2.26 Marine Benthic Fauna in Héraðsflói Bay

Indicator 2.26 - Marine Benthic Fauna in Héraðsflói Bay

This indicator applies only to Landsvirkjun's project.

Changes in the flow of water and sedimentation in rivers are the two factors related to the projects that are most likely to affect the marine ecosystem in Héradsflói Bay.

Fljótsdalur Power Plant will greatly impact the flow of fresh water into the Bay, especially in late summers when discharge is expected to be about 200 to 300 m3 per second instead of 600 to 700 m3 per second as it was before the rivers were harnessed.

héraðssandur


Héradsflói Bay


Metrics, Targets & Monitoring Protocol


Metrics: What is measured?

  1. Grain size and distribution of sediment in selected sample plots. (Project effect: indirect)
  2. Diversity and density of benthic fauna at selected sampling spots. (Project effect: induced).


Targets

Will monitor and report data and aim for reserving diversity and density of benthic fauna at selected spots.


Monitoring Protocol

Data will be collected in three areas: Héradsflói, and in Vopnafjordur and Borgarfjordur East for comparison. In each area six monitoring stations will be established and three samples taken at each station. The following factors will be monitored:

  • Temperature and salt
  • Grain size and the amount of organic matter in sediment
  • Bethnic fauna species

Collection of data will begin in 2006 and will be repeated at regular intervals (not decided yet how often, but the next collection of data is planned after about 10 years).

Rationale for Indicator Selection


Changes in the flow of water and sedimentation in rivers are the two factors related to the projects that are most likely to affect the marine ecosystem in Heradsfloi Bay.

Fljótsdalur Power Plant will greatly impact the flow of fresh water into the Bay, especially in late summers when discharge is expected to be about 200 to 300 m3 per second instead of 600 to 700 m3 per second as it is currently.

The fresh water that enters the Bay floats on top of salty sea water. Limited monitoring on the salt levels in the Bay indicates that the changes in fresh water flows will not influence the benthic fauna.

Sedimentation is expected to decrease by 5.5 to 6 million tons per year once the power plant is in operation. The large sediment particles will remain in the reservoir and the rivers will continue carrying some of the finer grains into the Bay.

Research has shown that the benthic fauna is closely related to the grain size in the sea bottom. Changes in sedimentation could therefore influence the composition of the sediment of the sea bottom, which could lead to changes in the benthic fauna in Héradsflói Bay.

Baseline


Bethnic fauna in Héradsflói Bay and Borgarfjordur is similar, but there is more of the fine kind of sedimentation in Borgarfjordur. Vopnafjördur has a higher ratio of the fine kind, and the carbon content is obviously highest there. On all of the areas, there are reigning species of lugworm that take feed from the surface. There also turned out to be a community of lugworms that dig themselves down and feed from the sediment. The fauna was mainly split ino two communities, see graph below.

The overall outcome of the baseline study is that the biosphere of the bays is similar, and the same specied typical at all sampling places. You can view a profile of sampling and stations in Vopnafjördur, Héradsflói and Borgarfjordur by clicking here. The picture below shows the sampling stations.

2.25-botndyralif-synatokusvaedi

The graph below shows the baseline study in 6 sampling stations (Stöð).


Botndyralif-sjavar-i-Heradsfloa-grunnastand



Examples of Benthic Fauna found in Héradsflói Bay:

sandmaðkur arctica islandica stjórnufiskur
Heteromastus filiformis
Arctica islandica Ctenodiscus crispatus

Performance


Not yet applicable. Baseline data collected in 2006 and next research planned in about 10 years.