Weights assigned to studies depended on the relative size of the within- and between-study covariance matrices reported as components in mixmeta objects. Thus, additional work should be done to quantify the additive and synergistic effects of multiple local stressors on coral reefs. A study species is often confounded with geography and morphology. Bessell-Browne P, Negri AP, Fisher R, Clode PL, Jones R. Cumulative impacts: thermally bleached corals have reduced capacity to clear deposited sediment. Lethal and sublethal effects of dredging on reef corals. Sediment delivery resulting in deposition and water quality deterioration can cause degradation at the spatial scale of corals or entire reefs. Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico. The seven reefs that Lesneski is trying to restore went from well over 50% coral cover, to just 2% coral cover by the time her program launched in 2019. Of the 129 benchmark studies, 123 (95.3%) were found in the DSE search. These are statistically significant differences between treatment and control corals, with 95% confidence, which may not reflect biologically significant differences in some cases. as data extraction progressed. 1992;2:6818. Relatively asymmetric funnel plots indicate greater risk of publication bias. Both authors edited, read and approved the final manuscript. For a full reference list of all articles included in our review (Tables 3, 4) and all those that were excluded at the full-text screening (with reasons for exclusion), see the project database [Additional file 3]. WebDetection of adverse effects for physiological effects of sediment exposure on coral adults, plotted as concentration vs. duration of exposure to either deposited sediment (left panels) or suspended sediment (right panels). Sci Rep. 2015;5:18084. The effects of water flow and sedimentation on interactions between massive Porites and algal turf. WebWhen polluted stormwater flows into the nearshore environment, it poses a health threat to swimmers and causes significant harm to coral reefs and other marine life. Of the six benchmark studies that were not found in the DSE search [Additional file 2], one could not be located and five were reclassified as ineligible upon review of the full texts using PECO criteria [Additional file 3]. Pastorok RA, Bilyard GR. After this pilot round, each study had data extracted independently by one reviewer. Estuar Coast Shelf Sci. More runoff impacts reefs, mostly by mobilizing more chemicals and sediment on land, Asner said. Additionally, all studies included in the synthesis experimentally exposed corals to sediment and included appropriate experimental controls. All 86 studies from 65 articles that we included in the narrative synthesis were further included in our data synthesis database [Additional file 3]. Accessed 5 Mar 2021. Juveniles can also experience mortality (dark red in Figs. The red, dashed line in A represents the LOAEL and in C represents the doseresponse threshold, where the confidence interval (in gray) no longer overlaps with zero. The effect of shading on coral reef structure and function. Other less commonly reported responses, like gene expression, were found in too few studies to synthesize, especially considering the ongoing methodological developments in the field. This kind of study requires cooperation among regulators, scientists, and other stakeholders, but the BACI design is arguably the gold-standard for ascribing causative, in situ relationships between an event and a subsequent biological response. (40.0%, 18 of 45), Montipora spp. While this kind of ground-truthing can be logistically difficult even in a relatively controlled laboratory setting, its omission from most study designs complicates comparison across studies in unpredictable ways (i.e., some studies may over- or under-estimate deposition rates). For these relationships, it is likely that suspended sediment weakly interacts with coral larvae through decreased light availability in the water column, thus affecting symbiotic algae, but that secretion of protective mucus and beating of cilia may protect the planktonic coral larvae from suspended particles after 60h of exposure [52]. Management actions that address local-scale stressors on coral reefs can rapidly improve water quality and reef ecosystem condition. Part of Coral Reefs. 1985;92:21530. Sediment runoff interferes with the ability of corals to survive, feed, grow and reproduce, and also contributes to the exacerbation of other issues, such as ocean warming and acidification as cloudy, darker water captures more heat, and minerals in the sediment change the acidity of the water. 