Connectivity promotes resilience to marine heat waves

Extreme climate events, such as hurricanes and heatwaves, are increasing in frequency and intensity due to climate change. These disturbances can have major ecological consequences, leading to habitat degradation and biodiversity loss.

In many cases, it can be challenging for ecosystems to recover from extreme disturbances, and severely impacted areas may not be able to recover at all.

Vranken S., Wernberg T., Scheben A., Pessarrodona A., Batley J., Coleman M.A. 2025. Connectivity enhances resilience of marine forests after an extreme event. Scientific Reports 15: 5019.

Recovery depends on individual persistence or recolonization by dispersing individuals, both of which depend on population connectivity to promote dispersal and increase adaptive potential through genetic diversity. However, the relative importance of survival versus recolonization can vary. Understanding this balance is important for predicting resilience to future climate events.

One type of extreme climate event is marine heat waves, which occur when sea surface temperatures exceed the 90th percentile of the mean for at least five days. A severe marine heat wave in 2010-2011 off the coast of Australia provided a unique opportunity to study the resilience of kelp forests to extreme climate events. This heat wave lasted several weeks, impacting around 2,300 km² area of kelp forest.

Recent research took advantage of this marine heat wave to study whether connectivity and genetic diversity increase kelp resilience to the event. In 2018 and 2019, they collected kelp samples from kelp forests in areas impacted by the marine heat wave, as well as samples from scattered individuals and drifting individuals, which represent potential new populations and dispersing individuals. They sequenced samples to characterize population structure and migratory pathways for kelp populations.

Recovery patterns varied among kelp populations almost a decade after the marine heat wave. Some areas showed no recovery, while others recovered due to recolonization, surviving individuals, or a combination of recolonization and survival. Based on satellite data of sea surface temperature, areas more severely impacted during the heat wave had more challenges in recovery, but factors like availability of propagules and grazing pressure from herbivores also impacted recovery.

Population connectivity increased recolonization of impacted kelp populations. For areas that were severely affected by the marine heat wave, connectivity to a surviving population was a key source for dispersing individuals. This dispersal helped maintain genetic diversity and promote faster recovery, highlighting the importance of dispersal for resilience to disturbances.

By identifying key areas of connectivity and dispersal routes, researchers and conservation managers can improve management strategies to conserve kelp forests. As climate change continues to drive more frequent and intense disturbances, connectivity among populations will be essential for promoting resilience in marine ecosystems.

State	Year	Policy	Description
New Hampshire	2026	SB592	Enables regional, conservation, and energy resource planning for habitat strongholds and wildlife corridors
New Hampshire	2019	SB200	Requires the New Hampshire Department of Transportation to consider fish and wildlife crossings and mitigation measures in all future road and culvert projects
New Hampshire	2016	SB376	Requires the fish and game department to identify existing and needed wildlife corridors connecting wildlife habitats in the state and to make recommendations for legislative changes

State	Year	Policy	Description
Maine	2023	LD258	Appropriates $7.5 million to Department of Transportation to improve roadways with potential adaptations for wildlife
Maine	2023	LD1881	Establishes compensation fee program relating to fish and wildlife habitats and associated corridors, including compensation paid by solar energy development
Maine	2023	LD508	Requires Department of Environmental Protection to review its permitting laws concerning climate change, habitat connectivity, ecological resilience, and coastal environments

State	Year	Policy	Description
New Jersey	2025	S3618	Directs state agencies to develop a Wildlife Corridor Action Plan
New Jersey	2024	S3916/A5486	Expands eligibility for existing wildlife fencing programs by including farmers leasing farmland
New Jersey	2007	NJAC7:13	Requires the state to incorporate wildlife crossings or a natural bank for terrestrial threatened and endangered species and/or species of concern when a new bridge or culvert project would cause habitat fragmentation

State	Year	Policy	Description
New Mexico	2023	SB72	Appropriates money to new Wildlife Corridors Fund for implementation of wildlife crossing projects under New Mexico Wildlife Corridor Action Plan
New Mexico	2022	HB 2	Allocates funding for projects to reduce wildlife-vehicle collisions and allows the Department of Transportation and Department of Game to implement their Wildlife Corridors Action Plan
New Mexico	2019	SB 228	Requires the creation of a Wildlife Corridor Action Plan that includes comprehensive guidance to agencies for identifying, prioritizing and maintaining important areas for wildlife movement

State	Year	Policy	Description
Washington	2023	HB1216/SB5196	Requires Department of Ecology to prepare environmental impact statements for clean energy projects that consider impacts to habitat connectivity and wildlife migration corridors
Washington	2022	SB5689	Provides funding for US 97 Wildlife Crossing Improvements project
Washington	2019	SEO 1031.02	Recognizes the effect of roadways in creating barriers to wildlife movement, breeding, and migrations; the Washington State Department of Transportation will promote and support Practical Solutions and Planning and Environmental Linkages to integrate habitat connectivity and biodiversity plans; will make use of the highway prioritization map known as Habitat Connectivity Investment Priorities; and will corporate and coordinate with other agencies involved in wildlife habitat protection, specifically along highways

Connecting Science to Conservation

Connectivity promotes resilience to marine heat waves

Vranken S., Wernberg T., Scheben A., Pessarrodona A., Batley J., Coleman M.A. 2025. Connectivity enhances resilience of marine forests after an extreme event. Scientific Reports 15: 5019.

