Coastal Habitats Research Articles

Shoreline Translocation during Road Expansion Was Successful for Most Waterbirds but Not for Waders

Coastal wetlands are one of the most threatened ecosystems due to, firstly, their relative rarity and, secondly, the strong human interest in these coastal sites for infrastructure development, and recreation. These coastal wetlands also serve as important migration stopover sites for a range of waterbirds. There is great international interest in mitigating the negative effects of human land development and in restoring degraded habitats. I evaluated the response of one waterbird community to the mitigation action implemented during road expansion in an important waterbird coastal habitat in central Norway. Using a novel mitigation method, the shoreline was moved seawards to allow space for a continued shoreline habitat and the extended road. By weekly monitoring the waterbird community during spring and autumn migration periods (n = 7 of each), I found similar biodiversity, evenness, and abundance of geese, dabbling ducks, diving ducks, gulls, and waders when data for the whole wetland were used. However, after construction waders were partially displaced from the zone closest to the road to a zone further away. For some groups of birds, shoreline translocation can be a fruitful mitigation action aiming to reduce the negative effects of infrastructure expansion in coastal areas.

Education4Conservation, an evolving international program and 14-year curriculum of environmental education.

Education4Conservation evolved from an environmental education program in Balikpapan Bay, Indonesian Borneo, after its critical evaluation. The initial goal of the program was to support the development of future conservation leaders who would join the ongoing efforts to conserve proboscis monkeys (Nasalis larvatus) and their coastal forest habitat in Balikpapan Bay. We realized that to achieve this goal, we would need to work with students from the age of 4 years and continue to educate them for many years. We also realized that we needed to focus more on mentoring teachers and incorporating their feedback into the curriculum. The new program, which is in line with the new Indonesian national curriculum (Kurikulum Merdeka), has proved attractive to teachers and has spread from Kalimantan to other Indonesian islands and countries outside Asia. The curriculum continues to improve through regular monthly revisions that incorporate feedback from teachers, while teachers' pedagogical skills have improved through guidance provided by responses to each of their reports. We have been following and supervising participants since the Education4Conservation program began in 2022. Although a preliminary evaluation seems to indicate substantial improvements over the earlier program (in terms of high participation, positive teacher response, improved reporting skills, and increased clarity and applicability of the curriculum), it remains to be seen whether the program ultimately achieves its primary goal to help raise some of the students into conservation leaders.

Global conservation priorities of coastal habitats towards extreme sea level rise risks

Approximately 70% of the world's largest megacities (>10 million people) are within 60 km of the coast, contributing to 50% of the world's GDP. Sea level rise will intensify coastal flood threats, making cities without sufficient habitat protection even more vulnerable. However, there is currently a lack of thorough evaluation at the global scale about conservation priorities based on the current habitat cover and the high sea level rise in order to adapt coastal flood risks. Here we assessed the disparity among habitat coverage, exposed population and extreme sea level rise to identify priority areas for future coastal conservation. These priority areas are characterized by a large population residing in low-elevation coastal zones (LECZs), high extreme sea levels (ESLs), and insufficient habitat coverages. In many highly populated countries like China and India, the flooding risk has been underestimated due to insufficient adaptation based on natural processes from coastal habitats. These highly populated countries are especially concerning because they have comparatively less vegetation protection capability and are subjected to high ESLs. Globally, Asian and European nations, such as China, Japan, Bangladesh, Viet Nam, the United Kingdom, Belgium, Ireland, the Netherlands, and Germany, have the highest potential for mitigating coastal risks through natural habitat conservation and restoration. We found that the main contributors to variations in the extreme sea level rise risks are not due to exposure headcounts (6%), but due to inadequate habitat cover (42%), which can be improved through targeted conservation and restoration. Our research identified the global priorities for managing climate resilience that most urgently require ecosystem conservation and restoration in order to prepare for the risks of coastal flooding.

Accelerated differentiation of neo-W nuclear-encoded mitochondrial genes between two climate-associated bird lineages signals potential co-evolution with mitogenomes.

