Assessment ofASU sampling package CHAPTER FIVE Assessment of Artificial Substrate Unit sampling package 5.1 Introduction In Australia, comprehensive inventory data for most marine invertebrate taxa for a region is the exception rather than the rule (Ponder et al. 2002; Smith, 2005). For this reason, rapid assessment methods are increasingly being regarded as an important tool for addressing the current demand for biodiversity information by government and management agencies (Arvanitidis el a/., 2005; Smith, 2005). There are many different approaches to assess, monitor and conserve biodiversity and combinations of methods are proving useful (Giangrande el al., 2005). Challenges facing the cataloguing ofterrestrial invertebrates are similar to those experienced by marine invertebrate surveys. Developing rapid assessment methods to encompass such a diverse assemblage has led to novel approaches, many ofwhich include the used ofsampling packages. For example, to efficiently assess arthropod assemblages Kitching el al., (200 I) developed a 'sampling package' approach, using a number ofcollecting methods to sample regional fauna. As different collection techniques were more successful for certain taxa, a greater range of fauna could be sampled and a better overall community assessment was obtained. In freshwater habitats, sampling packages based on Artificial Substrate Units (ASUs), and, combining a number ofstructures, are widely implemented across the United States, United Kingdom, France and Belgium as a standardised monitoring method (De Pauw el aI., 1986; Costello & Thrush, 1991). Research has gone into developing effective and efficient ASU sampling protocols with experimentation into ASU composition (material, volume, particle size), deployment length, placement in the environment, representativeness of local fauna, and pollution sensitivity ofcolonizing fauna (De Pauw et al., 1986). The use ofa standardised method of monitoring freshwater habitats, which 153 Assessment ofASU sampling package is repeatable across time and location, is valuable for long-term monitoring ofchanges and is a sound means ofcomparing biodiversity (De Pauw et al., 1986). The development ofrapid assessment sampling packages for the marine environment is also beginning to progress. Zimmerman & Martin (2004) outline the construction of 2 ARMs - artificial reef matrixes, a 0.5 m , mainly cement structure with added features such as crevices, PVC pipe, coral rubble tray, filter matting and kitchen scourers. This structure targeted the macroinvertebrate fauna such as echinoderms, sponges and molluscs, and the attachment of small complex ASUs in the form ofthe kitchen scourers sampled the small invertebrate fraction ofthe reef community. Constructing and deploying these structures may be time consuming but is important as part of a non­ destructive method ofcataloguing invertebrate biodiversity in fragile and/or protected coral reef areas (Zimmerman & Martin, 2004). Once a method is determined to be useful, it is important to test and re-test outcomes and look at its wider application. Re-testing is part ofthe application of logical progression in scientific research, thus refining models and further elaborating hypotheses (Underwood, 1990; 1991). Continuing research on successful techniques has demonstrated that some methods that are appropriate for one habitat/region may not be as functional or accurate elsewhere (Arvanitidis et al., 2005). For studies investigating ASUs for monitoring and assessment, one ofthe most pressing questions being tested is how representative the assemblages recruiting to ASUs are of natural habitats and/or the local species pool (Myers & Southgate, 1980; Smith & Rule, 2002; Mirto & Danovaro, 2004). For this project, the aim was to determine if ASUs could recruit assemblages that were representative ofbiodiversity, defined by species richness and taxonomic distinctness measures. Previous studies have found that ASU assemblages were representative of local fauna in red coralline algae, kelp forests and other macroalgal habitats (Myers & Southgate, 1980; Edgar, 1991 a; Norderhaug et al., 2002). However, in a local study of fauna recruiting to scourer ASUs, Smith & Rule (2002) found ASU assemblages to be largely unrepresentative ofthose occurring in 154 Assessment ofASU sampling package adjacent natural habitats; in particular, the ASUs under-sampled amphipod fauna. Smith & Rule (2002), however, deployed ASUs for a period of five months, a long deployment period, which may explain the low diversity and abundance ofamphipod fauna (see section 4.6). The objective ofthis study is to formulate and test an ASU sampling package for the rapid assessment ofamphipod biodiversity. Therefore, the aim ofthe first section is to