Kelp forests throughout many temperate zones are in decline due to various human stressors, chiefly marine warming. Conservation measures including restoration are presently of great interest and focus on both historical and novel methodologies. Of paramount importance for these efforts is an understanding of the mechanics of kelp decline to identify the factors and triggers leading to stepwise declines and thus support the development and spatial prioritization of strategic intervention to facilitate resilience. Here, we utilized a unique dataset documenting the demographic dynamics of giant kelp, Macrocystis pyrifera, in response to multiple disturbances across >40 years off San Diego (California, USA). The recruitment and life history of >14,000 individuals were used to evaluate cohort structure, size, and longevity forced by algal community structure and disturbance. Cohort dynamics varied spatially by depth and study subregion, thus aiding identification of areas to prioritize intervention to foster resilience. Five algal assemblages were characterized providing context for cohort dynamics in response to physical disturbances and sea urchin grazing. A trend of decreasing cohort size and resilience was observed over time accentuated by the marine heat wave of 2014-2015 (MHW) after which competition with understory canopies increasingly interfered with giant kelp cohort development and plant size structure. Cohort recruitment ranged on a continuum from discrete ("pulsed") to more gradual ("trickled") episodes. Pulsed cohorts mainly produced single cohort-dominated age stands punctuated by major disturbances. Pulsed events were more common than trickled recruitment, especially at deeper sites. Trickled cohorts resulted in relatively mixed age stands, especially when individual cohorts overlapped within sites. Trickled recruitment increased over time as understory dominance increased. Cohort longevity was highly variable among sites and among cohorts within a site, with high first-year mortality mostly due to warming, waves, or their combination. Longevity was inversely related to temperature and sea urchin density, and was greatest at deeper sites, especially after the MHW. The downward trend of single cohort dominance and individual plant size over time and its step downward after the MHW suggest that deeper areas should be prioritized for restoration. Regardless, understory canopies will increasingly dominate Southern California with continued warming.

Introduction Coastal wetland restoration often involves planting nursery-grown potted plants to accelerate vegetation development, particularly when stressful conditions or insufficient source material inhibit natural recruitment. Under these conditions, planting more densely or larger, more developed plants may increase vegetation survival and growth. Prior wetland studies suggest that planting densely ameliorates stressful conditions characteristic of the high marsh, which can facilitate the persistence and growth of plantings in the field. Objectives We tested the effects of density and size of nursery-grown plants used to accelerate vegetation cover in a restored tidal marsh in southern California. Methods During a 6-month period, we assessed the survivorship and growth of plantings and soil salinities at mid and high marsh elevations Results In the high marsh, pot size, but not plant density, affected the growth of all species tested. Gains in growth were three times greater for large pots versus small pots. For the dominant marsh plant species (Salicornia pacifica), we found a marginally significant interaction between plant density and elevation on growth, which was 5% greater for high- versus low-density plots in the high marsh. Clustering and using larger pots increased planting survival, though the relative importance of either varied by species. Hypersaline soil surface layers were, on average, 22 ppt higher in the high marsh than the mid marsh. Conclusion Overall, our results suggest that in a stressful, hypersaline environment, larger pot size-rather than higher planting density-was an effective strategy for increasing plant growth and accelerating vegetation development at the restoration site.

Coastal development has negatively impacted estuarine ecosystems over the past two centuries. In southern California, USA, salt marshes are valued for their high animal and plant diversity and for providing foraging and nesting habitat for species of conservation concern. Given the ecological importance of this regionally rare habitat, coastal managers have prioritized salt marsh restoration, despite its many challenges. We review lessons learned on the effect of design and adjoining landscape on early vegetation development in a 60.7 ha tidal wetland restoration project in a southern California estuary where nearly one-third of 37.6 ha of planned salt marsh was excavated to high marsh elevations. Initial planting to facilitate vegetation development in large areas of the high marsh (> 1.7 m MLLW) was unsuccessful, likely due to hypersaline soils. In some areas, subsurface freshwater intrusion likely enhanced planted vegetation, which outperformed vegetation planted at comparable high elevations in other areas. In the mid-marsh (< 1.7 m MLLW), vegetation development from natural recruitment exceeded that of the planted high marsh. After five years, vegetation cover in the high marsh remained low. To address this issue, the marsh plain was re-graded lower in some areas and a planting program was established to hasten vegetation development. Lessons learned pertain to the critical importance of initial wetland design, which in this project led to sparse vegetation cover and the necessity of re-grading and largescale planting to facilitate vegetation establishment.