There is considerable evidence for mitochondrial-nuclear co-adaptation as a key evolutionary driver. Hypotheses regarding the roles of sex-linkage have emphasized Z-linked nuclear genes with mitochondrial function (N-mt genes), whereas it remains contentious whether the perfect co-inheritance of W genes with mitogenomes could hinder or facilitate co-adaptation. Young (neo-) sex chromosomes that possess relatively many N-mt genes compared to older chromosomes provide unprecedented hypothesis-testing opportunities. Eastern Yellow Robin (EYR) lineages in coastal and inland habitats with different climates are diverged in mitogenomes, and in a ~ 15.4 Mb nuclear region enriched with N-mt genes, in contrast with otherwise-similar nuclear genomes. This nuclear region maps to passerine chromosome 1A, previously found to be neo-sex in the inland EYR genome. To compare sex-linked Chr1A-derived genes between lineages, we assembled and annotated the coastal EYR genome. We found that: (i) the coastal lineage shares a similar neo-sex system with the inland lineage, (ii) neo-W and neo-Z N-mt genes are not more diverged between lineages than are comparable non-N-mt genes, and showed little evidence for broad positive selection, (iii) however, W-linked N-mt genes are more diverged between lineages than are their Z-linked gametologs. The latter effect was ~7 times stronger for N-mt than non-N-mt genes, suggesting that W-linked N-mt genes might have diverged between lineages under environmental selection through co-evolution with mitogenomes. Finally, we identify a candidate gene driver for divergent selection, NDUFA12. Our data represent a rare example suggesting a possible role for W-associated mitochondrial-nuclear interactions in climate-associated adaptation and lineage differentiation.

Are restoration plans missing the target? Land tenure and cyclone risks reshuffles priorities for mangrove restoration

Coastal wetlands, vital for fisheries habitats, have suffered extensive losses. Ecosystem restoration offers opportunities to improve fish catch and restore the valuable services these ecosystems provide. Successful restoration is dependent on choosing a site where restoration is feasible, which encompasses biophysical, social, governance, logistical, and resource factors. However, factors that influence feasibility such as land tenure (governance feasibility) and future climate risks (biophysical feasibility) are often overlooked in quantitative analyses of site selection. We ask how spatial priorities for restoration change when considering how feasibility is affected by land tenure, cyclone risk, and both factors together. Specifically, we analyzed a case‐study of mangrove restoration to improve fish catch in Queensland, where there is interest in restoring coastal habitats to support fish habitats. We found that the rank order of planning units by restoration feasibility was highly influenced by both land tenure and cyclones, with cyclones changing ranks with clustered regions along the coastline and land tenure variably changing ranks throughout. In planning units where fisheries benefit is expected to be high, but cyclone risk substantially reduces restoration feasibility, practitioners could consider strategically planting mangroves near established mangrove forest and selecting resilient species for restoration. Formalizing regulations for incentives to private land holders and amending legislation for easier permitting are additional suggestions for addressing land tenure challenges. Our study emphasizes the importance of systematic approaches to considering feasibility in spatial planning for restoration to minimize the risk of failure.

Assessment of plastic debris and biofouling in a specially protected area of the Antarctic Peninsula region

The aim of this paper is to characterize the plastic and to study a potential relationship between plastic debris characteristics and the presence of fouling biota in an Antarctic Specially Protected Area Robert Island, on the Antarctic peninsula region. A combination of lab-based sorting, advanced spectral analysis and general linear modelling was used to assess the abundance and type of plastic debris washed up on the shore. Observations recorded 730 debris items, with 85 % being plastic. Polystyrene (PS) and Polyethylene terephthalate (PET) were the dominant plastics (61 %). Biofouling was observed on 25 % of plastic debris, with debris complexity and degradation significantly increasing the likelihood of fouling occurring. There was no correlation found between biofouling type and plastic polymer type. Findings raise concerns that even with the highest level of environmental protection, an external marine-based source of pollution can intrude the coastal habitat, with uncertain consequences to local flora and fauna.