1997;147984. If the original study detected a statistically significant decline in condition of the treatment group as compared to the control group, then that treatment group was coded as a 1 (presence of adverse effect). We adopted a fixed slope, random intercept approach and fit models with three possible fixed-effects structures: (1) exposure concentration (reduced model), (2) concentration and duration (reduced model), and (3) concentration, duration, and the interaction between the two (full model), and five possible random-effects structures: (1) species, (2) study, (3) study nested within article, (4) species and study, and (5) species and study nested within article. 4, 5, 6), tissue necrosis (orange in in Figs. Even relatively thin layers of sediment not harmful to most adult corals may inhibit coral larvae from settling on otherwise suitable surfaces [23, 25,26,27]; this can limit reef regeneration and persistence. In developing the structure of this systematic review, we adopted the PECO approach [35], which defines the relevant Population (including species), Exposure, Comparator, and Outcomes as pillars of the research question and serve as inclusion/exclusion criteria during the screening process. Larcombe P, Costen A, Woolfe KJ. The doseresponse thresholds reported below are the lowest concentrations at which sediment-exposed corals (treatment) are expected to have a lower or reduced response than corals not exposed to sediment (controls) (Fig. Townsville, Queensland, Australia; 1989. Sediment delivery resulting in deposition and Thereafter, progress and questions were discussed by the entire review team on a weekly basis until data extraction was complete, which promoted consistency among team members. The negative effects of sediments on coral health through smothering coral tissue and shading the photosynthetic symbionts are well known ( Rogers, 1990 ). Syst Rev. Symbiotic crabs maintain coral health by clearing sediments. NOAELthe no-observed adverse-effect level, i.e., the highest exposure level at which an adverse effect was NOT detected. Response to higher sediment loads by Pocillopora damicornis planulae. Coral responses are color coded with a key shown at the right side of Fig. Mar Policy. 1995;20:5163. Biological significance is dictated by ecological context (i.e., species, population, location, etc. Weber M, Lott C, Fabricius KE. 1979;41:26988. 1987;94:5375. The very brown water here indicates the presence of a lot of fine dirt particles and the turbidity of this water is very high. Coral Reefs. Each article may report the results of multiple studies. Coral Reefs. 2014;502:12943. In this case, it is likely because the vast majority of studies focus on exposure concentrations greater than 25mg/cm2/day, with adverse effects occurring even at the lower end of tested concentrations. Decreased coral settlement on sediment-covered surfaces has been previously observed for Pocillopora damicornis [58], Acropora digitifera [23], and Acropora millepora [56]. We then explored the relationship between effect size (d) and stressor intensity with hierarchical mixed-effects models that fit exposureresponse curves (doseresponse meta-analysis, or DRMA, models, Fig. 2015;466:98109. Adverse effects in response to deposited sediment occur on the order of hours to days, while those in response to suspended sediment occur on the order of days to weeks. 2016;102:929. PeerJ. The impacts of LULCC on sediment yields demonstrate the profound influence of human actions on tropical hydrology 16, J. et al. 1. Damage to photosystem II in symbiotic dinoflagellates: a determinant of coral bleaching. We recommend that future studies report both mg/L and NTU measurements, whenever possible, so that thresholds for suspended sediment and turbidity can be disaggregated. 1999;154:22033. Mar Pollut Bull. Te FT. 8). Curr Opin Environ Sustain. In fact, no study included in our meta-analyses tested the effects of these stressors both separately and together, and only one experimental study measured total suspended solids (mg/L), turbidity (NTU), light attenuation (relative %), and deposition rate (mg/cm2/day) during the course of their experiment [48]. Bak RPM, Elgershuizen J. The majority of articles in our review (73.8%, 48 of 65) were conducted in the Pacific Ocean, followed by 18.5% (12 of 65) in the Atlantic Ocean, 3.1% (2 of 65) in the Indian Ocean, and 4.6% (3 of 65) in the trans-oceanic boundary between the Indian and Pacific Oceans (i.e., Malacca Strait). These metrics will depend on cooperation among scientists in the relevant field, but their creation will prove important in our ability to synthesize evidence across regions, taxa, and scientific labs with differing protocols. We made funnel plots of the effect size (d) plotted