Water

Water quality and sediments

On the coast, continental influence and ports modify the characteristics of seawater and the seabed. Weather conditions and marine dynamics also have an influence. The Port of Barcelona watches over its marine environment and has been regularly monitoring the quality of port waters and sediments for more than 20 years.

Annual reports on water quality and sediments

Characterisation

The waters of the port receive contributions from rainwater, discharges from the city's sanitation system in rainy seasons and the inflow of water from the Llobregat river.

The shelter of port waters favours the sedimentation of particles and organic matter in suspension on the port seabed, affecting its composition and increasing the finer materials. The main contaminants of the sediments accumulate there, such as heavy metals, organic compounds or organic matter.

 

Other effects

Nutrient inputs and organic matter in sheltered waters affect:

  • The concentrations of dissolved oxygen in water, consumed mainly by bacteria that degrade organic matter and put into it nutrients available to phytoplankton and the rest of the trophic chain.
  • The chlorophyll levels in water, higher in internal than in external waters, which are an indicator of the phytoplankton populations.

In port waters there is a higher ammonium concentration than in external waters, a clear indicator of the continental and residual origin of the contributions.

Physiochemical characteristics of port water

Regarding open waters, inland waters are: warmer, less saline due to continental inputs and runoff, less dense, due to lower salinity, and less transparent, with more matter in suspension and turbidity.

Control and analysis of port waters

For more than 20 years, the Port has been controlling and analysing its waters and sediments on a regular basis. The results show an improvement in its biological quality.

  • Control y análisis de las aguas del Port (27.02.2020)
    Caption
    Control and analysis of port waters (27.02.2020)

Ecosystems

The organisms that live in our waters are highly conditioned by environmental factors such as water renewal, hydrodynamics and water inputs from land. Communities of organisms are interrelated in the trophic chain.
fitoplacton
Pelagic Communities - Phytoplankton
It is the fraction of plankton made up of autotrophic (photosynthetic) organisms. It is the main primary producer of port waters and depends on agitation and nutrient conditions. In summer they can produce dangerous algal blooms.
zooplacton
Pelagic Communities - Zooplankton
It is the fraction of plankton made up of heterotrophs, which feed on organic matter produced by photosynthetic organisms. In the port we find tintinnids, ciliates, nauplii and multicellular organisms such as rotifers and copepods.
peces
Pelagic Communities - Fish
Numerous species have been identified in external and internal port waters. The most outstanding: red mullets, mullets, bream, gilthead bream, large bream, horse mackerel, eels, conger eels, sea bream, royal mullets and damselfish.
moluscos
Soft substratum benthic communities
Organisms that live in muddy or sandy bottoms and are bioindicators of the ecological state of the waters. In sheltered waters, polychaete annelids (70%) and molluscs abound; in open water there are polychaetes (25-50%), molluscs and crustaceans.
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Hard substrate benthic communities
They live on rocky, natural or artificial substrates. Its composition depends on the quality of the water (turbidity and suspended matter). There are coastal algae, mussels, barnacles, sea squirts and in open areas there are spirographs or echinoderms.
p2_b4_avifauna.jpg
Avifauna
Birds in port waters are mainly piscivorous. The most common are herring, sooty, black-headed and Audouin's gulls. In the port there is a colony of great cormorants and the common tern can often be seen fishing in sheltered waters.
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Phytoplankton in sheltered and open waters

The presence of these 3 phytoplankton species varies considerably in sheltered and open waters.

Physical oceanography

The most frequent swells in the port environment are less than 1 metre (80%), mainly in directions parallel to the coast. The maximum wave height is close to 7 metres. The period of waves is around 4 seconds. In autumn and winter there is an increase in swell and wave height.

 

Sea level variation

Sea level variation causes filling and emptying of the sheltered waters. The average monthly levels are at their maximum in the months of October and November and at their minimum in February and March. There are two types of tides:

  • The astronomical tide, caused by the gravitational effect of the Moon and the Sun, has a maximum range of 0.85 m, with a maximum and minimum every 12 hours.
  • The meteorological tide, caused by winds and/or atmospheric pressure, which oscillates between 13 and 98 cm.

In the external waters, the pattern of water currents is characterised by a bilayer structure with respect to the axis parallel to the coast (210°). In the surface water layer, up to 6 metres deep, the average speed is 0.04 m/s; in the deep layer, from 8 to 50 metres deep, up to about 0.20 m/s.

Inside the port, the movement of the waters follows two different patterns depending on the season of the year, as shown in the graph.

Know the state of the sea: waves and tides

Internal and external currents

In winter there is a general circulation from Bocana Nord to Bocana Sud, with a surface layer influenced by the wind, which can move in the opposite direction. In summer each inlet behaves independently and a three-layer structure is formed in the inlets and a bilayer in the channel between inlets.