2 Effects of Site and Sampling Day on Two Central California Siteskelp Forests

Hannah Perlkin

29 October 2011

Total= 2+20+38+36

Lit Cited= 4

{2} Effects of site and sampling day on two central Californiasiteskelp forests

ABSTRACT [20]

Comparing communities or ecosystemsis an invaluable tool whenused to evaluate the processescontributing to the structure (i.e. relative abundance of species) of ecological systems.Comparative surveys were done on two days between two sites of varying degrees of exposure along California’s central coast to address the questions: (1) is there a difference in species composition between sites and if so, does it vary by taxa? (2) is there a difference inspecies composition between sampling days and if so, does it vary by taxa? (3)is there difference in interaction effect between site and sampling day, and if so, does it vary by taxa?We focused surveys on 31species common and conspicuous species common to within the central California kelp forests were chosen due to their countability and consistent presence in the region at large. Statistics Analyses showed an overall difference in species composition between sites as well as differences in species composition between sites for algae and invertebrates whereas species composition for fish varied as a function of sampling day. This led to the conclusion that fish, as mobile organisms are most susceptible to day-to-day changes in the environment than sessile invertebrates and epifaunal and infaunalalgae. [yes… would have been good to bring n the swell exposure angle and add to your conclusion… but this is a really niuce job!]

INTRODUCTION [38] [nice!]

Comparing communities or ecosystems has been a very fruitful approach to advancing our understanding of the processes that influence the structure (i.e. relative abundance of species) and dynamics of ecological systems. [that was beautiful] For example, by comparing the structure of kelp forest ecosystems on islands with sea otters and islands without seaotters, Estes et al (1998) identifiedvarying densities of sea urchins and thus drastic differences in community structure. Additionally,Ling et al (2009) described a difference inabundanceofspiny lobster, an apex predator, betweensites withinmarine protected areas and those outside of MPAs,which led to strong structural differences between those two communities.Identifying differences between communities initiates the process of understanding the mechanismsand interactions that impact the relative abundance of species of that particular ecological system.

Similar to structure, exposure[to what???] of a community or ecosystem plays an important role in influencing its structure and comparative study studies can provide informationindicating its the relationships between exposure and community structureeffects. For example, Edwards (2004) found that sites more readily exposed to extreme ENSO events at a local scale experienced a change in community structure (i.e. relative abundance of species) that varied with degree of exposure. Qualitative observation and studies have shown variation in community structure within the central California coastal regionhowever, as pointed out by Foster and Vanblaricom (2000), few quantitative assessments of the system exist.

Two sites of relative global proximity were chosen to quantitatively describe any differences in community structure between sites(Fig Figure [spell it out] 1). The two sites, Hopkins Marine Life Refuge and Point Lobos State Reserve, havesimilar statuses as MPAsbut differing levels of exposure to the open ocean, Hopkins being very protected and Pt. Lobos exposed to oceanic conditions.This allowed for comparisonbetween variationsof exposure. The 31species chosen for sampling are species common to the central coast of California, easily countable and from three distinct taxonomic groups: fish, algae and invertebrates (Fig This is a table , not a figure! Also… save this for the Methods section 2).This comparative study of 31 species at two sites of variable exposure was conducted in order to address the central question: is there a difference in structure (i.e. relative abundance of species) between these sites? Specifically we sought to address six hypotheses: (1) H1: There is a difference in species composition between Hopkins and Point Lobos; (2) H1a: Difference in species composition between Hopkins and Pt Lobos varies by taxa; (3) H2: There is a difference in species composition between days; (4) H2a: Difference in species composition between days varies by taxa; (5) H3: Both Site and sampling day affect species composition (interaction effect); (6) H3a: the interaction between site and sampling day varies by taxa.

{good to close the Introduction with a sentence or two describing MAIN results and conclusions… e.g., community structure differed, fish also differed between days… we conclude that these are both related to exposure to swell… we think we’re awesome…]

Oh dear… it appears you deleted the begeezus out of the species you were going to count!

