2021 State of the Environment Report Marine Chapter – Expert Assessment – State and Trend – Secondary production (zooplankton)

Updated: 2021-03-27

The Marine chapter of the 2021 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "State and Trend of secondary production (zooplankton)". ***A PDF of the full Expert Assessment, including figures and tables (where provided) is downloadable in the "On-line Resources" section of this record as "EXPERT ASSESSMENT 2021 - Secondary Production (Zooplankton)"*** ---------------------------------------- DESCRIPTION OF SPECIES/COMMUNITY/PROCESS FOR EXPERT ASSESSMENT Secondary production in the ocean is the generation of biomass by zooplankton – the primary consumers of phytoplankton. The most common zooplankton, the copepods, are the most abundant animals on Earth, even potentially outnumbering insects (Schminke 2006). Zooplankton are important components of the biological pump, shunting carbon from surface to deeper waters through sinking of faeces, exuviae and carcasses (Turner 2015). The recruitment of fish and the carrying capacity of marine ecosystems – the mass of fish, squid, shellfish, marine mammals, seabirds and sea turtles – is regulated by secondary production (Bakun 2006). Productivity hotspots, such as Eden and Bonney upwelling zones, have high densities of zooplankton, sustaining invertebrates, fish and whales alike (Gill 2002). DATA STREAM(S) USED IN EXPERT ASSESSMENT We analysed secondary production (zooplankton) data in Coastal areas (from nets at IMOS National Reference Stations, see Eriksen et al. (2019) for detailed methodology) and Offshore bioregions (from the IMOS Australian Continuous Plankton Recorder Survey, see Richardson et al. (2006) for detailed methodology). ---------------------------------------- 2021 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details] • 2021 • Assessment grade: Very good Assessment trend: Improving Confidence grade: Somewhat adequate Confidence trend: Somewhat adequate Comparability: Somewhat comparable (2016 assessment was based the same data sources but trends were assessed in terms of biomass). • 2016 • Assessment grade: Very good Assessment trend: Stable Confidence grade: Limited evidence or limited consensus Confidence trend: Limited evidence or limited consensus Comparability: Not previously assessed • 2011 • (not previously assessed) ---------------------------------------- CHANGES SINCE 2016 SOE ASSESSMENT The 2016 assessment based only on IMOS CPR data suggested the trend in zooplankton abundance was stable. The longer IMOS time series now available, together with combined information from both the NRS and AusCPR, have provided more data and greater confidence in the results.