... Macroalgae of Puerto Morolos Reef System, Mexican Caribbean Ligia Collado-Vides1, Ileana Orte... more ... Macroalgae of Puerto Morolos Reef System, Mexican Caribbean Ligia Collado-Vides1, Ileana Ortegón-Aznar1, Abel Senties Granados2, Lourdes Comba-Barrera1, y ... mamillosa (Montagne)Weber-Van Bosse X X С lanuginosa J. Agardh L X X X C, mexicana Sonder ex Kützing ...
Iconic ecosystems like the Florida Coastal Everglades can serve as sentinels of environmental cha... more Iconic ecosystems like the Florida Coastal Everglades can serve as sentinels of environmental change from local to global scales. This characteristic can help inform general theory about how and why ecosystems transform, particularly if distinctive ecosystem properties are studied over long time scales and compared to those of similar ecosystems elsewhere. Here we review the ways in which long‐term, comparative, international research has provided perspectives on iconic features of the Everglades that have, in turn, informed general ecosystem paradigms. Studies in other comparable wetlands from the Caribbean to Australia have shed light on distinctive and puzzling aspects such as the “upside‐down estuary” and “productivity paradox” for which the Everglades is known. These studies suggest that coastal wetlands on carbonate (karstic) platforms have: (1) hydrological and biogeochemical properties that reflect “hidden” groundwater sources of water and nutrients, (2) very productive, mat...
Tropical coastal marine ecosystems including mangroves, seagrass beds and coral reef communities ... more Tropical coastal marine ecosystems including mangroves, seagrass beds and coral reef communities are undergoing intense degradation in response to natural and human disturbances, therefore, understanding the causes and mechanisms present challenges for scientist and managers. In order to protect our marine resources, determining the effects of nutrient loads on these coastal systems has become a key management goal. Data from monitoring programs were used to detect trends of macroalgae abundances and develop correlations with nutrient availability, as well as forecast potential responses of the communities monitored. Using eight years of data (1996e2003) from complementary but independent monitoring programs in seagrass beds and water quality of the Florida Keys National Marine Sanctuary (FKNMS), we: (1) described the distribution and abundance of macroalgae groups; (2) analyzed the status and spatiotemporal trends of macroalgae groups; and (3) explored the connection between water quality and the macroalgae distribution in the FKNMS. In the seagrass beds of the FKNMS calcareous green algae were the dominant macroalgae group followed by the red group; brown and calcareous red algae were present but in lower abundance. Spatiotemporal patterns of the macroalgae groups were analyzed with a non-linear regression model of the abundance data. For the period of record, all macroalgae groups increased in abundance (Ab i) at most sites, with calcareous green algae increasing the most. Calcareous green algae and red algae exhibited seasonal pattern with peak abundances (F i) mainly in summer for calcareous green and mainly in winter for red. Macroalgae Ab i and long-term trend (m i) were correlated in a distinctive way with water quality parameters. Both the Ab i and m i of calcareous green algae had positive correlations with NO 3 À , NO 2 À , total nitrogen (TN) and total organic carbon (TOC). Red algae Ab i had a positive correlation with NO 2 À , TN, total phosphorus and TOC, and the m i in red algae was positively correlated with N:P. In contrast brown and calcareous red algae Ab i had negative correlations with N:P. These results suggest that calcareous green algae and red algae are responding mainly to increases in N availability, a process that is happening in inshore sites. A combination of spatially variable factors such as local current patterns, nutrient sources, and habitat characteristics result in a complex array of the macroalgae community in the seagrass beds of the FKNMS.
