Bryozoan Colonies Research Articles

Identification of early biomarkers in proteomic profiles of the phaeophyteSaccharina japonicaproximal to and beneath the front of bryozoan colonies

AbstractThe sessile bryozoanMembranipora membranaceafrequently colonizes the phaeophyteSaccharina japonica.Identifying early colonization markers using proteomics could assist in the early detection of epiphytic contamination. Different sections of thallus tissue proximal to the bryozoan (i.e. the 1-cm zone beyond the boundary of the colony) and tissue from the colony-front (i.e. the narrow zone under the newly formed front of the colony after removing the bryozoans) were separated. From the proteomic profiles ofS. japonica, we detected 151 protein spots (99 up-, 50 down-, and 2 similarly regulated) from proximal tissues and 151 spots (69 up-, 75 down-, and 7 same-regulated) from colony-front tissues. Hundred and ten spots were detected from distal healthy thallus tissue, used as a control. The protein SSP15 was specifically up-regulated in the proximal tissues by ca. 1395-fold, while it exhibited little expression at the colony-front and in distal healthy tissues. ATPases were markedly up-regulated in both the proximal and colony-front tissues by 3198- and 2475-fold, respectively. Rpl1P and SRSF proteins were specifically up-regulated only in colony-front tissues by 5724- and 273-fold, respectively. Therefore, these proteins may be used as specific biomarkers for the early detection of bryozoan colonization on each tissue type of the seaweed.

Ambient occlusion – A powerful algorithm to segment shell and skeletal intrapores in computed tomography data

During the last decades, X-ray (micro-)computed tomography has gained increasing attention for the description of porous skeletal and shell structures of various organism groups. However, their quantitative analysis is often hampered by the difficulty to discriminate cavities and pores within the object from the surrounding region.Herein, we test the ambient occlusion (AO) algorithm and newly implemented optimisations for the segmentation of cavities (implemented in the software Amira). The segmentation accuracy is evaluated as a function of (i) changes in the ray length input variable, and (ii) the usage of AO (scalar) field and other AO-derived (scalar) fields. The results clearly indicate that the AO field itself outperforms all other AO-derived fields in terms of segmentation accuracy and robustness against variations in the ray length input variable. The newly implemented optimisations improved the AO field-based segmentation only slightly, while the segmentations based on the AO-derived fields improved considerably.Additionally, we evaluated the potential of the AO field and AO-derived fields for the separation and classification of cavities as well as skeletal structures by comparing them with commonly used distance-map-based segmentations. For this, we tested the zooid separation within a bryozoan colony, the stereom classification of an ophiuroid tooth, the separation of bioerosion traces within a marble block and the calice (central cavity)-pore separation within a dendrophyllid coral. The obtained results clearly indicate that the ideal input field depends on the three-dimensional morphology of the object of interest. The segmentations based on the AO-derived fields often provided cavity separations and skeleton classifications that were superior to or impossible to obtain with commonly used distance-map-based segmentations. The combined usage of various AO-derived fields by supervised or unsupervised segmentation algorithms might provide a promising target for future research to further improve the results for this kind of high-end data segmentation and classification. Furthermore, the application of the developed segmentation algorithm is not restricted to X-ray (micro-)computed tomographic data but may potentially be useful for the segmentation of 3D volume data from other sources.

BRYOZOAN EPIBIOSIS ON FOSSIL CRABS: A RARE OCCURRENCE FROM THE MIOCENE OF IRAN

Epibionts are uniquely valuable in their ability to constrain paleoecological hypotheses about their own as well as their host's behavior and environment. Rarely preserved epizoic bryozoans are here reported on fossil crabs from the Miocene Mishan Formation in the Zagros Basin of southwestern Iran. One-hundred-thirty-eight decapod crustaceans were recovered from the upper marly member of the Mishan Formation. Of those, seven decapods (5%) were fouled by bryozoans. Of these seven decapods, five had bryozoans growing attached to the cuticle of the hard outer surface of the exoskeleton of the host crabs and thus fouled while the host crab was potentially alive. Forty percent of the bryozoan colonies occurred on the host crab's dorsal carapace, and 60% were found on chelipeds. On average, 30% of the surface area of the host crabs' fouled skeletal components were covered by bryozoan colonies. The brachyurans were mostly leucosiids, including Leucosia persica and Myra sp. The bryozoans were all cheilostomes and included Acanthodesia sp., Thalamoporella sp., and an indeterminate ascophoran. These bryozoans are all the first reported occurrences in the Mishan Formation. The low incidence of crabs fouled by bryozoans is attributed to preservational bias. The results from this study are compared to those of fossil and extant host crabs reported in the literature. The bryozoan-crab relationship documented here is best described as commensalism.

