Photos by
Kim Heiman

Carrie Kappel

Ph.D. student in Biological Sciences, Stanford University
B.S. in Biology, 1995 Brown University

Research Interests:

Spatial scaling of coral diversity and rarity
Marine species at risk

Working seascapes and the US Endangered Species Act
Threats to marine species at risk

Disturbance and diversity on rocky shores

1. Spatial scaling of coral diversity and rarity across Bahamian seascapes

Overview

Biological diversity of coral reef ecosystems is threatened by over-exploitation, climate change, pollution, and disease. Increased frequency or severity of disturbance and the introduction of novel disturbances put species with small populations especially at risk. Explaining variation in the distribution of particular species of concern and of species diversity in general is critical to conservation planning, including design of marine protected areas. The main objectives of my research are (1) to describe and compare patterns of species diversity and distribution of common and low abundance stony coral species at nested spatial scales and across multiple habitat types within The Bahamas and (2) to test how well habitats quantified via remote sensing and/or identified based on dominant species serve as a proxy for diversity and distribution of low abundance species and overall species diversity. Because of limited resources and the need to address large spatial scales, current approaches to reserve network design focus on achieving maximum representation of different habitat types as proxies for the diversity and functions they support. The question of how well habitats can serve as surrogates for the distribution of low abundance species is an open one. Rare species often exhibit strong local spatial aggregation, so their distributions may not be predictable at the scale of habitat patches within an island seascape. On the other hand, low abundance species are found disproportionately in high diversity assemblages. If habitats which harbor such assemblages are similar in community structure at the spatial scale of management planning, different patches of the same habitat, (as long as they are not too small), will likely be largely interchangeable.

Methods

Fio and I are part of the interdisciplinary Bahamas Biocomplexity Project (BBP), funded by the National Science Foundation’s Biocomplexity in the Environment program. This project seeks to understand how a Bahamian marine reserve network may function with respect to fisheries, biodiversity, and social systems. The Bahamas is in the process of expanding their existing set of MPAs into an interconnected network of marine reserves (to include up to 40 sites), and has sought scientific input. This opportunity motivated development of the BBP. My research leverages the efforts of this larger study and builds on it by asking additional questions about the diversity and distribution of coral species, and then applying these results to reserve network design.

As part of ongoing fieldwork with the BBP, I am quantifying diversity and abundances of stony coral species in six habitat types where corals are commonly found (forereef, reef crest, patch reef, Porites reef, gorgonian plain, Sargassum hardbottom) at a set of islands that span the archipelago N-S and E-W. We have completed surveys at Abaco, Bimini, Andros, San Salvador, Exuma Cays, and South Caicos (in the Turks and Caicos). Sampling is conducted across a set of nested spatial scales. For the most diverse habitat, Montastraea forereef, three replicate sites (separated by 200 m) are sampled within each area, and three areas (each 5 km apart), are sampled within each region (i.e. the 6 islands, 100s km apart). For other habitats, sampling is replicated across areas (n=3 per region) and regions (n=6) only. At each ~50x50 m site, 40-1 m2 quadrats are randomly placed, a number sufficient to characterize species diversity patterns in the most species-rich habitat. Depth and maximum vertical relief are recorded, and each quadrat is filmed using high resolution PAL digital video. For a subset of sites, coral species are also identified in situ. Viewing on a large monitor allows identification of the majority of stony corals (> 1 cm) to species level to yield a dataset of species’ frequency of occurrence (# of quadrats) by site.

2. Marine species at risk

Working seascapes and the US Endangered Species Act

2003 marked the 30th anniversary of the Endangered Species Act as well as the first major re-examination of U.S. ocean policy in over 30 years, being undertaken by the congressionally appointed US Commission on Ocean Policy, and the private Pew Oceans Commission. As part of a broader re-examination of the ESA on its anniversary, I worked with collaborators Paul Armsworth, Fiorenza Micheli and Erik Bjorkstedt on an analysis of marine biodiversity conservation under the Endangered Species Act. We have written up our results as a chapter for the forthcoming book, The Endangered Species Act at 30: Lessons and Prospects, edited by Mike Scott, Dale Goble, Frank Davis, and Geoff Heal.

