Crystal Cove Long-Term trends

From 1996-2006, average barnacle cover in plots at Crystal Cove was generally high, but dropped sharply across all plots in 2006. Barnacle cover has since rebounded slightly. Mussel cover in Mytilus plots was consistently high, with the notable exception of a large drop associated with the 1997-1998 El Niño. Subsequent storm events have resulted in patchy distribution of mussels, which has persisted over time. Dramatic increases in the cover of upright red algae- which can obscure mussel recruits during sampling – have been associated with consistently low levels of visible mussel cover since fall 2013. The abundance of Silvetia compressa (golden rockweed) has historically been high in permanent plots at this site. Seasonal fluctuations in coverage have been observed up until 2016, with percent cover in plots consistently rebounding to a high level (note that sites were only sampled in fall beginning in 2016).

Surfgrass cover along permanent transects has generally remained high over the long term, exhibiting some seasonal fluctuation. Surfgrass co-occurs with the feather boa kelp Egregia menziesii and several species of upright red algae (e.g. Pterocladiella and Laurencia) which have been consistently present in these transects in low abundance. The data show that habitat is influenced to some degree by the movement of sand.

Abundance of the sea star Pisaster has been extremely variable at this site over the years. Abnormally high numbers of Pisaster were observed in 2013, with site-wide counts exceeding 175 individuals in fall of that year, before plummeting to a total of 11 observed individuals in spring 2014. Sea Star Wasting Syndrome, which was first observed at this site on November 4, 2013 (after the fall 2013 survey), is a likely contributor to the sharp decline. Since 2014, Pisaster have rarely been encountered at this site and abundance has remained extremely low. Prior to the outbreak, sea stars were consistently found in a wide range of size classes. Following the outbreak, mostly small (<100 mm) individuals were found. However, beginning in 2018, increasing numbers of individuals >100 mm have been measured.

In order to standardize species resolution across all MARINe groups and over time, some species (typically rare) were lumped for graphical presentation of Long-Term monitoring data. See lumped categories for definitions (some variation occurs between methods and over time).

If you experience any barriers accessing the trend graphs below, please contact (pacificr@ucsc.edu) for help.

Photo Plots

Below are the trends observed for each Photo Plot target species at this site. Long-Term percent cover trend graphs also include any species that reached a minimum of 25% cover during any single point in time within a given target species assemblage. Breaks in trend lines represent missed sampling events. For additional species observed that did not meet this 25% threshold, please use the Graphing Tool.

Chthamalus/Balanus (Acorn Barnacles) – percent cover

Chthamalus/Balanus (Acorn Barnacles) – motile invertebrate counts

Mytilus (California Mussel) – percent cover

Mytilus (California Mussel) – motile invertebrate counts

Silvetia (Golden Rockweed) – percent cover

Silvetia (Golden Rockweed) – motile invertebrate counts

Transects

Below are the trends observed for each Transect target species at this site. Long-Term trend graphs also include any species that reached a minimum of 25% cover during any single point in time within a given target species assemblage. Breaks in trend lines represent missed sampling events.

Phyllospadix (Surfgrass)

Species Counts and Sizes

Species Counts and Sizes (where recorded) for Pisaster are shown below for this site. At some sites, other sea star species and Katharina are counted in addition to Pisaster. The sum of all individuals across all plots is displayed. Note that data gaps are represented by breaks in long-term count trend lines, but are not shown in size plots.