Diversity of marine bryozoans inhabiting demosponges in northeastern Brazil

As primary or obligate sessile organisms, bryozoans depend upon a substratum resource that affects their abundance, distribution and diversity. These animals can colonize virtually any type of substratum, including other organisms and artificial structures. Associations between bryozoans and sponges are commonly reported in the literature, but there are few studies discussing the association between these two taxa in detail. Here we present data on the bryozoan community found on shallow-water sponges from Bahia coast, northeastern Brazil, including their taxonomic status, colony form and adaptative structures utilized by these bryozoans to grow on sponges. Twenty-one bryozoan species were found attached to the surface of sixteen species of sponges. Five new species of cheilostome bryozoans are described. A total of 105 colonies were studied and most of them are erect delicate branching (44 colonies) and encrusting patches (34 colonies). The majority of bryozoan colonies were attached to the surface of rugose-textured sponges (67 colonies; 61%). This suggests that bryozoans are more likely to settle on irregular and rough surfaces. Patches colonies were mainly attached to the portion of the sponge that was in contact with the seabed, and spot colonies were particularly found in spatial refuges, showing the preference of larvae to settle on shaded and less exposed substrata. Most erect bryozoans were attached to the lateral sponge surface, other colonies grew on the underside and few on the upper surface of the sponges. These colonies were attached either using anchoring rhizoids, rigid bases, or stolons. The bryozoan species and genera reported here are common in northeastern Brazil and considered generalists in terms of larval settlement requirements. The bryozoan-sponge association studied is considered a non-obligatory commensalism (inquilinism).

Epizoan encrustation on Marsupites testudinarius – additional argument favoring an epifaunal mode of life of uintacrinoids?

Uintacrinoids (Uintacrinoidea Zittel) are among the best-known Late Cretaceous crinoids, but owing to their unusual morphology and widespread distribution their mode of life has become a subject of much discussion. Of several competing hypotheses, nektonic, pseudoplanktonic, hemipelagic, semi-infaunal and epibenthic lifestyles have been suggested. Recent study synthesizing and extending previous data has shown that these crinoids were epibenthic, holding their arms vertically for feeding. However, evidence supporting a rheophilic epibenthic model over an alternative rheophobic semi-infaunal model is still limited. Here we report epizoans, mostly represented by serpulids and bryozoans, encrusting thecal plates of Marsupites testudinarius from the Lägerdorf in Germany. Although a definitive interpretation whether recorded infestations occurred syn vivo or post mortem is not certain, it is remarkable that all epizoans (or their traces) are attached to the convex side (latera) of well-preserved isolated plates displaying no signs of reworking. Furthermore, a bryozoan colony crossing plate boundaries has been also found on the surface of a sub-articulated theca suggesting that it may have been colonised syn vivo. Recorded epibiotic associations, whether syn vivo or post-mortem, must have developed prior to burial of the specimens, above the surface of sea floor, and thus provide another argument against rheophobic semi-infaunal mode of life of uintacrinoids.

Structural integrity and viability of Fredericella sultana statoblasts infected with Tetracapsuloides bryosalmonae (Myxozoa) under diverse treatment conditions

Fredericella sultana is an invertebrate host of Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease in salmonids. The bryozoan produces seed-like statoblasts to facilitate its persistence during unfavourable conditions. Statoblasts from infected bryozoans can harbor T. bryosalmonae and give rise to infected bryozoan colonies when conditions improve. We aimed in the present study to evaluate the integrity and viability of T. bryosalmonae-infected statoblasts after a range of harsh treatment conditions. We tested if statoblasts could survive ingestion by either brown trout or common carp. After ingestion, the fish faeces was collected at different time points. We also tested physical stressors: statoblasts collected from infected colonies were desiccated at room temperature, or frozen with and without Bryozoan Medium C (BMC). After treatments, statoblasts were assessed for physical integrity before being incubated on BMC to allow them to hatch. After 4 weeks, hatched and unhatched statoblasts were tested by PCR for the presence of the parasite. We found that statoblasts ingested by brown trout and those frozen in BMC were completely broken. In contrast, statoblasts ingested by common carp and those subjected to dry freezing were able to survive and hatch. T. bryosalmonae was detected by PCR in both hatched and unhatched infected statoblasts, but neither from broken nor uninfected statoblasts. Our results confirmed for the first time the ability of infected statoblasts to survive passage through a fish, and freezing. These findings suggest potential pathways for both persistence and spread of T. bryosalmonae-infected statoblasts in natural aquatic systems.

