Pacific Rocky Intertidal Monitoring: Trends and Synthesis
Carpinteria 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).
The anemone plots at Carpinteria consist primarily of the solitary anemone, Anthopleura sola rather than the colonial anemone Anthopleura elegantissima (note that these were considered a single species prior to the past several years and they are not distinguished in our sampling methods). Cover of Anthopleura has hovered around 30% plus or minus 10% since plot inception in 1992. At the same time, other red algae (a lumped group with filamentous red algae as its primary component) have fluctuated wildly from 10 to nearly 80% cover, largely coincident with periods of sand inundation. In recent years, one species of red algae (Gracilaria spp.) along with patches of Phyllospadix sp. have been increasing within and around the anemone photoplots, though these trends are not apparent in the figure.
The barnacle plots at this site consist of a mixture of Chthamalus dalli/fissus (note that species were not distinguished until 2001) and Balanus glandula with the former dominating some plots and a more even mixture in others. Unlike some other monitoring sites, most of these barnacle plots are located atop rock outcrops and, with one exception, are not subject to periodic sand scour and/or burial. Thus they have not experienced dramatic fluctuations in barnacle cover as a whole, though one plot is subjected to regular scour and is nearly always covered by ephemeral Ulva with little barnacle cover. The plots experienced a strong recruitment pulse in 1994 resulting in a mean barnacle cover around 90%. This was followed by a gradual decline to less than 40% cover through 1998, an increase to 60% by 2004, and a decline to 30% by 2008. Presently the mean cover is stable at around 40%. Motile invertebrate counts at this site began seasonally in the fall of 2000 and were changed to annual sampling in 2004. Within the barnacle plots, limpets are abundant and have fluctuated between 50 and 200 individuals per plot on average. Littorines are also abundant and have varied widely throughout the years from almost none in 2007 to an average of around 1000 individuals per plot in 2002. Presently the numbers of both limpets and littorines are approaching 200 individuals per plot.
The Pollicipes plots at this site started out in 1992 with abundant Pollicipes cover (~60%) compared to mussel cover (~10%). Throughout the years, there has been a gradual reversal in the relative cover of these two species with mussels presently around 50% and Pollicipes around 30%. Pollicipes has shown seasonal variation (lower in spring, higher in fall) with the inverse pattern reflected in bare rock. Motile invertebrate counts within the Pollicipes plots show the regular occurrence of whelk snails (Nucella spp.) and shore crabs (Pachygrapsus crassipes) in the range of 5-10 individuals per plot on average. Limpets are generally more abundant but have fluctuated wildly from just a few to nearly 100 individuals per plot on average.
The Mussel plots at Carpinteria have been highly variable throughout the years ranging from over 90% mean cover of Mytlius to nearly zero. Periods of mussel decline were caused by extensive mussel bed breakouts that are in turn the result of frequent episodes of pounding surf on the outer reef at this site. Pulses in cover of the ephemeral alga Ulva spp. have occurred in the wake of these mussel breakouts. Data gaps are caused by the presence of harbor seals on this portion of the site which, when present, prevent access to the plots. Motile invertebrate sampling shows that chitons (Nuttalina spp.) and snails (Nucella spp. and Tegula funebralis) are regular occupants of these mussel plots, along with littorines, which were more common in the fall of 2003, and limpets, which show two strong abundance peaks in fall of 2003 and fall of 2009.
The mean cover of Surfgrass (Phyllospadix spp.) at this site has fluctuated throughout the years from about 10 to 90%, with seasonal variation (lower in spring, higher in fall) and one period of particularly low cover from the fall of 1998 to the spring of 2000. During that latter period, the apparent decline in Phyllospadix was met by a corresponding increase in the kelp Egregia menziesii, while seasonal dips through the years resulted in increases of red algae (primarily filamentous red algae but also including Gracilaria sp. and a few other species). Egregia had another pulse of cover in the fall of 2008 but this did not coincide with an apparent Phyllospadix decline. The disparity between these two events is likely the result of changes in sampling methodology: in the early years, samplers would record the topmost species encountered at the sampling point, but after 2000, in situations where fronds of Egregia lay atop a Phyllospadix understory, both species would be recorded for that sampling point. Thus, some portion of the apparent Phyllospadix decline of the late 1990's may be misleading as the increasing Egregia may have been merely covering over a healthy Phyllospadix understory. Since 2001, Phyllospadix cover has hovering around 50% with some minor and/or seasonal variation.
Seastar (Pisaster ochraceus) abundance within the original transect swaths has been variable at this site from over 70 stars counted and measured to just a few. Seastar numbers were particularly low from 1994 through 1999 followed by a period of higher numbers from 2002 to 2006. Seastar numbers show some seasonal variation with higher numbers in the spring compared to the fall. In the spring of 2004, the push for methodological consistency among sites prompted the addition of a series of three large irregular plots to be sampled alongside the transects. Compared to the transect data, these plots contained a higher number of stars during their first few seasons of sampling (expected given the greater amount of area sampled), but with declines converging toward the transect data numbers in more recent seasons. Seastar sizes have been measured since fall 2000. A large recruitment pulse was evident in the spring of 2002. The growth of these seastars through time is can be seen in these trend graphs through spring 2006, after which abundance drops off. No other significant recruitment events have observed. Given the pulse of larger stars appearing in spring 2010, along with general observations, it seems that stars are able to migrate to and from the reef from the contiguous subtidal. These data have historically been collected within three short transect swaths.
Below are the trends observed for each Photo Plot target species at this site. Long-Term percent cover trend graphs show all 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 Interactive Map.
For motile invertebrate Species Counts, a mean across all plots was calculated, and only those species with a value of at least 5 individuals for at least one sample are shown. For motile invertebrate size trend graphs by site, please use the Interactive Map.
Chthamalus/Balanus (Acorn Barnacles) - percent cover
Chthamalus/Balanus (Acorn Barnacles) - motile invertebrate counts
Pollicipes (Goose Barnacle) - percent cover
Pollicipes (Goose Barnacle) - motile invertebrate counts
Mytilus (California Mussel) - percent cover
Mytilus (California Mussel) - motile invertebrate counts
Below are the trends observed for each Transect target species at this site. Long-Term trend graphs show all 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.
Species Counts and Sizes
Species Counts and Sizes (where recorded) for Pisaster are shown below for this site. The sum of all individuals across all plots is displayed.
Pisaster (Ochre Star) - counts
Pisaster (Ochre Star) - sizes in Transects