Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
NRS 534 Term Paper BJC Fuller / Advances in seascape ecology: applying landscape metrics to marine systems 1(5) NEWS & VIEWS What is seascape ecology? Landscape ecology is a relatively new, multidisciplinary field which studies the relationship between ecological functions and spatial patterns (Boström et al. 2012, Pittman et al. 2011, Wedding et al. 2011), and was primarily developed to inform management practices in terrestrial systems (Pittman et al. 2011). Several important tools, models, and methods of analysis have emerged which advance our understanding of the influence of geographic heterogeneity on the health and sustainability of ecosystems on several scales (Pittman et al. 2011, Wedding et al. 2011). Generally, these metrics assess three fundamental landscape properties: 1) composition, the diversity of patch types; 2) configuration, the arrangement of those patch types; 3) and fractal dimension, the complexity of that arrangement (Wedding et al. 2011). While these tools have been developed for and applied in terrestrial systems for nearly 50 years (Pittman et al. 2011), their use in describing spatial patterns in marine contexts has only recently emerged, prompting the analogous term Ecol Fragmented Landscapes / April 2013 seascapes. This newest branch of landscape ecology treats the physical characteristics of marine environments, including geographic and chemical properties, as fundamentally landscape-like patterns which can be correlated with the ecology, life-history, and biodiversity of species in those ecosystems. The complex geographic heterogeneity that exists on land does not end at the water’s edge; geophysical processes give rise to incredibly diverse coastal environments which support rich species assemblages in both familiar and unique ways. We know that aquatic environments offer special mechanisms for enhancing patch connectivity and maintaining community structure, and these factors are crucial for sustaining the ecological integrity of these systems from multiple perspectives. Some of the most commonly recognized marine spatial patters include the patch mosaics of mangroves, coral reefs, seagrass beds, and tidal marshes, and the zonation of rocky shore and salt marsh biota (Pittman et al. 2011, Boström et al. 2012). Additionally, seascapes may not necessarily refer to any particular physical geography of the underwater landscape, but can © 2013 (REV 118) 20130429 NRS 534 Term Paper BJC Fuller / Advances in seascape ecology: applying landscape metrics to marine systems also be used to describe variation in chemical composition throughout the water column. These chemical ‘landscapes’ play hugely influential roles in the ecology of pelagic organisms, some of which never encounter benthic geography. For example, Yu et al. (2011) studied the correlation between the pH ‘landscape’, or what they refer to as the “ocean acidification seascape”, of nearshore waters off California and the calcification of urchin larvae. Most fascinating of all, though, is the application of landscape metrics which define pelagic distributions of biota as seascapes themselves. Mitchell et al. (2008) described complex spatial arrangements of phytoplankton in the water column this way. These biological ‘patches’ influence ecological functions, community dynamics, and biodiversity in much the same way as do geographic landscapes and seascapes, and they are, in turn, influenced by physical parameters like turbulence. Phytoplankton patches don’t last long, only on the order of 100 to 1000 seconds, but nonetheless they are distinctive enough to allow conceptual modeling of their distribution, which has implications for determining grazing efficiency and taxonomic diversity of predatory species. It also emphasizes the concept of scale in the context of time in addition to space; these biological seascapes might not be obvious at large timescales, but become readily apparent when that scale is narrowed appropriately. This is probably the case with other dynamic mosaics, such as chemical seascapes. It should be noted, though, that no landscape (terrestrial or marine) is perfectly static; appreciating the lifespan of mosaics is critical in recognizing spatial patterns which might be masked by assuming inappropriate timescales. Coral reef connectivity and management From the plethora of studies concerning marine ecology, we know that aquatic biota is indeed responsive to pelagic and benthic seascapes; by comparison, though, little has been done to assess these relationships in the way that landscape ecology has done for terrestrial systems (Boström et al. 2012). However, several studies have used these metrics to analyze aspects of coral reef ecospatial relationships (Mumby 2006, Olds et al. Ecol Fragmented Landscapes / April 2013 2(5) 2012, Berkström et al. 2012, Moberg & Rönnbäck 2003). These habitats provide a wonderful opportunity to assess correlations