Plastic responses of bryozoans to ocean acidification.

Phenotypic plasticity has the potential to allow organisms to respond rapidly to global environmental change, but the range and effectiveness of these responses are poorly understood across taxa and growth strategies. Colonial organisms might be particularly resilient to environmental stressors, as organizational modularity and successive asexual generations can allow for distinctively flexible responses in the aggregate form. We performed laboratory experiments to examine the effects of increasing dissolved carbon dioxide (CO2) (i.e. ocean acidification) on the colonial bryozoan Celleporella cornuta sampled from two source populations within a coastal upwelling region of the northern California coast. Bryozoan colonies were remarkably plastic under these CO2 treatments. Colonies raised under high CO2 grew more quickly, investing less in reproduction and producing lighter skeletons when compared with genetically identical clones raised under current surface atmosphere CO2 values. Bryozoans held under high CO2 conditions also changed the Mg/Ca ratio of skeletal calcite and increased the expression of organic coverings in new growth, which may serve as protection against acidified water. We also observed strong differences between source populations in reproductive investment and organic covering reaction norms, consistent with adaptive responses to persistent spatial variation in local oceanographic conditions. Our results demonstrate that phenotypic plasticity and energetic trade-offs can mediate biological responses to global environmental change, and highlight the broad range of strategies available to colonial organisms.

Novel brominated metabolites from Bryozoa: a functional analysis

Marine invertebrates are a promising source of novel natural products with biological activities. The phylum Bryozoa is relatively under-investigated in this context, although a number of compounds with medical potential has been discovered in recent years. Here, we report on the novel group of brominated metabolites from the bryozoan Terminoflustra membranaceatruncata, including analysis of biological activities of the tribrominated terminoflustrindole A (Cm-1) and the structures of the related dibrominated variants terminoflustrindoles B and C. Terminoflustrindole A was previously shown to have fungicidal properties. Although they vary by just one bromine group in each case from terminoflustrindole A, in this study, we report that terminoflustrindoles B and C exhibit no antimicrobial activity in the same assays. In addition to displaying antifungal activity, Terminoflustrindole A was also found to exhibit potent cytotoxic activity when tested against tumour cell lines. The gradient distribution of this compound within the bryozoan colony was demonstrated using LC-MS-analysis.

Field-based experimental acidification alters fouling community structure and reduces diversity.

Increasing levels of CO2 in the atmosphere are affecting ocean chemistry, leading to increased acidification (i.e. decreased pH) and reductions in calcium carbonate saturation state. Many species are likely to respond to acidification, but the direction and magnitude of these responses will be based on interspecific and ontogenetic variation in physiology and the relative importance of calcification. Differential responses to ocean acidification (OA) among species will likely result in important changes in community structure and diversity. To characterize the potential impacts of OA on community composition and structure, we examined the response of a marine fouling community to experimental CO2 enrichment in field-deployed flow-through mesocosm systems. Acidification significantly altered the community structure by altering the relative abundance of species and reduced community variability, resulting in more homogenous biofouling communities from one experimental tile to the next both among and within the acidified mesocosms. Mussel (Mytilus trossulus) recruitment was reduced by over 30% in the elevated CO2 treatment compared to the ambient treatment by the end of the experiment. Strong differences in mussel cover (up to 40% lower in acidified conditions) developed over the second half of the 10-week experiment. Acidification did not appear to affect the mussel growth, as average mussel sizes were similar between treatments at the end of the experiment. Hydroid (Obelia dichotoma) cover was significantly reduced in the elevated CO2 treatment after 8weeks. Conversely, the percentage cover of bryozoan colonies (Mebranipora membranacea) was higher under acidified conditions with differences becoming apparent after 6weeks. Neither recruitment nor final size of barnacles (Balanus crenatus) was affected by acidification. By the end of the experiment, diversity was 41% lower in the acidified treatment relative to ambient conditions. Overall, our findings support the general expectation that OA will simplify marine communities by acting on important ecological processes that ultimately determine the community structure and diversity.

