Three years on from the State of Nature 2016, this latest review of the biggest threats to nature in the UK, based on changes in key indicators, shows a continuing downward trend. The report reveals that for UK priority species, those of greatest conservation concern, more have shown strong or moderate decreases in abundance (41%) than increases (26%) since 1970. This picture is repeated over the short term with 44% of species having strong or moderate decreases in abundance, 36% with increases and 21% with little change over the last 10 years (2006-2016).
Marine biodiversity in the UK is monitored and assessed under an overarching framework called the UK Marine Strategy. To develop the Marine Strategy, a concerted effort has been undertaken to develop a suite of indicator metrics for different components of the marine ecosystem. In order to ensure alignment with this key policy framework, the State of Nature report drew on these indicator metrics (fish, seabirds, mammals and plankton) for reporting on marine biodiversity trends.
Data on plankton, which form the base of the marine ecosystem, was provided by the Continuous Plankton Recorder survey revealing key plankton trends, largely related to the signals of climate change. These include an increase in the proportion of warmer water copepod species with increasing Sea Surface Temperatures, and an increase in the Phytoplankton Colour Index (PCI), which measures the ‘greenness’ of the silk of each CPR sample, and is a proxy for total phytoplankton biomass. As shown in the State of Nature report, this index has shown a clear increasing trend in UK seas since 1958.
The State of Nature report highlights the complex and interactive drivers affecting marine ecosystems. As well as large-scale climate change trends, fishing continues to damage the seafloor and alter the size composition of fish communities, although recovery in abundance is shown for many fish species from historical over-exploitation. Noise and plastic pollution are also emerging threats.