The latest “Our Marine Environment” report produced by the Ministry for the Environment and Stats NZ examined the most pressing issues in our oceans, seas, coastlines and estuaries. They identified four main threats on our big blue backyard.
1) Native marine species and habitats under threat
It’s estimated that 30% of Aotearoa New Zealand’s biodiversity is found in the sea, much of which is in trouble. Very few species have been formally assessed but of those that have, 22% of marine mammals, 90% of seabirds and 80% of shorebirds are threatened with, or at risk of, extinction.
The number of invasive species are on the rise and many have a significant negative impact on native species. Shellfish and seagrass beds are ecosystem engineers, as they themselves provide habitats for other species to live amongst. Many of these habitats are decreasing in size and abundance or are under threat.
2) Our activities on land are polluting the marine environment
Our activities on land, especially agriculture and forestry, and growing cities, increase the amount of sediment, nutrients, chemicals, and plastics that enter our coasts and oceans. Citizen science data collected at 44 sites showed more than 60% of beach litter was plastic and about 11% were cigarettes. It’s no foreign concept the dangers that plastic pose on marine life both internally and externally. Sediments too can smother animals, clogging their gills and degrading habitats. There are some pollutants such as pharmaceuticals and cleaning products where the environmental impacts are not even fully known or understood.
3) Our activities at sea are affecting the marine environment
Fishing has long-term and wide-spread effects on species in habitats. In 2018, 84% of routinely assessed stocks were considered to be fished within safe limits, an improvement from 81% in 2009. Of the 16% classed as overfished, 9 stocks were collapsed. About 24% of the fishable area has been trawled since 1990.
As an island nation 99.5% of our imports and exports move via the ocean and shipping traffic and vessel size has increased. A rise in boat traffic is associated with the spread of invasive species, pollution and construction of potentially disruptive wharves and coastal infrastructure.
4) Climate change is affecting marine ecosystems, taonga species and us
Long term measurements off the Otago coast reveal an increase in ocean acidity over the last 20 years by 7.1%. Satellite data recorded an average of 0.2C per decade for coastal sea-surface temperatures since 1981. An unprecedented marine heatwave occurred in the Tasman Sea between November 2017 and February 2018 during our hottest summer on record and more extreme weather and wave events like this may occur more frequently.
The rate of sea-level rise has increased, the past 60 years the sea has risen at more than double the rate of the previous 60 years.
These pressures do not act in isolation but interact and build to cause more harm. The consequences of these problems are not fully known.Working together across mātauranga Māori and other science disciplines is improving our holistic, place-based knowledge that is crucial in understanding cumulative effects.