Infaunal macroinvertebrate assemblages of the eastern Great Australian Bight: effectiveness of a marine protected area in representing the region's benthic biodiversity

Abstract

Marine reserves are used widely throughout the world to conserve biodiversity, but in many instances uncertainties exist over how well these areas represent biodiversity at a regional scale (i.e. 100–1000 km). In the present study, infaunal assemblages were examined in the eastern Great Australian Bight (GAB) to evaluate the efficacy of the Benthic Protection Zone of the GAB Marine Park in representing regional biodiversity. Distributional patterns in infauna were further examined in relation to epifaunal species composition and environmental conditions to investigate structural forcing. Grab samples of infauna were collected from the same 65 sites sampled in an earlier survey of epifauna. In total, 240 taxa belonging to 11 phyla were collected. Most taxa were uncommon, with 96% representing less than 2% of the total number of individuals collected and 39% occurring at only one site. Unlike the epifauna, the infauna of the eastern GAB does not appear to be particularly diverse. Sessile filter feeders dominated the infaunal communities of the inner shelf, whereas motile, deposit-feeding organisms dominated the shelf break. As was the case with the epifauna, the highest numbers of taxa and individuals were recorded near the head of the bight and in inner-shelf waters off the western Eyre Peninsula, where productivity is enhanced by upwelling. Cluster analysis identified three community groupings, which were strongly correlated with depth. All three communities and 72% (172) of the 240 taxa collected were represented within the Benthic Protection Zone of the GAB Marine Park, confirming findings from the epifaunal survey that this protected area is well placed to represent the benthic biodiversity of the eastern GAB.

Imperfect detection distorts depth‐related trends in marine macrofaunal species richness

“…The second model included only a linear depth term and represented the positively linear hypothesis (H 2 ) (Escaravage et al 2009). The third model did not include depth and represented the hypothesis that richness was unrelated to depth (H 3 ) (Currie et al 2009). All models included percentage mud and very fine sand as additional covariates because we expected substrate to affect species richness in this region (Sanders 1968, Gray 1981, Karakassis and Eleftheriou 1997, Bergen et al 2001, Cosentino and Giacobbe 2008, Jayaraj et al 2008, Post 2008, Joydas and Damodaran 2009, Karenyi 2014.…”

“…Macro-infaunal diversity most consistently relates to water depth as an environmental variable , Bergen et al 2001, Escaravage et al 2009); though correlates of water depth, including food availability, oxygen concentration and water movement, are likely responsible for observed diversity patterns (Snelgrove and Butman 1994). Three main macro-infaunal species richness-depth relationships have been described across continental shelves of different regions (Bergen et al 2001, Currie et al 2009, Escaravage et al 2009, Renaud et al 2009). Hypothesis 1 suggests a unimodal relationship between species richness and depth across the continental shelf with a peak in species richness at the middepths (Bergen et al 2001, Renaud et al 2009).…”

“…Hypothesis 2 proposes a general increase of species richness with depth (Escaravage et al 2009). Hypothesis 3 suggests no relationship between species richness and depth (Currie et al 2009). Thus far, no single pattern has been accepted due mainly to a lack of clarity on 1) the major driving process, since depth has many covariates; and 2) variations in species detection probability.…”

Comparison of sampling methods to assess benthic marine biodiversity : Are spatial and ecological relationships consistent among sampling gear?

“…Currie et al (2009) and Ward et al (2006) reported on patterns of epifaunal and infaunal communities as related to environmental variables in the Great Australian Bight (GAB), one of the world's largest temperate carbonate shelfs. Ward et al (2006) reported on the results of the specimens collected with an epibenthic sled (1.8 m wide, 0.6 m high, 50 mm mesh bag), and Currie et al (2009) reported on the results of the specimens collected with a Smith-McIntyre grab, both of which were deployed on the same survey. For infaunal taxa, cluster analysis (using ANOSIM and BIO-ENV) resulted in three assemblages robustly correlated with depth (ρw=0.22).…”

“…In some cases data from different gear types deployed on the same survey are reported in different scientific papers (e.g. Currie et al, 2009 andWard et al, 2006), creating difficulties identifying parallel datasets for comparison of equipment-specific results.…”