Salish Sea Ecosystem Conference

Hood Canal benthic sub-regions as described by foraminiferal assemblage

Studies using benthic foraminiferal assemblages to assess changes in environmental conditions have been pioneered by the Puget Sound Foram Research project (University of Washington), and have focused on anthropogenically impacted embayments. Foraminifera are marine, shelled, unicellular protists that are sensitive to environmental perturbation. This study utilized foraminfera obtained from 113 grab samples collected at the sediment-water interface along Hood Canal in six non-consecutive years from 1985. Forty-one foraminiferal species inhabited Hood Canal with an average of 10 species per sample in the upper canal and 12 species per sample in the lower canal. Higher diversity and higher rates of shell dissolution are also found in the southern canal. Linear regressions, hierarchical clustering analysis and canonical correspondence analysis show that this large, restricted waterway is home to many distinct assemblages of foraminifera, which indicate the presence of smaller scale, local habitats within the canal. Five sub-regions are classified: the northern portion of the main canal, smaller impacted embayments such as Quilcene and Port Gamble, the midsection, the Great Bend, and Lynch Cove. Each region has unique environmental parameters including water acidity, economic use, point sources of pollution, and fresh water input; these are reflected in the species components of the regional assemblages. Impacted embayments have foraminiferal assemblages with pollution tolerant taxa such as Eggerella advena, higher dissolution rates of calcareous species, and the invasive species Trochammina hadai. Assemblages in the southern regions have taxa that are tolerant of low oxygen events, and these regions experience seasonal hypoxic cycles. This study aims to lay the groundwork for future investigations into environmental and habitat stressors within each of the sub-regions.