Sandy bottoms have limited species richness but substantially contribute to the regional coastal fish β-diversity: A case study of the Central Mediterranean Sea

Global marine biodiversity loss impairs entire ecosystems and their stability. Robust biodiversity estimates are key to inform policies and management strategies, and need to consider the contribution of diverse habitats, including those for which estimates of biodiversity are scattered or totally absent. This study assessed the fish diversity associated with three main coastal habitats (rocky bottoms, Posidonia oceanica meadows, sandy bottoms), and their role in shaping the overall coastal fish diversity, also in relation to potential environmental and anthropogenic drivers affecting patterns of fish diversity in coastal areas. Using underwater visual census, we sampled 62 sites distributed on the three habitats, for a total of 496 replicates. We assessed the contribution of each habitat to β-diversity, divided into Local Contribution to β-diversity (LCBD), a comparative indicator of the contributions to β-diversity of each habitat, and Species Contribution to β-diversity (SCBD), which measures the relative importance of each species in affecting β-diversity. Finally, we modelled species diversity in relation to potential environmental and anthropogenic drivers. Overall, 72 species were recorded, with the highest species richness observed on rocky bottoms (56 species, 16 unique to this habitat), followed by P. oceanica (38 species, 0 unique) and sandy bottoms (32 species, 14 unique). Sandy bottom assemblages had a significantly higher contribution to LCBD than P. oceanica meadows and rocky bottoms, and two of the five species with the highest contribution to SCBD are exclusively associated with sandy bottoms. Finally, sea surface temperature, sea surface salinity, and habitat were highlighted as significant predictors of species richness. Our findings, aside from highlighting the environmental drivers of coastal fish diversity in the Mediterranean Sea, unravel the potential key role of sandy bottoms in contributing to overall coastal fish diversity and can inform conservation planning.

Taxonomy and molecular phylogeny of genus Plagiocampa (Ciliophora, Prostomatea), with redescriptions of two poorly known species

Prostomateans, as common inhabitants in diverse aquatic environments, are among the simplest ciliate lineages, and serve as trophic links in food webs. However, only a few members are well-known and thoroughly studied, and the diversity of this group remains elusive. The unique genus Plagiocampa has a long history of research, but few studies have been performed using up-to-date methods. In the present work, Plagiocampa longis Kahl, 1927 and Plagiocampa minima Kahl, 1927, collected from Chinese coastal habitats, were investigated based on microscopical observation, protargol staining, and SSU rRNA gene sequencing. Their ciliature and morphometric data as well as gene sequences are documented. Phylogenetic analyses revealed that the family Plagiocampidae is likely monophyletic and has a closer relationship with parasitic Cryptocaryon.

Chriselatium schubarti, a new genus and new species of inland sesarmid crab from Java, Indonesia (Brachyura, Thoracotremata)

Abstract A new genus and new species of sesarmid crab is described from Bogor in West Java Province, Indonesia. Chriselatium schubarti new genus, new species, is morphologically most similar to Selatium, and Lithoselatium, but differs markedly in a suite of carapace, cheliped, ambulatory leg, and male pleonal characters. While Selatium and Lithoselatium are found in mangroves and coastal habitats, Chriselatium new genus was collected in a freshwater habitat that is over 60 km from the nearest coastline.

River-sea migration patterns of juvenile Japanese seabass influence migrations in subsequent stages

The Japanese seabass Lateolabrax japonicus, an important commercial fishery species, exhibits partial migration, where some individuals migrate upstream into rivers, and others inhabit estuarine and coastal areas within the same population. Although this migratory behavior has been documented in juvenile seabass, the prevalence of river use and the ecological significance of partial migration in subsequent developmental stages remain unclear. To understand the river use of subadult and adult Japanese seabass, we estimated the river use history using otolith Sr/Ca ratios from individuals captured in both marine and riverine environments. Based on hierarchical clustering with Dynamic Time Warping, Sr/Ca ratios at age 0 were clustered into three habitat use patterns: coastal resident, estuarine resident, and river migrant. Groups that used coastal and riverine habitats at age 0 tended to use coastal and riverine habitats, respectively, from spring to fall of age 1 and above, with overlapping distributions during winter. Subadult and adult river use patterns were linked to juvenile river use, indicating a carryover effect. Additionally, seasonal migration between the sea and rivers became less active with age, and the high growth sustained by river use also declined with age, suggesting that the benefits of river use are less for older (subadult and adult) seabass. This study highlights that juvenile habitat use experience drives subadult and adult partial migration of Japanese seabass, with individuals seeking environments adapted from past experiences. Our findings indicate that the seabass population consists of individuals adapted to various environments, from the sea to the rivers, maximizing the use of biological productivity.