Functional differentiation in bryozoan colonies: a proteomic analysis

Bryozoans are typical modular organisms. They consist of repetitive structural units, the zooids. Bryozoan colonies grow by zooidal budding, with the distribution pattern of the budding loci underlying the diversity of colony forms. Budding is usually restricted to the zooids at the periphery of the colony, which form a "growing edge" or local terminal growth zones. Non-budding parts of the colony can be functionally subdivided, too. In many species colonies consists of regular, often repetitive zones of feeding and non-feeding modules, associated with a periodical degeneration and regeneration of the polypide, retractile tentacle crown with a gut and the accompanying musculature. So, there is functional differentiation in bryozoan colonies but its mechanisms are unknown. Presumably, budding and/or polypide recycling in different colony parts are induced or inhibited by certain determinants of functional specialization. An effective tool of their identification is the comparison of proteomes of functionally different zones. Here we report the results of proteomic analysis of three bryozoan species from the White Sea, which have a different colony form: Flustrellidra hispida, Terminoflustra membranaceotruncata and Securiflustra securifrons. Using differential two-dimensional electrophoresis (2D-DIGE), we compared proteomes of the growing edge and the zones consisting of feeding and non-feeding zooids in these species. We estimated the overall proteome variability, revealed proteins whose relative abundance gradually changed along the proximal-distal colony axis and suggested that they might be involved in the functional differentiation of the colony.

Limits in the evolution of biological form: a theoretical morphologic perspective.

Limits in the evolution of biological form can be empirically demonstrated by using theoretical morphospace analyses, and actual analytic examples are given for univalved ammonoid shell form, bivalved brachiopod shell form and helical bryozoan colony form. Limits in the evolution of form in these animal groups can be shown to be due to functional and developmental constraints on possible evolutionary trajectories in morphospace. Future evolutionary-limit research is needed to analyse the possible existence of temporal constraint in the evolution of biological form on Earth, and in the search for the possible existence of functional alien life forms on Titan and Triton that are developmentally impossible for Earth life.

A new early brachyuran (Crustacea, Decapoda) from the Middle Jurassic of northwest France, epibionts and ecological considerations

The earliest known crabs are of Early and Middle Jurassic age; in general, they are rare. Here we describe a new species of homolodromioid from the late Bathonian of Sarthe (France), based on a single dorsal carapace, Tanidromites raboeufi n. sp. This specimen has mostly well-preserved cuticle, and shows two episkeletozoans (bryozoan colonies) on its dorsal side, which is unique amongst early brachyurans (Early and Middle Jurassic). These bryozoans are identified as juvenile colonies of the morphogenus Berenicea (sheet-like tubuluporines), typical encrusters of hard substrates. Their presence directly on the carapace crab shows that they were closely cohabitating with this early brachyuran in its palaeoenvironment. One of these colonies appears to have attached to the internal carapace surface, indicative of post-mortem settlement and growth. Colony sizes suggest a growth phase of at least several months on the sea floor, implying a certain resistance to decomposition of the crab carapace. This is of note in the light of extant homolodromioids which are known to have extremely fragile carapaces. This association demonstrates that post-mortem associations may yield palaeoecological insights into both substrate and colonising organisms.

Bioerosion structures in Crepidula (Mollusca, Gastropoda) as indicators of latitudinal palaeoenvironmental changes: Example from the marine Quaternary of Argentina

Late Quaternary marine skeletal concentrations from Argentina are rich in molluscs exhibiting a great variety of bioerosion structures. The shells of Crepidula, a characteristic gastropod occurring along more than 2000km of coastline between the Río de La Plata margin and southern Patagonia, show traces of dwelling, predation and anchoring activities made by porifers, bryozoans, annelids, other gastropods and brachiopods. Caulostrepsis, Entobia, Maeandropolydora, Iramena, Oichnus, Finichnus, Pennatichnus, Pinaceocladichnus, Podichnus and Renichnus occur on the outer shell surface. Finichnus and Oichnus are the only traces present along the entire area and the full time span considered. The most characteristic structures are produced by bryozoans, polychaetes and predatory gastropods. Traces produced by annelids and predatory gastropods occur preferentially in the central shell sector, where predators gained access to the soft parts of the prey. By contrast, encrusting or branching bryozoan colonies are widely distributed as they can attach to any sector regardless of shell features available. No strict correlation is evident between ichnodiversity and either time or latitude, but ichnodiversity is linked to local oceanographical/biotic controls. For Patagonia, with a great majority of ichnotaxa made by bryozoans, the general trend of higher bioerosion degree and ichnodiversity at higher latitudes is controlled by sea surface temperature/productivity: for the modern and the Holocene, several ichnodiversity peaks match with well-constrained conditions (substrate, salinity, thermal fronts). By contrast, this does not hold for the Pleistocene: dissimilar conditions probably prevailed, especially during the Last Interglacial (colder waters richer in nutrients).