ABSTRACT Nearshore benthic habitats of Biscayne Bay fit the prediction of communities at risk due... more ABSTRACT Nearshore benthic habitats of Biscayne Bay fit the prediction of communities at risk due to their location adjacent to a large metropolitan center (Miami) and being influenced by changes in hydrology through the activities of the Comprehensive Everglades Restoration Plan (CERP). We examine whether the proposed programmatic expansion of mesohaline salinities through the introduction of additional fresh water would result in: (1) increases in seagrass cover; (2) expansion in the distribution and cover of Halodule; and (3) a reduction in the dominance of Thalassia, as hypothesized by CERP. Seagrasses were present at 98 % of sites where they covered 23 % of the bottom. Salinity was the only physical variable with a significant relationship to the occurrence of all SAV taxa. Occurrence of Thalassia, Halimeda, and Penicillus increased significantly with increasing salinity, but Halodule, Syringodium, Laurencia, Udotea, Batophora, Caulerpa, and Acetabularia showed a significant negative relationship with salinity. Mesohaline habitats had higher cover of seagrass and Halodule, and reduced dominance by Thalassia. Thus, we expect increases in the extent of mesohaline habitats to achieve the established CERP goals. We also examined the nutrient content of seagrass blades to evaluate whether: (1) nutrient availability is higher in areas close to canal discharges; and (2) tissue nutrient levels are related to seagrass abundance. The low abundance of Thalassia along the shoreline is not only due to its exclusion from low-salinity environments but also by higher nutrient availability that favors Halodule. Percent N and P, and N:P ratios in seagrass tissue suggest that Biscayne Bay receives high N inputs and is P limited. Thus, increased P availability may facilitate an expansion of Halodule. The data presented suggest that increased mesohaline salinities will increase seagrass abundance and support co-dominance by Halodule and Thalassia as hypothesized, but raise concerns that current high N availability and increases in P may prompt a shift away from seagrass dominated to algal-dominated communities under scenarios of enhanced fresh water inputs.
Population modeling based on species’ demography makes it possible to predict the pace of an inva... more Population modeling based on species’ demography makes it possible to predict the pace of an invasion and evaluate the likelihood of success of different control strategies. We modeled the initial (density-independent) rate of increase of Caulerpa taxifolia (Vahl) C. Agardh (aquarium strain), a green alga that has markedly altered marine communities where it has invaded in the Mediterranean Sea. Parameter values for patch growth (from stolon extension) and reproduction (by asexual fragmentation and reattachment) were gleaned from published studies. Only the most conservative model, invoking field growth rates and low levels of fragment reattachment (2.5 m−2 of existing patch each summer), closely matched observed increases (4–14 × annually). The most effective times for control (greatest reduction in rate of increase) were removal of established patches before summer and removal of fragments after summer. These times correspond to just before maximum growth and just after maximum reproduction, respectively. Only a combined strategy, incorporating 99% removal of all fragments and annual removal of 99% of established patches, was predicted to eliminate C. taxifolia entirely (λ < 1). This level of effort is only likely to be possible during the first few years of an invasion, arguing strongly for careful monitoring and rapid response to potential high-impact invaders.
The genus Blennothrix belongs to the family Oscillatoriaceae (subfamily Oscillatorioideae), diffe... more The genus Blennothrix belongs to the family Oscillatoriaceae (subfamily Oscillatorioideae), differing from others in the subfamily by the presence of several trichomes in a sheath. Freshwater members of Blennothrix have been recently divided into eight species (Komárek 1998), with the taxon B. ganeshii Watanabe et Komárek reported from three sites in two tropical basins of the central region of Mexico. However, information on anatomical (vegetative and reproductive) characters and environmental distribution is scarce and species determination is uncertain. This study analyses the anatomical structure of Blennothrix populations distributed in different sites along the central tropical region of Mexico in order to determine the taxonomic status of the studied populations. Eight populations were sampled, with concurrent environmental data recorded. Morphological characters previously considered to be of taxonomic importance, as well as complementary features such as algal mat length, filament diameter, trichome width, length of cells, and thickness and shape of the sheath were measured in several filaments of each sample. Our results showed that all the observed populations in the central region of Mexico fit within the circumscription of B. ganeshii . However, two important morphological features were observed in all populations. First, branches were rarely present and varying in frequency from 1 to 3 trichomes per filament. Second, the presence of a transverse lamellation due to constriction in the longitudinal axis of the sheath was observed. Some morphological characters described for this species were extended.
The great morphological variation in the apical region of main axes and branches in species of Ge... more The great morphological variation in the apical region of main axes and branches in species of Gelidium and Pterocladia suggests different patterns of growth. Those patterns have been reconstructed from the ontogenetic sequence of morphological stages and regeneration of the apex. Using the architectural approach, models for four species of Gelidium from the Pacific coast of central Chile and the Pacific coast of Mexico's tropical region, were constructed based on the following criteria: growth pattern, specialization of laterals, symmetry, apical dominance and rhythm of apical and lateral growth. Those models allow for a formal evaluation of apical differences between species.
