U.S. Fish and Wildlife Service Grant: Coral Metal Toxicity Study in Hawaii

FWS PROJECT OFFICER: Jeff Phillips, Fish & Wildlife Biologist, U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Boulevard, Room #3-122, Honolulu, Hawaii, 96850, 808-792-9400, 808-792-9580 fax, Jeff_Phillips@fws.gov.

PROBLEM DESCRIPTION AND RESOURCE IMPLICATION: There is growing concern regarding the capacity of coral reefs to sustain the increasing frequency of insults associated with anthropogenic activities (e.g. global warming, pollution). A number of studies have now clearly demonstrated that at the local scale, the presence of dense human populations has increased the amount of sediment and contaminants being discharged into adjacent coral reefs, resulting in high metal concentrations in seawater, sediment, corals and tissues of other marine organisms from tropical areas (e.g. Brown and Holley, 1982; Hanna and Muir, 1990). While these works serve as a very useful baseline for these areas, such studies do not specifically address how the metal pollution affects the biology of these tropical organisms. Although increasing efforts have focused on understanding metal toxicity in temperate organisms, virtually nothing is known about metal toxicity effects on corals, the keystone species of reef ecosystems. Furthermore, the current water quality guidelines for metals used to protect tropical corals are derived from temperate systems and few considerations have been given as to whether they are appropriate for the protection of tropical ecosystems (Chapman et al., 2006). As such, the toxicity of metals to various life stages of tropical corals and the abilities of corals in different seasonal physiological states to cope with metal stress are significant knowledge gaps in the context of risk assessment, especially in heavily populated tropical coastal regions such as Hawaii, where land-based metal contamination is a major concern, (De Carlo et al., 2004; Hallacher et al., 1985).

To date, metal toxicity studies using Scleractinian corals (e.g. Howard et al., 1986a, 1986b; Reichelt-Brushett and Harrison, 1999, 2000) have incorporated neither different coral life stages nor seasonal variation and report data for corals collected at a single time period. However, the physiological state of adult corals varies seasonally. For example, higher zooxanthellae densities occur during the winter season (Fagoonee et al., 1999; Stimson, 1997), and during the spawning season the majority of coral energy reserves is spent on reproduction. We hypothesize that this seasonal variation in coral physiology results in differences in the sensitivity of corals to environmental stressors, such as toxic metals, over time. In this context, we will examine the sensitivity of the adult and early life stages of one major species of tropical corals (Montipora capitata or Pocillopora damicornis, with the other species potentially being funded in FY 2010) to Cu, Zn, and Pb toxicity to evaluate the influence of temporal variation on risk assessment and toxicological evaluation. The consideration of seasonal variation of coral physiology in toxicity studies will increase the ecological relevance of the resulting toxicological data. The production of lethal concentration (LC50) and/or effects concentration (EC50) values for Cu, Zn, and Pb in adult and early life stage corals will indicate if different life stages are more or less sensitive to metals when compared to the criteria currently used to protect marine life, such as the Water Quality Criteria established by the United States Environmental Protection Agency (USEPA). A better understanding of the relationship between toxic metal concentrations and the seasonal life events for corals is critical to improving the criteria used to protect coral ecosystems and promote the long term survival of these important marine resources.

MANAGEMENT PLAN CATEGORY:

OBJECTIVES: The objectives of this study are to:

(1) Assess the lethal toxicity of 3 contaminants (Cu, Zn and Pb) in adults of one Hawaiian coral species Montipora capitata or Pocillopora damicornis (the other species may be done in a follow-up study, depending on FY2009 results) over 4 seasons: winter, spring, summer, and autumn.
(2) Assess the lethal and sublethal toxicity of 3 contaminants (Cu, Zn, and Pb) in the early life stages of one Hawaiian coral species, M. capitata or P. damicornis, over the peak spawning season (May to August).
(3) Evaluate temporal variation in the sensitivity of the different life stages of corals to metal toxicity.
(4) Compare the sensitivity of adult and early life stage corals for each metal selected and identify the most sensitive life history stage.
(5) Provide guidelines on the concentrations of Cu, Zn, and Pb in different seasons in a tropical environment that will allow coral reef sustainability and growth.

