Rocky Reefs Research Articles

Chromosome-Level Assembly of the Southern Rock Bream (Oplegnathus fasciatus) Genome Using PacBio and Hi-C Technologies.

The Rock Bream (Oplegnathus fasciatus) is an economically important rocky reef fish of the Northwest Pacific Ocean. In recent years, it has been cultivated as an important edible fish in coastal areas of China. Despite its economic importance, genome-wide adaptions of domesticated O. fasciatus are largely unknown. Here we report a chromosome-level reference genome of female O. fasciatus (from the southern population in the subtropical region) using the PacBio single molecule sequencing technique (SMRT) and High-through chromosome conformation capture (Hi-C) technologies. The genome was assembled into 120 contigs with a total length of 732.95 Mb and a contig N50 length of 27.33 Mb. After chromosome-level scaffolding, 24 chromosomes with a total length of 723.22 Mb were constructed. Moreover, a total of 27,015 protein-coding genes and 5,880 ncRNAs were annotated in the reference genome. This reference genome of O. fasciatus will provide an important resource not only for basic ecological and population genetic studies but also for dissect artificial selection mechanisms in marine aquaculture.

Rocky reef biodiversity survey: Punta Pardelas, Argentina.

BackgroundTemperate rocky reefs in the SW Atlantic are productive areas that support highly diverse communities of invertebrates, algae and fishes. Rocky outcrops form complex structures which offer a diversity of microhabitats that lead to a great variety of co-existing species. Subtidal biodiversity within the Natural Protected Area Península Valdés is largely unexplored and studies are mainly limited to fish. A total of 560 high definition photoquadrats from seven rocky reefs (1-25 m depth) at Punta Pardelas were obtained during March 2019. In total, 4491 occurrences were recorded and identified to phyla (n = 2), superclasses (n = 1), classes (n = 5), subclasses (n = 2), orders (n = 2), families (n = 1), subfamilies (n = 1), genera (n = 10) and species (n = 43) levels. This dataset was developed to provide a baseline inventory of Punta Pardelas inside the Natural Protected Area, that was only partially reported more than 50 years ago. Such data represent the first step towards monitoring these less-accessible ecosystems.New informationMost of the available information about Atlantic Patagonian marine biodiversity is related to rocky intertidal communities or rocky reef fish communities. Despite having more than 4000 km of coastline, in the last 20 years only four studies have focused on subtidal benthic communities from shallow rocky reefs in Argentina (Genzano et al. 2011, Rechimont et al. 2013, Bravo et al. 2015, Bravo et al. 2020a). However, none of them described the epi-benthic community of different surface orientations on the rocky reefs. This dataset includes several surface orientations (i.e. horizontal, vertical, overhang and cave floor) and their microhabitats. We found almost double the number of taxa previously reported for the area. Through stratified sampling of different surface orientations, we recorded species that are often overlooked and thus registered as part of the existing biodiversity. For example, overhang surfaces in our study showed a unique assemblage and a great diversity of sponges. This work will be valuable as baseline information that is currently out of date in Nuevo Gulf rocky reefs.

Dominance of Scorpaena maderensis among scorpaenids of littoral rocky reefs in Corsica (NW Mediterranean): Further evidence of Mediterranean Sea warming.

The population of Scorpaenidae was investigated in the Nature Reserve of Scàndula (Corsica, France, NW Mediterranean). While absent from Corsica a few decades ago, the Madeira rockfish Scorpaena maderensis is now the most abundant scorpaenid species in shallow rocky reef areas, far outnumbering Scorpaena notata and Scorpaena porcus. Considered as a subtropical species of Atlantic origin, the northward progression of the thermophilic S. maderensis and its dominance in Corsican waters is further evidence of the ongoing warming of the Mediterranean Sea.

Habitat associations and impacts on a juvenile fish host by a temperate gnathiid isopod.

