Changes in marine phytoplankton diversity: Assessment under the Marine Strategy Framework Directive

Abstract

The Marine Strategy Framework Directive requires EU Member States to assess the Good Environmental Status (GES) of their marine waters in a coherent and strategic manner. For the regional assessment of biodiversity, the OSPAR Intersessional Coordination Group of Biodiversity Assessment and Monitoring (ICG-COBAM) provides substantial advice. Through expert working groups, phytoplankton indicators are currently being developed to measure the state and the change in pelagic diversity, to quantify food web dynamics and to measure the extent of eutrophication impacts. We developed a multi-metric indicator that is compliant with the common OSPAR indicator "Changes in plankton diversity" (PH3). The aim was to describe the structure of the phytoplankton community (alpha diversity) and to detect significant temporal changes (beta diversity) to evaluate the health of pelagic habitats. In this pilot study, we used three coastal time-series in the Western Channel and the north of the Bay of Biscay (North Atlantic, France) to test the efficiency and the performance of several existing diversity indices. We validated two alpha diversity indices, namely the Menhinick Index (D) and the Hulburt Index (δ), based on their complementary ecological information, their strong relationship with habitat characteristics, and their relative ease of interpretation for stakeholders. Temporal shifts or rate of change in community structure were detected by the Local Contributions to Beta Diversity index (LCBD; a beta diversity measure). For the years where significantly high LCBD values were found, the Importance Value Index (IVI) was calculated to potentially identify the taxa (genus) responsible for the "unusual" community structure. For example, at the Ouest Loscolo site in 2008, an elevated LCBD (0.45) coincided with a high dominance value (Hulburt's Index) caused by the occurrence of a monospecific bloom of Leptocylindrus spp. (IVI = 73%) in July (2.2x10 6 cells L-1) and October (8x10 6 cells L-1). In this way, PH3 informs on different aspects of phytoplankton diversity from a community to a genus level. At the current stage of development, however, PH3 acts as a "surveillance" rather than an operational indicator since the relationship to GES is not directly tracked. In the future, by additional testing of PH3 and extending the geographical scope, the robustness of the assessment could be further determined across the OSPAR Maritime Area.

Dynamics of phytoplankton community in scallop farming waters of the Bohai Sea and North Yellow Sea in China

“…It has been reported that the biomass and community structure of phytoplankton can be impacted by physical, chemical and biological factors in the farming waters such as water temperature, nutrients and bivalve grazing [ 34 ]. Of note, nutrients including nitrogen, phosphorus and silicon are necessary for the basic composition of phytoplankton, controlling the growth and proliferation of phytoplankton in aquatic systems [ 18 ].…”

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

“…Nevertheless, the improved knowledge on phytoplankton dynamics and the complexity of the involved processes means that assessment of this biological compartment can no longer be limited to its biomass only [38]. There is a clear need for further consideration of phytoplankton biodiversity, functional groups, trait-based approaches to identify community structure changes [39,40] following mainly modifications of nutrient pressures, but also to consider possible effects or other relevant parameters, such as light regime, residence time, etc.…”

Coastal Ocean and Nearshore Observation: A French Case Study

“…The frequency of the measurements is two times per month Long-term series on marine phytoplankton and related hydrological conditions are not only of interest in the study of phytoplankton population and community dynamics, but also on the impact of climate change on marine biodiversity (Widdicombe et al, 2010;Wiltshire et al, 2010;Hernández-Fariñas et al, 2014). PHYTOBS observations along French metropolitan coasts detected significant temporal changes in phytoplankton communities (Rombouts et al, 2019) and also contributed to highlight different environmental controls that might favor the bloom developments (Thorel et al, 2017) (Alory et al, 2006;Marchesiello et al, 2010); or (iii) to help to validate lagoon models or numerical simulations (Ouillon et al, 2005) SOMLIT ( Initially designed for maritime navigation purposes, some of the oldest tide gauge records date back to the 18th century (e.g., Woppelmann et al, 2006). Data archeology have successfully recovered sea-level information valuable for climate studies (Testut et al, 2006;Pouvreau, 2008) In order to meet the ambitious motivations and challenges, ILICO (started in 2016) inherited a great number of facilities and organizations, some of which were built over decades.…”