against sample size (nT) to detect possible publication bias [43, 44]. Coastal development results in erosion, and runoff containing the excess sediment can block the light zooxanthellae need. We recommend protocols for future work (see Implications for research, below), which could be implemented in-parallel across a network of researchers and regulators at multiple locations across a region. Palmer AR. Mar Pollut Bull. Runoff from lawns, sewage, cities, and farms feeds algae that can overwhelm reefs. The runoff of these pollutants from agriculture is, therefore, a major threat to inshore coral reefs and seagrass meadows in our Great Barrier Reef. What types of pollution affect coral reefs? Short-term responses include physiological changes that are likely adverse if they persist. In fact, this review benefited from several publications associated with the Western Australian Marine Science Institutions Dredging Science Node, a strategic research initiative that enhanced capacity with government and the private sector to predict and manage the environmental impacts of dredging in their region [101]. Jones RJ, Hoegh-Guldberg O, Larkum AWD, Schreiber U. Temperature-induced bleaching of corals begins with impairment of the CO2 fixation mechanism in zooxanthellae. Google Scholar. Physiological responses (e.g., reduced photosynthesis of symbionts) can occur as quickly as 12h and 1h after exposure to deposited sediment and suspended sediment, respectively (Tables 5, 6; Fig. Each row of panels represents a different coral response. 1995;53:17787. 1997;315:62934. Effects of sediment exposure on corals: a systematic review of experimental studies. Damage and recovery of four Philippine corals from short-term sediment burial. To ensure repeatability of quality assessment after the pilot round, the review team iteratively assessed an additional five studies until no conflicts emerged. Included in our review (narrative and data syntheses) are 65 articles, in which are the results of 86 studies (Fig. Dr Surez-Castro said one of the impacts of sediment runoff on coral reefs is a massive reduction in light levels that were key for coral and sea grass growth and Carpenter KE, Abrar M, Aeby G, Aronson RB, Banks S, Bruckner A, et al. Limnol Oceanogr. We considered English abstracts for non-English full texts during the article screening process. WebAt the time of the initial survey there was no evidence of coral death caused by sediment run-off during the 1984/85 wet season in spite of evidence from Bonham (1985) of extensive sediment run-off into the coastal environment from the new road site. Our narrative synthesis illustrates how sediment exposure (concentration and duration), coral taxonomy, and coral life-history stage shape biological responses to sediment stress (Objective 1). Increased turbidity and deposited sediment can also result in irritation and abrasion of coral tissue, especially if paired with wave action. Rogers [18] observed that normal, background levels of sediment on coral reefs are on the order of 10mg/cm2/day for deposition rates and 10mg/L for total suspended sediment concentrations, above which are considered high with the potential to adversely affect corals. Birkeland C, Rowley D, Randall RH. Dredging Science Node. Coral reef management and conservation in light of rapidly evolving ecological paradigms. However, adults are slightly less sensitive to deposited sediment than immature coral stages (cf. This definition is independent of response magnitude; while the effect may potentially reduce a corals fitness, the reduction in fitness may not be measurable. Higgins JPT, Altman DG, Gtzsche PC, Jni P, Moher D, Oxman AD, et al. WebRunoff of sediment and other contaminants from developed watersheds threatens coastal ecosystems and services. 1978;9:146. This makes it difficult and potentially misleading to convert from one unit to the other. Proxies for bleaching included the density of zooxanthellae, the density of chlorophyll-a, the proportion of tissue without zooxanthellae, and indices of tissue paling that were specific to certain regions/species. Sediment type, exposure levels, taxa, and coral responses that are most relevant at a particular site will be informed by field monitoring and/or associated field experiments. LJT screened, critically appraised, and extracted the data, then conducted statistical analysis. In: Frontiers 2017: Emerging Issues of Environmental Concern. Opportunities to improve future experiments by specifically addressing each of the limitations of this systematic review and meta-analysis were discussed above, in the13 section. Regardless, a diagnostic funnel plot showed little evidence for publication bias [Additional file 3: