A landscape level understanding of habitat associations to integrate intertidal crabs into ecosystem models of tropical estuaries

Vermeiren, Peter Elisa Juliaan (2012) A landscape level understanding of habitat associations to integrate intertidal crabs into ecosystem models of tropical estuaries. PhD thesis, James Cook University.

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View at Publisher Website: https://doi.org/10.25903/cm28-fs17


The increasing pressures of climate change and urbanization on the ecological functioning and the goods and services provided by tropical estuaries means there is an urgent need for increased understanding of the structure and functioning of important biological components. Intertidal crabs are key components of tropical estuaries and have many characteristics that make them useful model species to study fundamental ecosystem processes. However, most research on their spatial ecology is focused on small scale, habitat-specific interactions, and so lacks applicability at larger within- and across-estuary scales where many fundamental ecosystem processes operate, and where impacts of climate change and urbanization are likely to manifest themselves. To fill this gap, this study aimed to develop enhanced background understanding of intertidal crab spatial ecology needed to allow intertidal crabs to be incorporated into landscape level ecosystem models. A broadly applicable model of intertidal crab habitat associations within the estuarine landscape was developed. This habitat association model focused on the low intertidal zone, between mean low water at spring tide and the lower edge of the mangrove forest, the zone where ecological linkage between intertidal crabs and the estuarine ecosystem is most pronounced.

A distinct intertidal crab assemblage occupied the low intertidal zone. The surface activity pattern of this assemblage was influenced by exposure, temperature and humidity. Consequently, to gain a landscape level understanding of the habitat-associations of intertidal crabs sampling needed to be conducted within a short time frame, while still including high replication. None of the traditionally used methods to sample intertidal crab distribution allows for this type of sampling design. Hence, a new photographic technique capable of high resolution, large-scale spatial distribution mapping was developed.

Maps of intertidal crabs occupying the low intertidal zone of Stuart Creek, North Queensland, Australia, were developed based on the photographic technique. This enabled successful modeling of distinct, temporally stable habitat associations using classification and regression tree models build on independently collected training and test data. Models of these habitat associations were strongly supported by sensitivity testing, with high sensitivity and low percentages of false positives, in predicting occurrence patterns of six species (Uca coarctata, Uca seismella, Macrophthalmus japonicus, Metopograpsus latifrons, Metopograpsus frontalis and Metopograpsus thukuhar) across eight dry tropical estuaries along 160 km of North Queensland coast. The cumulative model of intertidal crab habitat-associations revealed the low intertidal zone of tropical estuaries as a heterogeneous landscape of taxonomic clusters. Using stable isotope analysis of the dominant species within distinct clusters, unique resource use patterns of intertidal crab assemblages were integrated in the habitat-association model. This final model has the potential to provide a framework for the integration of intertidal crabs in landscape level ecological models of tropical estuaries, and opens the way for new, larger-scale perspectives and investigation of questions regarding niche interactions and the functional roles of the distinct intertidal crab assemblages.

Scientific baselines to support landscape level management are lacking for tropical estuaries. This is largely because much of the diversity of estuarine organisms has not been studied sufficiently to allow spatial distribution patterns to be defined, while others that have been studied show highly variable spatial organization. However, the high predictability of intertidal crab habitat-associations, in combination with their key role in many fundamental ecosystem processes, provides scope to use the understanding gained in this thesis as a scientific baseline to support management of estuaries. Additionally, photographic data underlying the habitat-association model can be collected and analyzed with high accuracy by citizen scientists. Engagement of citizen scientists has the capacity to provide large datasets over broad geographic regions, and to increase the dialogue between science and society. The latter dialogue is crucial as many of the main urban and economic centers of the next few decades will centre on tropical estuaries.

Item ID: 40217
Item Type: Thesis (PhD)
Keywords: Australia; crabs; distribution; ecosystem models; estuaries; estuarine ecology; estuarine landscape; Fiddler crabs; Grapsidae; habitat modelling; habitat selection; habitat; intertidal ecology; intertidal environment; intertidal organisms; Macrophthalmus japonicus; Macrophthalmus; mangrove management; marine ecosystem management; niches; North East Australia; North East Queensland; Ocypodidae; predictive habitat modeling; Queensland; sensitivity analysis; shellfish; spatial distribution; spatial niche; Townsville Region; tropical estuaries; Tropical North Queensland
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Publications arising from this thesis are available from the Related URLs field. The publications are:

Vermeiren, Peter, and Sheaves, Marcus (2015) Predictable habitat associations of four crab species across the low intertidal landscape of a tropical estuary over time. Estuaries and Coasts, 38 (1). pp. 285-295.

Vermeiren, Peter, and Sheaves, Marcus (2014) Predicting habitat associations of five intertidal crab species among estuaries. Estuarine, Coastal and Shelf Science , 149. pp. 133-142.

Vermeiren, Peter, and Sheaves, Marcus (2014) A remote photographic technique for high replication, large scale understanding of spatial distribution patterns of intertidal crabs. Hydrobiologia, 724 (1). pp. 79-89.

Date Deposited: 03 Sep 2015 01:37
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 33%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 33%
96 ENVIRONMENT > 9609 Land and Water Management > 960903 Coastal and Estuarine Water Management @ 34%
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