Over 160 marine, estuarine and diadromous, (those that use both marine and freshwater habitats during at least some part of their lives), species *, are listed as either endangered (E), threatened (T), candidate (C) species or species of concern (SOC) under the ESA. Jurisdiction over most marine species' protection under ESA falls to the National Marine Fisheries Service’s Office of Protected Resources. Early listings were for species like whales and sea turtles – the charismatic megafauna we generally think of when we think of endangered marine species. The 1990’s saw a flurry of listings for Pacific salmonid stocks, including individual runs of chinook, chum, coho, and sockeye salmon and steelhead. Since the salmonid listings, marine and diadromous species listings have been on the rise and have been steadily diversifying. 1998 brought listing of the first marine plant, Johnson’s seagrass, Halophila johnsoni. The first marine invertebrate, white abalone, Haliotis sorenseni, was listed in 2001. Other invertebrates are being considered for listing and are on the candidate list. These include black abalone, Haliotis cracherodii, and the Caribbean corals, Acropora palmata, Acropora cervicornis, and Acropora prolifera. Thirty years after creation of the Act, the list of species protected under ESA gained its first fully marine fish, the smalltooth sawfish, Pristis pectinata, in 2003.

Threats to marine species at risk

I recently compiled data on the threats to marine and diadromous species listed under the ESA and on the IUCN Red List in order to assess the relative importance of the various drivers of endangerment. Using published data from ESA listing decisions and from the IUCN Red List database, I tallied the numbers of vulnerable species threatened either currently or historically by:

Overexploitation (targeted harvest, incidental catch and bycatch, and indirect effects)
Habitat destruction or loss
Pollution (runoff and eutrophication, sedimentation, contaminants, debris, and thermal pollution)
Disease
Invasive Species
Climate Change
Water diversion and flow modification
Aquaculture and hatcheries
Vessel interactions (boat strikes and disturbance)
Acoustic disturbance
Human disturbance
Natural threats and intrinsic factors (natural threats such as predation, storms, and floods, and life history traits like small range size, low intrinsic growth rate, late age of maturity, etc.)

Preliminary results suggest that over-harvest is the primary driver of endangerment of marine and diadromous species. Incidental catch and bycatch affect nearly half of the species at risk. Habitat destruction, which is cited as the foremost threat to terrestrial and freshwater species (Wilcove et al. 1998), ranks second for their marine counterparts. However, the majority of marine and diadromous listed species are affected by both fishing and habitat loss. In particular, diadromous, estuarine and coastal species are most likely to be affected by habitat degradation.

3. Shifts in species dominance and diversity on rocky shores under human and natural disturbance

Overview & Methods

Through intensive biodiversity surveys of rocky intertidal habitats of Monterey Bay, CA, we assessed how human and natural disturbances interact to affect coastal communities. I was specifically interested in examining whether differences in human disturbance, (primarily in the form of trampling and collecting), and wave exposure are linked to differences in dominance and diversity patterns within these communities and whether disturbances differ in their effects on common and rare species. Our eight survey areas span a gradient in human disturbance, taking advantage of existing marine reserves and other areas that have different levels of access and legal restriction of human activities. The areas fall into 4 categories: (1) open access, no restrictions; (2) open access, reserve, but little or no enforcement; (3) closed access, no restrictions (‘de facto reserve’); (4) closed access, reserve, restrictions enforced. Each area was divided into a wave-exposed and a protected site and transects were stratified by tidal elevation within each. Using our dataset, I compared relative rank abundance patterns among areas, sites, and levels of human disturbance.

Results

Species richness - The first result that comes out of my analysis is that observed species richness (or estimated species richness) does not differ significantly across the different levels of disturbance. This pattern holds true whether you look at natural disturbance from waves or human-mediated disturbance. This suggests that species richness of these communities is not particularly sensitive to the effects of disturbance within the observed range.

Diversity - If, instead of comparing species richness, you instead compare the areas using a diversity index that takes into account both richness and relative abundance of species, significant differences emerge between restricted and open access areas in wave-exposed sites. There are a number of different diversity indices, but they all make the same basic assumption that a community with a more even distribution of individuals among its constituent species is more diverse than one in which most of the individuals (or most of the biomass) is in a few common species and all the others are relatively rare.

Dominance under human disturbance - The fact that there is a difference in diversity at wave-exposed sites, as measured by Simpson’s index, but not in species richness, tells us that the underlying patterns of relative abundance must be different between open access and restricted access areas.

Rare species - As with the common species, rare species showed a significant response to human-mediated disturbance in wave-exposed sites. Rare species responded in a number of different ways to disturbance and it’s unclear exactly what the effect of disturbance is on rare species. Though it’s possible that rare species are responding directly to physical disturbance by humans, they are unlikely to be collected in most cases and also unlikely to be trampled, just given their low abundances. Instead, there may be a link between the differences observed within the rare and common components of the community. Several of the common species, including mussels and articulated corallines are biogenic habitat-formers and it may be that changes in their abundances have led to indirect effects on the abundance of certain rare species that live on or around them. For other species, especially those with the characteristics of fugitive species, i.e. good colonization abilities but poor competitive abilities, the opening up of primary space may allow them to move in and set up shop.