Changes in limpet diet according to habitat type

Limpets are a key taxon regulating the benthic community structure and serving as prey for various predators in rocky shores, however, their role in food web dynamics is still unclear. To determine environmental factors influencing the limpet diet, carbon and nitrogen stable isotopes in limpets and food sources were analyzed on three different coastal habitats. Sediment organic matter contributed the most (86 %) to the limpet diet in bedrocks around tidal flats with abundant sediment supply from the terrestrial matter inflow and the sediment resuspension. Microphytobenthos and macroalgae were the main food sources (57 % and 20 %, respectively) for the limpets around beaches, where benthic flora was abundant. Limpets in bedrocks, erosional habitat, primarily consumed relatively abundant phytoplankton (33 %) and microphytobenthos (28 %). Contrary to previous studies, habitat type, rather than latitude or seawater characteristics, was the most important factor determining the limpet diet. This result also suggests that limpets are non-selective scraper that consume abundant food sources.

Overwintering potential of the Mediterranean fruit fly (Diptera: Tephritidae) in Austria.

The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), one of the most important invasive pests of fresh fruits and vegetables from the coastal Mediterranean habitats, is expanding its current geographic distribution to cooler more temperate areas of Europe. Every year since 2010 the fly is detected in the area of Vienna, Austria. However, whether it can establish permanent populations is not known. In this current paper, the capacity of C. capitata to overwinter in Vienna, Austria (48.1° northern latitude) was studied over 2 consecutive winter seasons (2020-2022). Overwintering trials with different life stages (larva, pupa, and adult) of C. capitata were performed in the open field and in the protected environment of a basement without a heating system. Control flies were kept under constant conditions in a climate chamber (25 °C, 60% RH, 14:10 L:D). Our data showed that no life stage of the Mediterranean fruit fly was able to survive the Austrian winter in the open field. However, in the protected environment C. capitata outlived the winter months in all studied life stages at least in small numbers and several surviving females were able to lay eggs at the time of the following fruiting season. Implications of these findings for the ongoing geographic range expansion of the pest in temperate European countries are discussed.

Understanding Balanophyllia regia Distribution in the Canary Islands: Effects of Environmental Factors and Methodologies for Future Monitoring

The future of marine ecosystems is at risk due to climate change and other human impacts. Specifically, due to ocean warming, some tropical species are expanding their populations while populations of temperate species are in regression, making the establishment of conservation measures imperative to maintain local biodiversity. In this study we establish a baseline on the distribution and abundance of the temperate coral Balanophyllia regia from the Canary Islands. We found that the main environmental factors determining B. regia’s distribution and abundance were sea surface temperature and hydrodynamic conditions. Areas under large wave action and colder environments enhanced this warm-temperate species’ development. Since its metabolic performance depends exclusively on the surrounding environment, we also propose a methodology to potentially monitor climate change on coastal habitats through this azooxanthellate calcified coral. Results of a tagging experiment showed that a concentration of 20 mg/mL of calcein during 6 h might be enough to in situ label polyps of B. regia without compromising corallite survival. Long-term monitoring of population abundances and growth rates of B. regia through calcein tagging will allow us to identify alterations in local ecosystems early and focus future conservation investments on the most vulnerable areas with higher ecological and economic value.