Morphological and photosynthetic performance were analyzed in species of the genus Caulerpa from ... more Morphological and photosynthetic performance were analyzed in species of the genus Caulerpa from an exposed coral reef and a sheltered reef lagoon. Morphological characters, such as distance between modules, number of modules, stolon branches and rhizoid clusters per centimeter of stolon, indicated a uniformity among species within a specific habitat. “Guerilla,” or diffusive, growth forms were characteristic for lagoon species and “phalanx,” or compact, growth forms for reef species. Differences in photosynthesis were found between Caulerpa species. Sun-tolerant species were found on the reef, and both sun- and shade-tolerant species were present in the lagoon. In the lagoon, shade-tolerant species, such as C. lanuginosa J. Agardh, were found growing in the understory, and sun-tolerant species, such as C. paspaloides (Bory) Greville, formed the canopy. C. cupressoides (West in Vahl) C. Agardh was the only species found in both environments; it showed higher photosynthetic rates and a compressed morphology when growing on the reef and lower photosynthetic rates and expanded morphology for lagoonal ramets. These results suggest that C. cupressoides possesses a broad phenotypic ability to acclimate to lagoonal and reef settings in comparison to other Caulerpa species, enhancing its ecological success in this particular system.
The study of the ecological and evolutionary consequences of clonal growth in vascular plants has... more The study of the ecological and evolutionary consequences of clonal growth in vascular plants has been widely addressed; however, marine macroalgae, which are interesting modular organisms that combine ‘simple’ morphologies and complex life cycles, have been almost ignored. This paper presents a review and analysis of the ecological and evolutionary consequences of clonality in marine macroalgae, including three main subjects: (1) modular construction (modules and ramets); (2) life cycle and evolutionary perspectives, and (3) ecological perspectives of clonality in marine macroalge. The biological emergent attributes of clonality are present in marine macroalgae e.g. high longevity of the genet by the continual renewal of modules, and variable morphological plasticity of ramets and modules in relation to environmental conditions. However, experimental work is still needed to solve questions such as the effect of crowding on survival rates and use of resources, as well as its effect on sexual or asexual patterns of reproduction. I expect that the study of the evolutionary consequences of the combined presence of alternation of generations and clonal growth in marine macroalgae will make important contributions to clonal plant theory.
... 25 January 1999 Biomechanical properties of Udotea (Halimedales, Chlorophyta) in a Mexican re... more ... 25 January 1999 Biomechanical properties of Udotea (Halimedales, Chlorophyta) in a Mexican reef lagoon L. COLLADO-VlDESI, RE DEWREEDE'* AND KLD MILLIGAN' I Lab. ... L. COLLADO-VI DES. RE DEWREEDE AND KLD MILLIGAN. 1998. ...
The coastal bays of South Florida are located downstream of the Florida Everglades, where a compr... more The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan will strongly impact the hydrology of the region. Submerged aquatic vegetation communities are common components of benthic habitats of Biscayne Bay, and will be directly affected by changes in water quality. This study explores community structure, spatio-temporal dynamics, and tissue nutrient content of macroalgae to detect and describe relationships with water quality. The macroalgal community responded to strong variability in salinity; three distinctive macroalgal assemblages were correlated with salinity as follows: (1) low-salinity, dominated by Chara hornemannii and a mix of filamentous algae; (2) brackish, dominated by Penicillus capitatus, Batophora oerstedii, and Acetabularia schenckii; and (3) marine, dominated by Halimeda incrassata and Anadyomene stellata. Tissue-nutrient content was variable in space and time but tissues at all sites had high nitrogen and N:P values, demonstrating high nitrogen availability and phosphorus limitation in this region. This study clearly shows that distinct macroalgal assemblages are related to specific water quality conditions, and that macroalgal assemblages can be used as community-level indicators within an adaptive management framework to evaluate performance and restoration impacts in Biscayne Bay and other regions where both freshwater and nutrient inputs are modified by water management decisions.
Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were s... more Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances.