Native vegetation is planted in wetland restoration projects to supplement natural recruitment and achieve a habitat mix that supports ecological functioning. The native cordgrass Spartina foliosa—an ecosystem engineer with a wide elevation range—is frequently planted in wetland restorations in Southern California to jumpstart low marsh development. Although plantings can increase vegetation cover, planted S. foliosa can also convert areas designed as tidal creeks or mudflat to salt marsh, hindering progress towards restoration objectives. At the restored San Dieguito Wetlands (SDW) in Southern California, S. foliosa was planted during (2008–2009) and after wetland construction (2011–2018). In 2023, S. foliosa occupied 10.8 ha at SDW, but had converted 42

Projections for population viability under climate change are often made using estimates of thermal lethal thresholds. These estimates vary across life history stages and can be valuable for explaining or forecasting shifts in population viability. However, sublethal temperatures can also depress vital rates and shape fluctuations in the reproductive viability of populations. For example, heatwaves may suppress reproduction, causing recruitment failure before lethal temperatures are reached. Despite a growing awareness of this issue, tying sublethal effects to observed recruitment failure remains a challenge especially in marine environments. For the urchin Strongylocentrotus purpuratus, larval supply is known to decline near the southern edge of the range during marine heatwaves despite temperatures remaining below temperatures thought to limit larval survival. We experimentally show that sublethal suppression of gametogenesis by marine heatwaves can partially explain these historical collapses in recruitment. This response differs by sex: male spermatogenesis is less sensitive to elevated temperatures and marine heatwaves than females who exhibit substantial reductions in production of mature oocytes. Results were similar between animals from warmer and cooler regions of their range. Overall, we show sublethal thermal sensitivities of reproduction can narrow the thermal envelope for population viability compared to predictions from lethal limits.

Two species of non-native sea lavender, Limonium ramosissimum (Poir.) Maire (Algerian sea lavender) and Limonium duriusculum (Girard) Fourr. (European sea lavender) are prolific invaders of California salt marshes. We examined the efficacy of three non-herbicide treatments [tarping, selective removal (hand pulling), and scraping], and one herbicide (Telar®) treatment, in eliminating L. ramosissimum and L. duriusulum, as well as treatment impacts to native vegetation within three southern California salt marshes. Our experiments demonstrated that the non-herbicide treatments initially suppressed cover of L. ramosissimum and L. duriusulum to near zero but varied over time in their suppression of L. ramosissimum and L. duriusulum, and their effects on native species. Depending on the tarping duration, tarping eradicates L. ramosissimum and L. duriusulum at least a year post treatment with little to no long-term negative impacts to native vegetation. Selective removal had minimal effect on native species but did not consistently suppress L. duriusulum over time. Scraping eradicates L. ramosissimum and L. duriusulum; however, its negative impacts on native species make it an undesirable treatment across large areas. The herbicide treatment was not as effective in suppressing L. ramosissimum, either initially or over time, and it negatively impacted native species. Our findings support the use of tarping as the primary management method to control or eradicate dense infestations of L. ramosissimum and L. duriusulum in salt marshes. We suggest that a combination of tarping and selective removal be used to control L. ramosissimum and L. duriusulum in areas of lower infestation.

