Response of a marine benthic invertebrate community and biotic indices to organic enrichment from sewage disposal

Abstract

Nutrient enrichment is a significant cause of ecosystem change in coastal habitats worldwide. This study focuses on the change in a benthic macroinvertebrate community and environmental quality as assessed through different biotic indices following the construction of a sewage outfall pipe in the west of Scotland, from first implementation to seven years after operation of the pipe. Benthic macroinvertebrates are an important part of marine ecosystems because they mediate ecosystem processes and functions, are a key part of food webs and they provide many ecosystem services. Results indicated a clear change in benthic communities over time with an increase in species richness and changes to benthic community composition (specifically feeding type, bioturbation mode and ecological group) towards those indicative of organic enrichment. No clear spatial zonation was observed because organic carbon content increased over the entire area. According to a suite of benthic indices calculated, some negative changes were detectable following the start of sewage disposal, but largely negative community changes, and a change from ‘good’ to ‘moderate’ quality, only occurred seven years after implementation. The increase in species richness in response to increasing disturbance reduced the utility of a multi-metric index, the Infaunal Quality Index, which, instead of amplifying the signal of negative impact, dampened it. We suggest that any change in communities, regardless of direction, should be heeded, and species richness is a particularly sensitive and early warning indicator for this, but a suite of approaches is required to understand benthic community changes.

Shorebirds Affect Ecosystem Functioning on an Intertidal Mudflat

“…Organic compounds are recycled and remineralized within sediments, particularly in coastal marine areas where nitrogen and phosphorous loads can be very high (Correll et al, 1992;Hochard et al, 2010). Nitrogen loading into marine systems can lead to eutrophication and decline in water quality, making its source and removal pathways of high interest (Burgin and Hamilton, 2007) and changes in nutrient loads can impact benthic communities (Culhane et al, 2019). MPB mediate fluxes of NO 3 − , NO 2 − , PO 4 3− and NH 4 + between the water column and sediment layers (Sundback et al, 1991;Correll et al, 1992;Feuillet-Gerard et al, 1997), contributing to this process either by direct uptake/release or by altering oxygen concentration (Sundback and Graneli, 1988).…”

Effects of pollution on marine organisms

“…Several studies examined the long‐term impacts of wastewater disposal in the marine environment. For example, 7 years of wastewater disposal on the west coast of Scotland resulted in an increase in benthic community species richness and changes to benthic community composition associated with organic enrichment, though four multi‐metric indices with predefined quality classifications (Infaunal Quality Index [IQI], Benthic Quality Index [BQI], AZTI Marine Biotic Index [AMBI], and Benthic Opportunistic Polychaete Amphipod Index [BOPA]) did not detect negative impacts until 7 years after the outfall began operating, despite community composition changes and organic enrichment that occurred throughout the 7 years (Culhane, Briers, Tett, & Fernandes, 2019). Results of an 18‐year benthic community monitoring study associated with the installation and operation of deepwater ocean outfalls off the coast of Sydney, Australia indicate that sediment granulometry has a greater effect in shaping benthic community structure than accumulation of chemicals of concern near the deepwater ocean outfalls, which Besley and Birch (2019) conclude demonstrates that the three Sydney deepwater ocean outfalls have not caused significant ecological impact.…”

Benthic macroinvertebrates as bioindicators of environmental quality of Pará River estuary, a wetland of Eastern Amazon

“…N. caetensis and tubificids, which are deposit consumers, were dominant in this river. Biostimulation can occur in areas with moderate organic enrichment (CULHANE et al, 2019) when organic supply is moderate, or sufficiently diluted; it does not compromise availability of oxygen for the biota, which contributes to increasing the abundance and the number of benthic species (ROSENBERG;RESH, 1993;ROSA FILHO, 2012;KRUMHANSL et al, 2015;CULHANE et al, 2019).…”