The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Key... more The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Keys National Marine Sanctuary (FKNMS) for a period of 7 years as part of a sea grass monitoring program. To evaluate the validity of using the functional-form group approach, we designed a sampling method that included the functional-form group and the component genera. This strategy enabled us to analyze the spatiotemporal patterns in the abundance of calcareous green algae as a group and to describe synchronous behavior among its genera through the application of a nonlinear regression model to both categories of data. Spatial analyses revealed that, in general, all genera displayed long-term trends of increasing abundance at most sites; however, at some sites the long-term trends for genera opposed one another. Strong synchrony in the timing of seasonal changes was found among all genera, possibly reflecting similar reproductive and seasonal growth pattern, but the variability in the magnitude of seasonal changes was very high among genera and sites. No spatial patterns were found in long-term or seasonal changes; the only significant relation detected was for slope, with sites closer to land showing higher values, suggesting that some factors associated with land proximity are affecting this increase. We conclude that the abundances of genera behaved differently from the functional-form group, indicating that the use of the functional-form group approach may be unsuitable to detect changes in sea grass community structure in the FKNMS at the existing temporal and spatial scale of the monitoring program.
Green macroalgal blooms are becoming a common problem in coastal waters and estuaries. This study... more Green macroalgal blooms are becoming a common problem in coastal waters and estuaries. This study describes the first occurrence of a persistent macroalgal bloom of the genus Anadyomene J.V. Lamouroux (Cladophorales, Anadyomenaceae) in the world and particularly in Biscayne Bay, FL, USA. The morphological-based identification of species was verified by a molecular analysis that sequenced the variable C1D2 region of the large subunit (LSU) nrDNA. Results indicate that the bloom is composed of two species: Anadyomene stellata, reported previously for Florida, and a diminutive perforate undetermined species, Anadyomene sp., potentially representing an introduction in the area. General surveys in Biscayne Bay based on a stratified random design, to visually estimate the percent cover of submerged aquatic vegetation, date from 1999; using the same methods recent intensive surveys of the detected bloom were conducted once a year from 2010 to 2012. Results show that the Anadyomene bloom densities have persisted since 2005 through 2012 covering an area of approximately 60 km 2 of seagrass habitats. The spatial distribution of the bloom is restricted to the central inshore section of the Bay, an area affected by canals and groundwater discharges. The persistent 75% cover reported for several sites, has caused significant negative impacts to seagrass beds. This bloom occurring adjacent to metropolitan Miami, adds to the world trend of increasing green macroalgal blooms occurring at enriched coastal waters.
... Macroalgae of Puerto Morolos Reef System, Mexican Caribbean Ligia Collado-Vides1, Ileana Orte... more ... Macroalgae of Puerto Morolos Reef System, Mexican Caribbean Ligia Collado-Vides1, Ileana Ortegón-Aznar1, Abel Senties Granados2, Lourdes Comba-Barrera1, y ... mamillosa (Montagne)Weber-Van Bosse X X С lanuginosa J. Agardh L X X X C, mexicana Sonder ex Kützing ...
Iconic ecosystems like the Florida Coastal Everglades can serve as sentinels of environmental cha... more Iconic ecosystems like the Florida Coastal Everglades can serve as sentinels of environmental change from local to global scales. This characteristic can help inform general theory about how and why ecosystems transform, particularly if distinctive ecosystem properties are studied over long time scales and compared to those of similar ecosystems elsewhere. Here we review the ways in which long‐term, comparative, international research has provided perspectives on iconic features of the Everglades that have, in turn, informed general ecosystem paradigms. Studies in other comparable wetlands from the Caribbean to Australia have shed light on distinctive and puzzling aspects such as the “upside‐down estuary” and “productivity paradox” for which the Everglades is known. These studies suggest that coastal wetlands on carbonate (karstic) platforms have: (1) hydrological and biogeochemical properties that reflect “hidden” groundwater sources of water and nutrients, (2) very productive, mat...
