Interactions between Sponges and the Water Column: Nutrient Utilisation and Feeding by New Zealand Subtidal Sponges

Sponges are an important component of New Zealand subtidal communities and play many key functional roles in marine ecosystems, including competition for space, facilitating primary production, nutrient cycling, bioerosion, and interactions with the water column. Sponges are involved in the bidirectional movement of detritus, nutrients, micro-organisms and planktonic particles both to and from the benthos to the pelagic ecosystem, thereby affecting pelagic processes. As suspension-feeders, sponges are capable of filtering large volumes of water, and they depend on food that is suspended in the water column, meaning that their interaction with the water column is likely to be very important. The main goal of my research was to investigate the interactions between sponges and the water column and how this varies in relation to sponge characteristics, nutrient fluxes, seasonality and food supply. I studied the diet composition of 10 sponge species that are abundant and widely distributed along the south coast of Wellington, New Zealand. I found that the diet of the sponge species analysed comprised three types of picoplanktonic organisms: heterotrophic bacteria, Prochlorococcus, and Synechococcus. These micro-organisms (picoplankton) that sponges feed on are vital for benthic food webs because they are involved in the transformation and cycling process of dissolved inorganic nutrients before they become available to other marine organisms. The results from this thesis demonstrated that different sponge species have different retention efficiencies for different types of picoplankton and I propose that this suggests intra-phyletic food particle niche partitioning among sponges. While these findings support the partitioning of food resources between different co-existing sponge species, they also suggest that partitioning may not be essential for co-existence, as some species had similar retention efficiencies implying an overlap in resource use. By measuring rates of carbon assimilation in the form of planktonic food particles, combined with data on a number of characteristics of the sponge species analysed, I found that sponge assemblages play a key role in the transfer of energy from the water column to the benthos. The results from this thesis indicate that there is a wide range of food concentrations in the rocky reefs where the study species are living, over which retention rate, nutrient utilisation and carbon consumption varied temporally. This emphasises the importance of understanding temporal variation in productivity, and suggests that such variations are likely to have important implications for suspension-feeders. By integrating the feeding results with estimations of oxygen consumption rates, and the amount of carbon obtained from the different micro-organisms found in the water column, preliminary carbon budgets were created. These budgets were used to quantify the capacity of carbon obtained via heterotrophic suspension-feeding to support sponge metabolism, as well as infer the potential for this carbon to support other processes such as sponge growth and reproduction. Overall, this project was the first to consider the functional roles of sponges in New Zealand marine ecosystems and provided useful information on their ecological and biological importance. The large amounts of carbon that sponges transfer from the water column to the benthos, in conjunction with the other findings of my thesis, increase our understanding of the ecology of temperate sponges

Estimates of Particulate Organic Carbon Flowing from the Pelagic Environment to the Benthos through Sponge Assemblages

Despite the importance of trophic interactions between organisms, and the relationship between primary production and benthic diversity, there have been few studies that have quantified the carbon flow from pelagic to benthic environments as a result of the assemblage level activity of suspension-feeding organisms. In this study, we examine the feeding activity of seven common sponge species from the Taputeranga marine reserve on the south coast of Wellington in New Zealand. We analysed the diet composition, feeding efficiency, pumping rates, and the number of food particles (specifically picoplanktonic prokaryotic cells) retained by sponges. We used this information, combined with abundance estimates of the sponges and estimations of the total amount of food available to sponges in a known volume of water (89,821 m3), to estimate: (1) particulate organic carbon (POC) fluxes through sponges as a result of their suspension-feeding activities on picoplankton; and (2) the proportion of the available POC from picoplankton that sponges consume. The most POC acquired by the sponges was from non-photosynthetic bacterial cells (ranging from 0.09 to 4.69 g C d−1 with varying sponge percentage cover from 0.5 to 5%), followed by Prochlorococcus (0.07 to 3.47 g C d−1) and then Synechococcus (0.05 to 2.34 g C d−1) cells. Depending on sponge abundance, the amount of POC that sponges consumed as a proportion of the total POC available was 0.2–12.1% for Bac, 0.4–21.3% for Prochlo, and 0.3–15.8% for Synecho. The flux of POC for the whole sponge assemblage, based on the consumption of prokaryotic picoplankton, ranged from 0.07–3.50 g C m2 d−1. This study is the first to estimate the contribution of a sponge assemblage (rather than focusing on individual sponge species) to POC flow from three groups of picoplankton in a temperate rocky reef through the feeding activity of sponges and demonstrates the importance of sponges to energy flow in rocky reef environments

Geodivulgar: Geología y Sociedad

Con el lema “Geología para todos” el proyecto Geodivulgar: Geología y Sociedad apuesta por la divulgación de la Geología a todo tipo de público, incidiendo en la importancia de realizar simultáneamente una acción de integración social entre estudiantes y profesores de centros universitarios, de enseñanza infantil, primaria, de educación especial y un acercamiento con público con diversidad funcional

