Rikki Grober-Dunsmore

A Landscape Ecology Approach for the Study of Ecological Connectivity Across Tropical Marine Seascapes

Connectivity across the seascape is expected to have profound consequences for the behavior, growth, survival, and spatial distribution of marine species. A landscape ecology approach offers great utility for studying ecological connectivity in tropical marine seascapes. Landscape ecology provides a well developed conceptual and operational framework for addressing complex multi-scale questions regarding the influence of spatial patterning on ecological processes. Landscape ecology can provide quantitative and spatially explicit information at scales relevant to resource management decision making. It will allow us to begin asking key questions such as ‘how much habitat to protect?’, ‘What type of habitat to protect?’, and ‘Which seascape patterns provide optimal, suboptimal, or dysfunctional connectivity for mobile marine organisms?’. While landscape ecology is increasingly being applied to tropical marine seascapes, few studies have dealt explicitly with the issue of connectivity. Herein, we examine the application of landscape ecology to better understand ecological connectivity in tropical marine ecosystems by: (1) reviewing landscape ecology concepts, (2) discussing the landscape ecology methods and tools available for evaluating connectivity, (3) examining data needs and obstacles, (4) reviewing lessons learned from terrestrial landscape ecology and from coral reef ecology studies, and (5) discussing the implications of ecological connectivity for resource management. Several recent studies conducted in coral reef ecosystems demonstrate the powerful utility of landscape ecology approaches for improving our understanding of ecological connectivity and applying results to make more informed decisions for conservation planning.

Climate Change, Coral Reef Ecosystems, and Management Options for Marine Protected Areas

Marine protected areas (MPAs) provide place-based management of marine ecosystems through various degrees and types of protective actions. Habitats such as coral reefs are especially susceptible to degradation resulting from climate change, as evidenced by mass bleaching events over the past two decades. Marine ecosystems are being altered by direct effects of climate change including ocean warming, ocean acidification, rising sea level, changing circulation patterns, increasing severity of storms, and changing freshwater influxes. As impacts of climate change strengthen they may exacerbate effects of existing stressors and require new or modified management approaches; MPA networks are generally accepted as an improvement over individual MPAs to address multiple threats to the marine environment. While MPA networks are considered a potentially effective management approach for conserving marine biodiversity, they should be established in conjunction with other management strategies, such as fisheries regulations and reductions of nutrients and other forms of land-based pollution. Information about interactions between climate change and more “traditional” stressors is limited. MPA managers are faced with high levels of uncertainty about likely outcomes of management actions because climate change impacts have strong interactions with existing stressors, such as land-based sources of pollution, overfishing and destructive fishing practices, invasive species, and diseases. Management options include ameliorating existing stressors, protecting potentially resilient areas, developing networks of MPAs, and integrating climate change into MPA planning, management, and evaluation.

Resheeting of relict Acropora palmata framework may promote fast growth, but does it compromise the structural integrity of the colony?

Coral Reefs (2006) 25: 46 DOI 10.1007/s00338-005-0062-9 Reef sites There are positive signs for the recovery of Acropora palmata in the Caribbean region including recruitment of new colonies in many locations (Bruckner 2002; Zubillaga et al. 2005, Grober-Dunsmore et al. unpublished). In St. John, US Virgin Islands, we observed new branching growth, (Fig. 1a and b) and resheeting (Fig. 1c–f) on relict Acropora framework (dead colonies that remain in their original growth position, Fig. 1g). Resheeting occurs when a colony grows over the existing framework in a thin veneer of tissue (see Jordán-Dahlgren 1992), and allows the new colony to attain a large surface area quickly, with a rapid increase in coral cover. Much of this relict framework has lacked live coral cover for more than 20 years, and we have observed that it is frequently heavily colonized by a suite of bioeroders (e.g., sponges, molluscs). As a result, we may expect the structural integrity of these ‘regrowths’ to be compromised, with an increased susceptibility to breakage compared to new colonies. While this type of regeneration is welcome, we question whether the ‘regrowth’ will produce structures that are capable of surviving the increases in storm magnitude and frequency which are predicted over the next few decades (Trenberth 2005).