Detecting strong spatial and temporal variation in macrobenthic composition on an urban shelf using taxonomic surrogates

Surrogates of macrobenthic assemblages, intended to alleviate the effort and taxonomic expertise required for monitoring, can take many forms, such as using coarser levels (‘sufficiency’) or only a subset whole fauna (‘subsetting’). Here, power both approaches retain community-level patterns spatial temporal variation were evaluated an exceptionally long (47 yr) infaunal dataset generated from monitoring wastewater impacts on urban shelf in southern California, USA. Four sets (whole infauna, polychaetes, bivalves, malacostracans) at 5 resolutions (species, genus, family, order, functional guild) along pollution gradient subdivided into 2 bins based proximity outfall (near-field vs. far-field) 3 treatment phases. All detected weakening with improved treatment, i.e. communities became more similar richness, evenness, composition through time, robust when coarsened families guilds. Polychaetes mirrored (‘proxied’) whole-fauna most accurately, expected since they constitute individuals species. However, bivalves outperformed all other detecting (‘indicating’) itself, owing their breadth feeding strategies. These results strengthen consistently positive coarsening emerging tests elsewhere caveats subsetting: clade strengths serve different objectives. Comparable datasets should exist environmental agency archives elsewhere, promoting general surrogacy model. For programs still planning stages, regional insights could be acquired via analogous nested analyses single survey.