The success and cost‐effectiveness of kelp forest restoration hinges on understanding the colonization ecology of kelps, particularly with respect to dispersal potential, recruitment success, and subsequent establishment. To gain needed insight into these processes we examined spatial patterns and temporal trajectories of the colonization of a large artificial reef by the giant kelp Macrocystis pyrifera. The 151 ha artificial reef complex was constructed in three phases over 21 years, enabling dispersal, recruitment, and subsequent establishment to be examined for a wide range of environmental conditions, dispersal distances, and source population sizes. Natural colonization of all phases of the artificial reef by giant kelp was rapid (within 1 year) and extended across the entire 7‐km‐long reef complex. Colonization density declined with distance from the nearest source population, but only during the first phase when the distance from the nearest source population was ≤3.5 km. Despite this decline, recruitment on artificial reef modules farthest from the source population was sufficient to produce dense stands of kelp within a couple of years. Experimental outplanting of the artificial reef with laboratory‐reared kelp embryos was largely successful but proved unnecessary, as the standing biomass of kelp resulting from natural recruitment exceeded that observed on nearby natural reefs within 2–3 years of artificial reef construction for all three phases. Such high potential for natural colonization following disturbance has important implications for kelp forest restoration efforts that employ costly and logistically difficult methods to mimic this process by active seeding and transplanting.

Projections for population viability under climate change are often made using estimates of thermal lethal thresholds. These estimates vary across life history stages and can be valuable for explaining or forecasting shifts in population viability. However, sub-lethal temperatures can also lead to declines in vital rates and ultimately shape fluctuations in the reproductive viability of populations. For example, anomalous climatic events can suppress reproduction and lead to recruitment failure well before early life stages or adult stages become affected. These sub-lethal impacts make the effects of climate change more severe than lethal thresholds predict. Despite a growing awareness of this issue, tying sub-lethal effects to observed recruitment failure remains a challenge especially in marine environments. Here, we experimentally show that sub-lethal thermal suppression of female gametogenesis offers a plausible explanation for historical collapses in sea urchin recruitment during marine heatwaves. These sub-lethal thermal sensitivities of reproduction can narrow the thermal envelope for population viability compared to what lethal limits predict.

Salt marsh vegetation provides the structure that supports key wetland functions and the success of wetland restoration efforts depend on the establishment of vegetation, which can take decades. Field experiments aimed at identifying the factors that limit the colonization rate of marsh vegetation can be useful for guiding restoration efforts. We used field experiments and additional measurements to determine the causes for persistently low vegetation cover in a restored salt marsh in southern California. First, we characterized the soil properties of the marsh and found that high salinity and low soil moisture increased with elevation and improved with vegetation. Using this information, we conducted two field experiments-one in the high marsh and the other in the mid marsh to determine the effectiveness of different remedial actions (e.g. irrigation, soil decompaction, soil amendments, and planting and seeding different species) on increasing vegetation cover; the mid marsh experiment evaluated planting and seeding only. In the high marsh, plantings increased cover, and irrigation in combination with soil decompaction facilitated natural plant establishment. In the mid marsh, increases in vegetation cover varied by species planted. In both experiments, the marsh dominant (Salicornia pacifica) naturally recruited, increasing cover whereas seeding did not increase cover. In general, the magnitude and pace of vegetation growth was greater in the mid marsh relative to the high marsh that received less tidal inundation. Collectively, our results show how information gained from experiments conducted during wetland restoration can inform the processes underlying the establishment of vegetation.

The 2015–2016 El Niño provided insight into how low-inflow estuaries might respond to future climate regimes, including high sea levels and more intense waves. High waves and water levels coupled with low rainfall along the Southern California coastline provided the opportunity to examine how extreme ocean forcing impacts estuaries independently from fluvial events. From November 2015 to April 2016, water levels were measured in 13 Southern California estuaries, including both intermittently closed and perennially open estuaries with varying watershed size, urban development, and management practices. Elevated ocean water levels caused raised water levels and prolonged inundation in all of the estuaries studied. Water levels inside perennially open estuaries mirrored ocean water levels, while those inside intermittently closed estuaries (ICEs) exhibited enhanced higher-high water levels during large waves, and tides were truncated at low tides due to a wave-built sand sill at the mouth, resulting in elevated detided water levels. ICEs closed when sufficient wave-driven sand accretion formed a barrier berm across the mouth separating the estuary from the ocean, the height of which can be estimated using estuarine lower-low water levels. During the 2015–2016 El Niño, a greater number of Southern California ICEs closed than during a typical year and ICEs that close annually experienced longer than normal closures. Overall, sill accretion and wave exposure were important contributing factors to individual estuarine response to ocean conditions. Understanding how estuaries respond to increased sea levels and waves and the factors that influence closures will help managers develop appropriate adaptation strategies.

