The research, led by Shane Farrell, a former University of Maine doctoral student in the laboratory of Senior Research Scientist Douglas Rasher, is among the first investigations to grapple with the microbial consequences of kelp forest collapse in a cold-water system. While scientists have long documented the visible losses that follow the decline of foundation species — the large, structurally complex organisms that define entire habitats — the fate of the microscopic life that underpins ecosystem functioning has remained largely unexplored in temperate kelp systems. The new findings make clear that when kelp disappears, the reef does not simply lose a canopy; it loses an entire biochemical regime.

What distinguishes this study from much of the existing literature is its deliberate choice of scale. Microbial communities in marine environments can be sampled from the water column, from the surfaces of individual kelp fronds, or from within algal tissues, and each of those niches hosts distinct assemblages of organisms. Farrell and colleagues reasoned that the broadest and most ecologically meaningful unit was the reef itself — the integrated microbial community living on and within the benthic habitat. That decision reflects a growing recognition in ecology that habitats function as integrated systems of all the organisms they contain, including those invisible to the naked eye, and that understanding environmental change requires examining the full spectrum of life, not merely the species large enough to be counted by a diver.

Answering a question at that scale demanded a novel synthesis of traditional field ecology and cutting-edge molecular techniques. The team focused on six sites along the Maine coast — three dominated by kelp and three dominated by turf algae — and surveyed them during both spring and summer, capturing seasonal variation in both the biological community and its chemistry. Divers conducted surveys to characterize the algal assemblages at each site, establishing the ecological context for the molecular work. Back in the laboratory, the researchers applied metagenomics, sequencing the DNA present in reef samples to identify which microbial species were there and, crucially, which biochemical processes their genes encoded. They paired this with metabolomics, a technique that provides a snapshot of the small chemical compounds present in the environment at a given moment, revealing the molecular currency flowing through the ecosystem.

The results were striking. Kelp forests and turf-dominated reefs turned out to host microbial communities that were taxonomically and functionally different — different species, but also different suites of genes and, by extension, different capacities for metabolism and chemical transformation. The metabolomic profiles diverged as well, indicating that the two habitat states are characterized by fundamentally different chemical environments. In other words, the transition from kelp to turf does not merely swap one set of visible organisms for another; it rewrites the underlying biochemical operating system of the reef. This pattern aligns with what scientists working in other systems have observed: comparable state shifts on coral reefs and in terrestrial forests likewise produce profound reorganizations of microbial communities and their functions.

One of the most illustrative findings concerns photosynthesis at the microbial scale. The loss of kelp means the loss of canopy cover, the towering fronds that shade the reef below and shape its light environment. With that shade gone, the study found an apparent increase in the abundance of photosynthetically active microbial communities. Most notably, Synechococcus — a genus of cyanobacteria that tends to thrive in warmer, well-lit waters — was rare at the kelp forest sites but abundant on the turf-dominated reefs. That distribution suggests a possible shift in the reef’s primary energy economy, from one fueled largely by the carbon fixed and released by kelp to one increasingly driven by microbial photosynthesis under brighter, warmer conditions. Such a shift, the authors note, could ripple outward, altering fundamental processes such as nutrient retention and carbon storage, and potentially diminishing the beneficial services these ecosystems provide to humans.

The researchers are careful to frame the scope of their conclusions. The study does not provide direct measurements of the precise rates of metabolic processes underway on the reefs; metagenomics and metabolomics offer an inferential window, revealing which microbes and compounds are present rather than how fast reactions are proceeding. Even so, the snapshot is ecologically telling. The identity of the microbial species present, the functional genes they carry, and the metabolites accumulating in the environment together paint a coherent picture of how each habitat state is likely to function — and how differently a turf-dominated reef operates compared with the kelp forest it replaced. These microbial-scale changes, the authors argue, represent a critical but largely invisible dimension of ecosystem degradation that conventional monitoring, focused on fish and macroalgae, entirely misses.

The broader significance of the work lies in what it says about the cascading consequences of losing foundation species. Kelp forests are among the most productive habitats on Earth, and in the Gulf of Maine they anchor coastal food webs, shelter juvenile fish and invertebrates, buffer coastlines, and support fisheries. Rasher’s team has previously documented how warming-driven kelp decline erodes these services, from biodiversity losses to disrupted nutrient cycling and altered food web dynamics. The new study adds a deeper layer to that picture: the relationships between underwater forests, their microbial members, and the chemical landscapes they collectively create may be essential to kelp forest functioning and resilience in a warming world. If microbial communities shift in lockstep with the macroscopic habitat, then recovery of kelp may depend not only on replanting fronds or reducing local stressors, but on restoring the microbial and chemical conditions that a healthy forest generates and maintains.