between flora, fauna, and the physical structure of the reef. Because of their incredible biodiversity, it seems fundamental that we understand how abiotic patterns influence species distribution throughout reefs, which could allow us to break down the ecological complexity of these systems and have enormous implications for the management of reefs worldwide. Mumby (2006) attempted to accomplish some of these goals by correlating the availability of mangrove nursery habitats with the health of adult reef fish, and then translating these results into algorithms that inform management practices. The algorithms are fundamentally landscapeecology-derived metrics, and assess the spatial distribution of Caribbean mangroves that provide high-quality habitat for juvenile fish, the connectivity between nursery sites and adult reef habitat, the relative importance of mangroves in providing nursery habitats for key reefs, and those mangroves which are of highest priority for restoration. These algorithms are all important in understanding the affect of mangrove-reef spatial relationships on reef community structure and biological sustainability, and operate in much the same way as similar metrics (like connectivity) do in terrestrial systems. Most recently, Olds et al. (2012) looked specifically at the correlation between mangrove-reef connectivity and reef complexity. They describe coral reefs as “mosaics of seemingly disjointed [habitats] that are functionally connected by the movement and dispersal of organisms”, heightening the ecological parallels that exist between terrestrial and marine systems, and thus justifying the application of traditional landscape metrics in aquatic environments. Using a combination of field surveys and satellite imagery, benthic habitat classifications (including coral reefs, mangroves, seagrass beds) were identified, and five spatial pattern metrics were used to quantify connectivity between patches. They specifically highlight the importance of scaling so that results are meaningful and appropriate to the particular species of interest. These methods and concerns exactly mirror the approach of traditional landscape © 2013 (REV 118) 20130429 NRS 534 Term Paper BJC Fuller / Advances in seascape ecology: applying landscape metrics to marine systems ecology, reinforcing the universality of basic ecological norms across all ecosystems. In broader terms, Berkström et al (2012) describe coral reefs as part of a more comprehensive network of patches, including mangroves and seagrass beds, which they call “the tropical seascape”. In their extensive review of ecological connectivity in tropical seascapes, they find that the role of migrating fish in providing this connectivity is not well-understood through any particular study. However, through their assessment of what little has been learned on the topic, it is clear that these fish probably perform a number of ecologically important functions and should be studied more heavily in the future. They also draw conclusions about the importance of understanding connectivity throughout the tropical seascape in the context of reserve design and placement; while coral reefs are often the highest priority in determining the location of marine protected areas (MPAs), interlinked patches like mangrove and seagrass beds are rarely included. By appreciating the role of connectivity between these patches in collectively maintaining them, MPAs might be expanded to include habitats which support reefs via these important biotic and abiotic pathways; if the entire network is not protected, MPAs will have little chance of effectively maintaining high-priority patches. These metrics can also answer a number of important non-MPA-related questions pertaining to human interaction with the tropical seascape. Moberg & Rönnbäck (2003) investigated coastal anthropogenic pressures on the tropical seascape in order to address the limits of technological substitutes for ecosystem services (which they exemplify as artificial reefs, artificial seawalls, aquaculture in mangroves, etc.) and ways in which ecosystem restoration can not only rejuvenate these services but simultaneously result in a more resilient ecosystem. Some patch types, such as mangroves and seagrass beds, are more successfully restored than complex habitats like coral reefs. By understanding the interaction between geographic heterogeneity (some of which we create ourselves) and the health of the biotic communities which are supported by it, we can begin to predict the impact various management techniques will have in a given ecosystem, which may subsequently help us determine the most Ecol Fragmented Landscapes / April 2013 3(5) appropriate patch types in which to apply those techniques. Patch connectivity, of course, is an integral part of the tropical seascape which must be considered for these techniques to be successful, especially when replacing ecosystem services with technological