Sea urchins are voracious herbivores that influence the ecological structure and function of nearshore ecosystems throughout the world. Like many species that produce planktonic larvae, their recruitment is thought to be particularly sensitive to climatic fluctuations in temperature that directly or indirectly affect adult reproduction and larval transport and survival. Yet how climate alters sea urchin populations in space and time by modifying larval recruitment and year-class strength on the time-scales that regulate populations remains understudied. Using a, spatially replicated weekly-biweekly dataset spanning 27 years and 1100 km of coastline, we characterized seasonal, interannual, and spatial patterns of larval settlement of the purple sea urchin ( Strongylocentrotus purpuratus ). We show that large spatial differences in temporal patterns of larval settlement were associated with different responses to fluctuations in ocean temperature and climate. Importantly, we found a strong correlation between larval settlement and regional year class strength suggesting that such temporal and spatial variation in settlement plays an important role in controlling population dynamics. These results provide strong evidence over extensive temporal and spatial domains that climatic fluctuations shape broad-scale patterns of larval settlement and subsequent population structure of an important marine herbivore known to control the productivity, community state and provisioning services of marine ecosystems.

The Wheeler North Reef (WNR) is a large (70.4 ha [174 acre]) artificial reef in Southern California designed to mitigate the loss of kelp forest habitat and its associated community of algae, invertebrates, and fishes caused by the operation of the San Onofre Nuclear Generating Station (SONGS). Conditions of the SONGS' operating permit require that the success of WNR in compensating for the kelp forest resources destroyed by the 30 years of the power plant's operations be determined by long-term monitoring that is independent of the owners of SONGS. Performance standards pertaining to physical and ecological attributes of WNR are used as a basis for determining the success of WNR in meeting the mitigation objective to replace kelp forest resources in kind. We discuss details of the sampling design, evaluation criteria, and monitoring results and show how they are used to inform adaptive management that helps to ensure that the mitigation goals are met.

1. Anthropogenic practices that facilitate species introductions must be identified and modified to improve management and control the spread of non-native taxa in many environments. Maintenance practices that remove dense epifaunal invertebrates attached to offshore structures create a disturbance that may facilitate the establishment of non-native species. 2. We evaluated the effect of disturbance on the abundance (percent cover) of a nonnative bryozoan, Watersipora subatra, on an offshore oil platform in the Santa Barbara Channel, USA by removing the existing epifaunal community in experimental plots and comparing Watersipora cover in these plots to that in undisturbed control plots over a 15-month period. We explored the importance of larval supply and the epifaunal community in driving observed patterns, using measurements of Watersipora larval availability and colony recruitment and growth in the disturbed and control plots. We also examined the effect of disturbance on Watersipora establishment at the larger, platform-scale over c. 18 months with comparative surveys of cleaned and uncleaned portions of another oil platform. 3. Both the experimental disturbance and the larger platform cleaning facilitated Watersipora establishment, with cover increasing from c. 5% to 20-60% at shallower (<= 12 m) depths within 15 to 18 months following disturbance. 4. Initial Watersipora recruitment to the disturbed plots occurred during a period of elevated larval availability, as indicated by recruitment onto settlement plates. However, 1 year after the experimental disturbance, sessile invertebrates occupied all available settlement space, and there was little recruitment of Watersipora into disturbed plots despite the availability of larvae. 5. Synthesis and applications. Maintenance operations for offshore structures can include the manual removal of subtidal epibenthic invertebrates attached to the structure. Our study at offshore oil platforms found that this anthropogenic disturbance enhanced the establishment of the non-native invertebrate Watersipora subatra. The timing of disturbance relative to Watersipora's reproductive season was an important driver of this pattern. Scheduling maintenance practices to occur soon after the reproductive period of Watersipora could allow adequate time for native species to recruit and occupy the available bare space, thereby reducing the potential for establishment of this non-native species.