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About the Author: Katherine Hulting

State	Year	Policy	Description
Vermont	2023	Act59	Vermont's 30x30 law that commits to conserving and maintaining an ecologically functional landscape that sustains biodiversity and maintains landscape connectivity
Vermont	2016	Act 171	Primarily focuses on timber harvesting regulations, but calls for a study of necessary revisions to planning statutes that protect contiguous areas of forestland from fragmentation and promote habitat connectivity between forestlands

State	Year	Policy	Description
Colorado	2026	SB141	Creates optional collision prevention fee to fund wildlife safe passage projects
Colorado	2025	HB1093	Restricts local limits on residential density unless offset elsewhere, exempts areas near wildlife crossings, and allows municipalities to seek judicial review of land use initiatives
Colorado	2023	SB 23-092	Encourages minimal impacts to wildlife migration corridors when constructing solar panel farms
Colorado	2023	SB 214	Appropriates funding to the Colorado Wildlife Safe Passages Fund for wildlife crossing projects
Colorado	2022	SB22-151	Creates a $5 million fund for measures that reduce wildlife-vehicle collisions and reconnect habitat fragmented by roads
Colorado	2022	HB22-1072	Expands the scope of Habitat Partnership Program to fund efforts to conserve wildlife migration
Colorado	2021	SJR 21-021	Aims to protect and enhance habitat connectivity in the state through the establishment of a working group to develop state policies on corridors, as well as the commission of a report on state corridors and voluntary policies to support willing landowners in improving connectivity
Colorado	2019	EO 11	Directs Colorado agencies to identify policy, regulatory, and legislative opportunities to ensure the ongoing conservation of seasonal big game habitat and migration corridors
Colorado	2018	SB 18-143	States explicit goals for Division of Parks and Wildlife to invest in habitat conservation and wildlife crossings

State	Year	Policy	Description
California	2024	AB1889	Requires counties and municipalities to conserve wildlife corridors when planning new developments
California	2023	AB1760	Calls for a statewide analysis of wildlife corridors and connectivity to support conservation planning and climate change adaptation activities.
California	2023	SB145	Outlines provisions for transportation-related environmental mitigation, including funding for wildlife corridors, property and credit purchases for mitigation, reporting requirements, and mandates for wildlife crossings along Interstate 15.
California	2023	SB101	Provides funding for wildlife corridors and open spaces, including projects to improve connectivity and reduce barriers between habitat areas.
California	2022	AB2344	Establishes a state program to address roads with high wildlife-vehicle collisions, authorizes Caltrans to develop standalone wildlife connectivity projects, mandates an inventory and prioritization system for critical areas, and requires integration of wildlife passage features into relevant road designs.
California	2022	AB1384	Requires agencies to address vulnerabilities in Safeguarding California Plans, including protecting and enhancing wildlife corridors
California	2021	SB790	Approves compensatory mitigation credits for wildlife connectivity actions
California	2021	AB1183	Establishes the California Desert Conservation Program to protect biodiversity, including the protection and enhancement of habitat connectivity
California	2021	AB128	Appropriates funding for wildlife crossing projects, including the Liberty Canyon crossing for mountain lions
California	2015	AB 498	Amends the California Fish and Game Code to encourage, wherever feasible, voluntary steps to protect the functioning of wildlife corridors
California	2014	AB1471	Provides funds to the Sacramento- San Joaquin Delta Conservancy, in part to protect and restore aquatic, wetland, and migratory bird ecosystems including corridors.
California	2008	AB2785	Orders Dept. of Fish & Wildlife to investigate, study, and identify key wildlife corridors and linkages within the state, and to make those areas public

State	Year	Policy	Description
Florida	2024	SB1638	Dedicates annual funding to land purchases, conservation easements, and trail maintenance within Florida Wildlife Corridor
Florida	2023	HB1379	Creates annual appropriation to acquire lands that complete certain linkages and are under high population stress within Florida Wildlife Corridor
Florida	2023	SB2500 sec.146	Provides funding to buy Ocala to Osceola (“O2O”) Wildlife Corridor
Florida	2021	SB976	Tasks state agencies with maintaining wildlife connectivity and designates Florida Wildlife Corridor as an existing physical, geographically defined area
Florida	2021	SB2500	Appropriates $300 million to acquire lands to conserve Florida Wildlife Corridor
Florida	2019	SB7068	Creates a "Multi-use Corridors of Regional Economic Significance Program" that includes protection of wildlife corridors as an intended benefit
Florida	2008	SB542	Amends Florida Forever Act statues to include goals of connecting linkage corridors
Florida	2001	SB1468	Amends Florida Forever Act to establish that land acquisitions should include complete landscape linkages and corridors
Florida	1999	S908	Creates Florida Forever Program, with increased protection of lands that protect threatened or endangered species and plans to create a statewide system of connected landscape linkages