Factors affecting long term composition and productivity of delta invertebrate communities

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The development of bethic invertebrate populations goes through phases, and depends on a period of soil development that requires sediment and organic matter accretion for a period of around 10 to 20 years.

Long term monitoring of restored east coast Spartina marsh suggests that development of surface soils under vegetation, over a period 15 to 20 years, results in the development of detrital food webs, similar to reference conditions, providing forage opportunity for many estuarine dependent species. The recovery of reference levels of productivity and diversity in detrital food webs has not been verified in restored Puget Sound delta wetlands. Changes in basin water quality and poor recovery of tidal sediment and soil attributes may reduce productivity of key taxonomic groups, increasing the area necessary to provide the ecosystem services provided by less modified ecosystems. Standard, robust and comparable methods of assessing biological benthic communities may not need to be frequent, but should account for the many spatial and temporal factors that can confound comparison of benthic invertebrate communities. Proposals for evaluation of soil food web development should synthesize and build on existing work to establish performance measures that reduce the costs of extensive sampling and quantification of benthic communities.

Delta Strategy Analysis


The uncertainties in how this topic affects delta restoration has resulted in its inclusion in the ESRP River Delta Adaptive Management Strategy. This three criteria analysis should build off the analysis above, and supports development of learning projects.

Importance Viability Policy Relevance

Repeated observations have found rapid colonization and development of complex invertebrate populations that support target species on restoration sites.

There are many drivers, and a high level of spatial and temporal variation. Costs for producing quantitative data about invertebrate populations are high.

Should a conclusive pattern be identified, it is difficult to envision an approach to restoration that would manage for variation in invertebrate populations, or that would change the approach to restoration. More targeted investigation of the viability of higher trophic level organisms like fish or birds may provide more motive for policy change.