Habitat selection of non‐breeding American black ducks in an urban estuary

AbstractShellfish aquaculture is a globally expanding industry, including in urban estuaries that support non‐breeding waterfowl. The effects of shellfish aquaculture on the spatial distribution of non‐breeding waterfowl, however, are poorly understood and depend on the ecology of waterfowl and cultivated shellfish species. We investigated how proximity to shellfish aquaculture influenced habitat selection and movement patterns of American black ducks (Anas rubripes) during the non‐breeding season (~Oct–May) in 2020–2023 in Rhode Island, USA. The extent to which proximity to aquaculture influenced habitat selection of black ducks depended on factors specific to individuals' primary non‐breeding sites, although proximity to aquaculture did not have biologically meaningful influences on black duck movement rates across all sites. Black ducks across sites consistently selected for areas better suited for aquaculture (i.e., areas of potential future development) relative to areas poorly suited for aquaculture (i.e., areas less likely to be developed). The continued expansion of aquaculture into preferred black duck habitats will increase black duck interactions with aquaculture and therefore should be considered in the decision‐making process for siting future aquaculture leases. Future studies should quantify the extent to which continued expansion of aquaculture in those preferred coastal habitats directly influences black ducks.

Speeding up the recovery of coastal habitats through management interventions that address constraints on dispersal and recruitment.

Plans for habitat restoration will benefit from predictions of timescales for recovery. Theoretical models have been a powerful tool for informing practical guidelines in planning marine protected areas, suggesting restoration planning could also benefit from a theoretical framework. We developed a model that can predict recovery times following restoration action, under dispersal, recruitment and connectivity constraints. We apply the model to a case study of seagrass restoration and find recovery times following restoration action can vary greatly, from <1 to >20 years. The model also shows how recovery can be accelerated when restoration actions are matched to the constraints on recovery. For example, spreading of propagules can be used when connectivity is the critical restriction. The recovery constraints we articulated mathematically also apply to the restoration of coral reefs, mangroves, saltmarsh, shellfish reefs and macroalgal forests, so our model provides a general framework for choosing restoration actions that accelerate coastal habitat recovery.

High infectivity and waterborne transmission of seagrass wasting disease.

Pathogen transmission pathways are fundamental to understanding the epidemiology of infectious diseases yet are challenging to estimate in nature, particularly in the ocean. Seagrass wasting disease (SWD), caused by Labyrinthula zosterae, impacts seagrass beds worldwide and is thought to be a contributing factor to declines; however, little is known about natural transmission of SWD. In this study, we used field and laboratory experiments to test SWD transmission pathways and temperature sensitivity. To test transmission modes in nature, we conducted three field experiments out-planting sentinel Zostera marina shoots within and adjacent to natural Z. marina beds (20 ± 5 and 110 ± 5 m from bed edge). Infection rates and severity did not differ among outplant locations, implicating waterborne transmission. The infectious dose of L. zosterae through waterborne exposure was assessed in a controlled laboratory experiment. The dose to 50% disease was 6 cells ml-1 and did not differ with the temperatures tested (7.5°C and 15°C). Our results show L. zosterae is transmissible through water without direct contact with infected plants. Understanding the transmission dynamics of this disease in the context of changing ocean conditions will improve Z. marina protection and restoration in critical coastal habitats worldwide.

Blue carbon habitats in Aotearoa New Zealand—opportunities for conservation, restoration, and carbon sequestration

Coastal marine habitats (i.e. mangroves, saltmarshes, and seagrasses) have a high capacity for carbon sequestration (termed “blue carbon”) and the potential to reduce the effects of greenhouse gas emissions. However, blue carbon habitats have historically decreased as a consequence of land conversion, coastal development, and pollution and are under threat in many locations. Restoration of these habitats can reverse historic losses and generate carbon credits through increased carbon sequestration. With a long coastline, we hypothesized that there would be significant opportunities for coastal blue carbon in Aotearoa New Zealand. Results revealed Aotearoa estuaries and coastal areas contain approximately 20,932 ha of saltmarsh, 30,533 ha of mangrove, and 61,340 ha of seagrass, estimated to sequester a total of approximately 57,800 tC/year. A further 87,861 ha of land was estimated to be potentially suitable for blue carbon projects via tidal restoration, of which 56,482 ha was suitable for saltmarsh restoration (equivalent to 60,435 tC yr if restored), 17,291 ha was suitable for mangroves (26,455 tC/year), and 14,087 ha was suitable for seagrass (4790 tC/year). Both existing extent and restoration opportunity varied throughout the country, with greater opportunity in some regions than others. Nationwide, the total sequestration potential for blue carbon restoration was estimated at 91,680 tC yr−1 if all potential areas were restored. Carbon credits generated by blue carbon projects could be traded on a carbon market in Aotearoa, generate revenue for landowners, provide an additional pathway to meet domestic and international climate change targets, and result in a diversity of other ecological, social, and cultural co‐benefits from coastal restoration.

