Habitat loss and interspecific competition shape coral reef ecosystem processes

Metadata:

• Identification_Information
• Data_Quality_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Dauphin Island Sea Lab: Valentine Lab

Publication_Date:

Unpublished material

Title:

Habitat loss and interspecific competition shape coral reef ecosystem processes

Geospatial_Data_Presentation_Form:

spreadsheet

Description:

Abstract:

Despite contrasting views on the impacts of loss of live coral cover and habitat complexity on reef fishes, experimental studies designed to assess the relative impacts of these two factors have not been conducted (Pratchett et al., 2008). Lirman (1999) used a mensurative experiment to analyze the impacts of coral mortality and structural degradation, via comparisons of reef fish assemblages on live and dead A. palmata colonies. His results suggest that loss of structure provided by A. palmata plays a more important role than loss of living tissue in determining fish assemblage composition, although the distribution of a number of specialists was related to the presence of live coral tissue. However, mensurative experiments are prone to confounding factors and can only correlate measurements. The lack of manipulative experiments has inhibited researchers from properly assessing relative importance of live coral cover and structural complexity. Thus, the objective of this study was to determine how coral biodiversity loss affects coral reef ecosystem processes, using a series of manipulative and mensurative experiments designed to answer three specific questions: 1) How does coral biodiversity loss affect habitat availability? Since the densities of multiple coral species have simultaneously declined (Green et al., 2008), and the impacts of such cumulative losses on habitat complexity are uncertain, the first experiment quantitatively assesses the impacts of coral species richness and identity on reef rugosity using both mensurative and manipulative methods. I also investigated the impacts of coral biodiversity loss on several fish community metrics, including species richness and overall abundance, in order to assess the appropriate measure of habitat quality for coral reef fishes. 2) How does loss of live coral and structure influence fish assemblages? I used mensurative survey techniques and experimental manipulations to determine the individual effects of both live coral loss and three-dimensional structure on reef fish assemblages. Experimental plots were created using artificial A. palmata mimics to reconstruct exact reef shapes, as opposed to cinder blocks, which are proven to be ecologically irrelevant approximations of rugosity (Kroutil, 2005). 3) What are the responses, and the causal mechanisms, of trophic interactions to habitat loss? To determine how ecosystem processes, i.e. grazing and predation, are affected by habitat loss, and the spatial extent to which trophic interactions have been affected, processes were measured in `Complex' A. palmata stands, simple sites adjacent to (`Near') and removed from (`Far') structurally complex sites , and within experimentally recreated `Current' habitats using established tethering techniques (Valentine et al., 2007, 2008; Eklof et al., 2009). The `Current' sites were constructed to mimic the current state of isolated, non-living A. palmata skeletons that currently characterize Caribbean reefs.

Purpose:

Habitat loss has been a major concern for ecologists. The widespread loss of coral diversity throughout the Caribbean has severely impacted reef architecture, but the ramifications of this are still unknown. This study is the first to describe the mechanisms by which habitat loss may have significantly altered processes, as compared to the static measures typically described in the literature.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date:

200806

Ending_Date:

200908

Currentness_Reference:

ground condition

Status:

Progress:

Complete

Maintenance_and_Update_Frequency:

As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate:

-80.3051

East_Bounding_Coordinate:

-80.2858

North_Bounding_Coordinate:

25.1244

South_Bounding_Coordinate:

25.1123

Keywords:

Theme:

Theme_Keyword_Thesaurus:

None

Theme_Keyword:

habitat loss

Theme_Keyword:

coral

Theme_Keyword:

reefs

Theme_Keyword:

ecosystem

Theme_Keyword:

competition

Theme_Keyword:

fish

Theme_Keyword:

fish assemblages

Theme_Keyword:

coral mortality

Theme_Keyword:

degradation

Theme_Keyword:

trophic interactions

Theme_Keyword:

richness

Theme_Keyword:

abundance

Theme_Keyword:

grazing

Theme_Keyword:

predation

Theme_Keyword:

herbivory

Theme_Keyword:

artificial coral

Theme_Keyword:

damselfish

Theme:

Theme_Keyword_Thesaurus:

ISO Topic

Theme_Keyword:

biota

Theme_Keyword:

002

Theme_Keyword:

environment

Theme_Keyword:

007

Theme_Keyword:

oceans

Theme_Keyword:

014

Place:

Place_Keyword_Thesaurus:

None

Place_Keyword:

Florida

Place_Keyword:

United States of America

Place_Keyword:

Florida Keys National Marine Sanctuary

Place_Keyword:

Grecian Rocks

Place_Keyword:

North Dry Rocks

Place_Keyword:

Horseshoe Reef

Place_Keyword:

Dauphin Island Sea Lab

Access_Constraints:

Permission to access these data must be given by Dr. John Valentine or Nathan Lemoine of the Dauphin Island Sea Lab.

