University of Arizona Galapagos Marine Ecology (ECOL 496O/596O)D. Gori
Environmental Monitoring: Measuring the Impacts of Human Threats and Climate on Galapagos Ecosystems and Species
Introduction
In 1959, the Galápagos became an Ecuadorian national park, placing 97% of the total land area of the islands under protected status. Shortly after, in 1978, the archipelago was designated as a United Nations World Heritage Site and in 1986, over 17 million acres (7 million ha) of ocean surrounding the islands were declared a protected area under the Galápagos Marine Reserve (MR). Despite these protection efforts, the islands and the sea around them still face significant human threats which continue to endanger the long-term sustainability of Galápagos ecosystems and species. These threats include human population increase, invasion and spread of non-native species increasing pressure from ecotourism, and illegal commercial fishing in the MR.
In fact, marine ecosystems are currently the most threatened of Galápagos ecosystems and there is little evidence that the MR’s designation and management plan is resulting in any meaningful protection. Great pressures are being brought to bear from international as well as Ecuadorian commercial fishing vessels to harvest more and more from the MR and the tourist industry is also clamoring for development of a sport fishing industry (see numerous references in the readings packet).
Protection of the marine ecosystems around the islands is critical since resources essential to many Galápagos animals come from the sea. It is obvious in the case of marine iguanas, sea lions, and numerous seabird species that depend on the ocean around them for food, but beyond that, marine ecosystems themselves comprise incredibly complex food webs. Galápagos coral reefs, many species of bony fishes, sharks, rays, sea turtles and a diverse assemblage of invertebrates are to varying degrees interdependent on each other and these linkages extend to terrestrial ecosystems. Thus, threats to the oceanic ecosystems quickly become threats to the islands themselves because ecology and complex food webs do not recognize boundaries between interrelated ecosystems.
The Charles Darwin Research Station working in close cooperation with the National Park has been pivotal in focusing attention on the Galápagos ecosystems, combining research and environmentalmonitoring with solid conservation efforts.
What is Environmental Monitoring?
Environmental monitoring is a rapidly expanding discipline in conservation biology devoted to tracking changes in the biological and physical environment through time. The word “monitor” derives from the latin monere, to warn, and, thus, the goal of monitoring is to provide an early warning of impending problems so that actions can be taken to avoid them or lessen their impact. However, unlike research, it is difficult to raise funds for monitoring because it is not designed to answer intriguing theoretical questions in biology and, by its very nature, is designed to continue for indefinitely long periods of time. So the trend in environmental monitoring is to involve partners in data collection and, through the sharing of monitoring results between agencies, universities and non-profit organizations, to obtain a collaborative understanding of the health of ecosystems and the impacts of threats on the physical and biological environment.
Monitoring Objectives and Design of Monitoring Programs
The design of monitoring programs and the techniques or methods they employ are as diverse as the species and human impacts that they seek to track. The basic foundation of a monitoring program is a clearly articulated monitoring objective which specifies how much change in a particular variable or parameter that you want to detect statistically over some specified time period. For example, a possible monitoring objective for Galápagos sea lions is to be able to detect a 20% change in their numbers of sea lions at a particular location over a 5-year time period. Once this objective is identified, much of the methodology follows including the variable or parameter to be monitored, when you should monitor, how many sampling periods or population censuses you need for a single year, how many times you need to sample over a 5-year period, etc. (Elzinga et al.1998; Gibbs 1995; Gerrodette 2000).
Limitations of Monitoring Data
In contrast to controlled experiments in the field or laboratory, it is difficult to infer cause and effect from monitoring data. For, example if you see a decreasing trend in a marine iguana population (i.e., a decrease in the population) over a 5- or 10-year period, what caused it? The only thing for certain is that the population is declining (which is extremely valuable information in its own right). However, it is possible to set up monitoring to test specific hypotheses about the relationship between a particular threat and its impact on the monitoring target by collecting data on both. For example, in the Komodo Islands in Indonesia, the National Park there obtained money to patrol the coral reefs within the park in an attempt to stop dynamite (blast) fishing by local fisherman. Their monitoring question was how effective was the increased surveillance on the frequency of blast fishing and on reef fish populations. The hypothesis was that a reduction in blast fishing (threat or source of stress) would have a positive effect on reef fish populations. With assistance from The Nature Conservancy, the park rangers kept a record of blast fishing events (which are quite obvious due to the number of dead, floating fish after an event) and also monitored reef fish populations at a number of permanent locations within the park. What they found over a 3-year period was a significant decline in blast fishing events to near zero levels after 3-years and, over the same period, a steady increase in reef fish populations that correlated with the decrease in blast fishing. The cause for the increase in reef fish populations? The monitoring data suggests that it was the progressive curtailment of blast fishing.