substitutes. The Moberg & Rönnbäck (2003) study emphasizes the importance of recognizing seascapes in developing management frameworks which foster ecofriendly technology and promote the resilience of both ecological communities and the societies that depend on them. Future considerations The application of landscape ecology to marine ecosystems seems obvious, necessary, and relatively seamless. For each terrestrial process assessed by landscape ecology, there is likely an analogous marine process which can be assessed similarly. The future seems bright for this emerging field, which lies arguably at the crossroads of landscape and marine ecology. Metrics have already been applied to map ecosystem processes like benthic production, turbidity, and denitrification, which advance our understanding of the functional value of coastal environments across large areas (Eyre & Maher 2011). The study of sedimentary seascapes and the role of benthic invertebrates which modify those mosaics (termed ‘ecosystem engineers’) is also emerging, and is important in extending seascape ecology on and into the seabed. New technology will allow us to study these systems at greater and greater depths. Mathematical modeling of subterranean biological-geological interactions has already begun, and may result in new modeling methods that could eventually be applied to other seascapes and terrestrial systems as well (Meadows et al. 2012). Other studies have investigated the influence of seascapes on predation in coastal environments (Roliv & Schiel 2006), allowing us to understand the dependency of these interactions on geographic spatial patterns. This might cause us to revise previous models of predatorprey interactions to include metrics that consider patch composition, configuration, and fractal dimension. Since many useful tools have already been developed through the study of landscape ecolo- © 2013 (REV 118) 20130429 NRS 534 Term Paper BJC Fuller / Advances in seascape ecology: applying landscape metrics to marine systems gy, and can be applied, without much modification, to marine environments, it is likely that seascape ecology will advance to an equal or nearequal state with landscape ecology relatively quickly. As is the case with most offshoots of well-established fields, tools developed specifically for seascape ecology will most likely help advance landscape ecology as well. The studies examined here point out a number of important considerations that apply to all eco-spatial analysis. The potential of seascape ecology in complementing biological oceanography and marine ecology, as well as informing ecosystem-based management practices, seems timely and powerful, and is perhaps the missing link in solving many of the marine ecological problems facing the scientific, policy, and management communities today. Berkström C, Gullström M, Lindborg R, Mwandya AW, Yahya SAS, Kautsky N, Nyström M. 2012. Exploring ‘knowns’ and ‘unknowns’ in tropical seascape connectivity with insights from East African coral reefs. Estuar Coast Shelf S 107:1-21 This is a very comprehensive review of literature on the connectivity between coral reefs and supporting habitats like mangroves and seagrass beds, with a focus on ecosystems in East Africa. They refer to the mosaic of these patches as “the tropical seascape” and find that the connectivity between patches is relatively poorly understood, especially with regard to the role of migratory fish as biological linkers. The actual article itself is relatively brief, but paper includes extremely comprehensive tables summarizing the documentation of fish species around Zanzibar Island off Tanzania, and studies on fish connectivity between various habitats. They emphasize that it is important to approach environmental management from the perspective of seascapes, as opposed to habitats, since this approach takes into account the connectivity and relative importance of each patch within the ecosystem mosaic. There is a lot of information in this article, but identification of main points was not difficult. It seems that much of the detailed data would be useful in subsequent papers focusing specifically on the ecology and biology of fishes in the Zanzibar region, but not in drawing general conclusions about connectivity and seascapes in a more global sense. Boström C, Pittman SJ, Simenstad C, Kneib RT. 2011. Seascape ecology of coastal benthic habitats: advances, gaps, and challenges. Mar Ecol Prog Ser 427:191-217 This article appeared in a Marine Ecology Progress Series theme section focusing on seascape ecology, a special edition edited in part by the authors of Pittman et al. (2011). It is a highly useful review article that highlights both areas of progress and of need in the field, and evaluates the response of biota to fragmentation in various marine habitats. Along with Pittman et al. (2011) and Wedding et al. (2011), this article provides some wonderful Ecol Fragmented Landscapes / April 2013 4(5) background to the emerging field of seascape ecology and was critical in cross-referencing several key pieces of information. The variety of topics covered (e.g. the importance of scale; effects of patch size, edge, and fragmentation; geomorphology in salt marshes; connectivity in coral reefs and mangroves) make it a lengthy paper, but numerous tables, graphs, and maps help illustrate the main points more quickly. However, a comprehensive read is a must if the actual methods and application of landscape metrics used to generate the data are to be understood. Eyre BD, Maher D. 2011. Mapping ecosystem processes and function across shallow seascapes. Cont Shelf Res 31:S162-S172 This paper exemplified the power of using landscape metrics to map coastal ecosystem functions over various scales in various habitats. This information can then be used to identify conservation ‘hotspots’ and determine areas of high and low value to the overall health of the ecosystem. This particular study focused on mapping lagoons and river estuaries in Australia. In addition to maps, the data can be summarized using innovative diagrams, which provide a visual way to quickly compare the value of functions across different habitat classifications. The paper is not a difficult read, and any text which might need clarification can usually be understood by studying the figures. Meadows PS, Meadows A, Murray JMH. 2012. Biological modifiers of marine benthic seascapes: their role as ecosystem engineers. Geomorphology 157-158:31-48 This article reviews research on the role of marine benthic organisms in modifying the seabed seascape. The study introduces the idea of advanced mathematical modeling of this system, a concept which could be applied to other seascape/landscape systems. It also discusses the importance of looking at the fossil record in determining the interaction of biological and geological processes that contributed to the formation of present seabed seascapes and sediment composition. Key points in the paper are summarized in flow charts and diagrams, which are incredibly useful in generalizing conclusions drawn from analysis conducted on the species level. Their review is long and in-depth, and given the density of the paper their conclusions did not seem as comprehensive as it could have been. Mitchell JG, Yamazaki H, Seuront L, Wolk F, Li H. 2008. Phytoplankton patch patterns: Seascape anatomy in a turbulent ocean. J Marine Syst 69:247-253 This is a fascinating study which applied seascape ecology metrics to describe patterns of phytoplankton patches. These patches arise partly in response to turbulence and eddy currents, and form distinctive asymmetric patches with regular distribution. The study was most interesting for its recognition of biological distributions as seascapes in and of themselves, which seems to be a relatively new concept. It also emphasizes the importance of appreciating timescales when applying landscape metrics and recognizing seascapes; otherwise certain mosaics might not be recognized as seascapes if inappropriate timescales are used. The study used in situ fluorescence to identify plankton patches and correlated these with measures of physical oceanographic parameters such as salinity and temperature. Some graphs were difficult to comprehend; however the conceptual 2D distributions were very fascinating. Moberg F, Rönnbäck P. 2003. Ecosystem services of the tropical seascape: interactions, substitutions and restoration. Ocean Coast Manage 46:27-46 This is a rather elegant article which assesses the tropical seascape in attempt to answer two fundamental management questions: to what extent can technological substitutes for © 2013 (REV 118) 20130429 NRS 534 Term Paper BJC Fuller / Advances in seascape ecology: applying landscape metrics to marine systems ecosystem services be effective, and how can ecosystem restoration result in both the return of those services and the resilience of the system to future disturbances. It is an important article for understanding the potential of seascape ecology in a management context, and does a good job of providing background information about each patch type as well as examples of management projects that have been successful because of their integration within the tropical seascape patch mosaic. Mumby, PJ. 2006. Connectivity of reef fish between mangroves and coral reefs: Algorithms for the design of marine reserves at seascape scales. Biol Conserv 128:215-222 This study synthesized data on mangrove nurseries and the health of adult reef fish to develop four algorithms which inform management efforts in mangrove habitats. The study was fairly comprehensive, using landscape metrics to assess connectivity and patch importance throughout the Carribean. Information was well-organized and summarized in both tabular and graphic formats, which made it easier to identify the overall results and implications of the study. This article was