Impacts of green tides on estuarine fish assemblages

Abstract

All around the world, an increasing proportion of estuarine systems are facing massive proliferations of green macroalgae, called green tides, in response to nutrient enrichment. The consequences of this perturbation for ichthyofauna that use estuarine systems as essential fish habitats remain understudied. To estimate these consequences, we combined outputs of both macroalgae proliferation and fish community surveys conducted for the European Water Framework Directive in thirteen estuaries in northwestern France, a region where green tides are of great concern. The approach revealed the influence of green tides on estuarine fish communities. The response of each community to the green tides differed according to their functional guild composition. Benthic and marine juvenile guilds were negatively impacted, while demersal and pelagic fish guilds appeared to be more resilient. Green tides, which significantly affect the suitability of fish habitat, change the composition of the fish community and may hinder the future recruitment of marine fish species that rely on estuaries during the juvenile stage.

Green macroalgae blooms (Ulva spp.) influence trophic ecology of juvenile flatfish differently in sandy beach nurseries

“…via their prey, while S. maximus did not seem to do so. Our findings challenge the use of a broad "benthic fish" or "flatfish" category when investigating impacts of human disturbances, such as eutrophication (Le Luherne et al, 2016;Paumier et al, 2018), on the functioning of coastal ecosystems. thanks to Louis Quiniou for his time and expertise on handling the beach trawl and sampling juvenile flatfish in the intertidal zone.…”

“…Opportunistic macroalgae blooms are called green tides (GT) when they are composed of seaweeds from the Phylum Chlorophyta (Smetacek and Zingone, 2013;Van Alstyne et al, 2015). Shifts in fish assemblages have been related to GT (Paumier et al, 2018;Pihl et al, 1995;Quillien et al, 2018;Wennhage and Pihl, 2007), and benthic fish species, such as flatfish, have been found to be the most negatively impacted, with generally lower densities reported at sites with GT (De Raedemaecker et al, 2012;Le Luherne et al, 2017. Overall, opportunistic macroalgae blooms can decrease the quality of flatfish nurseries (De Raedemaecker et al, 2012;Jokinen et al, 2016), potentially leading to lower annual recruitment rates to the adult stock (Pihl et al, 2005).…”

First Comprehensive Quantitative Multi-Parameter Assessment of the Eutrophication Status from Coastal to Marine French Waters in the English Channel, the Celtic Sea, the Bay of Biscay, and the Mediterranean Sea

“…So, scores for each criterion have been integrated, considering a weighting grid to classify each geographical assessment unit with a GES or a non-GES status. The OOAO approach was only used to directly give a non-GES status when D5C6 (opportunistic macroalgae) criterion was above threshold, as there is a consensus on the positive relationship between excessive nutrient inputs and macrophytes abundances [49,50].…”

Characteristics and influence of green tide drift and dissipation in Shandong Rongcheng coastal water based on remote sensing

“…For fish, shrimp, sea cucumber and shellfish aquaculture areas, a large quantity of green tide algae would reduce primary productivity, and indirectly influence the aquaculture and ecological environment in the sea area. The decay and decomposition of green tide algae during the dissipation phase consumes the dissolved oxygen in water, which would cause quantities of shellfish to die due to lack of oxygen (Le Luherne et al, 2016;Paumier et al, 2018).…”