Fig. The effects of anthropogenic stressors on reproduction and recruitment of corals and reef organisms. Here, a large-scale conservation project is underway. For the purposes of this systematic review, an article is defined as any written document including scientific papers, abstracts, reports, book chapters, theses/dissertations, and other publications. Mar Biol. 2014;2:e387. Adults begin to bleach at 3.2mg/L SSC after only 2h exposure (Table 6; Fig. 2018;135:94153. Given that we employed a small team, we provide more detail about how we ensured repeatable and consistent decisions during different stages of the review, especially article screening, data extraction, and study validity assessment. Many studies tended not to report much detail concerning the sediment they used in their experiments. However, there were too few of these studies to warrant a co-stressor meta-analysis, as done previously for the effects of temperature and irradiance on corals [103]. Scope of inference We chose to focus on manipulative experiments so that we could directly ascribe the adverse effects experienced by corals to sediment exposure and not to other confounding variables like nutrient-enrichment, contamination, etc. Accessed 5 Mar 2021. Mar Biol. To disentangle the effects of deposited and suspended sediment/turbidity, researchers may build a mesocosm array in which coral colonies will be placed in aquaria exposed to different combinations of the two stressors. Meet. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. 4, 5, 6), localized bleaching (light orange in Figs. ROSES Reporting standards for Systematic Evidence Syntheses: Pro forma, flow-diagram and descriptive summary of the plan and conduct of environmental systematic reviews and systematic maps. Exposure Exposure to concentrations of suspended and/or deposited sediment of marine or terrigenous origin. When possible, scientists interested in the effect of sediment on complex coral responses (like bleaching or gene expression) should report some kind of standardized metric that is easily repeatable across species and studies [88]. 2014;3:114. 1993;115:22943. and study characteristics such as the sample sizes, means, and variations of coral response(s) to sediment and control conditions. Ricardo et al. Dallmeyer DG, Porter JW, Smith GJ. 4, 5, 6, Tables 3, and 4. 1992;43:683705. A tank system for studying benthic aquatic organisms at predictable levels of turbidity and sedimentation: case study examining coral growth. Sofonia JJ, Anthony KRN. The hydrodynamic and sedimentary setting of nearshore coral reefs, central Great Barrier Reef shelf, Australia: Paluma Shoals, a case study. Coral species are shown as four-letter codes, with a key provided at Additional file 4. The red, rectangular area in B is bounded by the LOAELs for concentration and duration, thereby representing the exposure conditions under which adverse effects have been observed in studies from our review. Key to numbered references [DS##] are provided at Table 3, Review of coral responses to varying deposited sediment concentrations at timescales ranging from hours to 2weeks. Nairobi: United Nations Environment Programme (UNEP); 2017. p. 3645. J Exp Mar Bio Ecol. Thomas S, Ridd PV, Day G. Turbidity regimes over fringing coral reefs near a mining site at Lihir Island, Papua New Guinea. In fact, this highlights the utility of our synthetic approach: in the absence of more specific information, we may adopt the most conservative threshold that uses the best available information to protect even the most vulnerable corals from stressful conditions. The impacts of LULCC on sediment yields demonstrate the profound influence of human actions on tropical hydrology 16, J. et al. 1992;I:28999. WebClimate change leads to: A warming ocean: causes thermal stress that contributes to coral bleaching and infectious disease. We identified exposure levels that adversely affect corals while accounting for sediment bearing (deposited vs. suspended), coral life-history stage, and species, thus providing empirically based estimates of stressor thresholds on vulnerable coral reefs. Environ Evid. 10D). There were no major inconsistencies in data extraction after the pilot round, so regular meetings served to identify and correct minor inconsistencies (e.g., number formatting, unit conversion and notation, capitalization, spelling, etc.) Coastal development and runoff lead to sedimentation, which directly impacts coral recruitment, growth, mortality, and the ecosystem services that coral reefs provide. Some well-documented impacts are: High concentrations of fine sediment can reduce coral diversity, affect reproduction, disrupt coral recruitment and increase susceptibility