Use_Constraints:

Acknowledgment of the DISL: Valentine Lab and the NOAA/UNC Wilmington Coral Reef Conservation grant would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected by users of these data. Users should be aware that comparison with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection, and computer processes over time. The distributor shall not be liable for improper or incorrect use of these data, based on the description of appropriate/inappropriate uses described in the metadata document. These data are not legal documents and are not to be used as such.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Dr. John Valentine or Nathan Lemoine

Contact_Organization:

DISL: Valentine Lab

Contact_Position:

Principal Investigator

Contact_Address:

Address_Type:

mailing and physical

Address:

101 Bienville Blvd.

City:

Dauphin Island

State_or_Province:

Al

Postal_Code:

36528

Country:

USA

Contact_Voice_Telephone:

251-861-2141 ext.2261 or 2294

Contact_Electronic_Mail_Address:

jvalentine@disl.org

Contact_Electronic_Mail_Address:

nlemoine@disl.org

Hours_of_Service:

8-5:00 CST

Contact_Instructions:

Please email Dr. John Valentine or Nathan Lemoine for further information.

Native_Data_Set_Environment:

Microsoft Excel

Data_Quality_Information:

Logical_Consistency_Report:

not applicable

Completeness_Report:

Data was collected during the summer months of 2008 and 2009 with no major lapses in data collection.

Lineage:

Process_Step:

Process_Description:

Fish assemblages (n = 21) and substrate composition (n = 37) were recorded over five meter transects haphazardly lain over the reef. Each transect was separated by a minimum of 5m to ensure independence of replicates. To characterize benthic assemblages, a diver passed a video camera (SONY DCR-TRV38, Tokyo, Japan) in an underwater housing along the transect. The housing had a 40cm scale bar attached to ensure the camera maintained a constant height above the substrate. 50 frames, randomly isolated from each transect video, were overlain with ten random points using Coral Point Count (CPCe v3.6). The substrate directly underneath each point was categorized into major functional groups (i.e. macroalgae, gorgonians, bare substrate). Corals were identified to a species. To calculate total percent cover for each transect, percent cover of each group in each frame was summed over the transect (Murdoch and Aronson, 1999). Structural complexity was determined by measuring rugosity (C) over each transect using the standard chain-link method (Aronson and Precht, 1995; Risk, 1972). A brass chain, consisting of 1cm links, was conformed to the substrate along each transect. Rugosity wa s calculated as: C = 1 - d/l where d is the 5m distance and l is the straightened length of the chain after it has been conformed to the substrate. d=l is the proportion of the total chain distance covered by the 5m transect, thus C is the proportion of extra chain required to cover 5 linear meters. Fish assemblages were observed along each transect after waiting a minimum of 20 minutes, allowing the fish to re-establish. I recorded the identity of each individual encountered within 0.5m on either side of the transect. Damselfish were identified to the genus level. For each transect, fish species richness, total fish abundance, fish density, and damselfish (Stegastes sp.) abundance was calculated. Two methods were used to determine whether coral species richness or identity was more important in generating habitat. First, mensurative experiments were used to generate treatments in the field by haphazardly laying 5m transect lines (n = 3) over areas of appropriate composition. Treatments consisted of a no-coral control, monocultures of the dominant species (A. palmata, P. astreoides, Siderastrea siderea, and Montastrea sp.), and two polycuture treatments (two and three species). Substrate composition and rugosity were calculated for each transect using the methods described above. Preliminary work showed that generating independent, replicate polyculture treatments of four or more species, as well as Diploria strigosa monocultures, would be impossible, so these treatments were included in the analysis. Second, I conducted manipulative experiments by articially generating treatments of coral species richness. The fractal dimension (D) of each treatment was calculated to provide plurality for substrate complexity metrics. Fractal dimensions measured the complexity of non-uniform surfaces and were especially useful when correlating substrate complexity with community metrics, given their ability to incorporate information over a variety of resolutions (Sugihara and May, 1990; Beck, 1998; Halley et al., 2004). D was calculated for a set of digital `reefs' constructed from photographs of live coral colonies. Treatments (n = 5) consisted of monospecific cultures and polyspecific mixtures of A. palmata, P. astreoides, S. siderea, D. strigosa, and M. annularis. Profiles of at least six individual colonies of each coral species were photographed in the field. Colonies were haphazardly selected in an attempt to capture as much intraspecific morphological variation as possible. A 1m scale bar was placed with one end at the coral base so that each colony was photographed from the same distance, removing any bias due to colony size. Photographs were imported into Adobe Photoshop (San Jose, USA), where the coral was isolated from the background image, providing the individual colony used to create the digital reefs. An articial `substrate', consisting of a straight line, was created on a blank image. A straight line was chosen to standardize the base value of D to 1. All colony photographs were scaled down between 30 - 40% to fit the colonies on a single frame while still allowing colonies to maintain their relative sizes. In order to best represent the shelter provided, each colony was placed on the line (i.e. substrate) in accordance with its position in the original photograph. As such, overhanging ledges and cavities in the original photograph were maintained in the digital reconstruction. For monospecic treatments, five `individuals' (i.e. photographs) of the same species were randomly selected and placed on the artificial reef. Considering each individual is photographed from a 1m distance, each colony was less than or equal to 1m in diameter. Therefore the artificial line represents a transect of approximately 10m, with the density of colonies being 0.5/m2, a reasonable approximation for natural reefs. Two polyculture treatments were constructed consisting of an intermediate and full polyculture using a density-constant, replacement design (cf. Bruno and O'Connor, 2005; Bruno et al., 2005). An intermediate richness treatment of three species was created by first randomly assigning species to each replicate, and then randomly assigning individuals from each species to the replicate. The full polyculture treatment consists of randomly chosen individuals from each species in each replicate. The end result is analogous to manually constructing and photographing reefs in natural settings, without the logistic and ethical concerns of relocating large, healthy coral colonies, especially endangered A. palmata. Once replicate reefs were created, D was calculated using the grid method (Sugihara and May, 1990; Halley et al., 2004). Caribbean coral reefs are characterized by isolated, remnant A. palmata colonies with little to no coral cover (Porter and Meier, 1992; Miller et al., 2002). To experimentally reproduce `Current' conditions, isolated mimics of A. palmata were placed in a sand channel bordering the reef. Two articial A. palmata branches, purchased from Living Color Enterprises, were mounted on a welded aluminum frame approximating the shape of live elkhorn stands. The empty cavity beneath the metal joint holding the coral blades was covered in fine plastic mesh to prevent cryptofaunal colonization of the frame. Frames were coated with black enamel paint to reduce visibility and corrosion and secured to the substrate with rebar hooks, lead weights, and also tethered to nearby sandscrews. Prior to deployment, a fractal dimension of each replicate was calculated and compared to values of natural A. palmata colonies. The colonies were allowed to acclimate over two weeks until the community stabilized (Kroutil, 2005). To determine if patch size affected fish assemblage composition, coral frames were repositioned to form a single large patch after the initial experiment was completed. To account for possible artifacts, four blank aluminum frames were deployed simultaneously as controls. Structural complexity of all habitats was quantified using D. A profile image of each site was captured using a camera placed on the substrate 1m from the tether site. To capture as much variability as possible, two photographs were taken per site at perpendicular angles. Pictures were digitized and traced over the reef outline. D was then calculated using the grid method described in the first experiment. D values for each site were pooled to represent an average measure of structural complexity. Grazing rates were estimated using established tethering techniques for seagrass (Thalassia testudinum, Kirsch et al., 2002) and a palatable algae (Laurencia sp., Kramer and Heck, 2007). Before use, ungrazed seagrass shoots (1-3 blades) were scraped of epiphytes and each blade photographed. Algae was spun in a salad spinner for 30 revolutions and patted dry before wet weight was determined on a Mettler PB303 (plus or minus 0.01g) scale. Lead weights, with three clothespins attached, were designated as either algae or seagrass tethers. For seagrass tethers, shoots were placed into each clothespin. Algae tethers held a single branch of algae per clothespin. Previous studies suggested that grazing occurred quickly, and preliminary results suggested that sufficient grazing occurred after one hour (Hay, 1984; Kramer and Heck, 2007). As such, all trials were run for a single hour to yield an hourly percent loss. Algae percent loss was determined by the difference in pre- and post-trial wet weights. Seagrass blades were rephotographed, and surface area of each shoot calculated using ImageJ Image Analysis software (Rasband, 1997). Each image was calibrated by lying a 4cm scale bar above each seagrass shoot; and percent loss calculated by comparing pre- and post-trial surface area. Invertebrate predation rates were measured by tethering crabs (Mithrax sculptus) collected from coralline algae fields at Rodriguez Key. Carapace width of each crab was measured, and two crabs tethered to each lead weight using monofilament line. Trial duration was one hour. The hypotheses tested seek to determine if coral habitat loss has altered ecosystem process and and whether loss of complex habitats represent a loss of highly productive ecotones. Accordingly, four tether groups were placed within each habitat over three days (n = 12): `Complex', `Near', `Far', and `Current'. A tether group consisted of a single replicate of algae, seagrass, and invertebrates. In `Complex' habitats, lead weights were placed in the understory of four haphazardly chosen A. palmata colonies. To assess the extent to which interspecific interactions (i.e. predation risk, competition) affect grazer foraging efficiency, I measured both attack frequency and intensity in each habitat. In each habitat, a tether group was chosen at random for a remote video each day (n = 3). Afterwards, attacker identity, attack frequency, and attack intensity were recorded for both seagrass and algae in each video. Additionally, attacker size was determined using ImageJ analysis software by taking a profile shot of each attacker and comparing its length to a known scale. Given that all lead weights were cast from the same mold, eliminating differences in diameter (8cm), tether weights makes ideal standardized scales for size analysis. Fish assemblages in `Complex', `Near', and `Far' habitats were characterized using replicate 15m visual transects (n = 5). All fishes encountered within 0.5m on either side of the transect line were identified to a species and recorded. In addition to total species richness and density, data was categorized by the density of damselfish, parrotfish, and acanthurids present in each habitat. Assemblage structure on live and artificial A. palmata colonies, as well as blank control frames, was obtained using visual surveys (n = 8). To test whether patch size affects fish assemblage structure on the artificial corals, assemblage structure on the combined bouquet of corals was recorded (n = 3). Considering the numerical dominance of damselfish in structurally complex habitats (Almany, 2004), taking appropriate measurements of damselfish community structure and aggression are necessary. As such, a size distribution of damselfish was constructed within each habitat. Given the difficultly of visually estimating sizes underwater, I recorded the number of damselfish falling into pre-defined size categories along 15m transects using a scale bar marked into sections (0-5cm, 5-10cm, 10-15cm, 15+cm, n = 5)).