As co-author Tim D’Angelo, a Senior Research Associate at Bigelow Laboratory, observed, every habitat is an integrated system of all the organisms it contains, even those that cannot be seen. The results reinforce a two-way relationship: microbial life is altered by environmental change, and in turn it acts as an engineer of its own environment, shaping the chemistry and conditions that larger organisms experience. A full understanding of ecosystem change, the authors contend, therefore requires investigation of the microbial component — a perspective that remains rare in studies of temperate reef systems. As warming continues to push coastal ecosystems across ecological thresholds, studies like this one suggest that the earliest and most fundamental signals of transformation may be written not in the visible landscape, but in the genes and molecules of the smallest inhabitants of the seafloor.

The research was supported by the National Science Foundation’s Established Program to Stimulate Competitive Research under Grant OIA-1849227, along with the Louise H. and David S. Ingalls Foundation, the PADI Foundation, the Essex Avenue Foundation, and the German Research Foundation. The study, published in the Proceedings of the National Academy of Sciences, was based on an observational field design combining dive surveys, metagenomic sequencing, and metabolomic profiling across seasonally sampled kelp and turf-dominated reefs. For the Gulf of Maine — one of the fastest-warming bodies of ocean water on the planet — the findings carry a sobering implication: the decline of kelp forests is not a single loss but a cascade, one that reaches from the canopy of swaying fronds down to the microscopic chemistry of the reef itself, and possibly to the resilience of the ecosystem as a whole.

Subject of Research: Microbial and metabolomic consequences of kelp forest collapse on temperate rocky reefs

Article Title: Loss of kelp forests reverberates down to microbial level

Article References: Loss of kelp forests reverberates down to microbial level. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: kelp forests, turf algae, microbiome, metagenomics, metabolomics, Maine coast, Gulf of Maine, ocean warming, foundation species, cyanobacteria, Synechococcus, ecosystem state shift

The new study, published in the journal Environmental Management, focuses on the Conservation Reserve Program, or CRP, a federally funded initiative administered by the United States Department of Agriculture’s Farm Service Agency. Under CRP, farmers agree to adopt conservation practices on their land, such as establishing wildlife habitat, riparian buffers, or tree plantings, and in exchange receive annual payments and cost-share assistance. Contracts run 10 to 15 years, and a field can remain enrolled for up to 30 years. Across the Southeast, many producers have used the program to plant longleaf pine, supported by regionwide initiatives from USDA agencies. The problem, the researchers argue, is that enrollment is often opportunistic, driven by which landowners happen to sign up rather than by where new forest would deliver the greatest environmental benefit at the landscape scale.

Benjamin C. Townsend, Nathan P. Nibbelink, and Puneet Dwivedi set out to change that by building a spatial prioritization approach that identifies future CRP opportunities capable of improving habitat connectivity for longleaf pine-associated wildlife. Their logic is elegant: rather than asking simply where longleaf pine could grow, they asked where planting it would most reduce the cost that animals pay to move through the landscape. Connectivity, in the language of landscape ecology, describes the ease with which wildlife can travel between habitat patches. When forests are fragmented, animals must cross hostile terrain, and the harder that journey becomes, the more isolated populations grow, with consequences that include reduced species richness, abundance, and genetic diversity.

The team’s workflow began with the raw geography of American agriculture. Using the USDA National Agricultural Statistics Service’s Crop Sequence Boundaries dataset, which algorithmically delineates individual crop fields across the contiguous United States, they screened every field in the South Atlantic Gulf region for CRP eligibility. Following the rules laid out in the 2018 Farm Bill and its extensions, a field qualified if it had been planted in commodity crops for a sufficient share of the preceding years. They then filtered those eligible fields for longleaf pine suitability using two independent datasets: LANDFIRE’s Environmental Site Potential, which maps the vegetation best fitted to each pixel’s biophysical profile, and the Florida Natural Areas Inventory’s Longleaf Sustainability Analysis, a Maxent-based model built from existing longleaf occurrences and variables covering climate, fire history, soils, and vegetation type. Only fields that passed both tests survived the cut.

Suitability alone was not enough. For restoration to genuinely improve connectivity, existing longleaf pine must already be present nearby. The researchers drew a 3-kilometer buffer around each candidate field, a distance chosen because it approximates the average juvenile dispersal range of the keystone, threatened, and culturally important species that inhabit longleaf ecosystems, from the gopher tortoise to the red-cockaded woodpecker. If at least 10 percent of that buffer, roughly 280 hectares, was already longleaf pine, the field was flagged as a prime opportunity. The result was a shortlist of 3,103 agricultural fields that are CRP eligible, suitable for longleaf pine, and positioned to stitch fragmented habitat back together.