The distribution and abundance of organisms is typically shaped by multiple biotic and abiotic processes. Micropredators are parasite-like organisms that are smaller than their hosts and/or prey and feed on multiple hosts during a given life stage. Unlike typical parasites, however, they spend much or most of their time free-living, associating only temporarily with hosts. In the ocean, micropredators can impact multiple fish species, and in particular can have significant lethal and sub-lethal effects on newly settled fish. Although gnathiid isopods are abundant and primary micropredators in coral reef ecosystems, their impacts are relatively unexplored within sub-tidal temperate rocky reefs. We investigated the distribution of juvenile gnathiid isopods along sub-tidal temperate rocky reefs and tested trap methodology. We also quantified both the sub-lethal and lethal impacts of feeding-stage juvenile gnathiid isopods on juvenile, post-settlement reef fish, Heterostichus rostratus (giant kelpfish). We were most interested in determining the relationship between gnathiid infestation level and fish swimming performance, in particular swimming metrics relevant to predator avoidance maneuvers. We found that Gnathia tridens was present in rocky reefs rather than embayments along the Southern California coastline and that within rocky reefs, gnathiids occurred in the highest densities in lighted traps. Surprisingly, we observed almost no influence of fish size or gnathiid sub-lethal infestation level on ambient or burst swimming performance metrics. However, burst duration was reduced by gnathiid infestation, which is important in predator avoidance. There were significant differences in survivorship among small fish compared to large fish as a result of gnathiid infestation. Larger fish survived higher numbers of gnathiids than smaller fish, indicating that parasite-induced mortality is greater for smaller fish. Investigations of the effects of micropredators on subsequent predator-mediated mortality, including the susceptibility of fishes and their individual responses to micropredators, can further contribute to our understanding of processes affecting recruitment in resident reef fish populations. Further research, especially within temperate sub-tidal ecosystems, is needed to understand and highlight the overlooked importance of micropredation in shaping fish populations within a reefscape.

A decade implementing ecosystem approach to fisheries management improves diversity of taxa and traits within a marine protected area in the UK

AbstractAimEcosystem Approach to Fisheries Management has highlighted the importance of studying ecosystem functions and services, and the biological traits that drive them. Yet, ecosystem services and the associated benefits that they provide are rarely the motive for creating marine protected area (MPA). Therefore, many MPA monitoring projects do not explicitly study these functions and services or the underlying biological traits linked to them.LocationLyme Bay MPA, located in the SW of England, was established in 2008 to protect the reef biodiversity across a 206‐km2 area, which includes rocky reef habitats, pebbly sand and soft muddy sediments. Mobile demersal fishing was excluded across the whole site to allow the recovery of the reef habitats.MethodsUsing a combination of towed underwater video and Baited Remote Underwater Video Systems changes in diversity (taxonomic and trait), and traits affected by mobile demersal fishing were assessed in Lyme Bay MPA over 10 years.ResultsThere was a consistent increase in the number of taxa and the trait diversity they provide within the MPA as well as an increase in functional redundancy, which may increase community resilience to perturbations. Outside of the MPA there was an increase in the abundance of mobile species, while the MPA showed an increase in filter feeders.Main conclusionsThe MPA showed a trend towards more diverse and potentially resilient rocky reef habitats. This study constitutes a novel MPA assessment using multiple sampling methods to encompass a wide range of taxa. It also reinforces the importance of effective MPA monitoring, which has demonstrated changes in trait diversity and trait composition driven by changes in taxonomic diversity.

Species richness and identity both determine the biomass of global reef fish communities

Changing biodiversity alters ecosystem functioning in nature, but the degree to which this relationship depends on the taxonomic identities rather than the number of species remains untested at broad scales. Here, we partition the effects of declining species richness and changing community composition on fish community biomass across >3000 coral and rocky reef sites globally. We find that high biodiversity is 5.7x more important in maximizing biomass than the remaining influence of other ecological and environmental factors. Differences in fish community biomass across space are equally driven by both reductions in the total number of species and the disproportionate loss of larger-than-average species, which is exacerbated at sites impacted by humans. Our results confirm that sustaining biomass and associated ecosystem functions requires protecting diversity, most importantly of multiple large-bodied species in areas subject to strong human influences.