Sea urchins are voracious herbivores that influence the ecological structure and function of nearshore ecosystems throughout the world. Urchin population growth rates may be particularly sensitive to climate change because adult reproduction and larval development can vary greatly with food availability and temperature, and the transport of their larvae, which spend months feeding in the plankton, are affected by changes in ocean currents. Yet how climate alters sea urchin populations in space and time by modifying larval recruitment and year-class strength remains untested. Using an unprecedented spatially replicated 27-year dataset we illustrate how ocean temperature and climate oscillations differentially affect larval recruitment of the purple sea urchin (Strongylocentrotus purpuratus) and give rise to geographic asynchrony between northern California (positive) vs southern California (negative). Importantly, we found a strong correlation between larval recruitment and regional year class strength suggesting that recruitment variation plays an important role in controlling population dynamics. These results are the first to show that climatic fluctuations shape broad-scale patterns of sea urchin larval recruitment and are likely to control dynamics of both populations and marine ecosystems that vary over the geographical range of their distribution.

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.

Fisheries management, including the development of fishery management plans (FMPs), requires the best available scientific information. To address this need, we piloted a collaborative at-sea sampling program (CASP) among California commercial lobster fishermen, scientists, and fishery managers to develop scientifically rigorous protocols and collect, analyze, and interpret essential fisheries information (EFI). Significant differences in catch characteristics among three regions (South, North Coast, and Northwest Islands) were documented. Legal CPUE was generally similar among regions, whereas sublegal CPUE was consistently highest in the South, followed by the North Coast and Northwest Islands. Evaluation of size structure revealed that legal lobsters were significantly smaller, just larger than legal size, in the South than in the other two regions, suggesting a higher exploitation rate there. Despite this, the South had significantly more prerecruits than the northern regions, a fact not considered in present fishery models. We also found a female bias in the legal sex ratios in the north regions and in the sublegal sex ratios in all regions that could affect model parameters for trap vulnerability and reproductive capacity. A discrepancy in the average weight of legal lobster for the Northwest Islands was identified which has implications for the spawning potential ratio, a reference point that elicits management action. The regional variations in catch characteristics suggest that the California lobster fishery would benefit from using more sophisticated models that incorporate area-based EFI to better inform the harvest control rules. This finding supports the recommendations of the lobster FMP scientific review panel and the interests of resource managers, with the CASP data illustrating the value of the additional EFI and a mechanism for obtaining it. The demonstrated utility of the CASP for both cross-checking and providing additional data supports its ongoing use to inform management of the lobster fishery and as a model for other fisheries.

Sedentary or low-mobility organisms show a high degree of dependency with their substrate, where its heterogeneity often determines small-scale spatial patterns of distribution, life history traits, and fishery yields. For sea urchins, this spatial structure is usually shaped by food availability, habitat structure, individual movement, and fishery dynamics. All of these have a significant impact on their physiological and reproductive status and in particular on their gonadal content. These patterns are of particular interest considering that the sea urchin fishery is a roe fishery where marketability depends on gonad yield and quality, which in turn is related to spatial and temporal variations in associated kelp beds. Thus, better gonad quality and yields generate higher profits for both fishers (divers) and processors. However, competition among divers within a non-cooperative system creates a "race for shellfish" precluding higher gonad yields per unit of effort. A spatially explicit agent-based model for the San Diego, California red sea urchin (Strongylocentrotus franciscanus) fishery was developed in order to assess the benefits of cooperative harvesting by depicting spatial and temporal variations in fishery yields. A cooperative harvesting scenario where divers consistently target those areas with higher yields avoiding low-quality sea urchins was compared against a non-cooperative situation where divers harvest at random or based only on densities of sea urchins. Sea urchin population at the end of the simulation period was 20% higher for the most cooperative scenario compared to the non-cooperative fishery. Further, for the most cooperative scenario where information sharing among divers is greatest and harvest is coordinated, sea urchin catches were at least 10% higher and gonad yield 35% higher than in the non-cooperative scenario. In this model, information sharing and organized harvesting typical of well-functioning cooperatives allowed fishers to optimize the use of the resource in terms of higher gonad yields per unit of effort while maintaining the productivity of the stock. This study also highlights the importance of community-based management (i.e., collaborative efforts in assessment, management, and governance of fisheries between fishers, scientists, and managers) toward improving fisheries sustainability.