crucial for highlighting the application of seascape ecology in directing management practices, since this area of seascape ecology is as of yet underdeveloped. Olds AD, Connolly RM, Pitt KA, Maxwell PS. 2012. Primacy of seascape connectivity effects in structuring coral reef fish assemblages. Mar Ecol Prog Ser 426:191-203 This study focused specifically on using metrics to assess the connectivity of mangroves and coral reefs, and the role of such connectivity in maintaining healthy adult reef fish assemblages. This was an important article in providing an in-depth look at how these metrics can be applied to marine connectivity, and built upon Mumby (2006). Reading was not terribly dense, but required some special knowledge of reef fish assemblages and coral reef/mangrove ecology in order to fully appreciate the results. Pittman SJ, Kneib RT, Simenstad CA. 2011. Practicing coastal seascape ecology. Mar Ecol Prog Ser 427: 187-190 This is a highly useful review article that appeared as the lead paper in a Marine Ecology Progress Series theme section focusing on seascape ecology. The authors were also the editors of the section, along with Ivan Nagelkerken, professor at The University of Adelaide in Australia. It discusses the emergence of seascape ecology as a subset of marine ecology, highlights various examples of marine spatial patterns, and points to some important directions for the future study of seascape ecology. This was a perfect article to provide some necessary background about the development of seascape ecology and the generally application of landscape metrics to marine systems. Likewise, it seemed to serve as an introduction to the remainder of the theme section, which made it easier to relate subsequent articles to each other throughout the research process. Ecol Fragmented Landscapes / April 2013 5(5) Rilov G, Schiel DR. 2006. Seascape-dependent subtital-intertidal trophic linkages. Ecol 87:731-744 This paper looked at settlement, predation, and trophic linkages between fish, crab, and mussel species in coastal environments around New Zealand. The goal was to understand the relationship between these predator-prey interactions and the seascape itself, with considerations for scale. It was primarily interesting for this reason, since the study of predator-prey interactions often acknowledge the influence of geographic heterogeneity, but only in the context of accounting for errors in modeling. The application of seascape ecology in understanding predator-prey interactions could have huge implications for revising models and explaining and removing errors in the analysis. The paper is heavy on statistics, which makes understanding the extent of the significance of interactions difficult without a working knowledge of multivariate ANOVA. Trophic webs help illustrate these interactions in the context of seascapes when statistical specifics aren’t necessary for conveying overall conclusions, which make the paper a bit more palatable. Wedding LM, Lepczyk CA, Pittman SJ, Friedlander AM, Jorgensen S. 2011. Quantifying seascape structure: extending terrestrial spatial pattern metrics to the marine realm. Mar Ecol Prog Ser 427:219-232 This is a very comprehensive review article that appeared in a Marine Ecology Progress Series theme section focusing on seascape ecology, which was edited in part by the authors of Pitmann et al. (2011). It gives a general background about the origins of seascape ecology, and covers advancements in some important topics including 2D and 3D seascape applications, the influence of scale, analytical techniques, and general problems encountered. Diagrammatical representations of analytical problems and factors that influence the accuracy of seascape metrics help illustrate the main points made in what is otherwise a straightforward but fairly dense read. Along with Pittman et al. (2011) and Boström et al. (2011), this article provides a nice overview of the advancements in seascape ecology and gives suggestions for future directions. Cross-referencing between these three articles proved highly useful. Yu PC, Matson PG, Martz TR, Hofmann GE. 2011. The ocean acidification seascape and its relationship to the performance of calcifying marine invertebrates: Laboratory experiments on the development of urchin larvae framed by environmentallyrelevant pCO2/pH. J Exp Mar Biol Ecol 400:288-295 This study looks at the relationship between pH ‘landscapes’, or what they refer to as the “ocean acidification seascape”, and the ability of urchin larvae to calcify their exoskeleton. This paper was fascinating for its treatment of seascapes in a chemical, as opposed to geographic, context, which was especially enlightening. This invites a much broader perspective on the application of the term seascape, and perhaps ushers in a new vein of seascape ecology that can be applied to wholly pelagic organisms that never encounter any sort of physical landscape. © 2013 (REV 118) 20130429