Warming may increase the vulnerability of calcareous algae to bioinvasions

Understanding the interactions between various stressors, and the resulting cumulative impacts they exert, is essential in order to predict the potential resilience of marine habitats to climate change. Crustose coralline algae (CCA) are a major calcifying component of marine habitats, from tropical to polar oceans, and play a central role as ecosystem engineers in many rocky reefs. These species are increasingly threatened by the stress of climate change. However, the effects of other stressors linked to global change, such as invasive species, have scarcely been addressed.We have studied the interactive effects of invasive algae and global warming on CCA, combining observational and experimental approaches. CCA sensitivity to invasive algae is heightened when they are concurrently exposed to elevated seawater temperature, and the interaction between these two stressors triggers drastic synergistic effects on CCA. The reduction and eventual disappearance of these “ecosystem foundation species” may undermine ecological functioning, leading to the disappearance and/or fragmentation of the communities associated with them.

Integrating Different Types of Knowledge to Understand Temporal Changes in Reef Landscapes

Reefs are highly diverse ecosystems threatened by anthropogenic actions that change their structure and dynamics. Many of these changes have been witnessed by different reef users who hold specific knowledge about the reefscape according to their experiences and uses. We aimed to understand whether fishers, divers, and reef scientists have different perceptions of general changes that have occurred in reefs and whether their knowledge converge, diverge or are complementary. We conducted 172 semi-structured interviews with stakeholders from Northeast and Southeast Brazil where either coral or rocky reefs occur, comprising most reefs occurring in the Southwestern Atlantic Ocean. Reef scientists and divers perceived corals have undergone the sharpest declines among reef species and indicate pollution and tourism as the major negative impacts on reefs. On the contrary, fishers noticed greater declines in fishing targets (i.e., groupers) and have hardly noticed differences in coral abundance or diversity over time. Divers had a broader view of changes in reef organisms, with some level of convergence with both reef scientists and fishers, while reef scientists and fishers provided information on more specific groups and economically relevant resources, respectively. The different stakeholders generally agree that reefscapes have undergone negative changes including diversity loss and abundance declines of reef organisms. The complementarity of information among different stakeholders enables a better understanding of how human behavior impact and perceive changes in natural ecosystems, which could be essential to manage reef environments, particularly those without baseline data.

EDNA captures depth partitioning in a kelp forest ecosystem.

Environmental DNA (eDNA) metabarcoding is an increasingly important tool for surveying biodiversity in marine ecosystems. However, the scale of temporal and spatial variability in eDNA signatures, and how this variation may impact eDNA-based marine biodiversity assessments, remains uncertain. To address this question, we systematically examined variation in vertebrate eDNA signatures across depth (0 m to 10 m) and horizontal space (nearshore kelp forest and surf zone) over three successive days in Southern California. Across a broad range of teleost fish and elasmobranchs, results showed significant variation in species richness and community assemblages between surface and depth, reflecting microhabitat depth preferences of common Southern California nearshore rocky reef taxa. Community assemblages between nearshore and surf zone sampling stations at the same depth also differed significantly, consistent with known habitat preferences. Additionally, assemblages also varied across three sampling days, but 69% of habitat preferences remained consistent. Results highlight the sensitivity of eDNA in capturing fine-scale vertical, horizontal, and temporal variation in marine vertebrate communities, demonstrating the ability of eDNA to capture a highly localized snapshot of marine biodiversity in dynamic coastal environments.