Project Objective
One of the goals of this class is to contribute to the emerging body of information on the status and health of Galápagos ecosystems by monitoring species and threats on San Cristóbal Island. Our monitoring results will be shared with the National Park and other interested parties via the class website. This work will be done as a part of every independent research project and will involve either: (1) the design and implementation of a new monitoring program for species or threat of your choice or (2) re-surveying a species that has been monitored previously. A description of monitoring programs initiated last year can be found on the following pages. We will assist you at every step once you have selected a target species or threat. In the interest of time, we will not worry about monitoring both a threat and a species, realizing that monitoring data is valuable even if a cause for change is unclear. The monitoring component of your project should include: (1) a detailed description of the methods and an explanatory diagram; (2) a sketch map showing the location of the census route and GPS locations; (3) raw monitoring data including notes on time of day and weather conditions; (4) a data summary; and (5) observations of what you learned including recommendations for how the monitoring should continue in the future. This is your chance to suggest improvements to the protocol that you have field tested.
In addition, we (Dave and Katrina) will be doing our own monitoring of iquanas and possibly other species. You are welcome to volunteer to help us if you have time and the interest. It is a good way to see lots of animals and to learn more about monitoring.
References
Gerrodette, T. 2000. TRENDS software and manual.
Gibbs, J. 1995. MONITOR software and manual.
Elzinga, C.L., D.W. Salzer, J.W. Willoughby. 1998. Measuring and monitoring plant populations. Bureau of Land Management Technical Reference 1730-1.
Species: Yellowtail damselfish
Site: Tijeretas
Monitoring Protocol: 4 belt transects, each 20 m by 2 m in size; long axis of transect goes from shallower to deeper water. Each belt transect is divided into 4 sampling zones, each 5 m x 2 m in size; Zone 1 → Zone 4 along each transect follows a gradient of shallower → deeper water. Observer slowly swims along the transect and counts all yellowtail damselfish within each zone (adults, juveniles?);
Sampling Frequency: Not explicitly indicated although from the way the data is displayed, assume only one census was made. No record of date or time of census.
Data Summary/Monitoring Parameter: Damselfish density (# of damselfish per 10 m2) is averaged across transects and summarized by zone; total average density (per 10 m2) across all zones for the 4 transects is also reported (Table 1)
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Monitoring Protocol Design/Implementation: N. Berg, G. Emerson, & J. Ramey
Year Sampled: 2004
Results:
Table 1. Average density of damselfish by depth zone at Tijeretas.
Zone / Average Density(# damselfish/10m2) / Depth
1 / 3.75 / Shallow
↓
↓
Deep
2 / 1.50
3 / 0.25
4 / 0.75
Total Av. Density = 1.56 damselfish/10m2
Location Map: See “Damselfish map” (Figure 1).
Species: Marine iguana
Site: Loberia; Two different census routes (areas) were established: West shore and East shore; (Figure 2). The West shore was divided into 6 zones that are separated by jetties of basalt cobbles/boulders and was approximately 340 meters in length; East shore was undivided and approximately 300 m in length.
Design: Observer walks slowly along and counts all iguanas and estimates the size in feet of each. Start and finish times for each census are recorded; for West Area, start and finish times are recorded for each census zone. General observations of the weather and temperature are made during census including weather changes that occur during census (and time of those changes). Iguana size classes include:
Table 2. Body length of marine iguanas by size class.
Iguana size / Length (in ft) snout to tail tipSmall / < 1
Small/Medium / 1 x < 2
Medium / 2 x < 2.5
Medium/Large / 2.5 x 3
Large / x > 3
Sampling Frequency: West shore was sampled on 7/19 (9:53-10:22 am) and 7/24 (12:40-1:15 pm); East shore was sampled on 7/20 (10:30-12:00 am) and 7/24 (2:00-2:40 pm).
Monitoring Parameter/Data Summary: Number of iguana seen in each survey area; size of each iguana counted (estimated to the nearest ½ foot) was also recorded.
Monitoring Protocol Design/Implementation: S. Sumner
Year Sampled: 2004
Results:
Table 3. Census results for marine iguanas by census area and date.
