Chapter 07: Vulnerability of macroalgae of the Great Barrier Reef to climate change

Assessing the vulnerability of benthic macroalgae is complicated by the fact that the taxon ‘algae’ is an unnatural (and, some suggest, outdated) grouping that encompasses several distinct and diverse evolutionary lines. Adl et al.3 suggest that ‘algae’ remains a useful functional term, denoting photosynthetic protists and their multicellular derivatives which are not embryophytes (higher plants), as well as cyanobacteria. However, they also show that ‘algae’, like ‘protists’, is not a formal taxon (and therefore should not be capitalised), nor a single, homogeneous group.This is Chapter 7 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

Lithothamnion prolifer Foslie: A common non-geniculate coralline alga (Rhodophyta: Corallinaceae) from the tropical and subtropical Indo-Pacific

A little-known, but ecologically important non-geniculate coralline, LitIhothamnion prolifer, is recorded from a number of tropical Indo-Pacific sites, including Fiji, Australia, Kiribati and Indonesia. The species occurs primarily on vertical walls of caves and overhangs in Fiji and Australia, but was also found as rhodoliths in Kiribati. LitIhothamnion prolifer is characterized by the combination of characters which follow. The thallus is extremely glossy, smooth, and rosy coloured. Thalli usually produce complanate protuberances, but protuberances become terete when growing on well lit, horizontal substrata, when unattached, or when growing on loose substrata. Conceptacles occur mainly on the tips of protuberances, and tetra/bisporangial conceptacles are large (to 1300 µm external diameter, with chambers up to 1100 µm diameter). The tetra/bisporangial conceptacles are flush or only slightly raised, and often extensive and irregularly shaped (resembling small son). They lack a raised rim, and have flattened pore plates. The rosette cells surrounding the tetra/bisporang ial pore appear somewhat sunken below the surrounding roof cells in SEM, and the cells of filaments lining the pore canals of let tetra/bisporangial conceptacles do not differ from the cells of filaments making up the rest of the roof. Old conceptacles persist and become buried in the thallus, and are then usually completely filled in by irregularly arranged calcified cells

Creation of a gilded trap by the high economic value of the Maine Lobster Fishery

Unsustainable fishing simplifies food chains and, as with aquaculture, can result in reliance on a few economically valuable species. This lack of diversity may increase risks of ecological and economic disruptions. Centuries of intense fishing have extirpated most apex predators in the Gulf of Maine (United States and Canada), effectively creating an American lobster (Homarus americanus) monoculture. Over the past 20 years, the economic diversity of marine resources harvested in Maine has declined by almost 70%. Today, over 80% of the value of Maine's fish and seafood landings is from highly abundant lobsters. Inflation-corrected income from lobsters in Maine has steadily increased by nearly 400% since 1985. Fisheries managers, policy makers, and fishers view this as a success. However, such lucrative monocultures increase the social and ecological consequences of future declines in lobsters. In southern New England, disease and stresses related to increases in ocean temperature resulted in more than a 70% decline in lobster abundance, prompting managers to propose closing that fishery. A similar collapse in Maine could fundamentally disrupt the social and economic foundation of its coast. We suggest the current success of Maine's lobster fishery is a gilded trap. Gilded traps are a type of social trap in which collective actions resulting from economically attractive opportunities outweigh concerns over associated social and ecological risks or consequences. Large financial gain creates a strong reinforcing feedback that deepens the trap. Avoiding or escaping gilded traps requires managing for increased biological and economic diversity. This is difficult to do prior to a crisis while financial incentives for maintaining the status quo are large. The long-term challenge is to shift fisheries management away from single species toward integrated social-ecological approaches that diversify local ecosystems, societies, and economies

Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire

Census-based approaches can provide important measures of the ecological processes controlling reef carbonate production states. Here, we describe a rapid, non-destructive approach to carbonate budget assessments, termed ReefBudget that is census-based and which focuses on quantifying the relative contributions made by different biological carbonate producer/eroder groups to net reef framework carbonate production. The methodology is presently designed only for Caribbean sites, but has potential to be adapted for use in other regions. Rates are calculated using data on organism cover and abundance, combined with annual extension or production rate measures. Set against this are estimates of the rates at which bioeroding species of fish, urchins and internal substrate borers erode reef framework. Resultant data provide a measure of net rates of biologically driven carbonate production (kg CaCO3 m(-2) year(-1)). These data have potential to be integrated into ecological assessments of reef state, to aid monitoring of temporal (same-site) changes in rates of biological carbonate production and to provide insights into the key ecological drivers of reef growth or erosion as a function of environmental change. Individual aspects of the budget methodology can also be used alongside other census approaches if deemed appropriate for specific study aims. Furthermore, the methodology spreadsheets are user-changeable, allowing local or new process/rate data to be integrated into calculations. Application of the methodology is considered at sites around Bonaire. Highest net rates of carbonate production, +9.52 to +2.30 kg CaCO3 m(-2) year(-1), were calculated at leeward sites, whilst lower rates, +0.98 to -0.98 kg CaCO3 m(-2) year(-1), were calculated at windward sites. Data are within the ranges calculated in previous budget studies and provide confidence in the production estimates the methodology generates

Larval retention and connectivity among populations of corals and reef fishes: history, advances and challenges

The extent of larval dispersal on coral reefs has\ud important implications for the persistence of coral reef\ud metapopulations, their resilience and recovery from an\ud increasing array of threats, and the success of protective\ud measures. This article highlights a recent dramatic increase\ud in research effort and a growing diversity of approaches to\ud the study of larval retention within (self-recruitment) and\ud dispersal among (connectivity) isolated coral reef populations. Historically, researchers were motivated by\ud alternative hypotheses concerning the processes limiting\ud populations and structuring coral reef assemblages,\ud whereas the recent impetus has come largely from the need\ud to incorporate dispersal information into the design of no-take marine protected area (MPA) networks. Although the\ud majority of studies continue to rely on population genetic\ud approaches to make inferences about dispersal, a wide\ud range of techniques are now being employed, from smallscale\ud larval tagging and paternity analyses, to large-scale\ud biophysical circulation models. Multiple approaches are\ud increasingly being applied to cross-validate and provide\ud more realistic estimates of larval dispersal. The vast\ud majority of empirical studies have focused on corals and\ud fishes, where evidence for both extremely local scale patterns of self-recruitment and ecologically significant\ud connectivity among reefs at scales of tens of kilometers\ud (and in some cases hundreds of kilometers) is accumulating.\ud Levels of larval retention and the spatial extent of\ud connectivity in both corals and fishes appear to be largely\ud independent of larval duration or reef size, but may be\ud strongly influenced by geographic setting. It is argued that\ud high levels of both self-recruitment and larval import can\ud contribute to the resilience of reef populations and MPA\ud networks, but these benefits will erode in degrading reef\ud environments