Tropical coastal marine ecosystems including mangroves, seagrass beds and coral reef communities ... more Tropical coastal marine ecosystems including mangroves, seagrass beds and coral reef communities are undergoing intense degradation in response to natural and human disturbances, therefore, understanding the causes and mechanisms present challenges for scientist and managers. In order to protect our marine resources, determining the effects of nutrient loads on these coastal systems has become a key management goal. Data from monitoring programs were used to detect trends of macroalgae abundances and develop correlations with nutrient availability, as well as forecast potential responses of the communities monitored. Using eight years of data (1996e2003) from complementary but independent monitoring programs in seagrass beds and water quality of the Florida Keys National Marine Sanctuary (FKNMS), we: (1) described the distribution and abundance of macroalgae groups; (2) analyzed the status and spatiotemporal trends of macroalgae groups; and (3) explored the connection between water quality and the macroalgae distribution in the FKNMS. In the seagrass beds of the FKNMS calcareous green algae were the dominant macroalgae group followed by the red group; brown and calcareous red algae were present but in lower abundance. Spatiotemporal patterns of the macroalgae groups were analyzed with a non-linear regression model of the abundance data. For the period of record, all macroalgae groups increased in abundance (Ab i) at most sites, with calcareous green algae increasing the most. Calcareous green algae and red algae exhibited seasonal pattern with peak abundances (F i) mainly in summer for calcareous green and mainly in winter for red. Macroalgae Ab i and long-term trend (m i) were correlated in a distinctive way with water quality parameters. Both the Ab i and m i of calcareous green algae had positive correlations with NO 3 À , NO 2 À , total nitrogen (TN) and total organic carbon (TOC). Red algae Ab i had a positive correlation with NO 2 À , TN, total phosphorus and TOC, and the m i in red algae was positively correlated with N:P. In contrast brown and calcareous red algae Ab i had negative correlations with N:P. These results suggest that calcareous green algae and red algae are responding mainly to increases in N availability, a process that is happening in inshore sites. A combination of spatially variable factors such as local current patterns, nutrient sources, and habitat characteristics result in a complex array of the macroalgae community in the seagrass beds of the FKNMS.
ABSTRACT Nearshore benthic habitats of Biscayne Bay fit the prediction of communities at risk due... more ABSTRACT Nearshore benthic habitats of Biscayne Bay fit the prediction of communities at risk due to their location adjacent to a large metropolitan center (Miami) and being influenced by changes in hydrology through the activities of the Comprehensive Everglades Restoration Plan (CERP). We examine whether the proposed programmatic expansion of mesohaline salinities through the introduction of additional fresh water would result in: (1) increases in seagrass cover; (2) expansion in the distribution and cover of Halodule; and (3) a reduction in the dominance of Thalassia, as hypothesized by CERP. Seagrasses were present at 98 % of sites where they covered 23 % of the bottom. Salinity was the only physical variable with a significant relationship to the occurrence of all SAV taxa. Occurrence of Thalassia, Halimeda, and Penicillus increased significantly with increasing salinity, but Halodule, Syringodium, Laurencia, Udotea, Batophora, Caulerpa, and Acetabularia showed a significant negative relationship with salinity. Mesohaline habitats had higher cover of seagrass and Halodule, and reduced dominance by Thalassia. Thus, we expect increases in the extent of mesohaline habitats to achieve the established CERP goals. We also examined the nutrient content of seagrass blades to evaluate whether: (1) nutrient availability is higher in areas close to canal discharges; and (2) tissue nutrient levels are related to seagrass abundance. The low abundance of Thalassia along the shoreline is not only due to its exclusion from low-salinity environments but also by higher nutrient availability that favors Halodule. Percent N and P, and N:P ratios in seagrass tissue suggest that Biscayne Bay receives high N inputs and is P limited. Thus, increased P availability may facilitate an expansion of Halodule. The data presented suggest that increased mesohaline salinities will increase seagrass abundance and support co-dominance by Halodule and Thalassia as hypothesized, but raise concerns that current high N availability and increases in P may prompt a shift away from seagrass dominated to algal-dominated communities under scenarios of enhanced fresh water inputs.
Population modeling based on species’ demography makes it possible to predict the pace of an inva... more Population modeling based on species’ demography makes it possible to predict the pace of an invasion and evaluate the likelihood of success of different control strategies. We modeled the initial (density-independent) rate of increase of Caulerpa taxifolia (Vahl) C. Agardh (aquarium strain), a green alga that has markedly altered marine communities where it has invaded in the Mediterranean Sea. Parameter values for patch growth (from stolon extension) and reproduction (by asexual fragmentation and reattachment) were gleaned from published studies. Only the most conservative model, invoking field growth rates and low levels of fragment reattachment (2.5 m−2 of existing patch each summer), closely matched observed increases (4–14 × annually). The most effective times for control (greatest reduction in rate of increase) were removal of established patches before summer and removal of fragments after summer. These times correspond to just before maximum growth and just after maximum reproduction, respectively. Only a combined strategy, incorporating 99% removal of all fragments and annual removal of 99% of established patches, was predicted to eliminate C. taxifolia entirely (λ < 1). This level of effort is only likely to be possible during the first few years of an invasion, arguing strongly for careful monitoring and rapid response to potential high-impact invaders.