High-resolution marine heatwave mapping in Australasian waters using Himawari-8 SST and SSTAARS data

Marine heatwaves (MHWs) have significant ecological and economic impact at local and regional scales. Consequently, there is a pressing need to map the fine-scale temporal and spatial patterns of MHWs, for both historical and near real-time events. Satellite remote sensing of Sea Surface Temperature (SST) provides fundamental data for the mapping of MHWs. This study used high-resolution Himawari-8 SST and the Sea Surface Temperature Atlas of the Australian Regional Seas (SSTAARS) data, which have a spatial resolution of ~2 km, to map recent and near real-time MHW events in waters around Australasia. The high-resolution MHWs mapping identified two broad areas of MHW hotspots that occurred between August 2015 and February 2019. The Tropical Warm Pool region (including the Great Barrier Reef and part of the Coral Sea) was affected by strong and prolonged MHW conditions for the greater part of 2016. The unusually strong 2015–16 El Niño event was believed to be the primary underlying driver for the MHWs, and the air-sea heat flux was likely the key local process controlling the heat budget. The south-east of the study area (including Australia's south-east coast, the Tasman Sea and New Zealand's east coast) suffered severe MHWs in 2015–16, 2017–18 and 2018–19. The 2015–16 summer Bass Strait and East Tasmania MHW event was likely due to the anomalous heat transported by the East Australia Current. The air-sea heat flux, however, was likely an important local driver for the MHW events in the Tasman Sea during the 2016 autumn, the 2017–18 summer and the 2018–19 summer. The anomalous heat flux into ocean was attributed to potential underlying climate drivers including ENSO teleconnections, positive SAM and their interaction. This mapping has not only enhanced our understanding of the spatio-temporal characteristics of several previously documented MHWs, but also identified and mapped several previously undocumented MHWs. Two case studies in the Beagle Marine Park located in north-eastern Bass Strait and the Elizabeth and Middleton Reefs situated ~550 km east of the Australian coast within the Lord Howe Marine Park proved the value of Himawari-8 SST and SSTAARS data in mapping fine details of MHWs in a small area, which could not be captured by the broad-scale DOISST data. During the 2017–18 summer event, the case studies revealed much stronger MHW influence in the shallow waters east of the Beagle Marine Park where most of the important rocky reef habitats exist. During the same event, the case studies also confirmed more severe MHW impact on the Elizabeth Reef than the Middleton Reef which resulted in bleaching to selective coral species on the Elizabeth Reef. The near-real time MHWs mapping showed that both the GBR and the Coral Sea marine parks were experiencing MHW conditions in early March 2020, with most affected areas having strong MHW class.

Marine diversity in the biosphere reserve of the most oceanic island in the Gulf of California: San Pedro Mártir.

San Pedro Mártir island is of high biological, ecological, and fishery importance and was declared a biosphere reserve in 2002. This island is the most oceanic in the Gulf of California, and information on its rocky reefs is scarce. The present study aimed to generate the first list of conspicuous invertebrate and fish species based on in situ observations and to examine the community structure of the shallow rocky reefs of the reserve. In addition, we estimated the ecological indicators of richness, abundance, Shannon diversity, and Pielou evenness to evaluate the conservation status of the biosphere reserve. Data were collected annually from 2007 to 2017 through 2,192 underwater SCUBA transects. A total of 35 species of invertebrates and 73 species of fish were recorded. Most of the species are widely distributed along the eastern Pacific. Overall, 64% of the species found in this study are commercially important, and 11 species have been listed as protected. The abundance of commercially important invertebrate species (i.e., the sea cucumber Isostichopusfuscus and the spiny oyster Spondyluslimbatus) is decreasing, while commercially important fish species have maintained their abundance with periods of increase. The ecological indicators and the abundance and size of the commercial species indicate that the reserve is in good condition while meeting its conservation objectives.