Process_Date:

200908

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Dr. John Valentine or Nathan Lemoine

Contact_Organization:

DISL: Valentine Lab

Contact_Position:

Principal Investigator

Contact_Address:

Address_Type:

mailing and physical

Address:

101 Bienville Blvd.

City:

Dauphin Island

State_or_Province:

Al

Postal_Code:

36528

Country:

USA

Contact_Voice_Telephone:

251-861-2141 ext.2261 or 2294

Contact_Electronic_Mail_Address:

jvalentine@disl.org

Contact_Electronic_Mail_Address:

nlemoine@disl.org

Hours_of_Service:

8-5:00 CST

Contact_Instructions:

Please email Dr. John Valentine or Nathan Lemoine for further information.

Cloud_Cover:

Unknown

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

Excel tables cataloging data in the following categories: Benthic Data, Tether Site Fractals, Algal Grazing, Seagrass Grazing, Attack Frequency, Attack Intensity, Invertebrate Predation, Live Acropora Colony Surveys, Damselfish Size Classes, Fish Transects and Fake Coral Fish Surveys.

Entity_and_Attribute_Detail_Citation:

Benthic Data contains the following attributes: transect name, date, percent coral cover,percent algal cover, percent CTB (corraline algae, turf algae, bare substrate), percent gorgonians, percent zooanthids, percent sponges, number of coral species, coral species ID, rugosity (C), fish species richness, total fish abundance, stegastes abundance.

Entity_and_Attribute_Detail_Citation:

Tether Site Fractals contains the following attributes: habitat. site number, photo, grid size, number of boxes.

