Declines in Puget Sound sediment-dwelling communities and a new focus on climate, nutrient, and other ecosystem stressors

The Washington State Department of Ecology has been collecting data on Puget Sound sediment-dwelling (benthic) invertebrates since 1989, as part of the Marine Sediment Monitoring Program. Benthic organisms serve key functions, including processing and storage of organic material and cycling of nutrients needed by other components of the ecosystem. Benthic invertebrates are an integral part of the marine food web and biogeochemical processes that support salmon, orcas, and humans and are a key component of the Puget Sound ecosystem. We are finding significant declines in the overall condition of benthic communities, with 44% of the study area adversely affected. Many of the adversely affected benthic communities were found in terminal inlets and bays. Throughout Puget Sound, an increase of pollution/hypoxia-tolerant species and a decrease in sensitive species has occurred over time. Deterioration of benthic communities does not correspond well with changes in individual chemical contaminants measured or laboratory tests of sediment toxicity. The spatial distribution of benthic communities is in part defined by the changing physical and oceanographic habitat. Changes in the abundance and composition of the benthic invertebrate community over time may indicate responses of the ecosystem to climatic stressors and large-scale ecological shifts such as changing hydrological, nutrient, oxygen, or acidic conditions

Spatial distribution of benthic macroinvertebrate biomass in Puget Sound: establishing a baseline

Since 1989, Ecology’s Marine Sediment Monitoring Program has collected data to assess the condition of Puget Sound’s sediment-dwelling invertebrate communities (benthos). These long-term data reveal declines in benthos abundance and taxa richness in parts of Puget Sound that do not appear to be correlated with concentrations of chemical contaminants in the sediment. In 2016, a biomass and size classification component was added to the suite of benthic community indices analyzed, as part of a large-scale program redesign intended to shed more light on alternate causes of declining benthos, such as climate change and nutrient enrichment. Benthic invertebrate biomass not only influences rates of nutrient cycling in the sediment (as organisms feed and bioturbate), but also relates to the contribution of planktonic larvae to the marine food web. Biomass estimates can provide valuable information on size structure within benthic communities not captured by abundance data alone, and may help us understand the effects of various stressors on the size and development of individual organisms. This poster will present a spatial distribution of benthic invertebrate biomass from the 2016 Long-term Monitoring Program, which will serve as a baseline for future monitoring efforts and allow for the examination of relationships between biological communities and the physical processes that govern them

Lessons from long time-series of benthic invertebrate communities in the southern Salish Sea, and an expansion of parameters to assess nutrient loading and climate change pressures

Changes in habitat and benthic invertebrates indicate responses of the ecosystem to stressors. Since 1989, the Washington State Department of Ecology has monitored sediments and benthic invertebrate communities annually at ten sentinel stations. This is a unique and important dataset, providing yearly insights into benthic community structure and abundance cycles of individual species. Except where events destabilized the habitats and communities, the sediments at these ten long-term stations, and the invertebrate communities inhabiting them, have largely remained stable over time, though with some drift and cycles in species composition and abundance. A few of these long-term stations, however, have experienced profound change. Little to no relationship has been found between the sediment contaminants measured at these ten stations and the benthic communities. The lack of correlation likely relates to factors such as low contaminant levels, and cleanups and source control of point-source pollution. Annual changes at these stations will be discussed and placed in context with patterns seen at larger geographic scales. To date, benthos monitoring has included only count and species-level identification of organisms collected in sediment grabs. This numeric information, combined with functional feeding guild grouping, has provided insight into patterns of resource-use by the benthos. The sediment program is expanding its focus and adding new parameters, to assess the response of the benthos to pressures associated with nutrient loading and climate change. With this new emphasis, biomass measurements and other ecological function information (such as bioturbation rates, temperature sensitivity, tolerance to hypoxic conditions, etc.) will be explored to better understand benthic invertebrate community changes in response to current or future nutrient loading and climate change pressures in Puget Sound

Development of invertebrate assemblages on artificial reef cones off South Carolina: Comparison to an adjacent hard-bottom habitat

Artificial reefs are often used to increase the amount of hard-bottom habitat in otherwise sandy areas, including parts of South Carolina's continental shelf. In 1997 and 2003, the SCDNR deployed two designed concrete reefs off the coast of Charleston, SC, for use in fishing experiments. This study was conducted to assess the development of epifaunal invertebrate assemblages on both the younger ("Area 53"—2 years old) and older ("Area 51"—8 years old) reefs. Each artificial reef was also compared to an adjacent natural reef, "Julian's Ledge", in an attempt to determine whether designed structures can form habitats that resemble natural hard-bottom areas over time. Macrofaunal invertebrates from each of the three reef sites were collected during Spring/Summer 2005. A total of 24,940 individuals were found, comprising at least 384 motile and sessile species. Cluster analysis revealed that species composition between reef sites was distinct, with Julian's Ledge displaying higher species number and diversity; however, evidence for convergence over time included a large group of species common to all three sites, and a higher level of similarity between Julian's Ledge and Area 51 than between Julian's Ledge and Area 53. Additional sampling at a later time period could help to elucidate whether these trends may be attributed to reef age, or other environmental variables. This study provided the first catalogue of invertebrate data for any of South Carolina's designed experimental artificial reefs

