Realm: Marine
Climate: Temperate
Biome: Temperate Shelf and seas ecoregions
Central latitude: 48.737685
Central longitude: -125.118645
Duration: 13 years, from 1966 to 2016

489 records

26 distinct species

Across the time series Phytichthys chirus is the most frequently occurring species

Methods

The study was carried out at a remote and rarely visited site approximately 12 km south of Bamfield on the west coast of Vancouver Island, British Columbia (Figure 1). Here, a gravel beach extends for about 200 m between two cliffs, which prevent shore access to the beach except at low tide and under calm sea conditions. The site is not subject to, or close to, human activities and in 1970 was included in what became Canada's Pacific Rim National Park. The beach was once accessible by a path down the steep cliff separating it from the forested land above, but because of land slips, the path no longer exists and access to the shore is difficult. The rocky, wave-exposed shore has no safe landing site for recreational water crafts, and no fishing occurs near shore. Two series of tidepools, both roughly perpendicular to the shore and separated by about 30 m, were studied. One series of three pools was located in the mid and upper intertidal with the lowest pool at the 1.97 m tide level near the lower limit of the MytilusPollicipes zone, and the highest in the Pelvetiopsis and Endocladia zone at the 3-m tide level. The highest pool in the second series (four pools) was at the 1.22-m tide level near the top of the Saccharina sessilis zone with other pools at the 0.84-, 0.57- and 0.42-metre tide levels (Figure 1). The higher of these two pools, pool 5, was in the middle of the Saccharina sessilis zone, while pool 6 was near the top of the Laminarian zone and tidepool 7 situated within this zone. Tidepool positions, surface areas, volumes and vertical shore heights relative to mean low low water (MLLW) are shown in Figure 1 of the paper. Fish sampling was conducted on 13 occasions between 1966 and 2016, whereby sampling can be grouped as eight historical events (19661993) and five recent sampling events (annually between 2012 and 2016). While most tidepools were sampled at each event, in 2016 only two pools were sampled (Table 1). Sampling captured all fish in each pool and consisted of dispersing rotenone into a pool when it was isolated at low tide followed by a thorough search of the pool during which all fish were recovered with small dip nets (Gibson, 1999; Green, 1971). This approach is unique in collecting rare and cryptic species (the full species list for the study period is reported in Table S1). Tidepools were sampled on the same low tide on each sampling date, led by the first author (JMG). On several occasions, the lowest pool (7) could not be sampled because of waves inundating the pool at low tide. Sampling in 1966 and 1971 was with a two-person team, while all other sampling events were conducted by a team of six or more field assistants. Fishes from different pools were preserved separately in 10% buffered formalin and later transferred to 45% isopropyl alcohol for identification. We considered how our methods might have influenced our results. First, to understand the impact of repeated sampling, we also resampled six of the tidepools after ~2 weeks (1983) and ~4 weeks (1985). Short-term recruitment results are reported in the supporting material and indicate rapid recovery (Figure S1). Second, these intertidal fishes all have a pelagic larval stage, but both the timing of spawning and timing of settlement of larvae into pools vary between species (Green per. obs.). The timing of our sampling was not always during the same time of the year (May, June and July); thus, we disregarded recruits from the year of sampling in our analyses. Our results are therefore not influenced by years when sampling was done later in the summer, such as in 1993 when surveys were in July.

Citation(s)

@Article{BioTIME_cit430, Study_id = {699}, Citation_id = {430}, Author = {Green, John M. and Dunbrack, Robert L. and Bates, Amanda E.}, Journal = {Diversity and Distributions}, Pages = {2170-2179}, Title = {Signals of resilience and change in tidepool fish communities on the Pacific coast of Vancouver Island, Canada}, Volume = {27}, Year = {2021}, Doi = {10.1111/ddi.13387}, Language = {English} }