to disease. An island-wide assessment concluded that runoff impacts to coral reef ecosystems of Puerto Rico were determined by coastal transport of sediment and contaminants by wind-driven currents and waves (Larsen and Webb, 2009; Warne et Poor water quality on Maui, Hawaii. Below is a review of these mechanisms, organized by coral response and life-history stage. Zuur A, Ieno EN, Walker N, Saveliev AA, Smith GM. This work was funded by the U.S. NOAA Grant NA18NMF4540325 to MJD. 2012;64:173765. WebElevated nutrient concentrations result in a range of impacts on coral communities and under extreme conditions can result in a collapse. Muscatine L. The role of symbiotic algae in carbon and energy flux in coral reefs. WebWhen polluted stormwater flows into the nearshore environment, it poses a health threat to swimmers and causes significant harm to coral reefs and other marine life. More runoff impacts reefs, mostly by mobilizing more chemicals and sediment on land, Asner said. 1999;135:45162. While fragmentation is necessary in most experimental frameworks, one consequence is that fragments often have different shapes or gross morphologies than the parent colony from which they were taken. In addition to 129 benchmark studies [Additional file 2] identified within the definitive reviews [15,16,17,18, 28, 29], our DSE searches returned 15,006 records (Fig. Anthony KRN, Hoegh-Guldberg O. Kinetics of photoacclimation in corals. Sediment cover on the benthos can prevent larvae from sensing chemical or textural cues that induce settlement [56, 57], including altered bacterial cues [27]. For manipulative experiments conducted in either the field or laboratory, this was the application of suspended or deposited sediment. Since corals rely on symbionts for up to 90% of their energy [63], a decrease in their photosynthetic efficiency is used as an indicator of decreased energy availability for corals. Stafford-Smith MG. Mortality of the hard coral Leptoria phrygia under persistent sediment influx. CFR 230.44: Clean Water Act Section 404(b)(1) Guidelines for Specification of Disposal Sites for Dredged or Fill Material. Measurements in the literature are most often quantum yield (Fv/Fm), a decrease in which is believed to be an early sign of coral bleaching [64] and is often used as an indicator of health of the coral symbiont, and thus of the host coral. Bleaching is often a precursor to tissue mortality due to the accompanying stressors of deposited and suspended sediments (i.e., starvation, hypoxia, abrasion, microbially mediated tissue damage, and tissue irritation) [65, 70, 72, 76]. Larvae avoid abrasion and smothering in the presence of sediment when they settle on downward facing surfaces [54]. The regulatory programs that apply to coral reefs manage a wide variety of local stressors that include physical destruction or alteration, water quality, and point sources of thermal pollution [8,9,10]. 10A). USA; 2010 p. 253306. The DRMA was based on the standardized results of 10 studies from 6 articles that used 4 coral species from 2 genera: Acropora digitifera, Acropora millepora, Acropora tenuis, and Pectina lactusa, in the Indian and Pacific Oceans (Table 4). WebRelating sediment impacts on coral reefs to watershed sources, processes and management: A review . Wesseling I, Uychiaoco AJ, Alio PM, Aurin T, Vermaat JE. Thus, sediment may lead to sublethal responses, such as reduced rates of growth, productivity, and calcification, as well as bleaching, disease susceptibility, physical damage (e.g., breaking and abrasion), and inability to regenerate following tissue damage [16, 19,20,21,22]. Hawais coral reefs and associated species need clean water to thrive. GBRMPA Res. We used these critical appraisals and tools to organize studies into groups of comparable records across which we should (and should not) meta-analyze. Mortality of coral recruits Settlement of coral larvae onto exposed, vertically facing surfaces increases the risk of abrasion and burial by suspended and deposited sediment, which may reduce their survival as juvenile recruits. 2023 BioMed Central Ltd unless otherwise stated. 