Changes to long-term status and trends sediment monitoring to assess nutrient enrichment and climate change pressures in Puget Sound

Long-term monitoring of Puget Sound sediments and sediment-dwelling invertebrates (benthos) has been conducted by the Washington State Department of Ecology since 1989 as part of the Puget Sound Ecosystem Monitoring Program. Like sediment programs developed for estuaries nationwide, this Puget Sound program was designed to characterize the impact of toxic contaminants from point-source discharges on the receiving environment. Thirty years of monitoring results indicate that: 1) chemical contaminants are low and below critical thresholds in most non-urban Puget Sound sediments; 2) sediments are non-toxic in 88% of the Puget Sound study area, with low-level toxicity increasing in both urban and non-urban terminal inlets; and 3) benthos abundance and taxa richness have declined in terminal inlets and other locations. Little correspondence was seen between chemistry, toxicity, and benthos measures, and findings suggest that benthos changes may be in response to nutrient loading and climate change, rather than chemical contamination. The sediment program had been redesigned to better assess these pressures. The sampling frame and periodicity have been revised, and sampling locations are aligned with those of other monitoring programs for better comparison of data. Also, while contaminant monitoring will continue, the parameter list has been expanded to include benthos biomass and ecological function, and a new suite of biogeochemical parameters which may be better indicators of Puget Sound nutrient and climate change. The new Puget Sound sediment monitoring design will be presented. Additionally, a brief session summary will highlight links between Puget Sound monitoring programs which have led to new questions, hypotheses, and indicators which can help us better asses the effects of nutrient loading and climate change on fragile Puget Sound habitats and biota

Living and dead bivalves are congruent surrogates for whole benthic macroinvertebrate communities in Puget Sound

To integrate paleoecological data with the “whole fauna” data used in biological monitoring, analyses usually must focus on the subset of taxa that are inherently preservable, for example by virtue of biomineralized hardparts, and those skeletal remains must also be identifiable in fragmentary or otherwise imperfect condition, thus perhaps coarsening analytical resolution to the genus or family level. Here we evaluate the ability of readily preserved bivalves to reflect patterns of compositional variation from the entire infaunal macroinvertebrate fauna as typically sampled by agencies in ocean monitoring, using data from ten long-established subtidal stations in Puget Sound, Washington State. Similarity in compositional variation among these stations was assessed for five taxonomic subsets (the whole fauna, polychaetes, malacostracans, living bivalves, dead bivalves) at four levels of taxonomic resolution (species, genera, families, orders) evaluated under four numerical transformations of the original count data (proportional abundance, square root- and fourth root-transformation, presence-absence). Using the original matrix of species-level proportional abundances of the whole fauna as a benchmark of “compositional variation,” we find that living and dead bivalves had nearly identical potential to serve as surrogates of the whole fauna; they were further offset from the whole fauna than was the polychaete subset (which dominates the whole fauna), but were far superior as surrogates than malacostracans. Genus- and family-level data were consistently strong surrogates of species-level data for most taxonomic subsets, and correlations declined for all subsets with increasing severity of data transformation, although this effect lessened for subsets with high community evenness. The strong congruence of death assemblages with living bivalves, which are themselves effective surrogates of compositional variation in the whole fauna, is encouraging for using bivalve dead-shell assemblages to complement conventional monitoring data, notwithstanding strong natural environmental gradients with potential to bias shell preservation

Data_Sheet_1_Living and dead bivalves are congruent surrogates for whole benthic macroinvertebrate communities in Puget Sound.ZIP

To integrate paleoecological data with the “whole fauna” data used in biological monitoring, analyses usually must focus on the subset of taxa that are inherently preservable, for example by virtue of biomineralized hardparts, and those skeletal remains must also be identifiable in fragmentary or otherwise imperfect condition, thus perhaps coarsening analytical resolution to the genus or family level. Here we evaluate the ability of readily preserved bivalves to reflect patterns of compositional variation from the entire infaunal macroinvertebrate fauna as typically sampled by agencies in ocean monitoring, using data from ten long-established subtidal stations in Puget Sound, Washington State. Similarity in compositional variation among these stations was assessed for five taxonomic subsets (the whole fauna, polychaetes, malacostracans, living bivalves, dead bivalves) at four levels of taxonomic resolution (species, genera, families, orders) evaluated under four numerical transformations of the original count data (proportional abundance, square root- and fourth root-transformation, presence-absence). Using the original matrix of species-level proportional abundances of the whole fauna as a benchmark of “compositional variation,” we find that living and dead bivalves had nearly identical potential to serve as surrogates of the whole fauna; they were further offset from the whole fauna than was the polychaete subset (which dominates the whole fauna), but were far superior as surrogates than malacostracans. Genus- and family-level data were consistently strong surrogates of species-level data for most taxonomic subsets, and correlations declined for all subsets with increasing severity of data transformation, although this effect lessened for subsets with high community evenness. The strong congruence of death assemblages with living bivalves, which are themselves effective surrogates of compositional variation in the whole fauna, is encouraging for using bivalve dead-shell assemblages to complement conventional monitoring data, notwithstanding strong natural environmental gradients with potential to bias shell preservation.</p