Evaluating the Newly Established Largemouth Blenny (Labrisomus xanti) Population off Santa Catalina Island, CA: Determining Densities, Habitat Preference, Size Ranges, and Year Classes

In 2015 the Pacific Ocean experienced a strong El Niño Southern Oscillation (ENSO). With this change in water temperature, marine species were able to expand outside their previous ranges and settle in new habitats. The first sighting of the species Labrisomus xanti, or largemouth blenny, on Santa Catalina Island was October 2015 and since then the species has been seen regularly around the island. In October and November of 2018, we surveyed three sites along the leeward side of Catalina Island. Largemouth blennies were counted, measured, and sex determined along diver transects at multiple depth strata. Substrate type was also recorded. We observed multiple sizes of largemouth blennies among sites, depths and between sexes. Among the three sampled locations, Empire Landing had significantly more individuals than Big Fisherman Cove and Yellowtail Point. These differences were likely due to the greater abundance of small and medium-sized boulders and lack of sand patches within the rocky reef at Empire Landing. Male largemouth blennies were significantly larger than females. The largest largemouth blennies were found at a depth of 4.5 m with the smallest individuals found in the shallow (1.5 m) depths. Individuals were significantly larger at Empire Landing and Yellowtail Point than at Big Fisherman Cove. Finally, length frequency analysis identified at least four putative age classes corresponding to the years 2014–2017 supporting a well-established population. However, further study is necessary before we can determine whether the population at Catalina Island is a self-sustaining population.

The metabolic depression and revival of purple urchins (Strongylocentrotus purpuratus) in response to macroalgal availability

Organisms can reduce their metabolism and/or decrease energy allocation to reproduction in order to survive starvation during extended periods of food limitation. This is especially important for coastal rocky reefs where widespread kelp deforestation has become increasingly common in recent decades. This deforestation often results in the formation of urchin barrens that have high densities of herbivorous sea urchins and little macroalgae for them to consume. While it is known that these barrens can persist for years to decades, and it has been suggested that urchins can reduce their metabolisms and/or consume microalgae during these periods, the mechanisms that allow for such prolonged survival in adverse conditions, and if these are mechanisms are reversible are not entirely understood. Here, we provide experimental evidence to show that urchin metabolism and gonad mass both decrease significantly when the urchins are deprived of macroalgae, and that these urchins regain normal metabolic activity and gonad masses when access to this food resource is restored. Our results have important implications for consumers in other ecosystems where access to energetic resources is spatially or temporally variable and can point to new avenues of research to explain how organisms adjust their energetic needs to survive extended periods of starvation.

Study of some affecting factors in the production of instant nutritional powder from sea snail Indothais lacera (Born, 1778)

Sea snail Indothais lacera (Born, 1778) is found along coral reefs and rocky reefs in the coastal zone from the north to the south of Vietnam. Currently, most of this species are being used as fresh seafood, so their economic value is not high. This study aims to investigate some optimal conditions in the production of instant nutritional powder from Indothais lacera to diversify food varieties and create a high economic value for this sea snail species. Experiments were carried out to examine the conditions of boiling and drying, then some nutritional compositions of snail meat were analysed after being boiled and dried. The results showed that using phosphoric acid to adjust the pH level of water for boiling sea snail indicated the optimum pH level of boiling water was 5.5; the shells were boiled in 5 minutes after boiling. Under these conditions, the protein content of boiled snail meat was 64.18±4.23%. The boiled snail meat was cut into small pieces then dried. The optimal drying condition was the temperature at 50oC for 15 hours, when the snail meat contained the highest content of protein and vitamin C of 66.07±4.81% and 0.66±0.036 mg/g, respectively; the moisture content of dried snail meat was 4.28±0.48% suitable for producing instant nutritional powder

Preliminary observations on the movement ecology of a crested horn shark (Heterodontus galeatus).

The residency and movements of a single acoustically tagged female crested horn shark (Heterodontus galeatus) were monitored in Jervis Bay, Australia. The individual was intermittently detected by receivers throughout the 8-year study period and showed preference for particular rocky reefs in terms of its residency indices and duration of residency events. This individual exhibited lower residency and dissimilar movement patterns to that of the well-studied and sympatric Port Jackson shark (Heterodontus portusjacksoni), highlighting the need for research into the basic life history and movement ecology of H. galeatus.