Numerical estimates were collected in the field along a 30m belt trMETHODS [2,2, 0, 4, 2, 3, 4, 0, 4, 3,4, 4, 3]= 36

General Approach

FISH
Oxylebius pictus / Painted greenling
Hexagrammos decagrammos / Kelp greenling
Sebastes mystinus / Blue rockfish
Sebastes carnatus / Gopher rockfish
Sebastes chrysomelas / Black and yellow rockfish
Sebastes atrovirens / Kelp rockfish
Embiotoca jacksoni / Striped surfperch
Embiotoca lateralis / Striped surfperch
Damalychthys vacca / Pile perch
ALGAE
Cystoseira osmundacea / Chained bladder kelp
Chondracanthus corymbifera / Turkish towel
Dictyoneurum californicum
Macrocystis pyrifera / Giant kelp
Dictyoneuropsis reticulate
Pterygophera californica
Eisenia arborea
INVERTEBRATES
Patiria miniata / Bat star
Pycnopodia helianthoides / Sun star
Pisaster brevispinus / Short spined star
Pisaster giganteus / Great spined star
Urticina piscivora / Fish eating anemone
Urticina lofotensis / White-spotted anemone
Pachycerianthus fimbriatus / Sand anemone
Balanophyllia elegans / Cup coral
Tethya aurantia / Ball sponge
Calliostoma ligatum / Ring-topped snail
Loxorhynchus grandis / Sheep crab
Haliotis rufescens / Red abalone
Strongylocentrotus fransiscanus / Red urchin
FISH
Oxylebius pictus / Painted greenling
Hexagrammos decagrammos / Kelp greenling
Sebastes mystinus / Blue rockfish
Sebastes carnatus / Gopher rockfish
Sebastes chrysomelas / Black and yellow rockfish
Sebastes atrovirens / Kelp rockfish
Embiotoca jacksoni / Striped surfperch
Embiotoca lateralis / Striped surfperch
Damalychthys vacca / Pile perch
ALGAE
Cystoseira osmundacea / Chained bladder kelp
Chondracanthus corymbifera / Turkish towel
Dictyoneurum californicum
Macrocystis pyrifera / Giant kelp
Dictyoneuropsis reticulate
Pterygophera californica
Eisenia arborea
INVERTEBRATES
Patiria miniata / Bat star
Pycnopodia helianthoides / Sun star
Pisaster brevispinus / Short spined star
Pisaster giganteus / Great spined star
Urticina piscivora / Fish eating anemone
Urticina lofotensis / White-spotted anemone
Pachycerianthus fimbriatus / Sand anemone
Balanophyllia elegans / Cup coral
Tethya aurantia / Ball sponge
Calliostoma ligatum / Ring-topped snail
Loxorhynchus grandis / Sheep crab
Haliotis rufescens / Red abalone
Strongylocentrotus fransiscanus / Red urchin
FISH
Oxylebius pictus / Painted greenling
Hexagrammos decagrammos / Kelp greenling
Sebastes mystinus / Blue rockfish
Sebastes carnatus / Gopher rockfish
Sebastes chrysomelas / Black and yellow rockfish
Sebastes atrovirens / Kelp rockfish
Embiotoca jacksoni / Striped surfperch
Embiotoca lateralis / Striped surfperch
Damalychthys vacca / Pile perch
ALGAE
Cystoseira osmundacea / Chained bladder kelp
Chondracanthus corymbifera / Turkish towel
Dictyoneurum californicum
Macrocystis pyrifera / Giant kelp
Dictyoneuropsis reticulate
Pterygophera californica
Eisenia arborea
INVERTEBRATES
Patiria miniata / Bat star
Pycnopodia helianthoides / Sun star
Pisaster brevispinus / Short spined star
Pisaster giganteus / Great spined star
Urticina piscivora / Fish eating anemone
Urticina lofotensis / White-spotted anemone
Pachycerianthus fimbriatus / Sand anemone
Balanophyllia elegans / Cup coral
Tethya aurantia / Ball sponge
Calliostoma ligatum / Ring-topped snail
Loxorhynchus grandis / Sheep crab
Haliotis rufescens / Red abalone
Strongylocentrotus fransiscanus / Red urchin

Your following text is more “Study System” than “General Approach”. General approach is simply that we conducted visual underwater surveys at two sites that differed by yada yada.. We used the surveys to characterize the fish, invert and alga assemblages and used multivariate stats to to test hypotheses of differences between sites and days.