Entity_and_Attribute_Detail_Citation:

Algal Grazing contains the following attributes: site, date, time deployed, time removed, weight ID, hours, percent loss, percent loss/hr.

Entity_and_Attribute_Detail_Citation:

Seagrass Grazing contains the following attributes: site, date, time deployed, time removed, weight ID, hours, percent loss, percent loss/hr.

Entity_and_Attribute_Detail_Citation:

Attack Frequency contains the following attributes: habitat, date, fish, tether type, number of attacks.

Entity_and_Attribute_Detail_Citation:

Attack Intensity contains the following attributes: habitat, seagrass, algae, invertebrates.

Entity_and_Attribute_Detail_Citation:

Invertebrate Predation contains the following attributes: habitat, date, weight ID, percent survival.

Entity_and_Attribute_Detail_Citation:

Live Acropora Colony Surveys contains the following attributes: number of spanish grunt, bluestripe grunt, french grunt, caesar grunt, schoolmaster, tomtate, sergeant major, beaugregory, three spot damsel, dusky damsel, juvenile cocoa damsel, adult cocoa damsel, yellowtail damsel, glasseye snapper, stoplight parrot, redband parrot, surgeonfish, bluehead wrasse, trumpetfish.

Entity_and_Attribute_Detail_Citation:

Damselfish Size Classes contains the following attributes: 0-2.5 cm, 2.5-5cm, 5-10cm, 10-15cm, 15-20cm, 20+ cm.

Entity_and_Attribute_Detail_Citation:

Fish Transects contains the following attributes: date; habitat; number of redtail parrotfish, redband parrotfish, stoplight parrotfish, striped parrotfish, princess parrotfish, midnight parrotfish, rainbow parrotfish, tellowtail parrotfish, unidentified parrotfish, sergeant major, yellowtail damsel, juvenile yellowtail damsel, juvenile cocoa damsel, adult cocoa damsel, sharpnose puffer, chub, spanish grunt, yellowtail snapper, bluestripe grunt, white grunt, french grunt, tomtate, striped grunt, schoolmaster, bluehead wrasse, juvenile bluehead wrasse, clown wrasse, slippery dick, doctorfish, juvenile doctorfish, surgeonfish, grey angelfish, french angelfish, porkfish, spanish hogfish, trumpetfish, red lip blenny, glassy sweeper, unidentified.

Entity_and_Attribute_Detail_Citation:

Fake Coral Fish Surveys contains the following attributes: habitat, bicolor, striped parrotfish, stoplight parrotfish, slipperydick, greater barracuda, surgeonfish.

Distribution_Information:

Distributor:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Dr. John Valentine or Nathan Lemoine

Contact_Organization:

DISL: Valentine Lab

Contact_Position:

Principal Investigator

Contact_Address:

Address_Type:

mailing and physical

Address:

101 Bienville Blvd.

City:

Dauphin Island

State_or_Province:

Al

Postal_Code:

36528

Country:

USA

Contact_Voice_Telephone:

251-861-2141 ext.2261 or 2294

Contact_Electronic_Mail_Address:

jvalentine@disl.org

Contact_Electronic_Mail_Address:

nlemoine@disl.org

Hours_of_Service:

8-5:00 CST

Contact_Instructions:

Please email Dr. John Valentine or Nathan Lemoine for further information.

Distribution_Liability:

The Dauphin Island Sea Lab's Valentine Lab makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. The DISL: Valentine Lab cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

Metadata_Reference_Information:

Metadata_Date:

2011

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Dauphin Island Sea Lab

Contact_Person:

Data Management Specialist

Contact_Position:

Data Management Specialist

Contact_Address:

Address_Type:

mailing and physical

Address:

101 Bienville Blvd.

City:

Dauphin Island

State_or_Province:

Al

Postal_Code:

36528

Country:

USA

Contact_Voice_Telephone:

251-861-2141

Contact_Electronic_Mail_Address:

metadata@disl.org

Hours_of_Service:

8-5:00 CST

Contact_Instructions:

Please email the metadata specialist for further information.

Metadata_Standard_Name:

FGDC Content Standard for Digital Geospatial Metadata

Metadata_Standard_Version:

FGDC-STD-001-1998

Metadata_Access_Constraints:

none

Metadata_Use_Constraints:

none