Date / Census Area / No. Small Individuals / No. Small/med / No. Medium / No. Med/large / No. Large / Total Number Observed7/17 / West / 2 / 3 / 4 / 9 / 19
7/24 / West / 1 / 5 / 1 / 9 / 16
7/20 / East / 3 / 8 / 23 / 34
7/24 / East / 23 / 29 / 52
Comparison of the two East area surveys suggests that there may be some difficulty in assigning individuals to Medium and Medium/large size classes; recommendation: combine the two classes into a single Medium class.
Location Maps: See “Iguana map” (Figure 2).
Species: Galápagos sea lion
Site: Waterfront, Puerto Baquerizo and Loberia
Design: Observer walks along beach and counts number of sea lions; waterfront is divided into 3 “beaches” and counts are recorded separately for each. The waterfront beaches are: bachelor, middle, and left. Raft is included in census, but at the time of note transcription it is unclear which beach the raft counts were included in. At Loberia, census was restricted to sandy beach at end of path where the class tidepools.
Sampling Frequency: Waterfront beaches were surveyed on 6 consecutive mornings at first light; as morning progresses, sea lions leave beach for the water. Loberia was surveyed only once on 7/24.
Data Summary/Monitoring Parameter: Number of sea lion individuals by beach.
Monitoring Protocol Design/Implementation: E. Regh & D. Sirakis
Year Sampled: 2004
Results:
Table 4. Census results for Galápagos sea lions by date and location.
Beach / 7/19 / 7/20 / 7/21 / 7/22 / 7/23 / 7/24 / Mean CountBachelor / 19 / 15 / 18 / 9 / 14 / 11 / 14.3
Middle / 168 / 104 / 134 / 76 / 121 / 135 / 123
Left / 21 / 26 / 22 / 15 / 30 / 33 / 24.5
Loberia / -- / -- / -- / -- / -- / 20 / 20
Total / 208 / 145 / 174 / 100 / 165 / 199
Location Map: No location map provided.
Species: Green sea turtle
Site: Loberia
Design: Observer swims slowly along transect lines, scanning from side-to-side, and following the route depicted in the location map; this was the hypothetical plan. In reality the transects were less straight as a result of a sea lion bull that frequently interrupted/interfered with the planned route. Still, an effort was made to systematically and completely cover the area bounded by the beach, waves and basalt rock jetties that define the inlet at Loberia (Figure 3).
Sampling Frequency: 5 surveys between 7/12 and 7/22, 2004; time of day and weather conditions were not recorded. Study suggested that more turtles were sited at low tide or when the tide was dropping.
Data Summary/Monitoring Parameter: Number of green sea turtles encountered.
Monitoring Protocol Design/Implementation: N. Radman & J. LaZarr
Year Sampled: 2004
Results:
Table 5. Number of green sea turtles counted at Loberia by survey date.
Census Date / No. of Turtles Counted7/12 / 2
713 / 1
7/16 / 2
7/20 / 5
7/22 / 0
Location Map: See “turtleurchin maps” (Figure 3)
Species: Green and pencil urchins
Site: Loberia and Tijeretas
Design: A 50 m x 12 m study area was established at Loberia (see location map) and the area was sampled using a 1 m x 1 m PVC quadrat. There were no details for how the study area was sampled, i.e., where the quadrat was placed within the study area. However, the quadrat was placed at 32 separate locations and sampled (Figure 4); the number of urchins by species, % cover of algae (ocular estimate), and algae height on the rock were recorded/estimated within the quadrat. At Tijeretas, 2 rocks were sampled and the number of urchins by species, % cover of algae, and algae height was recorded for each rock. There is no location map for where these rocks were located or estimates of their size; thus, a density calculation was not possible for this survey.
Sampling Frequency: Although not explicitly indicated, the survey appears to have been conducted once at each site
Data Summary/Monitoring Parameter: number of urchins by species, percent cover of algae, and algae height.
Monitoring Protocol Design/Implementation: T. Lutz & C. Strauss
Year Sampled: 2004
Results:
Table 6. Number and density of urchins counted, mean cover and height of algae at Loberia and Tijeretas.
Site / No. green urchins / No. pencil urchins / Mean (+ SD) density green urchins (#/m2) / Mean (+ SD) density pencil urchins (#/m2) / Mean algae cover (%) / Mean algae height (mm)Loberia / 5700 a. / 2419 a. / 8.5 (+ 11.5) / 4 (+ 3) / 32 / 7
Tijeretas, Rock 1 / 104 / 55 / 44 / 20
Tijeretas, Rock 2 / 124 / 23 / 71 / 20
a. Estimated for study area from mean density values.
Location Map: See “turtleurchinmap” (Figure 4).
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