Estuaries are important subcomponents of the coastal ocean, but knowledge about the temporal and spatial variability of their carbonate chemistry, as well as their contribution to coastal and global carbon fluxes, are limited. In the present study, we measured the temporal and spatial variability of biogeochemical parameters in a saltmarsh estuary in Southern California, the San Dieguito Lagoon (SDL). We also estimated the flux of dissolved inorganic carbon (DIC) and total organic carbon (TOC) to the adjacent coastal ocean over diel and seasonal timescales. The combined net flux of DIC and TOC (FDIC + TOC) to the ocean during outgoing tides ranged from − 1.8±0.5 × 103 to 9.5±0.7 × 103 mol C h−1 during baseline conditions. Based on these fluxes, a rough estimate of the net annual export of DIC and TOC totaled 10±4 × 106 mol C year−1. Following a major rain event (36 mm rain in 3 days), FDIC + TOC increased and reached values as high as 29.0 ± 0.7 × 103 mol C h−1. Assuming a hypothetical scenario of three similar storm events in a year, our annual net flux estimate more than doubled to 25 ± 4 × 106 mol C year−1. These findings highlight the importance of assessing coastal carbon fluxes on different timescales and incorporating event scale variations in these assessments. Furthermore, for most of the observations elevated levels of total alkalinity (TA) and pH were observed at the estuary mouth relative to the coastal ocean. This suggests that SDL partly buffers against acidification of adjacent coastal surface waters, although the spatial extent of this buffering is likely small.

Red and purple sea urchins (Mesocentrotus francisanus and Strongylocentrotus purpuratus) cohabit the west coast of North America and exhibit behavioral switching between sheltering, when food is abundant, and emergence and overgrazing, when food is scarce. To better understand individual urchin foraging behavior, we conducted a series of time-lapse behavioral studies within and at the edge of a resilient sea urchin barren. Photographs were taken at 15-min intervals for weeklong periods to observe behavior (1) in different microtopographic settings, (2) in response to food additions, and (3) along a spatial gradient from the leading edge of a sea urchin grazing front to; 100 m behind it. Movement was limited for both species when crowded or in complex microtopography. Consistent differences in sheltering behaviors and diel movement patterns were observed between species in the presence and absence of food indicating behavioral niche differentiation. Red sea urchins responded to food falls at distances of at least 3m and exhibit an ability to return to shelters at similar distances. Both species exhibit (1) local movement for up to weeklong periods indicating constraints on bulk movement and grazing front formation, (2) decreased movement rates owing to crowding and microtopography analogous to traffic jams, and (3) consistent instraspecific differences in individual movement behaviors (i.e., personality). We propose how small-scale behavioral modes may scale to larger-scale local population movements and affect the dynamics of sea urchin overgrazing.

The hunting-mode-habitat-domain-range framework suggests that the mechanism driving trophic cascades (i.e., trait-mediated indirect interactions [TMIIs] vs. density-mediated indirect interactions [DMIIs]) should depend upon the functional traits of predators and prey. For example, trophic cascades containing active, broad habitat domain range (BHDR) predators interacting with narrow habitat domain range (NHDR) prey are predicted to arise primarily via TMIIs, because these prey should reduce their conspicuous activity in the presence of these predators. Unfortunately, this hypothesis is difficult to test given the strong bias against studies assessing trophic cascades containing NHDR prey. Furthermore, this hypothesis ignores evidence that (1) active predators can have high consumption rates on prey, (2) continuously responding to active predators foraging across broad areas is energetically costly for prey, and (3) cues from active, BHDR predators may not influence prey density. We examined the TMIIs and total indirect interaction (TII) produced during interactions between an active, BHDR ladybeetle predator (Naemia seriata) and its NHDR prey (scale insects). We exposed scale insects to nonlethal and lethal ladybeetle predators in laboratory mesocosms for 15 weeks. We measured the growth of the scale insect's host plant (cordgrass) and the population density of scale insects. Contrary to theory, nonlethal ladybeetles did not induce TMIIs. However, lethal ladybeetles increased cordgrass total and root dry biomass by 36% and 44%, respectively, suggesting the presence of strong DMIIs. Additionally, both lethal and nonlethal ladybeetles reduced scale insect population density. Our findings suggest that DMIIs, rather than TMIIs, can result from interactions between active BHDR predators and NHDR prey.