Development of bryozoan fouling on cultivated kelp (Saccharina latissima) in Norway

Biofouling on cultivated kelp in open sea conditions is a challenge when fouling species such as the encrusting bryozoans Membranipora membranacea and Electra pilosa develop colonies that cover the surface of the kelp lamina. The bryozoan colonies make the flexible lamina brittle and susceptible to breakage and reduce the commercial value of the biomass for both human consumption and industrial applications. The development of the bryozoan fouling on cultivated Saccharina latissima in temperate coastal waters was studied at two locations in Norway from April to September. The time of settling and development of colonies of M. membranacea and E. pilosa were characterized. Sampling of bryozoan larvae abundance at the cultivation locations showed that the bryozoan colonies settled on the cultivated kelp in mid-June at both locations, followed by a rapid colony growth during late June and July. In August and September, the kelp was highly degraded by the bryozoan coverage and highly subjected to breakage of the lamina. Membranipora membranacea was the most prevailing of the two species. Although abundant at all cultivation depths, the results showed a decrease in bryozoan coverage with increasing depth. From a commercial point of view, S. latissima deployed in temperate Norwegian coastal waters in winter should be harvested in early June to avoid the negative impact from bryozoan fouling.

Differentiating Parasitism and Other Interactions in Fossilized Colonial Organisms.

Colonial species occur in a wide range of aquatic invertebrates, some having excellent fossil records, notably corals, bryozoans and graptolite hemichordates. In contrast to unitary animals, colonial animals grow by adding repetitive modules known as zooids. The ability of colonies to endure partial mortality and the typically plastic growth of benthic colonial species facilitates the formation of macrosymbiotic associations, some of which may be parasitic. However, as with unitary fossils, it is notoriously difficult to identify whether the symbioses are parasitisms (+/-) or mutualisms (+/+). Intergrowths between host colonies of stromatoporoid sponges, corals or bryozoans, and skeletal or soft-bodied symbionts are particularly common in Ordovician-Devonian shallow-water deposits. Soft-bodied symbionts in such intergrowths are represented by moulds in the host skeletons, a process of preservation termed bioclaustration. As yet, however, there is a lack of convincing data showing that any of these symbionts were parasites. By comparison with modern analogues, some fossil galls provide more convincing examples of parasitism, and the destructive effects of borings into the skeletons of benthic colonies also argue in favour of parasitism. Pelagic graptoloid hemichordates from the Early Palaeozoic occasionally contain cysts or tubes that have been attributed to parasites on the grounds that they would have adversely affected the hydrodynamics of the floating colonies. Future studies should test for parasitism by comparing the sizes of colonies hosting symbionts with those lacking symbionts.

Maternal investment in egg production: Substrate- and population-specific effects on offspring performance of the symbiotic crab Pachycheles monilifer (Anomura: Porcellanidae)

The porcelain crab Pachycheles monilifer is a non-obligate symbiotic species, living in association with marine invertebrates. In view of the importance of this relationship for the life cycle, this study investigated the reproductive performance of this crab in relation to its hosts. The crabs were collected in symbiosis with bryozoan and polychaete colonies on the southeastern coast of Brazil. Only the initial egg stages were used to estimate the fecundity and reproductive output (RO). To obtain the RO, the female and the egg-mass dry weight were used. Additionally, the genetic distance between the crab populations from the two substrates was evaluated, using partial sequences of the mitochondrial genes 16S and COI, in order to determine the intra- and interspecific genetic variation. The crabs found in bryozoans (CL, carapace length=4.6±1.3mm) were larger than those living among polychaetes (CL=4.1±1.1mm). The fecundity and RO of crabs inhabiting the bryozoans increased with carapace length, but in the females inhabiting the polychaetes only the fecundity was correlated with the female body size. In the polychaete colonies, the space available for the symbiotic porcelain crab is more restricted since it is a closed habitat, which could limit the size of its inquilines and consequently the reproductive fitness, whereas the females associated with polychaete colonies have a lower fecundity and RO. Our molecular results confirmed the existence of low genetic divergence and of potential gene flow between the two populations. Taken together, this information suggests that the differences in reproductive traits of these crab populations were due to the difference in hosts.

