Habitats and organisms in Finland's coastal waters are threatened by biodiversity loss, with some key species in worrying decline, Finnish experts said in a report published Friday.

With its brackish, shallow waters and coastline covering over 46,000 kilometres (28,600 miles), Finland's Baltic Sea waters are home to organisms adapted to conditions found nowhere else in the world.

A decline of important keystone species such as bladder wrack, eelgrass and the blue mussel were a cause for concern, the authors noted.

"The diversity of invertebrates that form the basis of food webs in the coastal waters of Finland is inherently relatively low, which makes the ecosystem particularly vulnerable," said associate professor and co-author of the report Christoffer Bostrom.

"If one species disappears locally, there is no species replacing that function," he added.

By studying changes in Finland's coastal marine environment for the first time, the experts at the Finnish Nature Panel were able to detect 45 different forms of biodiversity loss.

The local disappearance of species and decreases in others were the most common type of loss noted.

Coastal ecosystems are also important as they enable carbon and nutrient sequestration and oxygen production, and they uphold productive fish stocks.

The loss in biodiversity was driven by several factors, primarily eutrophication and climate change.

Eutrophication -- the excess input of nutrients into the sea from sources such as agricultural run-off, forestry and waste waters -- formed the main threat to marine biodiversity, said the report.

"None of Finland's coastal water areas are in good condition in terms of eutrophication," said Henri Sumelius, project researcher and lead author of the report.

The issue of eutrophication is well known in Finland, but increased efforts were needed to hinder harmful nutrients such as phosphorus and nitrogen from ending up in the sea, the researchers stressed.

"Despite some signs of recovery, the coastal areas have still not reached good ecological status," said Bostrom.

The Baltic Sea is among the world's seas changing fastest due to climate change, putting further pressure on the ecosystems, the report said.

For Finland to reach international targets on halting biodiversity loss, the Nature Panel recommended stronger protection of marine areas and the prioritisation of nature in decision-making.