The genus Blennothrix belongs to the family Oscillatoriaceae (subfamily Oscillatorioideae), diffe... more The genus Blennothrix belongs to the family Oscillatoriaceae (subfamily Oscillatorioideae), differing from others in the subfamily by the presence of several trichomes in a sheath. Freshwater members of Blennothrix have been recently divided into eight species (Komárek 1998), with the taxon B. ganeshii Watanabe et Komárek reported from three sites in two tropical basins of the central region of Mexico. However, information on anatomical (vegetative and reproductive) characters and environmental distribution is scarce and species determination is uncertain. This study analyses the anatomical structure of Blennothrix populations distributed in different sites along the central tropical region of Mexico in order to determine the taxonomic status of the studied populations. Eight populations were sampled, with concurrent environmental data recorded. Morphological characters previously considered to be of taxonomic importance, as well as complementary features such as algal mat length, filament diameter, trichome width, length of cells, and thickness and shape of the sheath were measured in several filaments of each sample. Our results showed that all the observed populations in the central region of Mexico fit within the circumscription of B. ganeshii . However, two important morphological features were observed in all populations. First, branches were rarely present and varying in frequency from 1 to 3 trichomes per filament. Second, the presence of a transverse lamellation due to constriction in the longitudinal axis of the sheath was observed. Some morphological characters described for this species were extended.
The great morphological variation in the apical region of main axes and branches in species of Ge... more The great morphological variation in the apical region of main axes and branches in species of Gelidium and Pterocladia suggests different patterns of growth. Those patterns have been reconstructed from the ontogenetic sequence of morphological stages and regeneration of the apex. Using the architectural approach, models for four species of Gelidium from the Pacific coast of central Chile and the Pacific coast of Mexico's tropical region, were constructed based on the following criteria: growth pattern, specialization of laterals, symmetry, apical dominance and rhythm of apical and lateral growth. Those models allow for a formal evaluation of apical differences between species.
Morphological and photosynthetic performance were analyzed in species of the genus Caulerpa from ... more Morphological and photosynthetic performance were analyzed in species of the genus Caulerpa from an exposed coral reef and a sheltered reef lagoon. Morphological characters, such as distance between modules, number of modules, stolon branches and rhizoid clusters per centimeter of stolon, indicated a uniformity among species within a specific habitat. “Guerilla,” or diffusive, growth forms were characteristic for lagoon species and “phalanx,” or compact, growth forms for reef species. Differences in photosynthesis were found between Caulerpa species. Sun-tolerant species were found on the reef, and both sun- and shade-tolerant species were present in the lagoon. In the lagoon, shade-tolerant species, such as C. lanuginosa J. Agardh, were found growing in the understory, and sun-tolerant species, such as C. paspaloides (Bory) Greville, formed the canopy. C. cupressoides (West in Vahl) C. Agardh was the only species found in both environments; it showed higher photosynthetic rates and a compressed morphology when growing on the reef and lower photosynthetic rates and expanded morphology for lagoonal ramets. These results suggest that C. cupressoides possesses a broad phenotypic ability to acclimate to lagoonal and reef settings in comparison to other Caulerpa species, enhancing its ecological success in this particular system.
The study of the ecological and evolutionary consequences of clonal growth in vascular plants has... more The study of the ecological and evolutionary consequences of clonal growth in vascular plants has been widely addressed; however, marine macroalgae, which are interesting modular organisms that combine ‘simple’ morphologies and complex life cycles, have been almost ignored. This paper presents a review and analysis of the ecological and evolutionary consequences of clonality in marine macroalgae, including three main subjects: (1) modular construction (modules and ramets); (2) life cycle and evolutionary perspectives, and (3) ecological perspectives of clonality in marine macroalge. The biological emergent attributes of clonality are present in marine macroalgae e.g. high longevity of the genet by the continual renewal of modules, and variable morphological plasticity of ramets and modules in relation to environmental conditions. However, experimental work is still needed to solve questions such as the effect of crowding on survival rates and use of resources, as well as its effect on sexual or asexual patterns of reproduction. I expect that the study of the evolutionary consequences of the combined presence of alternation of generations and clonal growth in marine macroalgae will make important contributions to clonal plant theory.