Observational data was taken at two sites along the central coast of California: Hopkins (36-37'15'' N 121-54'15'’W) andPt. Lobos (N 36° 30.328' W 121° 56.688')(Fig 1). Dives were conducted to and countswere collected for 31 species common to the central California coast (Fig 2). The sites were chosen due to their relative proximity, status as MPAs and differences in levels of swell exposure. The dive site located off of the Western point at the mouth of Whaler’s Cove in Pt. Lobos State Reserve has been a no-take, no-fishing ecological reserve since 1973 while fishing has been prohibited in the waters around Hopkins Marine Life Refuge since 1984.[cite others who have described these areas like Watanabe!]

Both sites comprise of kelp forests growing on granitic substrate however, they differ in their structure. Pt. Lobos has more rocky relief and is exposed to swell.Hopkins has relatively less relief and gets relatively little exposure to swell due to its extremely protected orientation in the Monterey Bay (Fig 1).We took note of the temperature at both sites.

We chose 31 species common to the central California coast. We knew that they were likely to be present, countable and were representative of a wide range of characteristics of species native to the area (variety of mobility, size,habitat preference within the kelp forest).

H1: Is there a difference in species composition between Hopkins and Point Lobos?

In order to address this question we made observations in a similar manner at both sites. We observed along parallel 30 meter belt transects initiated at a common transect. At Hopkins the common transect was a permanent black cable running north to south along which each buddy pair was assigned a meter mark 10 meters apart at which to run one 30 meter offshore transect (90° E) and one 30 meter onshore transect (270° W). At Pt. Lobos the common transect was a temporary meter tape laid out running roughly north to south. Here buddy pairs were assigned two

meter marks 5 meters apart from which to run transects for 30 meters at 90°E. Replications were represented by the multiple transects surveyed at each site on each day.

For fish, we recorded observations on the first leg of the swim, simultaneous toone buddy unreeling the meter tape and the other buddy following the navigational heading.Each buddy recorded fish observed in a 1x1x30 metervolume along his or her side of the transect.

We observed algae in the same general manner outlined above. We recorded observations on the second leg of theswim, from the 30 m mark of each buddy pair’s transect back to the zero mark located at the common transect. Each buddy was responsible for recording abundance of the 7 species of algae within a one-meter width from the buddy pair’s transect, making a 2-meter wide swath in total. For M.pyrifera, stipe count of each plant was recorded in addition to total number of plants.

We observed invertebrates in the same general manner outlined above. We recorded observations on the third leg of the swim, starting at the zero meter mark at the common transect and ending at the 30 meter mark of the buddy pair’s transect.Each buddy was responsible for recording abundance of the 13 species of invertebrates within a one-meter width from the buddy pair’s transect, making a 2-meter wide swath in total

To determine if there is a difference in species composition between the two sites statistics we used Permanova calculations in addition to calculations of percent dissimilarity based on mean abundances determined when comparing data sets.Specifically, the primary contributing species were looked at as a function of percent dissimilarity.Theeffectiveness of the number of transects used for statistical analysis was evaluated with power index calculations. [what about the MDS plots and how to interpret those???]

H1a: Does difference in species composition between Hopkins and Point Lobos vary by taxa?

In order to address this question, we collected datain the manner mentioned above for H1. We grouped species by their common taxa(Fig 2).

To determine which taxonomic groups varied as a function of site, statistical analysis was done to generate statistics using permanova.We calculated percent dissimilarities using the mean abundances by site for each taxonomic group. Additionally, power indices were constructedfor each speciesand species contribution was assessed (Fig 4).

H2: Is there a difference in species composition between sampling days?

To determine if there is temporal variation weasked if sites vary day-to-day. To maintain consistency we sampled in the manner mentioned above for H1 on two days, October 11, 2011 and October 13, 2011, while employing the same sampling methods each day. We calculated mean abundancesand compared them by site from between the two days, finding a percent dissimilarity between days. By observing average mean abundances between days we were able to ascertain whih species contributed most to the site effect.

H2a: Does difference in species composition between days vary by taxa?

In order to address this question, data was collected in species grouped by their common taxa (Fig 2). Specifically, we used mean abundances to calculate individual percent dissimilaritiesfor each taxonomic group as a function of each site between samplings days.