Ex-post evaluation of fishery management policies on wild fisheries production in northern Cabo Verde: An example of mackerel scad (Decapterus macarellus, Carangidae).

Government policies for marine fisheries have been implemented in Cabo Verde since its independence in 1975, with the aim to prevent overexploitation of wild fish species and promote sustainable fishing practices. Nonetheless, only minor amendments have been made to the legal harvesting size, considering biological sciences. This study, therefore, adopted a transdisciplinary approach to assess the political, ecological, and social dimensions of current fishery policy interventions applicable to the commercially valuable pelagic species Decapterus macarellus (mackerel scad). An ex-post analysis of relevant fishery management policies targeting D. macarellus was conducted. This was supplemented by strengths, weaknesses, opportunities, and threats (SWOT) analysis conducted by key fisheries stakeholders. Stocks assessment was conducted on catch data before (2003-2007) and after (2017-2021) the policy interventions. This was followed by a survey of 175 fishery sector actors to understand their perception of the policies, compliance challenges, and recommendations for reforms. Results showed that although the mackerel scad landing size comparably increased, landing catches were on the decline. Most fisheries stakeholders are aware of the policies implemented and acknowledge their favorable developmental outcomes. However, certain gaps exist in the national marine fisheries policies. For example, there is an absence of follow-up research on implemented fishing policies and a lack of monitoring data on the ecology and distribution of the mackerel scad, which hinders our understanding of the exact causes of the reported continual decrease in catches. There is, therefore, a need for regular monitoring of the environmental health of coastal and marine habitats to inform prioritization and/or reformulation of policy intervention measures to achieve intended conservation outcomes.

Range‐wide phylogeographic structure of the endangered Irrawaddy dolphin (Orcaella brevirostris) using expanded sampling from contemporary and historical specimens

AbstractThe Irrawaddy dolphin (Orcaella brevirostris) is an endangered cetacean that ranges throughout much of Southeast Asia and lives in coastal, estuarine, and riverine habitats including three river systems: Ayeyarwady, Mekong, and Mahakam. Many populations face risks from human interference, but overall rangewide diversity and connectivity is not well‐understood. Here we sequenced 77 complete mitogenomes from across the range of the Irrawaddy dolphin including all obligate riverine populations; eighteen of these were sequenced from historical museum specimens. Phylogenetic analysis showed haplotypes from each riverine population formed separate clades nested within the wider species implying each river system was separately invaded only once. All Irrawaddy dolphin mitogenomes were dated to a last common ancestor ~764 kya. Most lineages appeared after inundation cycles of the Sunda Shelf were initiated ~400 kya. Despite the lack of monophyly among many haplotypes from the same population, no population shared any haplotypes. Rangewide nucleotide diversity was average compared to other odontocetes, but riverine populations were especially low. Differentiation was significant among all populations analyzed with the most divergence occurring between isolated riverine populations. These analyses add more evidence for the necessity of conservation efforts directed towards riverine and other isolated populations of the Irrawaddy dolphin.

Under the cover of ice: Trematode infections affect survival and growth of wintering mussels

Parasites play many regulating roles that are increasingly recognized in different ecosystems. In coastal ecosystems, the trematode Himasthla elongata infects blue mussel Mytilus edulis, a foundation species that shapes the functioning of intertidal communities. Although the largest impacts of infections occur during the summer months, the parasites form long-lived cysts that can be harmful to their host mussels under winter conditions. Here, we experimentally show that even moderate levels of infection by H. elongata have a detrimental effect on the survival and growth rate of wintering blue mussels. These parasite-induced costs during winter may potentially affect populations of blue mussels in coastal habitats, with ramifications for the whole ecosystem.