Interactions between Sponges and the Water Column: Nutrient Utilisation and Feeding by New Zealand Subtidal Sponges

Sponges are an important component of New Zealand subtidal communities and play many key functional roles in marine ecosystems, including competition for space, facilitating primary production, nutrient cycling, bioerosion, and interactions with the water column. Sponges are involved in the bidirectional movement of detritus, nutrients, micro-organisms and planktonic particles both to and from the benthos to the pelagic ecosystem, thereby affecting pelagic processes. As suspension-feeders, sponges are capable of filtering large volumes of water, and they depend on food that is suspended in the water column, meaning that their interaction with the water column is likely to be very important. The main goal of my research was to investigate the interactions between sponges and the water column and how this varies in relation to sponge characteristics, nutrient fluxes, seasonality and food supply. I studied the diet composition of 10 sponge species that are abundant and widely distributed along the south coast of Wellington, New Zealand. I found that the diet of the sponge species analysed comprised three types of picoplanktonic organisms: heterotrophic bacteria, Prochlorococcus, and Synechococcus. These micro-organisms (picoplankton) that sponges feed on are vital for benthic food webs because they are involved in the transformation and cycling process of dissolved inorganic nutrients before they become available to other marine organisms. The results from this thesis demonstrated that different sponge species have different retention efficiencies for different types of picoplankton and I propose that this suggests intra-phyletic food particle niche partitioning among sponges. While these findings support the partitioning of food resources between different co-existing sponge species, they also suggest that partitioning may not be essential for co-existence, as some species had similar retention efficiencies implying an overlap in resource use. By measuring rates of carbon assimilation in the form of planktonic food particles, combined with data on a number of characteristics of the sponge species analysed, I found that sponge assemblages play a key role in the transfer of energy from the water column to the benthos. The results from this thesis indicate that there is a wide range of food concentrations in the rocky reefs where the study species are living, over which retention rate, nutrient utilisation and carbon consumption varied temporally. This emphasises the importance of understanding temporal variation in productivity, and suggests that such variations are likely to have important implications for suspension-feeders. By integrating the feeding results with estimations of oxygen consumption rates, and the amount of carbon obtained from the different micro-organisms found in the water column, preliminary carbon budgets were created. These budgets were used to quantify the capacity of carbon obtained via heterotrophic suspension-feeding to support sponge metabolism, as well as infer the potential for this carbon to support other processes such as sponge growth and reproduction. Overall, this project was the first to consider the functional roles of sponges in New Zealand marine ecosystems and provided useful information on their ecological and biological importance. The large amounts of carbon that sponges transfer from the water column to the benthos, in conjunction with the other findings of my thesis, increase our understanding of the ecology of temperate sponges

Participación de las mujeres en la pesca: nuevos roles de género, ingresos económicos y doble jornada

En el presente artículo describimos los cambios en las relaciones entre hombres y mujeres de una comunidad pesquera en Yucatán a partir del aprovechamiento de un recurso marino por parte de un grupo de mujeres pescadoras que conformaron una sociedad cooperativa. El estudio se enfoca en aspectos como la doble jornada que desempeñan las mujeres durante la temporada de pesca, los obstáculos a los que se han enfrentado y las estrategias que han desarrollado para mantener una actividad productiva considerada tradicionalmente como masculina. El que las mujeres tengan esta actividad representa por un lado, el reto de transgredir espacios de manera productiva a través de su trabajo en la pesca, y por otro, el cuestionar el lugar de hombres y mujeres en la familia, lo que plantea la posibilidad de avanzar en nuevas prácticas que se reconstruyen en la vivencia de la cotidianidad

Estimated mean flow rate, amount of water filtered and picoplanktonic cells removed by the study species over the sampling period.

<p>Flow rate is the volume of water filtered by the sponge considering the total number of oscula from three specimens of each species. Data presented are averages (± StdDev), calculated for three specimens of each sponge species.</p

Carbon consumed by sponges from the picoplanktonic organisms retained in the study area.

<p>Detailed legend: Carbon consumed by sponges (gC d⁻¹) in the area of the Marine Reserve from the three types of picoplanktonic organisms they retain. The graph shows a range of values for sponge percentage cover (0.1, 0.5, 1, 1.5 and 5%) measured at the site, as well as the percentage of POC consumed from the available POC within the MR. The values of the percentage of POC consumed by sponges from the total available in the MR are the numbers next to the black and grey dots.</p

Ranges of retention efficiency for the three types of picoplankton removed by the study species.

<p>Ranges of retention efficiency for the three types of picoplankton removed by the study species.</p

Ranges of ambient cell concentrations.

<p>The cell numbers are for the three types of picoplankton measured in the water surrounding the different study species.</p

Summary of the number of cells filtered by sponge assemblages from each type of picoplankton retained.

<p>Values (number of cells filtered, cells d⁻¹) were calculated using a range of estimated abundances of sponge percentage cover in the study area.</p