Uncovering the environmental drivers of short-term temporal dynamics in an epibenthic community from the Western English Channel

Abstract

Benthic communities, critical to the health and function of marine ecosystems, are under increasing pressure from anthropogenic impacts such as pollution, eutrophication and climate change. In order to refine predictions of likely future changes in benthic communities resulting from these impacts, we must first better constrain their responses to natural seasonality in environmental conditions. Epibenthic time series data (July 2008–May 2014) have been collected from Station L4, situated 7.25 nautical miles south of Plymouth in the Western English Channel. These data were analysed to establish patterns in community abundance, wet biomass and composition, and to link any observed patterns to environmental variables. A clear response to the input of organic material from phytoplankton blooms was detected, with sediment surface living deposit feeders showing an immediate increase in abundance, while predators and scavengers responded later, with an increase in biomass. We suggest that this response is a result of two factors. The low organic content of the L4 sediment results in food limitation of the community, and the mild winter/early spring bottom water temperatures allow the benthos to take immediate advantage of bloom sedimentation. An inter-annual change in community composition was also detected, as the community shifted from one dominated by the anomuran Anapagurus laevis to one dominated by the gastropod Turitella communis. This appeared to be related to a period of high larval recruitment for T. communis in 2013/2014, suggesting that changes in the recruitment success of one species can affect the structure of an entire community.

The Western Channel Observatory: a century of physical, chemical and biological data compiled from pelagic and benthic habitats in the western English Channel

“…This is illustrated in the peaks and troughs of diversity linked to the availability of food sources (see seasonal productivity peaks in Fig. 4e-j; Queirós et al, 2019;Tait et al, 2015;Talbot et al, 2019) and is also reflected by pigment data and stable isotopic signatures of both DIC and particulate organic carbon and nitrogen (Queirós et al, 2019;Tait et al, 2015). Benthic-pelagic connectivity has been found to be seasonally variable in terms of the origin of the suspended and dissolved matter fluctuating between the two ecospheres as well as in terms of the dominant flux directions (Queirós et al, 2015;Rühl et al, 2020;Tait et al, 2015).…”

The Western Channel Observatory: a century of oceanographic, chemical and biological data compiled from pelagic and benthic habitats in the Western English Channel

“…Despite a clear stratification cycle, benthic dynamics of the seafloor community at L4 remain tightly linked to the water column throughout the year, as illustrated particularly in the triggering of biomass of diversity peaks and troughs linked to availability of food sources from surface waters and elsewhere (Queirós et al, 2019;Tait et al, 2015;Talbot et al, 2019).…”