Brackish-Water Benthic Fauna Under Fluctuating Environmental Conditions: The Role of Eutrophication, Hypoxia, and Global Change

We studied the spatio-temporal impacts of physical and chemical environmental variables (depth, sediment type, salinity, temperature, oxygen, total phosphorus and total nitrogen) on soft-sediment zoobenthos in the open coastal Gulf of Finland during 2001-2015. The study included 55 sampling-stations...

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Bibliographic Details
Published in:Frontiers in Marine Science 2019-07, Vol.6
Main Authors: Rousi, Heta, Korpinen, Samuli, Bonsdorff, Erik
Format: Article
Language:English
Subjects:
Anoxia
Aquatic insects
Benthic fauna
benthic indicators
Benthos
Brackish water
Chironomidae
Climate change
Coastal zone
Coastal zones
Coasts
Ecosystems
Environmental conditions
Environmental impact
environmental variability
Eutrophication
Geographical distribution
Hypotheses
Hypoxia
hypoxia tresholds
Marine crustaceans
Mineral nutrients
Nutrient concentrations
Nutrients
Oxygen
Phosphorus
Salinity
Sediment
Sediments
Species
Studies
Taxa
Trends
Underwater habitats
Zoobenthos
zoobenthos assemblage
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Summary:We studied the spatio-temporal impacts of physical and chemical environmental variables (depth, sediment type, salinity, temperature, oxygen, total phosphorus and total nitrogen) on soft-sediment zoobenthos in the open coastal Gulf of Finland during 2001-2015. The study included 55 sampling-stations covering the east-west gradient of the Finnish coastal zone. The chosen environmental variables significantly influenced the distribution of the species in space and over time. Some zoobenthic taxa formed assemblages with each other, occurring in similar environmental conditions, while Gammarus spp. and Chironomidae clearly differed from other taxa in regards to ecological requirements. We showed the critical influence of oxygen (normoxia, hypoxia, anoxia) on individual species, some better adapted to low oxygen conditions (e.g. Chironomidae) than others (e.g. Monoporeia affinis). The nutrient concentrations in the surface sediment also significantly affected the benthic assemblage patterns. The number of species in space and time increased with increasing oxygen concentrations. This study clearly shows that in order to maintain healthy marine communities, it is essential to counteract excess nutrient inputs and their indirect effects on sufficient O2 conditions for the benthic habitats.
ISSN:2296-7745
2296-7745
DOI:10.3389/fmars.2019.00464