evaluate the most efficient ASU sampling package for collecting amphipod fauna. To determine the most efficient ASU sampling package, comparisons ofspecies richness of combinations ofASU types are made. As previous the section demonstrated that amphipod assemblages on different ASU types are variable across locations (section 4.4), combinations of ASU types were evaluated for each location, then, drawing from these results, a final ASU sampling package is formulated. This ASU sampling package is then rigorously tested by assessing its ability to adequately sample local and regional biodiversity, using measures oftaxonomic distinctness. Finally, the ASU sampling package is trialed at an additional location, Bare Island, Botany Bay, as a further test ofthe ability ofthis package to effectively sample amphipod biodiversity. This trial was conducted at Bare Island (- 3 degrees south ofthe Solitary Islands region) because the subtidal habitat is different from that found at the study locations in the Solitary Islands, and the fauna at this site is particularly well catalogued (J. K. Lowry, pers. comm.). 155 Assessment of ASU sampling package 5.2 Methods 5.2.1 Additional study site - Bare Island, Botany Bay Bare Island (33 0 59' 56"E 151 0 13' 88"S) is a small, 60-m wide, landmass 20 m from the shore in the protected waters of Botany Bay, Sydney, New South Wales (Figure 43; Figure 44). The island is a surrounded by a hard, sandstone reef which is dominated by the kelp Ecklonia radiata over the depth range from 0 - 6 m. Under the macroalgal canopy is a layer ofalgae consisting ofa sparse mix ofSargassum sp., dictyotaleans, Zonaria sp. and a turfoffilamentous coralline algae. The latter was heavily silted with a ~3 cm layer oforganic detritus at the time ofsampling. The topography below 6 m comprises walls and ledges covered in encrusting coralline algae. These "barrens" habitats are maintained by the grazing ofthe urchin Centrostephanus rodgersii and the limpets Patel/oida alticostata and Cel/ana tramoserica (Underwood et al., 1991). The reefterminates at a depth ofapproximately 10m and grades into a coarse, shelly, sedimentary habitat. Bare Island was chosen as the site for this experiment as it is an area with a well known local amphipod fauna (J. K. Lowry, pers. comm.) and also represents a very different benthic habitat to those at locations previously sampled in the Solitary Islands region. In addition, Bare Island is situated in a cool temperate bioregion, as opposed to the subtropical bioregion ofthe Solitary Islands. 156 Assessment ofASU sampling package ~o KIn Figure 43: Map ofthe Bare Island region, New South Wales, Australia. Modified from Kennelly & Underwood (1992). • Study site \ \ (J { I l....----.J 10m Figure 44: Map ofBare Island, Botany Bay, Sydney, New South Wales. Blue box indicates study site. 157 Assessment ofASU sampling package 5.2.2 Field and laboratory method 5.2.2.1 Collection of natural habitats at the Solitary Islands During the dive to retrieve the final sixteen-week ASU deployment, a general collection was made all natural habitats within a 10m radius ofthe deployed racks. An airlift was used to sample fixed habitats such as corals, corallimorphs, and bare rock. All other habitats were collected using the "butcher's bag" method, (see section 2.1.3 for full description of habitats at each location). These samples, along with previous collections of natural habitats, were used to establish the source ofrecruiting amphipod fauna and to establish a master list ofamphipod fauna for the location. Natural habitats were not sampled at the beginning ofthe experiment, as this would have removed a potential source ofrecruits and so natural habitats had the same recent recruitment history as the ASUs prior to sampling. 5.2.2.2 Deployment method at Bare Island Experimental racks were deployed on a flat, barren, sandstone ledge at 8 m at the edge of the kelp forest. The barrens area was chosen over a site within the thick kelp canopy due to the logistics ofclearing a space to house the racks with a buffer margin to reduce interference from kelp fronds. Two racks (described in section 2.3.5) containing two replicates ofeach ASU type were deployed at the study site giving a total offour replicates of each ASU type. Holes (6 cm deep) were drilled into the sandstone substrate using a pneumatic drill supplied by a SCUBA tank. Racks were secured in place by dynabolts (screws with expanding collars), which had an eyelet at the top, with four dynabolts used per rack. Malleable galvanized wire was looped through the dynabolt eyelet and the comer grid ofthe rack and the two ends ofthe wire were twisted together several times to secure the rack in place. 158 Assessment ofASU sampling package Samples were deployed