James Douglass, Ph.D.

Northeastern University Marine Science Center

Postdoctoral Fellow

2012

Smithsonian Marine Station at Fort Pierce

Postdoctoral Fellow

2010

College of William and Mary

Ph.D.

Marine Science

2008

Ecology of Real Estate

Southwest Florida Real Estate Investment Association monthly meeting  Cape Coral, Florida

2019-07-03

Florida algae crisis; description, causes, and cure

Oasis High School Marine Biology Class  Cape Coral, Florida

2018-11-01

Direct and indirect effects of disturbance on SW Florida seagrasses

47th Annual Benthic Ecology Meeting  Corpus Christi, Texas

2018-03-29

Quantifying the water quality benefits of submerged aquatic vegetation (SAV) restoration

Coastal and Heartland National Estuary Partnership

2020-2021
*With Edwin Everham and David Ceilley

Collaborative Research: The tropicalization of Western Atlantic seagrass beds

National Science Foundation

2018-2020
*With collaborators from 14 sites internationally and $918,000 total NSF funding.

Caloosahatchee River Estuary Patch-Scale Submersed Aquatic Vegetation Monitoring

South Florida Water Management District

2013-2014

Fish and seagrass communities vary across a marine reserve boundary, but seasonal variation in small fish abundance overshadows top-down effects of large consumer exclosures

JG Douglass, R Paperno, EA Reyier, AH Hines

2018-10-01

A growing number of examples indicate that large predators can alter seagrass ecosystem structure and processes via top-down trophic interactions. However, the nature and strength of those interactions varies with biogeographic context, emphasizing the need for region-specific investigations. We investigated spatial and temporal variation in predatory fish and seagrass communities across a Marine Protected Area (MPA) boundary in the Banana River Lagoon, Florida (USA), assessing trophic roles of intermediate consumers, and performing a large-consumer exclusion experiment in the MPA. Large, predatory fishes were most abundant within the MPA, while some mid-sized fishes were more abundant outside it. Small, seagrass-resident fishes, epifaunal invertebrates, and macrophytes also differed across the MPA boundary, but varied more among individual sites and seasonally. We cannot conclusively attribute these patterns to MPA status because we lack data from prior to MPA establishment and lack study replication at the level of MPA. Nevertheless, other patterns among our data are consistent with hypothesized mechanisms of top-down control. E.g., inverse seasonal patterns in the abundance of organisms at adjacent trophic levels, coupled with stable C and N isotope and gut contents data, suggest top-down control of crustacean grazers by seasonal recruitment of small fishes. Large-consumer exclosures in the MPA increased the abundance of mid-sized predatory and omnivorous fishes, but had few impacts on lower trophic levels. Results suggest that large-scale variation in large, predatory fish abundance in this system does not strongly affect seagrass-resident fish, invertebrate, and algal communities, which appear to be driven more by habitat structure and seasonal variation in small fish abundance.

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Spatial scale mediates the effects of biodiversity on marine primary producers

MES Bracken, JG Douglass, V Perini, GJ Trussell

2017-03-15

Most studies evaluating the effects of biodiversity on ecosystem functioning are conducted at a single location, limiting our understanding of how diversity–function relationships may change when measured across different spatial scales. We conducted a species‐removal experiment at three sites nested in each of three regions along the rocky intertidal coastline of the Gulf of Maine, USA, to evaluate the potential for scale‐dependent effects of species loss on the biomass of intertidal seaweed assemblages. We randomly assigned 50 plots in the mid‐intertidal zone at each site to one of five treatments (n = 10 plots each): an unmanipulated control, a polyculture plot that contained our three target seaweed species, and three monoculture plots. We manipulated diversity by removing all non‐target species from monoculture and polyculture plots, then removing additional biomass from polyculture plots, proportionate to species' relative abundances, so that the average amount removed from monoculture and polyculture plots was equivalent at each site. At the largest spatial scale, all sites considered together, after accounting for region and site nested within region seaweed diversity had consistent, positive effects on seaweed cover. Diverse polyculture plots always had higher cover than was predicted by the average performance of the component seaweed species and usually had higher cover than even the best‐performing component species. Diversity effects weakened and became less consistent at smaller spatial scales, so that at the scale of individual sites, diverse polycultures only performed better than the average of monocultures ~40% of the time. Hence, our results indicate that weak and/or inconsistent biodiversity effects at the level of individual sites may scale up to stronger, more consistent effects at larger spatial scales. Quantitative summaries of biodiversity experiments conducted at the scale of individual sites do not capture this spatial aspect of biodiversity effects and may therefore underestimate the functional consequences of biodiversity loss.

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Biodiversity mediates top–down control in eelgrass ecosystems: a global comparative-experimental approach

JE Duffy, PL Reynolds, C Boström, JA Coyer, M Cusson, S Donadi, JG Douglass, JS Eklöf, AH Engelen, BK Eriksson, S Fredriksen, L Gamfeldt, C Gustafsson, G Hoarau, M Hori, K Hovel, K Iken, JS Lefcheck, P-O Moksnes, M Nakaoka, MI O'Connor, JL Olsen, JP Richardson, JL Ruesink, EE Sotka, J Thormar, MA Whalen, JJ Stachowicz

2015-05-17

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom–up and top–down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top–down and bottom–up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top–down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale pat-terns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top–down control strongly influence functioning of threatened sea-grass ecosystems, and suggest that biodiversity is comparably important to global change stressors.

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