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WonderOcean ecology fact

Whales feed at depth and release nutrient-rich faeces near the surface, fertilising the phytoplankton, tiny drifting algae, at the base of the ocean food chain. Scientists call this the whale pump.

PLOS ONE study, 2010

OceanClimateBiologyMigrationScience

The story behind the card

The term comes from a 2010 study by the marine scientists Joe Roman and James McCarthy, who looked at whales and seals in the Gulf of Maine, off the north-eastern United States. Many whales dive to feed and then rest and breathe at the surface, where they release loose, floating plumes of faeces rich in nitrogen. The researchers estimated that marine mammals return about 23,000 tonnes of nitrogen a year to the sunlit surface layer of the Gulf, more than all the rivers flowing into it combined, and that before industrial whaling the flow was probably much larger. Other studies found a similar effect with iron in the Southern Ocean. Because phytoplankton also absorb carbon dioxide, recovering whale numbers may help both ocean productivity and carbon uptake.

Türkçe oku
Balinalar derinlerde beslenir, besin açısından zengin dışkılarını ise yüzeye yakın sularda bırakır. Bu dışkı, okyanus besin zincirinin temelindeki fitoplanktonu, yani suda sürüklenen minik algleri gübreler. Bilim insanları buna balina pompası der.
PLOS ONE çalışması, 2010

Terim, deniz bilimciler Joe Roman ile James McCarthy'nin, ABD'nin kuzeydoğu açıklarındaki Maine Körfezi'nde balinaları ve fokları incelediği 2010 tarihli çalışmadan gelir. Pek çok balina beslenmek için dalar, sonra dinlenmek ve nefes almak için yüzeye çıkar; burada azotça zengin, dağınık ve suyun üstünde kalan dışkı bulutları bırakır. Araştırmacılar, deniz memelilerinin körfezin güneş alan yüzey katmanına her yıl yaklaşık 23.000 ton azot geri taşıdığını hesapladı; bu miktar, körfeze dökülen bütün nehirlerin getirdiğinden fazladır. Sanayi ölçeğinde balina avcılığı başlamadan önce bu akışın çok daha büyük olduğu tahmin ediliyor. Başka çalışmalar, Güney Okyanusu'nda demir için benzer bir etki buldu. Fitoplankton karbondioksit de emdiği için balina nüfusunun toparlanması, hem okyanusun verimliliğine hem de karbon tutulmasına katkı sağlayabilir.

Sources and further reading

Background reading: Biological pump
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