A New Genus and Species of Pygmy Pipehorse from Taitokerau Northland, Aotearoa New Zealand, with a Redescription of Acentronura Kaup, 1853 and Idiotropiscis Whitley, 1947 (Teleostei, Syngnathidae)

Cylix tupareomanaia, new genus and species, is described from three specimens (35.5–55.5 mm SL), collected from rocky reefs at 12–17 m depth from Taitokerau Northland, New Zealand. The new taxon shares morphological synapomorphies with the superficially similar Australian endemic Idiotropiscis and Indo-Pacific Acentronura, including head angled ventrally approximately 25° from the principal body axis, enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin. Cylix tupareomanaia, new genus and species, however, is distinguishable from all other members of the Syngnathidae by the following combination of bony autapomorphic characters: a cup-like crest present anterodorsally on the supraoccipital; and large conspicuous midventral conical spines on the cleithral symphysis and first trunk ring between the pectoral-fin bases. The new species can be further differentiated by genetic divergence in the mitochondrial COX1 gene from Acentronura breviperula, A. tentaculata, Idiotropiscis australe, and I. lumnitzeri (estimated uncorrected p-distances of 19.5%, 20.4%, 17.9%, and 18.4%, respectively). A phylogenetic hypothesis from the analysis of two nuclear loci, 18S and TMO-4C4, supports the placement of C. tupareomanaia, new genus and species, as the sister taxon to a clade comprising the genera Acentronura and Idiotropiscis. Cylix tupareomanaia, new genus and species, represents the eighth member within the pygmy pipehorse clade to be described from the Indo-Pacific and the first new genus and species of syngnathid to be reported from New Zealand since 1921.

Environmental DNA reveals a multi‐taxa biogeographic break across the Arabian Sea and Sea of Oman

AbstractEnvironmental DNA (eDNA) is increasingly being used to assess community composition in marine ecosystems. Applying eDNA approaches across broad spatial scales now provide the potential to inform biogeographic analyses. However, to date, few studies have employed this technique to assess broad biogeographic patterns across multiple taxonomic groups. Here, we compare eDNA‐derived communities of bony fishes and invertebrates, including corals and sponges, from 15 locations spanning the entire length of the Omani coast. This survey includes a variety of habitats, including coral and rocky reefs, and covers three distinct marine ecoregions. Our data support a known biogeographic break in fish communities between the north and the south of Oman; however, the eDNA data highlight that this faunal break is mostly reflected in schooling baitfish species (e.g., sardines and anchovies), whereas reef‐associated fish communities appear more homogeneous along this coastline. Furthermore, our data provide indications that these biogeographic breaks also affect invertebrate communities, which includes corals, sponges, and broader eukaryotic groups. The observed community shifts were correlated with local environmental and anthropogenic differences characteristic of this coastline, particularly for the eDNA‐derived bony fish communities. Overall, this study provides compelling support that eDNA sequencing and associated analyses may serve as powerful tools to detect community differences across biogeographic breaks and ecoregions, particularly in places where there is significant variation in oceanographic conditions or anthropogenic impacts.

Shipwrecks fouling community: Similarities with natural rocky reefs at different distances and wave exposure regimes

Artificial reefs, such as shipwrecks, have been considered as an alternative to mitigate impacts on natural hard bottoms. On the other hand, unplanned artificial reefs can lead to several negative effects such as the introduction of toxic substances, further propagation of exotic and pathogen species, and impacts on the surrounding soft bottom habitat through alteration of bottom topography and dynamics. Artificial reefs are colonized by different organisms, exchanging larvae and spores with the nearest natural reefs, however, few studies have focused on the understanding of the benthic communities’ structures found on these coupling natural and artificial reefs. The aim of this study was to investigate whether benthic communities of centenary shipwrecks can be similar to natural rocky reef communities established at a short scale distance. The benthic cover of shipwrecks sunken more than 100 years ago and that of natural reefs located at a gradient distance of 0, 1 and 2 km, and differently exposed to wave action, were compared. Using multivariate analyses, we found that similarities were influenced by both wave exposure and distance. In exposed area, the benthic fouling community in shipwreck was similar to the benthic communities of the nearest reefs, with decreasing values of richness with distance. Sheltered area communities presented high dissimilarity. Once the presence of an artificial reef influences benthic communities of natural ones, we recommend the evaluation of the cost/benefits of introducing artificial reefs, considering local hydrodynamics and proximity to natural environments, to minimize undesirable changes in natural environment.

