrobenthic community from a proposed mussel spat catching area in the bay south of Te Puraka Point, Marlborough Sounds by R. J. Davidson and J. M. Davidson 98A Quebec Road, Nelson (03)546 8413 A report prepared for New Zealand Marine Farms Associauon 1994 j - 2 - 1.0 INTRODUCTION This report presents a biological description of the rnacrobenthic communities from a proposed 18.826ha mussel spat catching area in the bay immediately south of Te Puraka Point and immediately north of Waimaru Bay (Fig. I). The area is located in south-eastem Beatrix Bay, and effectively represents the division between Beatrix and Clova Bays, Marlborough Sounds. The study site is located on a eastern shore and is exposed to north-west to south-west winds. The bay has a relatively large fetch (approximately 20km to the north-west). Beatrix Bay receives water directly on the outgoing tide from Pelorus Sound and exhibited a 6-7m depth turbid layer of cold water during the study (author, pers. OOs.). This was a direct result of heavy rain 2 days prior. Water residence times in the Beatrix, Clova, Crail Bays complex are probably relatively long and may be in the order of those recorded for Hallam and Fitzroy Bays (11 days)(Gibbs et al., 1991). The inner boundary of the proposed mussel spat catching farm is located between 50 and 150 meters from the shore (Fig. I). The proposed farm stretches 1.35km in length on the inside boundary and 1.15km in length along the outside boundary. The proposed spat catching farm \ is 150m wide along its entire length (Fig. I). Depths on the inside boundary range between 11 19m, while depths on the outside boundary range between 31-33m depth. The proposed activity is green-lipped mussel (Perna canaliculus) spat catching. Details of farm structure and management practices are outlined in a report by the applicant. The Marlborough Sounds lie at the northern end of the South Island, adjacent to Cook Strait in the north and east and Tasman Bay in the west. Formed by the submergence of river valleys, the Sounds consist of approximately 1500km of bays, passages, peninsulas, headlands, cliffs, estuaries and beaches, often with an adjacent steep terrestrial topography. The Sounds are a resource of major environmental importance. In a nationwide report by the Department of Conservation, the Marlborough Sounds was identified as being of national conservation importance. The Sounds was also identified as having areas of international biological importance (Davidson et al ., 1990; Davidson et aI., in press). These values will be important consideration in the soon to be produced Marlborough District Council Coastal Plan and District Plan. - 3 - Multiple use (marine farming, fishing, boating, housing, waste water disposal, port development, forestry, agriculture) have the potential to degrade the environment of the Sounds. Marine farming for example, can have considerable impact on the environment through habitat modification or lowering water quality (Kasparet aI., 1985; Gowan and Bradbury, 1987; Kaspar et al. , 1988; Gowan et aI., 1990; Silvert, 1992). It is therefore important that all new marine farm proposals adequately identify natural values within and adjacent to a proposed marine farm. The aim of this study was therefore to provide environmental information on the proposed site and to identify features ofbiological value which could be threatened by the establishment ofthe proposed spat catching activity. 2.0 MATERIALS AND METHODS The proposed site was qualitatively investigated on the 21 and 22nd July 1994, using two rapid subtidal survey techniques. All of the inshore boundary and randomly selected parts of the proposed spat catching area between 10 to 26m depth were investigated using an Apollo scooter. Results from this preliminary investigation were recorded on waterproof paper. Based on these findings two representative areas were selected and a lead-lined transect line marked at 5 m intervals was installed perpendicular to the shore (Fig. 1). These sites were considered representative of the substrata, habitats and flora and fauna found over the proposed farm during the scooter run. Using SCUBA, depth, distance, substrate, habitat and associated conspicuous surface dwelling flora and fauna were recorded using waterproofpaper, clipboard and a pencil. This process was terminated at a distance of 100m from the low tide mark and at depths of 26-28.5m depth. The abundance of macroinvertebrates, macroalgae and fish were estimated on a scale of 1 = uncommon, 2 = occasional, and 3 = common. 509 Te Puraka Point Pt. 3 BII<. IX Orieri so. Gaz. 1982 p.4254 Recreation & Scenic Res. 18.826 ha. SCHEDULE OF COORDINATES Datum: New Zealand Map Grid Point North East •\ 1 6015765.3 2595233.1 T,.. I . r\(V 2 6015002.9 2595608.8 v\ 3 6014611.2 2595298.0 12 • .r<\ 4 6014704.4 2595180.5 so 5085 ~"\\ \- 5 6015021.7 2595432.3 V ,I 6 6015699.1 2595098.5 0.0 J XVI 6014584.2 2595342.8 DIan 0 f V XXII 6015803.8 2595278.2 ,/1 Proposed Marine Farming Licence N.z. Marine Farming Assoc. Survey morks adopted from SO 348 Bearing variation Geodetic DotLm 1949 to NZMG +3T30· SCALE 1:10,000 200 100 0 100 200 300 400 500 600 700 800 900 1000 metres I[ I ![[ ! II I ..LOCAL AUTHORITY: MARLBOROUGH DISTRICT MARLBOROUGH LAND DISTRICT Produced by the Deportment of Survey and Land Approved for internal reproduction Information under the Authority of the Surveyor General. by; CROWN COPYRIGHT RESERVED. REPRODUCTION PROHBITED NZ Marine Farming Assoc. without the permission of the Chief Surveyor. Prep. By GJR Date 5.7.94 Job No 726544 File 6475/01/02 Reference P26/6.4 - 4 - 3.0 RFSULTS AND DISCUSSION 3.1 Scooter Run Results from the scooter run across random parts of the proposed farm and along the entire length of the proposed marine farm and adjacent coast suggested that: 1) no bedrock or rubble habitat extended more than approximately 75 m distance from the low water mark and in most areas rock habitat extended approximately < 50m from the low tide mark; 2) the changes in substrata and associated communities in the proposed farm and adjacent shores showed similar trends in depth/distribution down the shore for the entire length of the inshore farm boundary; and 3) few fish species were recorded and most were present in relatively low densities. 3.2 Promes From two random transects a total of 21 species of invertebrate, 6 algae, 2 ascidians and 5 species of bony fish were recorded (fable I, Fig. 2, 3). No difference in species presence/absence was recorded between transects, while only small abundance variations being detected. Data from transects were therefore combined and presented in Table 1. This result was probably related to the similarity in habitats and depths, with all habitats recorded being common to both transects. Although tubeworms Galeolaria hystrix were recorded on rubble habitat in the present study, no mounds were observed. Relatively few species of fish were recorded, with spotties (Notolabrus celidotus) being numerically the most abundant. Few blue cod (Parapercis colias) were recorded, however, approximately five recently settled juveniles < lOem length were observed in or near the base - 5 - of the rubble bank. No lealherjaclrets (Parika scaber) were recorded from scooter or profiles, despite being regularly recorded from spat long-lines (A. King, pers. comm.). 3.3 Brachiopods Magasella sanguinea is the most widespread brachiopod recorded from shallow subtidal areas in the Marlborough Sounds (McKnight and Grange, 1991; Duffy et al., in prep; Chadderton and Davidson, in prep). It is most often recorded from broken/dead shell/sand substrata in depths > 8m. Chadderton and Davidson (in prep) recorded it in highest densities in Pelorus Sound from their sample site in Hallam Cove and recognised M. sanguinea as a species which characterised their matrix habitat (sandi shell substrata) in central Pelorus Sound. The author recorded this species of brachiopod in an average density of 4.1 per m,2 and in densities as high as 23.2 per m,2. Dense beds ofM. sanguinea have also been recorded in northern Fitzroy Bay (Davidson and Davidson, 1994). 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