Tideflat compaction, Damon Pt, Grays Harbor, Washington, USA

Description

What happens after a MarshMaster MM2LX is driven around an intertidal flat? This "compaction" was tested as a possible mechanical control technique for burrowing shrimp (Neotrypaea californiensis), which are a pest to shellfish aquaculture on tidelands. The project evaluated treatment efficacy and non-target effects on infauna, birds, eelgrass, and oysters. Over 2022-2023, we sampled large (~2.5 ha) areas at Damon Point (Grays Harbor, Washington, USA) before and after compaction on August 12-13 2022, which were re-compacted in May 2023. We tracked two compacted (beds 9, 11) and three interspersed reference beds (beds 8, 10, 12).

Steps to reproduce

Eelgrass.csv: Vegetative shoots of Zostera marina (eelgrass) were collected from a lower tidal elevation within 0.3 km of the study site. On 18 Aug 2022, 20 shoots were transplanted by embedding the attached rhizome underground within ten 0.25 m2 plots on each of 4 intertidal beds (9, 10, 11, 12). Shoot counts were carried out on 28 Aug 2022 (when some plots were replanted), 25 Sep 2022, 24 Mar 2023, and 18 May 2023. Beds 9 and 11 were recompacted thereafter, running over eelgrass transplants. Shoot counts were carried out again on 20 Jun 2023. Infauna.csv: Counts of invertebrates in different taxonomic groups from geo-referenced sediment cores. Cores were 10 cm diameter and 10 cm deep, sieved to 0.5 mm and preserved in 70% EtOH. Six samples were collected from each of the 5 beds on 16 Aug 2022, 25 Sep 2022, and 24 Mar 2023. Bird_byphoto.Archive: Lists all photographs in which birds were present within 14 m, as well as the photos where the water crossed through the field of view on ebb and flood tide. Go-Pro Hero 3Silver cameras with Cam-Do intervalometers were programmed to collect one image every 2 minutes. Birds were identified and counted within 7 m radius and also the next 7 m farther, representing the range at which it was possible to identifiy the smallest species (Dunlin, Calidris alpina). May2021Compaction_Nahcotta: Georeferenced sampling in June 2022 one year post-compaction at a site in Willapa Bay, Washington, USA, north of Nahcotta. Burrowing shrimp counts, plus counts of large worms and clams, come from 5-core samples (5 x 5" diameter stainless steel cores to 70 cm deep). Surface sediment was processed for organic content by loss-on-ignition, followed by dry sieving for grain size analysis. Penetrometer data show the length of the metal rod remaining above the sediment after a consistent force was applied three times by dropping a 5-pound weight. Before dropping the weight, the distance was 159 cm above the sediment, and this declined with each drop of the weight. Hole counts were in 0.25 m2. OysterOutplant.Archive.csv: Pacific oysters Crassostrea = Magallana gigas were settled on to shell in a hatchery and allowed to grow to >10 mm. 10 seeded cultch were tethered in each of 6 stations on each of 5 beds on 18 August 2022. These were collected on May 23, 2023 and recorded for live/dead, and the shell height of the 5 largest live oysters per 10 cultch at a station. ShrimpCoreSediment.Archive.csv: Burrowing shrimp (Neotrypaea californiensis) in 5 size classes by carapace length: R<4 mm, XS<8 mm, S<12 mm, M<17 mm, L>17 mm. Each sample consisted of 5 cores (5 inch diameter) to 70 cm depth. At the same points, sediment was collected, dried, and ashed at 500C for 3 hours for loss-on-ignition (percent organic), then sieved (percent fines <63 microns). Penetrometer measurement is how far above the sediment surface is the base plate for the weight (smaller distances represent higher penetration). All georeferences in WGS84

Institutions

Categories

Funding

Licence