METHODS:
Lethal toxicity test (LC50 ) on adult corals: Adult colonies of M. capitata or P. damicornis will be collected in December, March, June, and September. Corals will be exposed separately to Cu, Zn, and Pb in 96 hr chronic toxicity experiments. Coral nubbins (n=10) will be exposed to six treatments in plastic aquaria: one control and five increasing metal concentrations in seawater. Three replicate aquariums will be used for each treatment and 50% of the seawater will be replaced daily. Seawater samples (n=3 samples per concentration, total of 1296 analyses) will be collected after 24, 48 and 96 hours and the metal concentrations measured using High Resolution Sector Field ICP-MS and used to determine the integrated metal exposure concentration. Coral survival rates and signs of stress will be recorded daily. The LC50 of Cu, Zn and Pb in adult corals will be determined. Selected samples of adult coral tissues and skeletons will be analyzed for metals by ICP-MS, and for chlorophyll, zooxanthellae, and protein concentrations.
Lethal and sublethal toxicity tests (LC50 and EC50 ) on early life stage corals:
Fertilization Rate of M. Capitata: M. capitata is a broadcast spawning hermaphrodite that releases gamete bundles into the water column at the new moon lunar phase of summer months in Hawaii (Kolinski, 2004). The fertilization success of gametes from M. capitata will be estimated over the spawning season (May to August, depending on the availability of gamete bundles). At the new moon lunar phase, gamete bundles will be collected from different coral colonies of M. capitata. A gamete bundle from each of two different colonies will be placed in a 15-ml glass vial (Maté et al., 1997) and exposed to six different treatments: one control and five increasing metal concentrations in seawater. For each treatment, ten replicate glass vials will be used. The metal concentration in seawater for each treatment will be measured by High Resolution Sector Field ICP-MS (n=162). Fertilized egg development will be terminated after 3 hrs by adding 1 mL of a fixative (10 g/L sodium â-glycerophosphate, 4% formaldehyde buffered at pH 7) that maintains embryo integrity (Negri and Heyward, 2001). Fertilization of eggs and embryos will be assessed by dissecting microscope; eggs showing no cleavage will be designated as unfertilized. The EC50 of Cu, Zn, and Pb for the gametes of M. capitata will be evaluated for each metal over the spawning season. Selected samples of eggs will be analyzed for metals by ICP-MS and for chlorophyll, zooxanthellae and protein concentrations.
Survival and Settlement Rate of the Larvae of P. damicornis: P. damicornis is a brooding coral that releases fully developed larvae. Larvae are generally competent to settle immediately following release, and adults colonies release larve year round with a peak in production during summer (Jokiel et al., 1985). Colonies of P. damicornis will be collected in summer and placed in aquaria with flowing seawater and natural light. Larvae (n=20) will be collected just after spawning and placed in glass Petri dishes containing seawater and exposed to 6 different treatments: one control and five increasing metal concentrations. The metal concentration in seawater for each treatment will be measured by High Resolution Sector Field ICP-MS (n=162). For each treatment, five replicate Petri dishes will be used. Seawater in Petri dishes will be changed every two days. Survival and settlement rate of larvae will be recorded every day during the first week, and then every two days during the second week to evaluate the LC50 (survival rate) and EC50 (settlement rate) of Cu, Zn and Pb for the larvae of P. damicornis over the spawning season. The replication of experiments on larvae over time is contingent on the availability of larvae during the summer. Selected samples of larvae will be analyzed for metals by ICP-MS, and for chlorophyll, zooxanthellae and protein concentrations.
Statistical analysis: Comparisons of treatment data will be performed using 1- or 2-way analysis of variance (ANOVA) followed by the multiple comparison test of Tukey (Zar 1996). One-way ANOVA will be used to identify significant differences among treatments in the response measured e.g. survival rate, fertilization and settlement success. Two-way ANOVA will be used with time and metal concentration as fixed factors. The variability explained by each factor and their interaction will be derived from the sum of squares (Zar 1996). NOEC values will be determined for each test by calculating the highest concentration in which the response of corals (e.g. percentage of survival rate) was not significantly different from the control response (Hoffman et al., 1995).
FWS biologists will provide technical and field assistance with coral collection, spawning, toxicity testing, and logistics.

STUDY AREA: Work will be conducted in Kaneohe Bay, Oahu, in the vicinity of Coconut Island.

PROJECT DURATION: January 2009 to December 2009 with possibility of extension for an additional year.

PRIORITY: In 1998, the President issued Executive Order 13089 on Coral Reef Protection, establishing the multi-agency U.S. Coral Reef Task Force as well as directing agencies to expand their own research, preservation, and restoration efforts. The Secretary of Interior co-chairs the Coral Reef Task Force, and the U.S. Fish and Wildlife Service (Service) has been an active participant. In 2005, the Bush Administration issued the U.S. Ocean Action Plan in response to recommendations from the U.S. Commission and Pew Ocean Commission reports of 2004. One of the highest priority actions for the Service under the Ocean Action Plan is to promote coral conservation and education.

The proposed research will help the Service improve the management of marine and coastal resources. The results will help guide and prioritize the Service’s efforts to reduce pollution in waters that support coral reef ecosystems. This should be important in management of Fish and Wildlife refuges, as well as non-refuge areas that support coral reefs. The study will document whether current water quality and sediment quality criteria are sufficiently protective of corals, and could potentially help update criteria if needed.

PRODUCTS AND SCHEDULE:
June 2009: Mid-year report, with statement of work completed and in progress and results to date.
October 2009: Annual report, including results of the toxicity tests on adults over time, and toxicity data from spawning of summer 2009 (.rtf format)
December 2009: Final report, including details of all toxicity protocols used for adults and early life stage of corals, results and statistical analyses of all toxicity tests performed over one year on adults and early life stages of corals. This document will provide new data on the metal toxicity on corals that are of high concern for comparing with the actual Water Quality Guidelines used in tropical areas, and to ensure that the Water Quality Guidelines used take into consideration the sensitivity of corals to metals (.rtf format)
July 2010: Publication of 1 or 2 scientific journal articles for further dissemination of this research.

Results will be presented at a scientific meeting for further dissemination of this research. A hardcopy and/or electronic copy of any publications resulting from this work will be provided to FWS.

BUDGET: Total project budget is estimated at $97,029, Pacific Islands Fish and Wildlife Office contribution not to exceed $34,329.

Other major partners providing technical support: FWS, USGS.