H3 :Is there both site and sampling day affect on species composition (interaction effect)?

To address this question data was collectedin the manner mentioned above for H1at both Pt. Lobos and Hopkins on both sampling days and later analyzed back at the laboratory. We used permanovavalues to determine address the hypothesis.

H3a: Does interaction between site and sampling day vary by taxa?

To address this question we statistically analyzed mean species abundances by taxonomic group as a function of site by sampling day. We assessed each taxonomic group individually to attain a percent dissimilarity based on mean abundances.

Presence/Absence: PTERYGOPHERA?? EISENIA? DISCUSSION!

RESULTS

H1: Is there a difference in species composition between Hopkins and Point Lobos?

Statistics showed a strong site effecton overall species assemblagebetween Hopkins and Point Lobos (Fig 5, Permanova: site effect, P=0.001) and thus support the hypothesis stated above. Dissimilarity between sites was found to be 73.77% for day 1 and 71.84% for day 2. The primary contributors to species dissimilarity were: Balanophylliaelegans (31.54%) and Pterygophera californica(12.34%).Algae as a taxonomic group,was a powerful indicator of difference with a value of nearly 3 on the power index (Fig 3).

H1a: Does difference in species composition between Hopkins and Point Lobos vary by taxa?

Statistics support the hypothesis that species composition between Hopkins and Point Lobos vary by taxa.

We found no effect of site on the species composition of fishes (Permanova: site effect, P=0.319).

We found a strong effect of site on the species composition of algal assemblage (Fig 5. Permanova: site effect, P=0.001).We found average dissimilarity to be 81.29%. The primary contributors to species dissimilarity were found to be:Pterygophera californica(29.43%, Hopkins avg abundance: 0.15, Lobos avg abundance: 8.25), Cystoseira osmundacea (22.02%, Hopkins avg abundance: 7.88, Lobos avg abundance: 1.77), Chondracanthuscorymbifera (17.88%, Hopkins avg abundance: 6.38, Lobos avg abundance: 0.31).

We found a strong effect of site on the species composition of invertebrate assemblage (Fig 5. Permanova: site effect, P=0.001).We found average dissimilarity to be 66.00%. The primary contributors to species dissimilarity were: Balanophylliaelegans(53.27%, Hopkins average abundance: 28.67, Lobos average abundance: 9.88)

Patiriaminiata (16.82%, Hopkins average abundance: 9.69Lobos average abundance: 6.96).

H2: Is there a difference in species composition between sampling days?

We found no effect of sampling day on the overall species composition (Permanova: sampling day: P=0.382). We found dissimilarity to be 55.62% and thus reject the hypothesis stated above.

H2a: Does difference in species composition between days vary by taxa?

Statistics support the hypothesis that there is variation by taxa in species composition between days.

We found a strong effect of sampling day on the species composition of fishes (Permanova: sampling day: P=0.043). We found average dissimilarity between days to be 64.29%.

We found no effect of sampling day on the species composition of the algal assemblage (Permanova: sampling day: P=0.724).

We found no effect of sampling day on the species composition of the algal assemblage (Permanova: sampling day: P=0.515).

H3 :Is there both site and sampling day affect on species composition (interaction effect)?

We found no interaction effect on overall species composition (Permanova: site x day: P=0.375) and thus reject the hypothesis stated above.

H3a: Does interaction between site and sampling day vary by taxa?

Statistics support the hypothesis that there is variation by taxa for interactions between site and sampling day.

We found an interaction effect on the species composition of fishes (Permanova: site x day: 0.015).Both site and sampling day contributed substantially to variation in fish community composition(Fig 5).

We found no interaction effect on the species composition of the algal assemblage (Permanova: site x day:P=0.926).

We found no interaction effect on the species composition of invertebrates (Permanova: site x day: P=0.569).

DISCUSSION

H1: Is there a difference in species composition between Hopkins and Point Lobos?

The difference in overall species composition between Hopkins and Point Lobos can be attributed to several factors.A possible relationshipexists between thevariance in exposure and species abundance at the two sites. Since Hopkins has a northward facing coast it is protected from swell coming in from thesouthwest whereas the dive site used for sampling at Point Lobos is exposed to swell from the open ocean.