The heart of the method lies in how the team measured the benefit of each field. They constructed resistance layers, raster maps in which every pixel carries a value representing how difficult it is for wildlife to cross. Longleaf pine received the lowest resistance value of 1, other pine species a modest 5, non-pine natural vegetation such as wetlands and hardwood forests a value of 10, agriculture 100, and developed land, roads, quarries, and open water the punishing maximum of 1,000. These values, adapted from prior connectivity studies, capture the relative permeability of each land cover type rather than absolute movement costs, which remain unknown for most species. For every candidate field, the researchers then built two cost surfaces: one representing the landscape as it stands today, and one simulating the field’s conversion to longleaf pine.

To evaluate connectivity from every direction rather than between specific patches, the team employed an omnidirectional approach. Fifty nodes were placed at even spacing around the ring of each field’s 3-kilometer buffer, and least-cost paths, calculated with Dijkstra’s algorithm through the gdistance package in R, were computed for all 1,225 possible node pairs. Averaging these cost surfaces yielded a single map of mean movement cost for each pixel from any direction. The difference between the pre-CRP and post-CRP scenarios produced a measure the authors call uplift: the absolute reduction in movement cost that planting longleaf pine on that field would deliver. The higher the uplift, the greater the potential connectivity gain.

The geographic results are striking. High-uplift opportunities cluster in the Central Florida Ridges and Uplands, the Florida Panhandle, and the Carolina Sandhills, with Florida alone hosting 1,283 of the identified fields, followed by South Carolina with 808 and North Carolina with 796. At the county level, Aiken and Lexington in South Carolina and Levy, Okaloosa, and Santa Rosa in Florida each offer more than 200 opportunities. Central Florida’s Marion and Levy counties posted the highest median uplifts, at 2,598.7 and 904.6 respectively, while the Ocklawaha, Withlacoochee South, and Waccasassa watersheds emerged as connectivity hotspots. Crucially, many of these opportunities overlap the ranges of multiple focal species, including the federally threatened frosted flatwoods salamander, meaning a single well-placed field can benefit a wide suite of wildlife.

The statistical analysis revealed a counterintuitive pattern with real strategic value. In a linear regression explaining uplift, all five landscape variables proved significant, together accounting for 46 percent of the variation. Larger fields delivered more uplift, with each percentage increase in field size raising uplift by 1.4 percent. But the strongest driver was the presence of high-resistance land: every one-unit increase in the share of roads and developed areas within the buffer boosted uplift by 7 percent. Fields surrounded by clustered longleaf pine and aggregated land cover also performed better, with patch cohesion and contagion both showing positive relationships. In other words, the best places to plant are not the wildest landscapes but the fragmented ones, where new forest can punch a low-resistance corridor through an otherwise hostile matrix and link existing stands together.

The authors are careful to note the limits of their framework. Uplift represents a best-case scenario, since least-cost modeling captures only the single easiest path of movement, and the models assume a mature longleaf landscape that will take decades to materialize, a caveat that matters especially for the red-cockaded woodpecker, which requires trees at least 80 years old for its cavity nests. The approach also does not address the human dimension of enrollment, since landowners must voluntarily participate, and data limitations mean some suitable fields were inevitably missed. Still, the method’s reach extends well beyond the Southeast. The researchers point out that the same prioritization logic could be adapted to China’s Grain for Green Program or the European Union’s pledge to plant 3 billion additional trees by 2030, where choosing the right parcels of abandoned farmland could mean the difference between tree planting that helps biodiversity and planting that does not. For a foundation species clinging to fragments of its former empire, that kind of precision may be the lifeline it needs.

Subject of Research: Spatial prioritization of Conservation Reserve Program enrollment to enhance longleaf pine ecosystem habitat connectivity in the southeastern United States

Article Title: A Spatial Prioritization Approach for Identifying Future Conservation Reserve Program Opportunities to Enhance Longleaf Pine (Pinus palustris) Ecosystem Connectivity

Article References: Townsend, B. C., Nibbelink, N. P., & Dwivedi, P. (2026). A Spatial Prioritization Approach for Identifying Future Conservation Reserve Program Opportunities to Enhance Longleaf Pine (Pinus palustris) Ecosystem Connectivity. Environmental Management, 76(9), Article 303. https://doi.org/10.1007/s00267-026-02593-z

Image Credits: AI Generated

DOI: 10.1007/s00267-026-02593-z

Keywords: longleaf pine, habitat connectivity, Conservation Reserve Program, spatial prioritization, habitat fragmentation, landscape ecology, least-cost path, foundation species, ecosystem restoration, Southeastern United States, conservation planning, resistance surfaces