Moving on up: Vertical distribution shifts in rocky reef fish species during climate-driven decline in dissolved oxygen from 1995 to 2009.

Anthropogenic climate change has resulted in warming temperatures and reduced oxygen concentrations in the global oceans. Much remains unknown on the impacts of reduced oxygen concentrations on the biology and distribution of marine fishes. In the Southern California Channel Islands, visual fish surveys were conducted frequently in a manned submersible at three rocky reefs between 1995 and 2009. This area is characterized by a steep bathymetric gradient, with the surveyed sites Anacapa Passage, Footprint and Piggy Bank corresponding to depths near 50, 150 and 300 m. Poisson models were developed for each fish species observed consistently in this network of rocky reefs to determine the impact of depth and year on fish peak distribution. The interaction of depth and year was significant in 23 fish types, with 19 of the modelled peak distributions shifting to a shallower depth over the surveyed time period. Across the 23 fish types, the peak distribution shoaled at an average rate of 8.7 m of vertical depth per decade. Many of the species included in the study, including California sheephead, copper rockfish and blue rockfish, are targeted by commercial and recreational fisheries. CalCOFI hydrographic samples are used to demonstrate significant declines in dissolved oxygen at stations near the survey sites which are forced by a combination of natural multidecadal oscillations and anthropogenic climate change. This study demonstrates in situ fish depth distribution shifts over a 15‐year period concurrent with oxygen decline. Climate‐driven distribution shifts in response to deoxygenation have important implications for fisheries management, including habitat reduction, habitat compression, novel trophic dynamics and reduced body condition. Continued efforts to predict the formation and severity of hypoxic zones and their impact on fisheries dynamics will be essential to guiding effective placement of protected areas and fisheries regulations.

A multi-locus approach to elucidating the evolutionary history of the clingfish Tomicodon petersii (Gobiesocidae) in the Tropical Eastern Pacific

Marine species that are widely distributed in the Tropical Eastern Pacific (TEP) has served as a model for studying biogeographic patterns resulting from the effects of intraregional habitat discontinuities and oceanographic processes on the diversification and evolution of cryptobenthic reef fishes. Tomicodon petersii, a clingfish (Gobiesocidae) endemic to the TEP, is found on very shallow rocky reefs from central Mexico to northern Peru, and in the Cocos and Galapagos islands. We evaluated the effect of likely biogeographic barriers in different parts of the TEP on the diversification process of this species. We used one mitochondrial and three nuclear DNA markers from 112 individuals collected across the distribution range of T. petersii. Our phylogenetic results showed the samples constituted a monophyletic group, with three well-supported, allopatric subgroups: in the Mexican province, the Panamic province (from El Salvador to Ecuador), and the Galapagos Islands. The split between the Mexican and more southerly clades was estimated to occur at the end of the Miocene ca. 5.74 Mya, and the subsequent cladogenetic event separating the Galapagos population from the Panamic population at the junction of the Pliocene and Pleistocene, ca. 2.85 Mya. The species tree, Bayesian species delimitation tests (BPP), STACEY, and substantial genetic distances separating these three populations indicate that these three independent evolutionary units likely include two unnamed species. The cladogenetic events that promoted the formation of those genetically differentiated groups are consistent with disruptive effects on gene flow of habitat discontinuities and oceanographic processes along the mainland shoreline in the TEP and of ocean-island isolation, in conjunction with the species intrinsic life-history characteristics.