2012;7:e37795. Other less commonly reported responses of corals to sediment stress are listed in Additional file 4, along with a key to the coral species codes used in Figs. We examined all potentially eligible, un-duplicated articles within the Google Scholar search and the list of benchmark studies to understand why they were not also found in the DSE search. Lethal responses (i.e., tissue necrosis) occur at DSC as low as 4.9mg/cm2/day and for exposure durations less than one day (22h) (Table 5, Fig. Te FT. Mar Ecol Prog Ser. Introduction. Moeller M, Nietzer S, Schils T, Schupp PJ. MJD oversaw the review process and provided methodological guidance. Coral larvae may preferentially settle on the top of surfaces in low light levels [53]. Note that this is a graphical summary of existing studies and does not control for differences in power between studies (which are controlled for in the DoseResponse Meta-Analysis). Acevedo R, Morelock J (1988) Effects of Terrigenous Sediment Influx on Coral Reef Zonation in Southwestern Puerto Rico. These adverse effects may include physiological changes (e.g., reduced growth or photosynthetic rates), bleaching, tissue necrosis, and colony mortality. The effect of natural and anthropogenic nutrient and sediment loads on coral oxidative stress on runoff-exposed reefs May 2021 Marine Pollution Bulletin 168(10):112409 IHI12Proc 2nd ACM SIGHIT Int Heal Informatics Symp. How does sediment exposure affect corals? Planktonic coral larvae feed and receive translocated metabolites from their zooxanthellae [51]. Accessed 5 Mar 2021. The University of York; 1990. WebIncreased catchment runoff is one potential culprit. Mar Pollut Bull. May 10, 2016. More runoff impacts reefs, mostly by mobilizing more chemicals and sediment on land, Asner said. Zill JA, Gil MA, Osenberg CW. Environmental Evidence 2014;7:10817. Increased chemical pollution and sedimentation is a major driver of coral decline. Land use however, and in particular changes in forest cover, have significant impact on the amount of sediment discharged to coral reefs. 7. Sci Total Environ. 1984; 58 p. Nalley EM, Tuttle LJ, Barkman AL, Conklin EE, Wulstein DM, Richmond RH, Donahue MJ. Peer-reviewed publications and final reports took precedence over dissertation/thesis chapters of the same data. Warner ME, Fitt WK, Schmidt GW. Am Nat. 2017;609:27788. Our systematic review and meta-analysis was conducted according to the Guidelines and Standards for Evidence Synthesis in Environmental Management, version 5.0 [31, 32] and reported according to the procedures of ROSES (RepOrting standards for Systematic Evidence Syntheses) [33, Additional file 1]. This kind of experimental setup could be leveraged to quantify multiple responses of control and sediment-exposed corals over the typical duration of a dredging event. In the particular case of dissertations and theses, special care was taken to ensure that there was no duplication in our review between dissertation/thesis chapters and publications based on the same data. The critical threshold values that we identify in our meta-analyses are lower than previously estimated thresholds, which may affect policy and management decisions. Local management action to address coral-reef stressors can improve reef health and mitigate the effects of global climate change. WebSedimentation runoff can lead to the smothering of coral. Threshold estimates derived from continuous response variables (magnitude of adverse effect) largely matched the lowest-observed adverse-effect levels from a summary of studies, or otherwise helped us to identify research gaps that should be addressed to better quantify the doseresponse relationship between sediment exposure and coral health. 2015;10:e0125175. Riegl B, Bloomer JP. Mar Pollut Bull. Ricardo GF, Jones RJ, Nordborg M, Negri AP. Coral Reefs. The information presented here is important for society and coastal managers, because we confirm that sediments washed off the land may be damaging to coral reefs and that nutrient enrichment of as little as 1% in sediments washed off the land is potentially detrimental for coral reefs. However, model diagnostics revealed a mostly symmetrical, inverted funnel [Additional file 3: Fig. Unfortunately, however, too few articles consistently reported sediment type or comparisons among sediment types, thus limiting our ability to synthesize trends across studies. 2018;128:6371. Quantifying sediment The specifications of sediment exposure are also often reported inconsistently across studies. The biogeochemical mechanism by which coral sperm adhere and are stripped from the water surface in sinking flocs remains unclear. Therefore, the thresholds for sediment exposure described herein may not match apparent thresholds identified in the field or in individual experiments that focus on a limited set of taxa. Identifying the PECO: a framework for formulating good questions to explore the association of environmental and other exposures with health outcomes. All data generated or analyzed during this study are included in this published article [and its supplementary information files]. Meesters EH, Bos A, Gast GJ. Similarly, we screened the list of benchmark studies (described above) to include only potentially eligible, un-duplicated articles [Additional file 2].