Revising and refining the bryozoan zs-MART seasonality proxy

The zs-MART (zooid-size derived mean annual range of temperature) seasonality proxy is based on temperature-related variation in the sizes of zooids found in colonies of cheilostome bryozoans. It has been used in a number of studies for inferring palaeoseasonality. Here we present a revised version of the equation for the zs-MART proxy based on an appropriate regression analysis and an estimate of the error associated with predicted values. We use this improved version to recalculate data used in studies that have employed the zs-MART proxy and evaluate their conclusions in light of the revised estimates for seasonal regimes. In order to investigate trans-colony zooid-size profiles in zooid size, length and width, 1195 zooids from 40 transects through 19 fossil and Recent specimens of the malacostegine cheilostome bryozoan Acanthodesia were measured using a stereomicroscope with eyepiece graticule. The position of zooids within bifurcating rows of Acanthodesia colonies is found to influence zooid size, and this exemplifies potential problems for studies based on zooid-size transects and random sampling of zooids. Our demonstration that oscillatory signals in zooid size, possibly attributable to seasonal temperature regimes, can be detected whilst accounting for other sources of variation confirms that a more sophisticated zs-MART proxy may prove useful for constraining parameters in ocean models addressing questions about past climate. However, such a proxy will require more parameters than originally described along with larger raw datasets.

The Earliest Giant Osprioneides Borings from the Sandbian (Late Ordovician) of Estonia

The earliest Osprioneides kampto borings were found in bryozoan colonies of Sandbian age from northern Estonia (Baltica). The Ordovician was a time of great increase in the quantities of hard substrate removed by single trace makers. Increased predation pressure was most likely the driving force behind the infaunalization of larger invertebrates such as the Osprioneides trace makers in the Ordovician. It is possible that the Osprioneides borer originated in Baltica or in other paleocontinents outside of North America.

Vertical transmission ofTetracapsuloides bryosalmonae(Myxozoa), the causative agent of salmonid proliferative kidney disease

The freshwater bryozoan, Fredericella sultana, is the main primary host of the myxozoan endoparasite, Tetracapsuloides bryosalmonae which causes proliferative kidney disease (PKD) of salmonid fish. Because spores that develop in bryozoan colonies are infectious to fish, bryozoans represent the ultimate source of PKD. Bryozoans produce numerous seed-like dormant stages called statoblasts that enable persistence during unfavourable conditions and achieve long-distance dispersal. The possibility that T. bryosalmonae may undergo vertical transmission via infection of statoblasts has been the subject of much speculation since this is observed in close relatives. This study provides the first evidence that such vertical transmission of T. bryosalmonae is extensive by examining the proportions of infected statoblasts in populations of F. sultana on two different rivers systems and confirms its effectiveness by demonstrating transmission from material derived from infected statoblasts to fish hosts. Vertical transmission in statoblasts is likely to play an important role in the infection dynamics of both bryozoan and fish hosts and may substantially contribute to the widespread distribution of PKD.

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Here we explore how fossil cheilostome bryozoans can demonstrate El Nino/La Nina-Southern Oscillation (ENSO) variability in ancient tropical environments of the tropical eastern Pacific and southwestern caribbean when used collectively to produce frequency distributions of estimates of mean annual ranges in temperature (MARTs) via zooid-size MART analysis (zs-MART). The approach is based on linking variation in the sizes of constituent zooids in bryozoan colonies with the temperature regimes in which the zooids developed. The shapes of frequency distributions of zs-MART estimates from modern environments are consistent with known upwelling and non-upwelling environments and ENSO variability. Data from fossil colonies provide evidence that ENSO variability characterized caribbean environments in what is now present-day Panama during the miocene and Pliocene (thus supporting neither a permanent El nino nor a permanent la nina in the Pliocene), but not the Pleistocene after the isthmus of Panama closed. Western atlantic data provide further evidence for ENSO variability in the Pliocene of florida but not virginia. Our study shows the potential of bryozoan assemblages to infer variation in seasonal regimes thus encouraging the further development of this proxy for inferring ENSO variability.