... 25 January 1999 Biomechanical properties of Udotea (Halimedales, Chlorophyta) in a Mexican re... more ... 25 January 1999 Biomechanical properties of Udotea (Halimedales, Chlorophyta) in a Mexican reef lagoon L. COLLADO-VlDESI, RE DEWREEDE'* AND KLD MILLIGAN' I Lab. ... L. COLLADO-VI DES. RE DEWREEDE AND KLD MILLIGAN. 1998. ...
The coastal bays of South Florida are located downstream of the Florida Everglades, where a compr... more The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan will strongly impact the hydrology of the region. Submerged aquatic vegetation communities are common components of benthic habitats of Biscayne Bay, and will be directly affected by changes in water quality. This study explores community structure, spatio-temporal dynamics, and tissue nutrient content of macroalgae to detect and describe relationships with water quality. The macroalgal community responded to strong variability in salinity; three distinctive macroalgal assemblages were correlated with salinity as follows: (1) low-salinity, dominated by Chara hornemannii and a mix of filamentous algae; (2) brackish, dominated by Penicillus capitatus, Batophora oerstedii, and Acetabularia schenckii; and (3) marine, dominated by Halimeda incrassata and Anadyomene stellata. Tissue-nutrient content was variable in space and time but tissues at all sites had high nitrogen and N:P values, demonstrating high nitrogen availability and phosphorus limitation in this region. This study clearly shows that distinct macroalgal assemblages are related to specific water quality conditions, and that macroalgal assemblages can be used as community-level indicators within an adaptive management framework to evaluate performance and restoration impacts in Biscayne Bay and other regions where both freshwater and nutrient inputs are modified by water management decisions.
Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were s... more Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances.
The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Key... more The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Keys National Marine Sanctuary (FKNMS) for a period of 7 years as part of a sea grass monitoring program. To evaluate the validity of using the functional-form group approach, we designed a sampling method that included the functional-form group and the component genera. This strategy enabled us to analyze the spatiotemporal patterns in the abundance of calcareous green algae as a group and to describe synchronous behavior among its genera through the application of a nonlinear regression model to both categories of data. Spatial analyses revealed that, in general, all genera displayed long-term trends of increasing abundance at most sites; however, at some sites the long-term trends for genera opposed one another. Strong synchrony in the timing of seasonal changes was found among all genera, possibly reflecting similar reproductive and seasonal growth pattern, but the variability in the magnitude of seasonal changes was very high among genera and sites. No spatial patterns were found in long-term or seasonal changes; the only significant relation detected was for slope, with sites closer to land showing higher values, suggesting that some factors associated with land proximity are affecting this increase. We conclude that the abundances of genera behaved differently from the functional-form group, indicating that the use of the functional-form group approach may be unsuitable to detect changes in sea grass community structure in the FKNMS at the existing temporal and spatial scale of the monitoring program.
Green macroalgal blooms are becoming a common problem in coastal waters and estuaries. This study... more Green macroalgal blooms are becoming a common problem in coastal waters and estuaries. This study describes the first occurrence of a persistent macroalgal bloom of the genus Anadyomene J.V. Lamouroux (Cladophorales, Anadyomenaceae) in the world and particularly in Biscayne Bay, FL, USA. The morphological-based identification of species was verified by a molecular analysis that sequenced the variable C1D2 region of the large subunit (LSU) nrDNA. Results indicate that the bloom is composed of two species: Anadyomene stellata, reported previously for Florida, and a diminutive perforate undetermined species, Anadyomene sp., potentially representing an introduction in the area. General surveys in Biscayne Bay based on a stratified random design, to visually estimate the percent cover of submerged aquatic vegetation, date from 1999; using the same methods recent intensive surveys of the detected bloom were conducted once a year from 2010 to 2012. Results show that the Anadyomene bloom densities have persisted since 2005 through 2012 covering an area of approximately 60 km 2 of seagrass habitats. The spatial distribution of the bloom is restricted to the central inshore section of the Bay, an area affected by canals and groundwater discharges. The persistent 75% cover reported for several sites, has caused significant negative impacts to seagrass beds. This bloom occurring adjacent to metropolitan Miami, adds to the world trend of increasing green macroalgal blooms occurring at enriched coastal waters.
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Papers by Ligia Collado