Paradise Cove Long-Term trends

See below for trend graphs

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). Due to funding constraints, semi-annual sampling of plots/transects was reduced to annual sampling beginning in 2016.

Chthamalus/Balanus barnacle plots at Paradise Cove consist of a mixture of Chthamalus dalli/fissus (note that species were not distinguished until 2001) and Balanus glandula, with the former being the overwhelming dominant component. Barnacle cover was initially high (~80%) and remained in the 60-80% ranged, except in fall 2007, through 2012. Cover then declined to ~40% through 2016, after which barnacles recovered to 60% in 2018. In general, barnacle cover has varied inversely with bare rock cover. For a short time, Endocladia, the lower intertidal turfweed, grew epiphytically on barnacles, suggesting a potential zonal shift. However, Endocladia did not fully establish. Motile invertebrate counts at this site began seasonally in the fall of 2000 and were changed to annual sampling in 2004; Littorine snails were added to the protocol in the fall of 2001. Within the barnacle plots, Littorines were highly abundant, varying among seasons from approximately 1,000 to 2,000 individuals per plot. Limpets were less common, varying between 5 and 50 individuals per plot.

Mytilus mussel plots have been fairly stable throughout the years with mussel cover in the 80 to 90% range, with exception of 2011 to 2016 when mussel cover was ~60%. After 2016, mussel cover increased back to 80%. Not evident in the trend graph are changes in the size and depth of the mussel bed that have occurred throughout the years. For example, in 2006, a line of advancing seastars just below photoplots caused the mussels to move and pile up on one another, changing a tight monolayer to a loose multi-layered bed. As seastar numbers declined, the mussel bed returned to a dense monolayer. Motile invertebrate counts reveal consistently low abundances (<10 per plot) of snails (Tegula funebralis) and volcano limpets (Fissurella volcano). Limpets, on the other hand, were typically more abundant and highly variable, with peaks nearing 120 individuals per plot in spring 2008 and 2012. Limpets and Littorine snails were not counted in spring 2014.

Endocladia turfweed plots have been dynamic with Endocladia, barnacles, mussels, and bare rock being dominant during certain periods. Endocladia cover was initially low (~20%) in 1994, increasing to ~50-60% from 1996 to 2004, before declining precipitously in fall 2004. Cover of the turfweed has remained low through 2018. Barnacles initially contributed to 40% of cover in 1994, but then declined by 1996, remaining low through fall 2016; there was a slight increase in barnacle cover in 2017/2018. Mussel (Mytilus) cover was initially low, increasing starting in 2003 to almost 60% through 2008. Mussels have declined slowly since 2008. Bare rock cover was variable from 1994-2008, mostly between 20-50%, but slowly increased to ~80% by 2016 after which barnacle cover increased, resulting in a decrease in rock cover. In motile invertebrate counts, limpets where found to be common, ranging from 50-150 individuals per plot, with a peak in spring 2011. Littorine snails were abundant initially (~140 individuals per plot) but declined afterward in the range of 20-50 individuals per plot, except a short increase in spring 2008.

Phyllospadix Surfgrass transect sampling revealed relatively consistent seasonal variation, with higher cover in fall than in spring. Throughout the years, Phyllospadix cover was in the 50-80% range with exception of a marked short-term declines in 1997-1998, spring 2012, and spring 2016. In spring 1998, when surfgrass was at its lowest, bare rock cover was high (~60%); bare rock was relatively low during all other years. Sand cover was variable over time, with a peak of 50% in spring 2012, concurrent with a notable decline in Phyllospadix; the surfgrass decline may be attributed to burial by sand. Red algae cover exhibited a weak pattern of inverse seasonal trends to that observed for Phyllospadix.

Seastar (Pisaster ochraceus) plots were added to this site in the spring of 2002 and consist of three large irregular plots surrounding an area of medium relief rock and shallow tidepools. Initially, seastars were abundant (180 individuals) which then increased to nearly 300 individuals in fall 2002 and spring 2003. Seastars declined afterward, reaching ~50 individuals in 2011 and ~30 individuals in spring 2014. While the seastar wasting disease had devastated seastar populations south of the Santa Monica Bay by the fall of 2013, this site in the northern bay had remained disease free until spring 2014. During regular sampling in early March of spring 2014, seastar numbers were similar to the previous season. However, two diseased seastars were found, including one with missing arms. Seastar plots were resampled in late March and no seastars were found in plots or at the site, likely succumbing to a sitewide disease breakout. Seastars were absent from fall 2014 to spring 2018, with exception of one individual in fall 2015. A few individuals were found in fall 2018, all of small size (<50 mm). While smaller (<50mm radius) stars were common at this site throughout the years, most individuals counted prior to seastar wasting disease were larger than 70mm.