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RISING OCEAN TEMPERATURES IS HAVING FAR-REACHING CONSEQUENCES FOR NEW ZEALAND FISHERIES AND MARINE LIFE

The rising temperatures is leading to toxic algal blooms, which in turn are blamed for the closure of a number of shellfish harvests in the New Zealand waters.

RISING OCEAN TEMPERATURES IS HAVING FAR-REACHING CONSEQUENCES FOR NEW ZEALAND FISHERIES AND MARINE LIFE

TAT Newsdesk

29 Aug 2024

Global warming is having its effect in every nook and corner of the globe. According to Stats NZ Tatauranga Aotearoa, the satellite measurements of the New Zealand’s sea and coastal temperatures between 2022 and 2023 showed an alarming increase, hitting an all time record high annual temperatures in 40+ years, since 1982, when official measurements began.

Microscopic algae, also known as phytoplankton, are found in every ocean’s surface layer. They are the foundation of the marine food web, serving as a substantial carbon sink, taking up hundred million tonnes of carbon dioxide through the photosynthesis process. This absorbed carbon then sinks to the bottom of the ocean as the microalgae dies off or is fixed in tiny animals that graze on the plants. The presence and the activity level of microalgae is measured by tracking Chlorophyll A, a pigment generally used by plants for photosynthesis.

Scientists have observed a downward trend in this process, which could result in the expansion of a phenomena called Ocean Deserts. This depletion in the levels of beneficial microalgae is replaced by the harmful algal blooms which in turn affect the food web and fisheries in the region.

New Zealand’s oceans are undergoing this unfavourable transformation in the microalgal levels. It is also showing a shift in the biomass as well as a change in the makeup of microalgae which is impacting the biodiversity of marine species. This results in a stunted marine ecosystem, which is less resilient to environmental challenges, displays lower productivity and captures less carbon. The shellfish accumulate the toxins produced by the microalgae, higher levels of which can be poisonous for people and animals consuming the shellfish. Harmful algal blooms also appear to be on the rise in New Zealand. The toxins these microalgae produce accumulate in shellfish, and their consumption can be poisonous for people and animals and threaten the economic stability of fisheries. According to New Zealand’s Ministry of Primary Industries, the rise in harmful algal blooms and biotoxins found in marine life, resulted in the closure of highest number of shellfish harvest facilities in past decade. The fisheries and aquaculture sectors of New Zealand, worth NZ $ 4 billion have been impacted. They are facing difficulties in terms of viability of the harvesting facilities, stock losses and reduced recruitment of larvae.

On a global scale the harmful impacts of toxic algal blooms extrapolate to more than USD 4 billion loss to the blue economy.  It is also worth noting that The Great Barrier Reef, in the north-east coastal area of Australia has been the hottest in 400 years. It is reshaping the marine ecosystem of the area.

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